Climate modeling question: shouldn’t natural variation create a discrete period of time where we are seeing that the most recent discrete period or month is is not the hottest one on record?
The chart at NOAA shows a steady record where the most recent 12 month period is the hottest such period in the record stretching back to 1880.
If we were looking backward in the global temperature records after feedback loops start to contribute significantly to the global temperature, creating “runaway” global warming, wouldn’t that record look a lot like the one at this NOAA website?
I read a lot of give and take here about the details and possible outliers on significant issues like loss of arctic sea ice (Wadhams) or sea level rise (Hansen et al) and that serves to chase the outliers out of the public policy debate, but I wonder if/when a consensus slice of climate scientists is going to feel compelled to really sound an alarm about the global situation. I see the scientific community as essentially conservative in nature. I don’t mean republican-conservative, I mean risk-taking conservative. A “big” mistake in modeling makes you a fringe scientist like Wadhams. But the conservative consensus view may serve our species and many others very poorly by inadvertently supporting status quo human activity on the planet. As a decent scientist who worked on the Manhattan project put it: “I am become death, the destroyer of worlds.”
How does the current record of hottest periods on record look to the scientists and climate modelers here? Any cause for alarm? Can you wait until you are retired and safe with your pensions in place to sound the alarm?
wilisays
Since we seem to be discussing it, here is the abstract, full title, doi, list of authors, etc, for the Hansen et al. slr article:
Hansen, J., Sato, M., Hearty, P., Ruedy, R., Kelley, M., Masson-Delmotte, V., Russell, G., Tselioudis, G., Cao, J., Rignot, E., Velicogna, I., Kandiano, E., von Schuckmann, K., Kharecha, P., Legrande, A. N., Bauer, M., and Lo, K.-W.: Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming is highly dangerous, Atmos. Chem. Phys. Discuss., 15, 20059-20179, doi:10.5194/acpd-15-20059-2015, 2015.
There is evidence of ice melt, sea level rise to +5–9 m, and extreme storms in the prior interglacial period that was less than 1 °C warmer than today. Human-made climate forcing is stronger and more rapid than paleo forcings, but much can be learned by combining insights from paleoclimate, climate modeling, and on-going observations.
We argue that ice sheets in contact with the ocean are vulnerable to non-linear disintegration in response to ocean warming, and we posit that ice sheet mass loss can be approximated by a doubling time up to sea level rise of at least several meters.
Doubling times of 10, 20 or 40 years yield sea level rise of several meters in 50, 100 or 200 years.
Paleoclimate data reveal that subsurface ocean warming causes ice shelf melt and ice sheet discharge. Our climate model exposes amplifying feedbacks in the Southern Ocean that slow Antarctic bottom water formation and increase ocean temperature near ice shelf grounding lines, while cooling the surface ocean and increasing sea ice cover and water column stability.
Ocean surface cooling, in the North Atlantic as well as the Southern Ocean, increases tropospheric horizontal temperature gradients, eddy kinetic energy and baroclinicity, which drive more powerful storms.
We focus attention on the Southern Ocean’s role in affecting atmospheric CO2 amount, which in turn is a tight control knob on global climate. The millennial (500–2000 year) time scale of deep ocean ventilation affects the time scale for natural CO2 change, thus the time scale for paleo global climate, ice sheet and sea level changes. This millennial carbon cycle time scale should not be misinterpreted as the ice sheet time scale for response to a rapid human-made climate forcing.
Recent ice sheet melt rates have a doubling time near the lower end of the 10–40 year range. We conclude that 2 °C global warming above the preindustrial level, which would spur more ice shelf melt, is highly dangerous. Earth’s energy imbalance, which must be eliminated to stabilize climate, provides a crucial metric.
Whilst we’re on the topic of Arctic sea ice it may interest UK readers to learn that I’ve recently caught a leader writer in the Daily Mail promulgating porkie pies:
If you read the comments you will also note that the leader writer’s duly appointed legal eagle isn’t very good at simple sums.
SecularAnimistsays
To the best of my recollection, I have never heard any climate scientist assert that a 2C increase would be “safe”.
Rather, a 2C increase was presented as a point beyond which additional increases would most certainly NOT be safe.
In any case it is self-evident that the temperature increase that has already resulted from the GHGs we have already emitted is already having dangerous effects, which are already certain to get worse.
The bottom line remains what we have known it to be for two generations:
If we are to have any hope of averting the worst consequences of anthropogenic global warming, we must end all GHG emissions as rapidly as possible AND use organic agriculture and reforestation to sequester carbon in soils and biomass and thereby draw down the already dangerous anthropogenic excess of atmospheric CO2 to preindustrial levels.
Reading with interest all your comments and the nat geo article re: 10ft sea level rise by2100. I don’t think anyone is brave enough to discredit Hansen’s study but as Gavin pointed out it is but one avenue of thinking. We A: do not have enough proxy data, B: we do not yet know where to look for this data, C: we do not know precisely what form this data will take and how this data when collected correlates with all the other mass of raw data out there. As time drags on we get a clearer and clearer idea on how to use this data. James could well be correct, I for one do not doubt his credentials or vision for one second. My first momentary reaction to Gavin’s reply to Hansen’s article was to think Gavin was downplaying Hansen’s hype again, but then rational mind took over and I realised Gavin’s approach was 100% correct. As mentioned above until we have all the relevant data and know how to use it it we will have to put Hansen’s study into careful objective perspective. Now more than ever the CC naysayers are pouncing on every bit of loose innuendo and even half speculations like a cat with a mouse. I personally believe that Hansen is most probably correct. There is clear and irrefutable evidence that the CC process is rapidly accelerating. Our window of opportunity I believe shut permanently decades ago. We have being applying steady and relentless forcing to the climate system since the industrial revolution and now the juggernaut is accelerating downhill. Human ingenuity and money will be next to useless at reversing this trajectory now it’s well underway. I understand this and by what I can perceive so do many RC contributors. Also it does not matter exactly when the actic will be ice free in summer apart from academic games. The fact is it will be ice free in the not to distant future. The ice summer albedo is already at historically low levels so it is doing it’s growing part at warming the arctic ocean. But just for the record this year I’m estimating 1.5 – 1.8 millions sq kms of ice. The currect trajectory in S.I. extent is pretty much the steepest it’s ever been for this time of year.
Vendicar Decarian.says
156 – “Well, duh! Freezing emissions at today’s levels would clearly still mean increasing concentrations”
Most Americans are functionally innumerate. They think in terms of small counts and in terms of less than, equal to and greater than.
This makes them incapable of comprehending relative rates of change.
They will chronically confuse rates with fixed measurements. They confuse deficit and debt. They will conclude that if the deficit goes down, so too must the debt.
They can not understand that you can add to the debt but at the same time it’s value can decline.
Remember, lower taxes produce higher government revenues.
The next crop of Americans are functionally illiterate as well.
You actually ask for a ballpark figure for equilibrium SLR per present ppm rise in CO2.
There have been comments made in this thread that the IPCC underestimate SLR but this is usually specific to the SLR to be expected this century which is nowhere near equilibrium. I think we can have more confidence in the equilibrium SLR from the IPCC.
The relevant AR5 figure is Figure 13.14e which shows that the relationship between SLR and global average temperature rise is 2.3m/ºC with the complication of an extra 6m SLR being added to that total somewhere between 1ºC & 2ºC when Greenland melts out (although it will take some thousands of years to complete that Greenland melt-out).
(Regarding this AR5 Figure 13.14, the missing captions in the linked graphic explain that the individual graphs apply vertically to (if I remember correctly) values for ☻ Thermal expansion, ☻ Glaciers, ☻ Greenland, ☻ Antarctica, ☻ Global total and the two columns for equilibrium SLR and SLR after 2,000 years.)
Using this 2.3M/C & an ECS of 3ºC for a doubling of CO2 concentrations yields (for the present 400ppm CO2) 1.05m SLR (plus Greenland), a result that is rising with present CO2 emissions at something like 8.4mm/ppmCO2 or 17mm/year. (Scaling that Figure 13.14e graphic suggests that the SLR resulting from the Greenland melt-out is ten times more sensitive to temperature and thus to CO2.)
Killiansays
I said this back in February here at RC: “FWIW, this year looking a bit likely now of a lower total than the last two years, but I don’t think reliable guestimates are possible this early on, so…”
I didn’t get around to my ASI analysis the first week of July, but looking at export via Fram and the rapidly falling numbers of late, I’m liking my sceneario should export remain high and the AO negative (Yes, I know, there’s (supposedly) no correlation…).
General observation, I’ve been looking at the “quality” of the ice, and it’s bad. Comparing current year and past years, there is no ice anywhere that looks solidly packed. It’s more like, breath on me, I’ll break. There’s a lot of what I call “popcorn” ice, or what are clearly individual floes within mush or thinner pack, that once it starts to melt/break up transitions immediately to floes within mush or open water.
Feeling pretty good about volume and area lows between new records and 3rd lowest. I think extent is becoming a poor measure of overall quality. Less ice, more space sounds like a prescription for widely scattered floes.
I wonder how many humans will be alive by the end of this century? It’s a morbid thought but assuming we hit 4C GAT and the ice melts way faster than anyone anticipated and polar amplification kicks in, any guesses? Is anyone thinking about this? I don’t see any signs of things slowing down. I really would like a scientifically based worst case scenario…. based on the idea that collectively we’re not going to stop burning FF. Maybe we could start making some plans on how to deal with that eventuality.
Karsten V Johansensays
In their paper “Paleoclimate implications forhuman-made climate change” (2012) James Hansen and Makiko Sato writes on the second-last page (19 in my copy from the internet)”Observations of mass loss from Greenland and Antarctica are too brief for significant conclusions, but they are not inconsistent with a doubling time of a decade or less. The picture will become clearer as the measurement record lengthens.
What constraints or negative feedbacks might limit nonlinear growth of of ice sheet mass loss? (…))”
I wonder if anyone here could give me some hints about recent developments in research about these themes? (If there are any).
Lawrence Colemansays
Has anyone seen David Wasdell’s youtube video Catastophic CC & runawy global warming? I just did, boy!, can anyone here refute the logic of his research? He studies the various types of positive feedback and how it impacts upon the whole. To me it was a very succinct refresher course in Global warming. He puts the timescales into perspective and the terribly little time we have based on numerous double pos feedbacks we have in play at the moment. The part that really caught my attention was the topic of ‘Critical Threshold’ as the point at which no amount of human intervention has any more affect on the process as it is well into tipping territory and oscillation. We have passed the imbalance peak and currently we are in the accelerating stage of runaway GW. Question is exactly where is the ‘critical threshold’? is it still close up ahead..or have we already passed it without knowing?. Logic tell me based on this one simple fact that we have already passed the point of no return; and that is the melting of the methane clathrates in the arctic shallow ocean regions. This will continue to thaw at an accelerating pace for many many decades to come, the ocean CH4 outgassing will be exponential with a few additional pos f/b catastrophic events along the way. This process is already locked in. The tundra has hope as it is based on land temp and as long as we can control the atmospheric CO2 and bring it down to <300ppm then we should be able to stop the release of CO2&CH4 from the permafrost…BUT not the methane clathrates. Based on that haven't be already passed the critical threshold?
James@CANsays
Hello All!
On the subject of visualizations, this one should be spectacular:
“A lake in the North West Territories is about to fall of a cliff”!
Reading the NASA/GISS figures the temperatures seem to have altered, They seem to be higher than they were. Is there a reason for this?
[Response: Oh gosh…. I don’t know. Maybe they have one of those ‘updates‘ pages or something along with some graphs showing what difference the update makes? Nah, it couldn’t be that easy, could it? – gavin]
Lawrence Colemansays
The think the issue with Prof Wadhams, I saw his recent youtube vid is that he is speaking unreservedly, which would help the cause if many other climate scientists took this approach. Ok! we might not reach 0% ice coverage this summer but in the coming short years we surely will. Does Gavin also believe that there is sufficient CO2 in the atmosphere to push us over the 2C threshold – not even withstanding the forcing posed from methane hydrates that revert to CO2 upon gradual oxidisation anyway. I for one can’t hear anything exaggerated in what he had to say, as it followed my understanding of climate mechanics for at least the past 10 years.
If you accept his view that the IPCC has lost it’s bite and is giving a very digested version of the truth (well the ‘truth’ as it was 5 years back). All giving grist for the procrastinatic and self serving nature of world governments and we have a real dilemma. As I have said for years, by the time regional and world leaders are forced to come to the table to act due to a series of catastrophic CC induced disasters, it will be decades too late to do anything about it, the critical threshold will be well behind us and fading into history.
Lawrence Colemansays
186: Digby Skorgie, based on what you say there should be significant and measurable land ice mass loss especially around the perimeter but affecting a larger and larger inland portion of the continent as we go higher in altitude. Question: could this freshwater release from the land be causing the upper few metres of ocean surrounding the continent to freshen and become colder thus quickening and increasing the area of sea ice formation during the Antarctic autumn and winter? The temp anomalies you speak of would surely hasten the spring melt by a factor of weeks.
Research Letter
Modern solar maximum forced late twentieth century Greenland cooling
Authors: T. Kobashi, J.E. Box, B.M. Vinther, K. Goto-Azuma, T. Blunier, J.W.C. White, T. Nakaegawa and C.S. Andresen
First published: 21 July 2015
DOI: 10.1002/2015GL064764
Abstract
The abrupt Northern Hemispheric warming at the end of the twentieth century has been attributed to an enhanced greenhouse effect. Yet Greenland and surrounding subpolar North Atlantic remained anomalously cold in 1970s to early 1990s. Here we reconstructed robust Greenland temperature records (North Greenland Ice Core Project and Greenland Ice Sheet Project 2) over the past 2100 years using argon and nitrogen isotopes in air trapped within ice cores and show that this cold anomaly was part of a recursive pattern of antiphase Greenland temperature responses to solar variability with a possible multidecadal lag. We hypothesize that high solar activity during the modern solar maximum (approximately 1950s–1980s) resulted in a cooling over Greenland and surrounding subpolar North Atlantic through the slowdown of Atlantic Meridional Overturning Circulation with atmospheric feedback processes.
Len Conlysays
Has RealClimate made any comments about this article by the Russian physicist Dr. Helen Popova of Lomonosov Moscow State University?
“There is no strong evidence, that global warming is caused by human activity. The study of deuterium in the Antarctic showed that there were five global warmings and four Ice Ages for the past 400 thousand years. People first appeared on the Earth about 60 thousand years ago. However, even if human activities influence the climate, we can say, that the Sun with the new minimum gives humanity more time or a second chance to reduce their industrial emissions and to prepare, when the Sun will return to normal activity”, Dr Helen Popova summarized.
Diminishing solar activity may bring new Ice Age by 2030
[Response: It’s the same paper as the Zharkova claim – it ignores all other forcings except orbital and solar (which they often confuse), and they do no climate science at all. Ignore it. – gavin]
I don’t think RC has ever staked out some kind of ‘official position’ on the 2C limit
It’s not “safe safe safe safe safe 2C bad bad bad bad …”
Somewhere I read the observation that limits become targets — people have this stupidity about going right up to any perceived edge and hanging their toes over the precipice instead of staying safely several paces back from the place where the ground has been breaking off and falling.
Anyway, your explanation for the greater area of sea ice is what I’ve read elsewhere. It also means warmer water pushed down under the ice sheets and glacier tongues, thereby accelerating their melting. (I hope I’ve interpreted this correctly.) The paradox is that there’s more sea ice around the continent, but the place is getting hotter.
#193, 196–Thanks for not saying I was wrong, Zachary, but I rather think I was, all the same.
Remembering this discussion from 2009, I conflated Eric Steig with Eric Rignot, both of whom figured (the former as moderator, the latter as lead author of the research discussed):
“Would it be possible to have an article or two based on a worst case situation, rather than continuing to pretend it won’t happen? Thanks”
I would be very interested in reading those articles too. The IPCC insists on telling us what they are sure about, but what we need to know are the dangers that we are facing viz. the worst case scenarios.
I am sure this has been said before, but we don’t take out fire insurance based on the certainty of that our house burning down. In fact if we did it would be criminal offence – arson. We insure our house for its full cost hopng it will never happen. What would be fhe full cost if we were to be struck by an abrupt climate change?
Say a methane release in the Arctic that removes all the Arctic sea ice?
Edward Greischsays
212 Chuck Hughes: Worst case total number of humans in 2100: Somewhere between zero and 100,000. GW isn’t the only problem. Overpopulation to 2.5 times carrying capacity already is problem 2.
CH 212: I wonder how many humans will be alive by the end of this century?
BPL: I expect the worst die-off in human history. After agriculture fails, starving people will be vulnerable to plagues, and I expect various governments to try to take over each other’s land by military conquest. Eight countries _that we know of_ have nuclear weapons.
I sincerely hope I’m wrong. But the very high population we have now depends on a globally connected infrastructure that is about to collapse.
At a rough guess, 3.5 billion people will die in a period of about ten years, say 2040-2050. If the natural decrease rate after that averages 1%, we’ll be down to 2.1 billion by 2100. If it averages 5%, we’ll be down to 280 million or so.
Down in the comments for that YouTube video Chuck Hughes links to:
PlanetEarth Trimtab 6 days ago
NASA agrees with Paul about Arctic Methane. Here is some shocking new evidence of a possible 4-6C temperature rise by 2050 because of melting Arctic permafrost & release of methane: That’s only 35 years from now, folks “According to a NASA research report, “Is a Sleeping Climate Giant Stirring in the Arctic?”
Although that’s attributed to NASA, the source given is the Huffington Post
I gave up on HuffPo long ago when they got deeply into the antivax wackywoo.
Grains of salt, feathers in the wind, etc., so I’m not exactly breaking out the bubbly to celebrate the victory of sanity in CO2 mitigation. (Which would be mildly ironic anyway, given the CO2 content of champagne, however immaculately bio-sourced it might be.)
However, it does seem fair to call it a sign “of things slowing down.”
You say that “Logic tell me based on this one simple fact that we have already passed the point of no return; and that is the melting of the methane clathrates in the arctic shallow ocean regions”
What evidence have you seen (other than speculation) that methane clathrate is melting in the shallow regions of the Arctic Ocean?
Julius Tweezersays
Another question about sea-level rise: How much needs to occur to make it so obvious to anyone living near a coast line that it will effectively end this “climate debate” nonsense, and how soon might that happen? That may be what it takes for government (the US anyway) to start doing anything meaningful about it.
See Section: 7.3 Ice sheet mass loss and sea level rise, where they among other things say: “Ice mass losses from Greenland, West Antarctica and Totten/Aurora basin in East Antarctica are growing nonlinearly with doubling times of order 10 years. Continued exponential growth at that rate seems unlikely for Greenland…”
Note that this paper not yet peer-reviewed, but published in an “interactive public discussion” journal for open peer-review.
I am not aware of anyone else who is exploring the potential for exponential ice sheet loss seriously. It is controversial and hard to prove scientifically.
Digby Scorgiesays
Oops! Regarding 225, I should’ve said “ice shelves”, not “ice sheets”. As I understand it, the ice lost from the Antarctic ice sheet forms an upper layer of fresh water surrounding the continent. Being fresh, it freezes more readily than the saltier ocean waters, resulting in the increase in sea ice we see. At the same time the warmer, saltier water undermines the ice shelves and glacier tongues from below. Please correct me, anybody, if I’ve got something wrong.
wilisays
Kevin at 231, the recent numbers out of China on coal consumption may be _some_ kind of sign of _something_, but they might not be a reliable indicator of actual coal consumption or actual CO2 emissions levels recently in China:
“…Case in point: back in the late 1990s, China announced it was shuttering a bunch of smaller, illegal coal mines, and early estimates suggested that nationwide coal use dropped 20 percent in 1998.
But it turned out that those coal mines didn’t actually close, they just stopped reporting their numbers to the government. When BP reviewed the data years later, it turned out that China’s coal use hadn’t dropped at all in 1998…
Similarly, in its most recent five-year census, China revised upward its estimate for coal use in 2013 by about 8 percent.
That’s a massive edit.”
Lawrence Colemansays
233: Julius, the CC and sea level rise rates put it in the boiling frog analogy category – you know, put a frog in boiling water and he will immediately jump out, but increase the heat slowly and he’ll just sit there happily until he is slow cooked. The crazy thing is the time for CO2 to have reached 400ppm from the pre-industrial is geologically speaking in the blink of an eye (or being dropped into boiling water). I don’t personally think anyone would notice if one day all New Yorkers took canoes to go to work. Sad…but true. If only people would listen to the climate scientists…sigh!
Lawrence Colemansays
229 B.P.L. Read you comment with thought, aren’t you going by the usual boom/bust scenario for populations of anything?. Considering that humans can feed themselves and to a varying extents live outside the usual natural environmental conditions. Indeed the sheer crush of human poplulation has got to give sooner than later and there will be a collapse but I would say only down to sustainable levels again. 1.5-2billion.
Tony Weddlesays
Well, David Archer seems to think (PDF) that the Hansen paper has done a great job. Perhaps we can expect a Real Climate article about it, soon?
I’d think the issue already ‘obvious’ to some–though, unfortunately, not the governor of Florida. (Though I suppose you could argue that his attempts to ban the use of the words “climate change” by state officials is testament that impacts are indeed becoming obvious to others.)
The sun was shining, but all around the inlet people were bracing for more serious flooding. The Chrysler Museum of Art had just completed a $24 million renovation that emptied the basement, now accessible only by ladder, and lifted the heating and air-conditioning systems to the top floor. A local accounting firm stood behind a homemade barricade of stanchions and detachable flaps rigged to keep the water out. And the congregation of the Unitarian Church of Norfolk was looking to evacuate.
“We don’t like being the poster child for climate change,” said the Rev. Jennifer Slade, who added that the building, with its carved-wood sanctuary and soaring flood-insurance rates, would soon be on the market for the first time in four decades. “I don’t know many churches that have to put the tide chart on their Web site” so people know whether they can get to church.
Ironically enough, even the DOD has trouble dealing with the GOP on this issue:
At Naval Station Norfolk, sea-level rise prompted a decision in the late 1990s to raise the station’s 12 piers, said Joe Bouchard, base commander at the time. Construction has since been completed on only four, he said, adding that work was halted in 2008, when the recession hit, the federal budget deficit soared and Congress began frantically slashing spending.
“That’s when Washington went bonkers,” said Bouchard, an expert on the national security implications of climate change. “That’s spelled B-O-N-K-E-R-S, if you want to quote me.”
Ric Merrittsays
About looking for “signs of things slowing down”: the first sign I would consider an truly significant step would be a clear downward bend in the Keeling curve. Steps before that, however necessary, are best classed as preparatory.
Tony Weddlesays
New Scientist has an article about how surface temperature is now at the 1C limit that Hansen et al (2013) showed is the dangerous limit, whilst the 2C limit is “foolhardy”.
Chuck Hughessays
Barton Paul Levenson:
July 28th, 2015 at 5:56 AM
CH 212: I wonder how many humans will be alive by the end of this century?
BPL: I expect the worst die-off in human history. After agriculture fails, starving people will be vulnerable to plagues, and I expect various governments to try to take over each other’s land by military conquest. Eight countries _that we know of_ have nuclear weapons.
I sincerely hope I’m wrong. But the very high population we have now depends on a globally connected infrastructure that is about to collapse.
At a rough guess, 3.5 billion people will die in a period of about ten years, say 2040-2050. If the natural decrease rate after that averages 1%, we’ll be down to 2.1 billion by 2100. If it averages 5%, we’ll be down to 280 million or so.
BPL, I don’t doubt what you’re saying but do you have a method for coming up with those numbers or is it just a best guess estimate?
I think we should have some sort of plan for that eventuality. I don’t know what the plan would be but in cases where people are in hospice they tend to put their lives in order as best they can. As someone who spends a lot of time with young people I can tell you that they have NO IDEA about what lies ahead or what they can do about it. Going around telling people we’re screwed doesn’t work, as Gavin has pointed out. I do think a sober, realistic assessment detailing a “worst case scenario” would be helpful. Were it a tornado you would send people to the nearest shelter. I understand the population will drop and there’s probably nothing that can be done about that. However, mass panic in any situation always makes things worse. I guess what I’m saying falls under the category of mitigation which is OT. I just think that scientists may be keeping a lot of their personal thoughts to themselves simply because articulating it would be counter productive. If so, I disagree. I would like to hear their unvarnished opinions….. based on what they KNOW.
Richard Caldwellsays
233 Julius T asked, “How much needs to occur to make it so obvious to anyone living near a coast line that it will effectively end this “climate debate” nonsense, and how soon might that happen?”
Sea level rise is very slow, and small as compared to tides. Arctic sea ice melt is fast and very visible. That’s what will “end the ‘debate'”. We’re certainly in the last decade of the foolishness.
Richard Caldwellsays
229 Barton PL said, “At a rough guess, 3.5 billion people will die in a period of about ten years, say 2040-2050”
You’re forgetting geoengineering. It is surely probable that if global warming gets so bad that half of humanity is about to die we’ll stop global warming in its tracks with things such as brimstoning the stratosphere. Are you saying that such techniques are probably going to kill off half of us? Or that we’ll simply die off gracefully without attempting to save ourselves?
That geoengineering is distasteful is surely not a reason to pretend it doesn’t exist. I’ve never heard anything bad about geoengineering except that it’s not 100% safe and would encourage people to continue to burn dinosaurs. Please enlighten me by telling me what is PROVEN FATAL TO HALF OF HUMANITY about geoengineering.
Personally, I think global warming is easily stopped, but with minor/major disruptions in weather patterns, along with other side effects such as turning the sky green and reduced sunlight, affecting crops and other plants. Ocean acidification, on the other hand, is not stoppable without stopping CO2 emissions.
Enlighten me.
Edward Greischsays
Chuck Hughes and BPL: Look at rabbits vs foxes or lynxes graphs in a population biology book. The curves are similar to sine waves slightly out of synch. The foxes always follow the rabbits. The sine waves are not necessary pure sine waves. They can be distorted. They never stop at a reasonable number of either foxes or rabbits. They go way up and then way down, almost to zero. Sometimes a population does get to zero. There is a minimum number that has to survive to avoid zero. If there are too few, an extinction happens.
The rabbits eat everything that rabbits can eat, depleting their food supply or just getting too crowded to live. Then the foxes do the same, eating rabbits. You would think a treaty between the foxes and rabbits could stabilize both of their populations at a medium level, but it never happens.
Likewise, the human population will not stabilize at 3 billion without forcing by somebody more ruthless than Hitler. The population grows until there is no food in the grocery store. People eat everything they can, making most edible species extinct. Endangered species are hunted to extinction because there is no law in a collapsed civilization. Humans are hunted as food. When everything edible is gone, people die, skinny people first. The fat one gets to be on the top of the pile of corpses in the street.
A friend of mine participated in the Hungarian Revolution of 1956. When it was over, there was no food in the grocery stores, so my friend went out of Budapest to go squirrel hunting. There were no squirrels. There will be no penguins, no birds, no fish, no animals in the woods, no leaves on trees and so on.
You need to find a population biologist to teach a course on this.
Lawrence Colemansays
235 Digby Scorgie(got it right this time, apologies for that): Thanks for the reply. I’ve always been fascinated by the thermodynamics at the poles. Did you notice in 1970 any soot deposits already on the pristine landscape? They always say that the decadal ice mass loss in the Arctic is significantly higher than the Antarctic and whilst that may be true, the Antarctic ice albedo is increasing in line with the growing winter sea ice area. This has to be an important CC negative feedback in the scheme of things. While the arctic albedo is sinking to it’s lowest in millennia the Antarctic could be making up for this shortfall..but only in winter. I’m assuming the warm circum polar currents are only going to get warmer in time and rapidly erode the base of the ice shelfs and accelerate the glacial outflow to the ocean widening the seaice even further. It will be interesting to see how this will pan out.
The thing is, in previous crashes, there were always surrounding areas for people to go to. This one will be worldwide. We’re not just killing our agricultural base. We’re killing all the forests and all the oceans. This will be a crash like no other.
Lawrence Colemansays
242: Chuck Hughes, liked your comment to B.P.L. Still I don’t know what use a ‘closet’ scientist can be to anyone, if you have the knowledge then it’s your duty to convey it to whom it may concern.
We are in uncharted waters here, even paleo-climatic knowledge while better than nothing cannot prepare us for the types of changes ahead and the rates of change. If B.P.L is factoring in a M.A.D. scenario then he might be right, but other than that as I said earlier, humans can create their own food and shelter (ok the wealthier ones) and so we are not as vunerable to a natural bust condition as most other species.
I expect Barton will respond to your question, Chuck, but in the meantime I can give you a short answer. Barton’s scenario is based upon the work he’s done (and published, albeit he’s not happy with the journal in question)on drought statistics. He sees drought increasing to fatal levels over the next couple of decades. As famine increases, so does political and military conflict, possibly up to nuclear exchanges. Economic and technological collapse follow.
FWIW, I think that is a realistic possibility, but not the leading probability. Barton is far more able than I at the stats, and I’d bet heavily on his honesty and integrity, so I’m taking that piece as valid, as far as it goes. But drought metrics still constitute a tangled question per AR 5, and extrapolation can only get you so far. I suspect that a much more granular approach to the question is needed to really come to grips with our hydrological future.
I also think that we’re going to see meaningful mitigation, though perhaps not truly sufficient mitigation. And it’s already too late for some things–I suspect the Arctic sea ice may come under that heading, which implies large but not well-understood circulatory changes.
As far as population goes, much of the OECD has declining populations now–or would, were it not for immigration inflows, as in, notably, the US. Much of Latin America is getting down toward replacement levels, too; China actually faces population decreases in her not-too-far-distant future as the ‘one child’ generation ages and birth rates stay low; even India’s birth rate is half what it was in 1960 (lower than then-OECD rates.) The biggest proportion of population growth over coming decades is going to be Africa, based upon current trends and demographic structure:
At the same time, Africa in general has a nasty combination of high climate change impacts and low capacity to adapt, based on both economics and political characteristics. I’m not sure how those dynamics (or some recent positive trends) will play out. And “Africa” is extremely inhomogenous geographically and otherwise, which means that that point above about ‘granularity’ comes into play. But I expect there will be an awful lot of ‘churn’ in that region, even more than elsewhere.
(Though if I had to name one nation that is the scariest for me in thinking about future climate change and political unrest, it’d probably be Pakistan.)
Climate modeling question: shouldn’t natural variation create a discrete period of time where we are seeing that the most recent discrete period or month is is not the hottest one on record?
http://www.ncdc.noaa.gov/sotc/global/201506
The chart at NOAA shows a steady record where the most recent 12 month period is the hottest such period in the record stretching back to 1880.
If we were looking backward in the global temperature records after feedback loops start to contribute significantly to the global temperature, creating “runaway” global warming, wouldn’t that record look a lot like the one at this NOAA website?
I read a lot of give and take here about the details and possible outliers on significant issues like loss of arctic sea ice (Wadhams) or sea level rise (Hansen et al) and that serves to chase the outliers out of the public policy debate, but I wonder if/when a consensus slice of climate scientists is going to feel compelled to really sound an alarm about the global situation. I see the scientific community as essentially conservative in nature. I don’t mean republican-conservative, I mean risk-taking conservative. A “big” mistake in modeling makes you a fringe scientist like Wadhams. But the conservative consensus view may serve our species and many others very poorly by inadvertently supporting status quo human activity on the planet. As a decent scientist who worked on the Manhattan project put it: “I am become death, the destroyer of worlds.”
How does the current record of hottest periods on record look to the scientists and climate modelers here? Any cause for alarm? Can you wait until you are retired and safe with your pensions in place to sound the alarm?
Since we seem to be discussing it, here is the abstract, full title, doi, list of authors, etc, for the Hansen et al. slr article:
Hansen, J., Sato, M., Hearty, P., Ruedy, R., Kelley, M., Masson-Delmotte, V., Russell, G., Tselioudis, G., Cao, J., Rignot, E., Velicogna, I., Kandiano, E., von Schuckmann, K., Kharecha, P., Legrande, A. N., Bauer, M., and Lo, K.-W.: Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming is highly dangerous, Atmos. Chem. Phys. Discuss., 15, 20059-20179, doi:10.5194/acpd-15-20059-2015, 2015.
http://www.atmos-chem-phys-discuss.net/15/20059/2015/acpd-15-20059-2015.html
Abstract [my paragraph breaks].
There is evidence of ice melt, sea level rise to +5–9 m, and extreme storms in the prior interglacial period that was less than 1 °C warmer than today. Human-made climate forcing is stronger and more rapid than paleo forcings, but much can be learned by combining insights from paleoclimate, climate modeling, and on-going observations.
We argue that ice sheets in contact with the ocean are vulnerable to non-linear disintegration in response to ocean warming, and we posit that ice sheet mass loss can be approximated by a doubling time up to sea level rise of at least several meters.
Doubling times of 10, 20 or 40 years yield sea level rise of several meters in 50, 100 or 200 years.
Paleoclimate data reveal that subsurface ocean warming causes ice shelf melt and ice sheet discharge. Our climate model exposes amplifying feedbacks in the Southern Ocean that slow Antarctic bottom water formation and increase ocean temperature near ice shelf grounding lines, while cooling the surface ocean and increasing sea ice cover and water column stability.
Ocean surface cooling, in the North Atlantic as well as the Southern Ocean, increases tropospheric horizontal temperature gradients, eddy kinetic energy and baroclinicity, which drive more powerful storms.
We focus attention on the Southern Ocean’s role in affecting atmospheric CO2 amount, which in turn is a tight control knob on global climate. The millennial (500–2000 year) time scale of deep ocean ventilation affects the time scale for natural CO2 change, thus the time scale for paleo global climate, ice sheet and sea level changes. This millennial carbon cycle time scale should not be misinterpreted as the ice sheet time scale for response to a rapid human-made climate forcing.
Recent ice sheet melt rates have a doubling time near the lower end of the 10–40 year range. We conclude that 2 °C global warming above the preindustrial level, which would spur more ice shelf melt, is highly dangerous. Earth’s energy imbalance, which must be eliminated to stabilize climate, provides a crucial metric.
Whilst we’re on the topic of Arctic sea ice it may interest UK readers to learn that I’ve recently caught a leader writer in the Daily Mail promulgating porkie pies:
An Inconvenient Truth About The Mail’s Climate Coverage
If you read the comments you will also note that the leader writer’s duly appointed legal eagle isn’t very good at simple sums.
To the best of my recollection, I have never heard any climate scientist assert that a 2C increase would be “safe”.
Rather, a 2C increase was presented as a point beyond which additional increases would most certainly NOT be safe.
In any case it is self-evident that the temperature increase that has already resulted from the GHGs we have already emitted is already having dangerous effects, which are already certain to get worse.
The bottom line remains what we have known it to be for two generations:
If we are to have any hope of averting the worst consequences of anthropogenic global warming, we must end all GHG emissions as rapidly as possible AND use organic agriculture and reforestation to sequester carbon in soils and biomass and thereby draw down the already dangerous anthropogenic excess of atmospheric CO2 to preindustrial levels.
The peer reviewed paper by Hansen, Sato, et al is now out and available at: http://www.atmos-chem-phys-discuss.net/15/20059/2015/acpd-15-20059-2015.pdf
Hansen et al paper now online…
http://www.atmos-chem-phys-discuss.net/15/20059/2015/acpd-15-20059-2015.pdf
Reading with interest all your comments and the nat geo article re: 10ft sea level rise by2100. I don’t think anyone is brave enough to discredit Hansen’s study but as Gavin pointed out it is but one avenue of thinking. We A: do not have enough proxy data, B: we do not yet know where to look for this data, C: we do not know precisely what form this data will take and how this data when collected correlates with all the other mass of raw data out there. As time drags on we get a clearer and clearer idea on how to use this data. James could well be correct, I for one do not doubt his credentials or vision for one second. My first momentary reaction to Gavin’s reply to Hansen’s article was to think Gavin was downplaying Hansen’s hype again, but then rational mind took over and I realised Gavin’s approach was 100% correct. As mentioned above until we have all the relevant data and know how to use it it we will have to put Hansen’s study into careful objective perspective. Now more than ever the CC naysayers are pouncing on every bit of loose innuendo and even half speculations like a cat with a mouse. I personally believe that Hansen is most probably correct. There is clear and irrefutable evidence that the CC process is rapidly accelerating. Our window of opportunity I believe shut permanently decades ago. We have being applying steady and relentless forcing to the climate system since the industrial revolution and now the juggernaut is accelerating downhill. Human ingenuity and money will be next to useless at reversing this trajectory now it’s well underway. I understand this and by what I can perceive so do many RC contributors. Also it does not matter exactly when the actic will be ice free in summer apart from academic games. The fact is it will be ice free in the not to distant future. The ice summer albedo is already at historically low levels so it is doing it’s growing part at warming the arctic ocean. But just for the record this year I’m estimating 1.5 – 1.8 millions sq kms of ice. The currect trajectory in S.I. extent is pretty much the steepest it’s ever been for this time of year.
156 – “Well, duh! Freezing emissions at today’s levels would clearly still mean increasing concentrations”
Most Americans are functionally innumerate. They think in terms of small counts and in terms of less than, equal to and greater than.
This makes them incapable of comprehending relative rates of change.
They will chronically confuse rates with fixed measurements. They confuse deficit and debt. They will conclude that if the deficit goes down, so too must the debt.
They can not understand that you can add to the debt but at the same time it’s value can decline.
Remember, lower taxes produce higher government revenues.
The next crop of Americans are functionally illiterate as well.
Guest @145.
You actually ask for a ballpark figure for equilibrium SLR per present ppm rise in CO2.
There have been comments made in this thread that the IPCC underestimate SLR but this is usually specific to the SLR to be expected this century which is nowhere near equilibrium. I think we can have more confidence in the equilibrium SLR from the IPCC.
The relevant AR5 figure is Figure 13.14e which shows that the relationship between SLR and global average temperature rise is 2.3m/ºC with the complication of an extra 6m SLR being added to that total somewhere between 1ºC & 2ºC when Greenland melts out (although it will take some thousands of years to complete that Greenland melt-out).
(Regarding this AR5 Figure 13.14, the missing captions in the linked graphic explain that the individual graphs apply vertically to (if I remember correctly) values for ☻ Thermal expansion, ☻ Glaciers, ☻ Greenland, ☻ Antarctica, ☻ Global total and the two columns for equilibrium SLR and SLR after 2,000 years.)
Using this 2.3M/C & an ECS of 3ºC for a doubling of CO2 concentrations yields (for the present 400ppm CO2) 1.05m SLR (plus Greenland), a result that is rising with present CO2 emissions at something like 8.4mm/ppmCO2 or 17mm/year. (Scaling that Figure 13.14e graphic suggests that the SLR resulting from the Greenland melt-out is ten times more sensitive to temperature and thus to CO2.)
I said this back in February here at RC: “FWIW, this year looking a bit likely now of a lower total than the last two years, but I don’t think reliable guestimates are possible this early on, so…”
I didn’t get around to my ASI analysis the first week of July, but looking at export via Fram and the rapidly falling numbers of late, I’m liking my sceneario should export remain high and the AO negative (Yes, I know, there’s (supposedly) no correlation…).
This is looking scary: http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn/nowcast/ictn2015072318_2015072400_040_arcticictn.001.gif
General observation, I’ve been looking at the “quality” of the ice, and it’s bad. Comparing current year and past years, there is no ice anywhere that looks solidly packed. It’s more like, breath on me, I’ll break. There’s a lot of what I call “popcorn” ice, or what are clearly individual floes within mush or thinner pack, that once it starts to melt/break up transitions immediately to floes within mush or open water.
Feeling pretty good about volume and area lows between new records and 3rd lowest. I think extent is becoming a poor measure of overall quality. Less ice, more space sounds like a prescription for widely scattered floes.
rs now has a nice summary of the Hansen et al. paper on his blog: http://robertscribbler.com/2015/07/24/warning-from-scientists-halt-fossil-fuel-burning-fast-or-age-of-superstorms-3-20-feet-of-sea-level-rise-is-coming-soon/#comment-45698
I wonder how many humans will be alive by the end of this century? It’s a morbid thought but assuming we hit 4C GAT and the ice melts way faster than anyone anticipated and polar amplification kicks in, any guesses? Is anyone thinking about this? I don’t see any signs of things slowing down. I really would like a scientifically based worst case scenario…. based on the idea that collectively we’re not going to stop burning FF. Maybe we could start making some plans on how to deal with that eventuality.
In their paper “Paleoclimate implications forhuman-made climate change” (2012) James Hansen and Makiko Sato writes on the second-last page (19 in my copy from the internet)”Observations of mass loss from Greenland and Antarctica are too brief for significant conclusions, but they are not inconsistent with a doubling time of a decade or less. The picture will become clearer as the measurement record lengthens.
What constraints or negative feedbacks might limit nonlinear growth of of ice sheet mass loss? (…))”
I wonder if anyone here could give me some hints about recent developments in research about these themes? (If there are any).
Has anyone seen David Wasdell’s youtube video Catastophic CC & runawy global warming? I just did, boy!, can anyone here refute the logic of his research? He studies the various types of positive feedback and how it impacts upon the whole. To me it was a very succinct refresher course in Global warming. He puts the timescales into perspective and the terribly little time we have based on numerous double pos feedbacks we have in play at the moment. The part that really caught my attention was the topic of ‘Critical Threshold’ as the point at which no amount of human intervention has any more affect on the process as it is well into tipping territory and oscillation. We have passed the imbalance peak and currently we are in the accelerating stage of runaway GW. Question is exactly where is the ‘critical threshold’? is it still close up ahead..or have we already passed it without knowing?. Logic tell me based on this one simple fact that we have already passed the point of no return; and that is the melting of the methane clathrates in the arctic shallow ocean regions. This will continue to thaw at an accelerating pace for many many decades to come, the ocean CH4 outgassing will be exponential with a few additional pos f/b catastrophic events along the way. This process is already locked in. The tundra has hope as it is based on land temp and as long as we can control the atmospheric CO2 and bring it down to <300ppm then we should be able to stop the release of CO2&CH4 from the permafrost…BUT not the methane clathrates. Based on that haven't be already passed the critical threshold?
Hello All!
On the subject of visualizations, this one should be spectacular:
“A lake in the North West Territories is about to fall of a cliff”!
http://www.theglobeandmail.com/news/national/a-lake-in-the-northwest-territories-is-about-to-fall-off-a-cliff/article25628207/
As always, thanks to everyone for sharing your research and your ideas.
Sincerely… James in Canada.
Expect the unexpected when you least expect it:
https://www.youtube.com/watch?t=431&v=1-gcu4IMXmE
Reading the NASA/GISS figures the temperatures seem to have altered, They seem to be higher than they were. Is there a reason for this?
[Response: Oh gosh…. I don’t know. Maybe they have one of those ‘updates‘ pages or something along with some graphs showing what difference the update makes? Nah, it couldn’t be that easy, could it? – gavin]
The think the issue with Prof Wadhams, I saw his recent youtube vid is that he is speaking unreservedly, which would help the cause if many other climate scientists took this approach. Ok! we might not reach 0% ice coverage this summer but in the coming short years we surely will. Does Gavin also believe that there is sufficient CO2 in the atmosphere to push us over the 2C threshold – not even withstanding the forcing posed from methane hydrates that revert to CO2 upon gradual oxidisation anyway. I for one can’t hear anything exaggerated in what he had to say, as it followed my understanding of climate mechanics for at least the past 10 years.
If you accept his view that the IPCC has lost it’s bite and is giving a very digested version of the truth (well the ‘truth’ as it was 5 years back). All giving grist for the procrastinatic and self serving nature of world governments and we have a real dilemma. As I have said for years, by the time regional and world leaders are forced to come to the table to act due to a series of catastrophic CC induced disasters, it will be decades too late to do anything about it, the critical threshold will be well behind us and fading into history.
186: Digby Skorgie, based on what you say there should be significant and measurable land ice mass loss especially around the perimeter but affecting a larger and larger inland portion of the continent as we go higher in altitude. Question: could this freshwater release from the land be causing the upper few metres of ocean surrounding the continent to freshen and become colder thus quickening and increasing the area of sea ice formation during the Antarctic autumn and winter? The temp anomalies you speak of would surely hasten the spring melt by a factor of weeks.
Slowdown of ocean circulation:
Has RealClimate made any comments about this article by the Russian physicist Dr. Helen Popova of Lomonosov Moscow State University?
“There is no strong evidence, that global warming is caused by human activity. The study of deuterium in the Antarctic showed that there were five global warmings and four Ice Ages for the past 400 thousand years. People first appeared on the Earth about 60 thousand years ago. However, even if human activities influence the climate, we can say, that the Sun with the new minimum gives humanity more time or a second chance to reduce their industrial emissions and to prepare, when the Sun will return to normal activity”, Dr Helen Popova summarized.
Diminishing solar activity may bring new Ice Age by 2030
Lomonosov Moscow State University Press Release
http://astronomynow.com/2015/07/17/diminishing-solar-activity-may-bring-new-ice-age-by-2030/
[Response: It’s the same paper as the Zharkova claim – it ignores all other forcings except orbital and solar (which they often confuse), and they do no climate science at all. Ignore it. – gavin]
It’s not “safe safe safe safe safe 2C bad bad bad bad …”
Somewhere I read the observation that limits become targets — people have this stupidity about going right up to any perceived edge and hanging their toes over the precipice instead of staying safely several paces back from the place where the ground has been breaking off and falling.
http://lowres.jantoo.com/transportation-garages-car_crashes-traffic_accidents-car_accidents-accident-07641529_low.jpg
My realclimate unforced variations is not updating. Is this a problem with my computer??? Or are the moderators frustrated? Thanks
http://retractionwatch.com/2015/07/22/second-correction-for-controversial-paper-on-economic-gains-of-climate-change/
Just noted for reference. Eli is on the case.
219. Lawrence Coleman
Please, mate, it’s Scorgie, not Skorgie!
Anyway, your explanation for the greater area of sea ice is what I’ve read elsewhere. It also means warmer water pushed down under the ice sheets and glacier tongues, thereby accelerating their melting. (I hope I’ve interpreted this correctly.) The paradox is that there’s more sea ice around the continent, but the place is getting hotter.
#193, 196–Thanks for not saying I was wrong, Zachary, but I rather think I was, all the same.
Remembering this discussion from 2009, I conflated Eric Steig with Eric Rignot, both of whom figured (the former as moderator, the latter as lead author of the research discussed):
https://www.realclimate.org/index.php/archives/2009/11/is-pine-island-glacier-the-weak-underbelly-of-the-west-antarctic-ice-sheet/
Mea culpa.
Chuck Hughes asked in #200
“Would it be possible to have an article or two based on a worst case situation, rather than continuing to pretend it won’t happen? Thanks”
I would be very interested in reading those articles too. The IPCC insists on telling us what they are sure about, but what we need to know are the dangers that we are facing viz. the worst case scenarios.
I am sure this has been said before, but we don’t take out fire insurance based on the certainty of that our house burning down. In fact if we did it would be criminal offence – arson. We insure our house for its full cost hopng it will never happen. What would be fhe full cost if we were to be struck by an abrupt climate change?
Say a methane release in the Arctic that removes all the Arctic sea ice?
212 Chuck Hughes: Worst case total number of humans in 2100: Somewhere between zero and 100,000. GW isn’t the only problem. Overpopulation to 2.5 times carrying capacity already is problem 2.
CH 212: I wonder how many humans will be alive by the end of this century?
BPL: I expect the worst die-off in human history. After agriculture fails, starving people will be vulnerable to plagues, and I expect various governments to try to take over each other’s land by military conquest. Eight countries _that we know of_ have nuclear weapons.
I sincerely hope I’m wrong. But the very high population we have now depends on a globally connected infrastructure that is about to collapse.
At a rough guess, 3.5 billion people will die in a period of about ten years, say 2040-2050. If the natural decrease rate after that averages 1%, we’ll be down to 2.1 billion by 2100. If it averages 5%, we’ll be down to 280 million or so.
Down in the comments for that YouTube video Chuck Hughes links to:
Although that’s attributed to NASA, the source given is the Huffington Post
I gave up on HuffPo long ago when they got deeply into the antivax wackywoo.
“I don’t see any signs of things slowing down.”
https://www.realclimate.org/index.php/archives/2015/07/unforced-variations-july-2015/comment-page-5/#comment-634055
Well, there’s this:
http://www.bloomberg.com/news/articles/2015-03-13/china-s-carbon-emissions-drop-for-the-first-time-since-2001
Grains of salt, feathers in the wind, etc., so I’m not exactly breaking out the bubbly to celebrate the victory of sanity in CO2 mitigation. (Which would be mildly ironic anyway, given the CO2 content of champagne, however immaculately bio-sourced it might be.)
However, it does seem fair to call it a sign “of things slowing down.”
Lawrence,
You say that “Logic tell me based on this one simple fact that we have already passed the point of no return; and that is the melting of the methane clathrates in the arctic shallow ocean regions”
What evidence have you seen (other than speculation) that methane clathrate is melting in the shallow regions of the Arctic Ocean?
Another question about sea-level rise: How much needs to occur to make it so obvious to anyone living near a coast line that it will effectively end this “climate debate” nonsense, and how soon might that happen? That may be what it takes for government (the US anyway) to start doing anything meaningful about it.
Karsten V Johansen @213,
I think what your are looking for regarding the latest update on the case for exponential ice-sheet loss is to be found in Hansen et al:s recent paper which is currently under review in ACP:
http://www.atmos-chem-phys-discuss.net/15/20059/2015/acpd-15-20059-2015.pdf
See Section: 7.3 Ice sheet mass loss and sea level rise, where they among other things say: “Ice mass losses from Greenland, West Antarctica and Totten/Aurora basin in East Antarctica are growing nonlinearly with doubling times of order 10 years. Continued exponential growth at that rate seems unlikely for Greenland…”
Note that this paper not yet peer-reviewed, but published in an “interactive public discussion” journal for open peer-review.
I am not aware of anyone else who is exploring the potential for exponential ice sheet loss seriously. It is controversial and hard to prove scientifically.
Oops! Regarding 225, I should’ve said “ice shelves”, not “ice sheets”. As I understand it, the ice lost from the Antarctic ice sheet forms an upper layer of fresh water surrounding the continent. Being fresh, it freezes more readily than the saltier ocean waters, resulting in the increase in sea ice we see. At the same time the warmer, saltier water undermines the ice shelves and glacier tongues from below. Please correct me, anybody, if I’ve got something wrong.
Kevin at 231, the recent numbers out of China on coal consumption may be _some_ kind of sign of _something_, but they might not be a reliable indicator of actual coal consumption or actual CO2 emissions levels recently in China:
http://www.vox.com/2015/5/22/8645455/china-emissions-coal-drop
“Be very, very wary of China’s energy statistics”
“…Case in point: back in the late 1990s, China announced it was shuttering a bunch of smaller, illegal coal mines, and early estimates suggested that nationwide coal use dropped 20 percent in 1998.
But it turned out that those coal mines didn’t actually close, they just stopped reporting their numbers to the government. When BP reviewed the data years later, it turned out that China’s coal use hadn’t dropped at all in 1998…
Similarly, in its most recent five-year census, China revised upward its estimate for coal use in 2013 by about 8 percent.
That’s a massive edit.”
233: Julius, the CC and sea level rise rates put it in the boiling frog analogy category – you know, put a frog in boiling water and he will immediately jump out, but increase the heat slowly and he’ll just sit there happily until he is slow cooked. The crazy thing is the time for CO2 to have reached 400ppm from the pre-industrial is geologically speaking in the blink of an eye (or being dropped into boiling water). I don’t personally think anyone would notice if one day all New Yorkers took canoes to go to work. Sad…but true. If only people would listen to the climate scientists…sigh!
229 B.P.L. Read you comment with thought, aren’t you going by the usual boom/bust scenario for populations of anything?. Considering that humans can feed themselves and to a varying extents live outside the usual natural environmental conditions. Indeed the sheer crush of human poplulation has got to give sooner than later and there will be a collapse but I would say only down to sustainable levels again. 1.5-2billion.
Well, David Archer seems to think (PDF) that the Hansen paper has done a great job. Perhaps we can expect a Real Climate article about it, soon?
#233, Julius–IMO, there are a couple of incipient instances. For one, I wrote a bit about ‘sunny day flooding’ in Miami in this summary:
http://doc-snow.hubpages.com/hub/How-Do-We-Know-That-Climate-Change-Will-Be-Mostly-Bad
I’d think the issue already ‘obvious’ to some–though, unfortunately, not the governor of Florida. (Though I suppose you could argue that his attempts to ban the use of the words “climate change” by state officials is testament that impacts are indeed becoming obvious to others.)
I think the same applies to Norfolk, VA:
http://www.washingtonpost.com/business/economy/in-norfolk-evidence-of-climate-change-is-in-the-streets-at-high-tide/2014/05/31/fe3ae860-e71f-11e3-8f90-73e071f3d637_story.html
Ironically enough, even the DOD has trouble dealing with the GOP on this issue:
About looking for “signs of things slowing down”: the first sign I would consider an truly significant step would be a clear downward bend in the Keeling curve. Steps before that, however necessary, are best classed as preparatory.
New Scientist has an article about how surface temperature is now at the 1C limit that Hansen et al (2013) showed is the dangerous limit, whilst the 2C limit is “foolhardy”.
Barton Paul Levenson:
July 28th, 2015 at 5:56 AM
CH 212: I wonder how many humans will be alive by the end of this century?
BPL: I expect the worst die-off in human history. After agriculture fails, starving people will be vulnerable to plagues, and I expect various governments to try to take over each other’s land by military conquest. Eight countries _that we know of_ have nuclear weapons.
I sincerely hope I’m wrong. But the very high population we have now depends on a globally connected infrastructure that is about to collapse.
At a rough guess, 3.5 billion people will die in a period of about ten years, say 2040-2050. If the natural decrease rate after that averages 1%, we’ll be down to 2.1 billion by 2100. If it averages 5%, we’ll be down to 280 million or so.
BPL, I don’t doubt what you’re saying but do you have a method for coming up with those numbers or is it just a best guess estimate?
I think we should have some sort of plan for that eventuality. I don’t know what the plan would be but in cases where people are in hospice they tend to put their lives in order as best they can. As someone who spends a lot of time with young people I can tell you that they have NO IDEA about what lies ahead or what they can do about it. Going around telling people we’re screwed doesn’t work, as Gavin has pointed out. I do think a sober, realistic assessment detailing a “worst case scenario” would be helpful. Were it a tornado you would send people to the nearest shelter. I understand the population will drop and there’s probably nothing that can be done about that. However, mass panic in any situation always makes things worse. I guess what I’m saying falls under the category of mitigation which is OT. I just think that scientists may be keeping a lot of their personal thoughts to themselves simply because articulating it would be counter productive. If so, I disagree. I would like to hear their unvarnished opinions….. based on what they KNOW.
233 Julius T asked, “How much needs to occur to make it so obvious to anyone living near a coast line that it will effectively end this “climate debate” nonsense, and how soon might that happen?”
Sea level rise is very slow, and small as compared to tides. Arctic sea ice melt is fast and very visible. That’s what will “end the ‘debate'”. We’re certainly in the last decade of the foolishness.
229 Barton PL said, “At a rough guess, 3.5 billion people will die in a period of about ten years, say 2040-2050”
You’re forgetting geoengineering. It is surely probable that if global warming gets so bad that half of humanity is about to die we’ll stop global warming in its tracks with things such as brimstoning the stratosphere. Are you saying that such techniques are probably going to kill off half of us? Or that we’ll simply die off gracefully without attempting to save ourselves?
That geoengineering is distasteful is surely not a reason to pretend it doesn’t exist. I’ve never heard anything bad about geoengineering except that it’s not 100% safe and would encourage people to continue to burn dinosaurs. Please enlighten me by telling me what is PROVEN FATAL TO HALF OF HUMANITY about geoengineering.
Personally, I think global warming is easily stopped, but with minor/major disruptions in weather patterns, along with other side effects such as turning the sky green and reduced sunlight, affecting crops and other plants. Ocean acidification, on the other hand, is not stoppable without stopping CO2 emissions.
Enlighten me.
Chuck Hughes and BPL: Look at rabbits vs foxes or lynxes graphs in a population biology book. The curves are similar to sine waves slightly out of synch. The foxes always follow the rabbits. The sine waves are not necessary pure sine waves. They can be distorted. They never stop at a reasonable number of either foxes or rabbits. They go way up and then way down, almost to zero. Sometimes a population does get to zero. There is a minimum number that has to survive to avoid zero. If there are too few, an extinction happens.
The rabbits eat everything that rabbits can eat, depleting their food supply or just getting too crowded to live. Then the foxes do the same, eating rabbits. You would think a treaty between the foxes and rabbits could stabilize both of their populations at a medium level, but it never happens.
Likewise, the human population will not stabilize at 3 billion without forcing by somebody more ruthless than Hitler. The population grows until there is no food in the grocery store. People eat everything they can, making most edible species extinct. Endangered species are hunted to extinction because there is no law in a collapsed civilization. Humans are hunted as food. When everything edible is gone, people die, skinny people first. The fat one gets to be on the top of the pile of corpses in the street.
A friend of mine participated in the Hungarian Revolution of 1956. When it was over, there was no food in the grocery stores, so my friend went out of Budapest to go squirrel hunting. There were no squirrels. There will be no penguins, no birds, no fish, no animals in the woods, no leaves on trees and so on.
You need to find a population biologist to teach a course on this.
235 Digby Scorgie(got it right this time, apologies for that): Thanks for the reply. I’ve always been fascinated by the thermodynamics at the poles. Did you notice in 1970 any soot deposits already on the pristine landscape? They always say that the decadal ice mass loss in the Arctic is significantly higher than the Antarctic and whilst that may be true, the Antarctic ice albedo is increasing in line with the growing winter sea ice area. This has to be an important CC negative feedback in the scheme of things. While the arctic albedo is sinking to it’s lowest in millennia the Antarctic could be making up for this shortfall..but only in winter. I’m assuming the warm circum polar currents are only going to get warmer in time and rapidly erode the base of the ice shelfs and accelerate the glacial outflow to the ocean widening the seaice even further. It will be interesting to see how this will pan out.
The thing is, in previous crashes, there were always surrounding areas for people to go to. This one will be worldwide. We’re not just killing our agricultural base. We’re killing all the forests and all the oceans. This will be a crash like no other.
242: Chuck Hughes, liked your comment to B.P.L. Still I don’t know what use a ‘closet’ scientist can be to anyone, if you have the knowledge then it’s your duty to convey it to whom it may concern.
We are in uncharted waters here, even paleo-climatic knowledge while better than nothing cannot prepare us for the types of changes ahead and the rates of change. If B.P.L is factoring in a M.A.D. scenario then he might be right, but other than that as I said earlier, humans can create their own food and shelter (ok the wealthier ones) and so we are not as vunerable to a natural bust condition as most other species.
#24r, Chuck–
I expect Barton will respond to your question, Chuck, but in the meantime I can give you a short answer. Barton’s scenario is based upon the work he’s done (and published, albeit he’s not happy with the journal in question)on drought statistics. He sees drought increasing to fatal levels over the next couple of decades. As famine increases, so does political and military conflict, possibly up to nuclear exchanges. Economic and technological collapse follow.
FWIW, I think that is a realistic possibility, but not the leading probability. Barton is far more able than I at the stats, and I’d bet heavily on his honesty and integrity, so I’m taking that piece as valid, as far as it goes. But drought metrics still constitute a tangled question per AR 5, and extrapolation can only get you so far. I suspect that a much more granular approach to the question is needed to really come to grips with our hydrological future.
I also think that we’re going to see meaningful mitigation, though perhaps not truly sufficient mitigation. And it’s already too late for some things–I suspect the Arctic sea ice may come under that heading, which implies large but not well-understood circulatory changes.
As far as population goes, much of the OECD has declining populations now–or would, were it not for immigration inflows, as in, notably, the US. Much of Latin America is getting down toward replacement levels, too; China actually faces population decreases in her not-too-far-distant future as the ‘one child’ generation ages and birth rates stay low; even India’s birth rate is half what it was in 1960 (lower than then-OECD rates.) The biggest proportion of population growth over coming decades is going to be Africa, based upon current trends and demographic structure:
http://www.indexmundi.com/facts/indicators/SP.DYN.CBRT.IN/compare?country=in#country=in:zj:oe:zg
At the same time, Africa in general has a nasty combination of high climate change impacts and low capacity to adapt, based on both economics and political characteristics. I’m not sure how those dynamics (or some recent positive trends) will play out. And “Africa” is extremely inhomogenous geographically and otherwise, which means that that point above about ‘granularity’ comes into play. But I expect there will be an awful lot of ‘churn’ in that region, even more than elsewhere.
(Though if I had to name one nation that is the scariest for me in thinking about future climate change and political unrest, it’d probably be Pakistan.)