The time has come: the new IPCC report is here! After several years of work by over 800 scientists from around the world, and after days of extensive discussion at the IPCC plenary meeting in Stockholm, the Summary for Policymakers was formally adopted at 5 o’clock this morning. Congratulations to all the colleagues who were there and worked night shifts. The full text of the report will be available online beginning of next week. Realclimate summarizes the key findings and shows the most interesting graphs.
Update 29 Sept: Full (un-copyedited) report available here.
Global warming
It is now considered even more certain (> 95%) that human influence has been the dominant cause of the observed warming since the mid-20th century. Natural internal variability and natural external forcings (eg the sun) have contributed virtually nothing to the warming since 1950 – the share of these factors was narrowed down by IPCC to ± 0.1 degrees. The measured temperature evolution is shown in the following graph.
Figure 1 The measured global temperature curve from several data sets. Top: annual values. Bottom: averaged values over a decade.
Those who have these data before their eyes can recognise immediately how misguided the big media attention for the “wiggles” of the curves towards the end has been. Short-term variations like this have always existed, and they always will. These are mostly random, they are (at least so far) not predictable, and the IPCC has never claimed to be able to make predictions for short periods of 10-15 years, precisely because these are dominated by such natural variations.
The last 30 years were probably the warmest since at least 1,400 years. This is a result from improved proxy data. In the 3rd IPCC report this could only be said about the last thousand years, in the 4th about the last 1,300 years.
The future warming by 2100 – with comparable emission scenarios – is about the same as in the previous report. For the highest scenario, the best-estimate warming by 2100 is still 4 °C (see the following chart).
Figure 2 The future temperature development in the highest emissions scenario (red) and in a scenario with successful climate mitigation (blue) – the “4-degree world” and the “2-degree world.”
What is new is that IPCC has also studied climate mitigation scenarios. The blue RCP2.6 is such a scenario with strong emissions reduction. With this scenario global warming can be stopped below 2 ° C.
A large part of the warming will be irreversible: from the point where emissions have dropped to zero, global temperature will remain almost constant for centuries at the elevated level reached by that time. (This is why the climate problem in my opinion is a classic case for the precautionary principle.)
Sea-level rise
Sea levels are rising faster now than in the previous two millennia, and the rise will continue to accelerate – regardless of the emissions scenario, even with strong climate mitigation. (This is due to the inertia in the system.) The new IPCC scenarios to 2100 are shown the following graph.
Figure 3 Rise of the global sea level until the year 2100, depending on the emissions scenario.
This is perhaps the biggest change over the 4th IPCC report: a much more rapid sea-level rise is now projected (28-98 cm by 2100). This is more than 50% higher than the old projections (18-59 cm) when comparing the same emission scenarios and time periods.
With unabated emissions (and not only for the highest scenario), the IPCC estimates that by the year 2300 global sea levels will rise by 1-3 meters. [Correction: the document actually says: “1 m to more than 3 m”]
Already, there are likely more frequent storm surges as a result of sea level rise, and for the future this becomes very likely.
Land and sea ice
Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent.
The Greenland ice sheet is less stable than expected in the last report. In the Eemian (the last interglacial period 120,000 years ago, when the global temperature was higher by 1-2 °C) global sea level was 5-10 meters higher than today (in the 4th IPCC report this was thought to be just 4-6 meters). Due to better data very high confidence is assigned to this. Since a total loss of the Greenland ice sheet corresponds to a 7 meters rise in sea level, this may indicate ice loss from Antarctica in the Eemian.
In the new IPCC report the critical temperature limit at which a total loss of the Greenland ice sheet will occur is estimated as 1 to 4°C of warming above preindustrial temperature. In the previous report that was still 1.9 to 4.6 °C – and that was one of the reasons why international climate policy has agreed to limit global warming to below 2 degrees.
With unabated emissions (RCP8.5) the Arctic Ocean will likely become virtually ice-free in summer before the middle of the century (see figure). In the last report, this was not expected until near the end of the century.
Figure 4 The ice cover on the Arctic Ocean in the 2-degree world (left) and the 4-degree world (right).
Rainfall
The IPCC expects that dry areas become drier due to global warming, and moist areas even wetter. Extreme rainfall has likely already been increasing in North America and Europe (elsewhere the data are not so good). Future extreme precipitation events are very likely to become more intense and more frequent over most land areas of the humid tropics and mid-latitudes.
Oceans
At high emissions (red scenario above), the IPCC expects a weakening of the Atlantic Ocean circulation (commonly known as the Gulf Stream system) by 12% to 54% by the end of the century.
Last but not least, our CO2 emissions not only cause climate change, but also an increase in the CO2 concentration in sea water, and the oceans acidify due to the carbonic acid that forms. This is shown by the measured data in the graph below.
Figure 5 Measured CO2 concentration and pH in seawater. Low pH means higher acidity.
Conclusion
The new IPCC report gives no reason for complacency – even if politically motivated “climate skeptics” have tried to give this impression ahead of its release with frantic PR activities. Many wrong things have been written which now collapse in the light of the actual report.
The opposite is true. Many developments are now considered to be more urgent than in the fourth IPCC report, released in 2007. That the IPCC often needs to correct itself “upward” is an illustration of the fact that it tends to produce very cautious and conservative statements, due to its consensus structure – the IPCC statements form a kind of lowest common denominator on which many researchers can agree. The New York Times has given some examples for the IPCC “bending over backward to be scientifically conservative”. Despite or perhaps even because of this conservatism, IPCC reports are extremely valuable – as long as one is aware of it.
Update & Correction (28 Sept): The upper value of the sea-level range is 98 cm, not 97 cm – I overlooked the fact that IPCC corrected this between the final draft and the approved version of the SPM.
Some media wrongly report a rise of “only” up to 82 cm by the year 2100. That is a misunderstanding: 82 cm is the average for the period 2081-2100, not the level reached in 2100. Both the curves up to 2100 and those 20-year averages are shown in Fig. 3 above. Note that the additional rise of up to 16 cm in the final decade illustrates the horrendous rates of rise we can get by the end of the century with unmitigated emissions.
It is also worth noting that the 98 cm is the upper value of a “likely” range (66% probability to be within that range). As IPCC also notes, we could end up “several tens of centimeters” higher if the marine-based parts of the Antarctic ice sheet become unstable. Leading ice experts, like Richard Alley and Rob De Conto, consider this a serious risk.
Further Commentary:
Mike Mann: Climate-Change Deniers Must Stop Distorting the Evidence
Stefan Rahmstorf: The Known Knowns of Climate Change
Re: my #46 (also discussed at #95,92,58, 55,);
More about the BBC from
To-day’s Guardian
[My comment; I’m sure that many people in RC could add some flesh to these bones when it comes to the BBC’s choice of ‘expert’ Bob Carter and his contributions to the subject]
Lauri @~96
This about says it all:
“like playing your favorite game on your smartphone. It is the ingenuity of the humankind that creates more efficient ways of accomplishing the same things with less resources.”
The nothingness signification of the human race is reaching its endgame.
The toxic materials that go into creating electronic devices which are “thrown away” faster and faster is indeed a toxic endgame. If playing a game on a smartphone is an end in itself, there is nothing in our futures.
MARodger @95,
I should think that almost the entire UK cabinet is in denial about climate change, not just one member. This is the same in every major nation on earth. If this were not true, we’d see a lot stronger advocacy for effective mitigation strategies. Indeed, any country with a largely non-denialist cabinet would already be enacting such strategies. Or maybe some countries would be doing that if they didn’t realise that any effective mitigation strategy also ensures economic contraction and a need for massive investment in alternative living arrangements at the same time – which is impossible.
Oh well, we can dream.
deconvoluter @92.
I note that while BBC Radio 4 managed a good job on the AR5 release fist thing in the morning, by lunchtime they had lost the plot.
The World at One (BBCi) featured the AR5 launch as its top story but the main man was Bob Carter. In 6 of the 11 minutes used he told the audience that the IPCC didn’t do real science but the NIPCC did and came to the opposite conclusions. 95%? It’s all natural. NIPCC is mainly self-funded. No govt money, industry or green lobby groups. Some money from a “libertarian thinktank”. And what should be done over AGW? Paraphrased .We need to improve emergency responses & adapt to climate. “No government tries to predict or stop an earthquake or volcanic erruption. No sensible govt would dream of trying to “stop climate change.” It is a ludicrous idea.”
Despite preceding comment from the Energy Secretary Ed Davey and 4 minutes with Peter Stott, Carter did dominate the story. Stott was bogged down in responding to ‘the pause’ and Himalayan glaciers when he should have been directly responding to Carter’s nonsense. I can see how this story spiraled out of control but the BBC is rightly be criticised.
This is not the forum for an extended discussion, but Lauri, #96, says “The predictions of the “Limits of growth” have already proven misleading.”
Lauri, needless to say, cites no page number or specific prediction. There is a considerable literature lately about this. It’s not hard to find: type “limits” into Wikipedia and auto-complete will already offer the article. Recent work of Ugo Bardi is on topic.
#105
Check out this.
http://en.wikipedia.org/wiki/The_Limits_to_Growth
Pretty easy to find.
Top Climate Scientists Assess Latest Report from U.N. Panel
Yale Environment 360 asked some leading climate scientists to discuss what they consider to be the most noteworthy or surprising findings in the recently released report of the Intergovernmental Panel on Climate Change’s working group on the physical science of a warming world.
#105-6 and previous related comments:
A reductio of infinite growth:
http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-energy/
Also apposite is the following post in the series.
Hi guys, is there any conditions to be met to be accepted as a translated version of a RealClimate article? We’ve made a Portuguese version of this article, and if applicable, would it be possible to have a link on the title pointing to it? (it’s also been sent to RealClimate by email)
Anyway, thanks for your great work keeping this website.
Economic contraction? I find it hard to see how massive investment in infrastructure and in living arrangements amounts to an economic contraction. These sorts of activities are expensive, but they also employ lots, and lots, of people. It does mean a huge change in economic activities, but power infrastructure, public transport, retrofitting most and rebuilding some housing provide a huge economic boost to the areas in which they’re undertaken. And a flow-on effect to other areas because of the boost in economic activity generally.
I can see that some people wouldn’t like it much if we did some things like rationing (or denying) power for gigantic electronic billboards and other things we’re used to that use power (or water) for purposes that are deemed wasteful or counter-productive. Many businesses and employees don’t like it when buggy-whips, typewriters, asbestos products, whalebone corsets, and spittoons are superseded or rejected by technical or social improvements, but that’s been the way of the world for a good while now.
As I see it, building renewable power generation and retro-fitting existing buildings for greater efficiency is a great driver for an economy re-focusing on what is really important. And I don’t see the economic “contraction” you’re so fearful about.
The experts weigh in on the new IPCC SLR projections:
Aslak Grinsted:
http://www.glaciology.net/Home/Miscellaneous-Debris/comparisonofsealevelprojections
http://www.glaciology.net/Home/Miscellaneous-Debris/optimisticicesheetprojectionsinar5
Anders Levermann:
http://e360.yale.edu/feature/yale_e360_forum_on_ipcc_report_2013/2698/
Would be interesting to hear Stefan Rahmstorf and Martin Vermeer weigh in too.
Lauri @ 96,
“This is easy. Economic growth is no longer equal to increased use of physical resources. More and more of economic activity is due to immaterial services, like playing your favorite game on your smartphone. It is the ingenuity of the humankind that creates more efficient ways of accomplishing the same things with less resources. The predictions of the “Limits of growth” have already proven misleading.”
Surely you jest! Either that, or you have very little understanding of some very basic physics.
Susan Anderson’s points apply in spades and here’s my two cents. You obviously don’t understand ‘Limits to Growth’!
Here’s is presentation tiltled: ‘Growth has an Expiration Date’ by Tom Murphy Associate Professor of Physics UCSD.
http://fora.tv/2011/10/26/Growth_Has_an_Expiration_Date
Or you can read his blog post at Do The Math
http://physics.ucsd.edu/do-the-math/2011/11/growth-has-an-expiration-date/
Hint, your example of immaterial services, such as playing games on smartphones is anything but immaterial… Do you have any idea how much energy it takes to power the internet?!
And do you suppose smartphones are just poofed into existence by some form of magic?!
Tony Weddle wrote: “… any effective mitigation strategy also ensures economic contraction …”
The transfer of trillions of dollars in wealth and investment from the fossil fuel corporations to other sectors of the industrial economy is not “economic contraction”.
The reality is that continued business-as-usual use of fossil fuels will lead inevitably to global economic collapse, whereas renewable energy technologies are the basis for the New Industrial Revolution of the 21st Century, which can provide sustainable, equitable prosperity for everyone.
Suggestion for Gavin, these links Fred Magyar reminds us of above (thank you) have been mentioned before; they might merit a place in your right sidebar list of reliable sources.
secular animist said:
“The reality is that continued business-as-usual use of fossil fuels will lead inevitably to global economic collapse, whereas renewable energy technologies are the basis for the New Industrial Revolution of the 21st Century, which can provide sustainable, equitable prosperity for everyone.”
Problem is too many “everyone”s, so poor and dirty, and annoying.
Mightn’t we should just let natural selection run a few stretches of disaster to reduce the carrying load, wash away the residue, pretty up the sea shores? Then we can look around for new things to do with all that room and resource, shared out among those important enough to survive. Petroleum dollars can buy a lot of security and insulation from risk (e.g. Paraguayan mountain valley).
We should consider that the underlying cause of climate change is the relentless pursuit of economic growth in a 90% fossil-fueled economy. Economic growth entails increasing consumption of resources and greenhouse gas emissions which lead to the loss of ecosystems that the economy itself depends on. If we’re serious about stabilizing climate, we have to get serious about the steady state economy as the sustainable alternative to growth.
Read Supply Shock: Economic Growth at the Crossroads and the Steady State Solution.
See supplyshock.org
Tony Weddle’s post @103 illustrates the sort of economic fallacy foisted on us by the U. of Chicago, fun-with Hayek (Friedrich, not Salma)crowd–to wit that funds spent on infrastructure of by the ebil gummint somehow disappear from the economy into a black hole.
It is true that the multiplier for the efficacy of these funds may vary depending on their target, but I’ll take funds spent on NASA over those spent on advertising any day. Likewise as SA and others have pointed out, we are talking about replacing the entire energy infrastructure of the freakin’ planet. We are bound to learn something interesting as a result of that, and I would bet it will be of commercial as well as academic interest. Isn’t $41.3 billion per Koch bro enough? Let’s direct some money toward ensuring the survival of our progeny.
Fred: “Do you have any idea how much energy it takes to power the internet?!”
As an illustration, some researchers recently calculated that some US $500K/day of electricity is being stolen by malefactors in pursuit of ill-gotten gains of about US $2K/day via Bitcoin mining using compromised computers, by the particular subset of malware under scrutiny.
That’s just one little organism in the Internet jungle.
Re the comment from deconvoluter comment #104 that I should have been “directly responding to Carter’s nonsense” that would have been a bit difficult since I hadn’t heard what he’d said. According to the BBC producer they were unable to play me the clip of what he had said, as I recall, due to a technical problem. Instead, in that interview, I did make clear the very robust, rigorous and comprehensive nature of the IPCC report and rather than concentrating on Himalayan glaciers or the pause I described the important conclusion coming from the assessment that there is 95% certainty that human influence on climate is the dominant cause of the warming observed since the mid 20th century.
Re #118 “Bitcoin mining ” The rise of digital currency like Bitcoin, and carbon footprints
The new (2013 introduced) ASIC architecture is roughly 60 times more energy efficient than one of the best GPU’s. Hence, ASIC miners are used today to farm Bitoin, powered with the USB port.
Perwis #111,
Seems that Levermann essentially agrees with Grinsted (to which I gave one link earlier).
Though, reading his contribution one wonders if trusting the creativity of the reader (of the IPCC report) was such a great idea…
Peter Stott @119.
The comment @104 was me, not deconvoluter. It was apparent that you were but responding to the BBC’s questions and not to ‘Carter’s nonsense’ which never got the slightest mention during your piece. And I failed to mention but you did indeed begin by describing the standing and the importance of the IPCC report. My point @104 was that it was the BBC questioning that ‘bogged you down’. About half your interview (as transmitted) was taken up with ‘pause’ and Himalayas.
I am surprised to learn that Carter had been interviewed before you and BBC technical problems prevented you hearing what he had said. And it’s even more surprising your interviewer did not put to you something of the accusations made by Carter about AR5 & IPCC. I had assumed the BBC’s decision to interview/include Carter at least had the excuse of being rushed. It appears no such excuse can be made.
Fred Magyar @112, and others,
I wrote on a lightly tone but not completely in jest. One example of the studies I thought exist is “Growth in global materials use, GDP and population during the 20th century by Fridolin Krausmann et al., Ecological Economics 68 (2009) 2696–2705.” They write in the conclusions:
“… In the past century, materials use grew at a smaller rate than GDP, and material productivity continuously improved at an average rate of 1% per year. By the centennial perspective, it is evident that relative dematerialization is a standard feature of economic development.”
Don’t get me wrong: I completely agree that the current level of resource use in unsustainable. And the dematerialization is too slow, in comparison. (Sorry I don’t have the citation, but) the favorable decrease of CO2 emissions per GDP has slowed down in the recent years, and it has been argued that the reason is the increased share of global GDP growth in less developed economies where energy efficiency is lower.
Please remember that the discussion started from a statement that how can the IPCC predict continuous economic growth over the 21st century (because we will run out of resources). I don’t see any problem in that prediction. With more severe resource depletion, resource prices will increase and the economic growth will transform itself.
MARodger @122
Apologies for misattributing you.
John Ashton gave a very interesting talk to the Royal Society on Thursday in which he suggested that climate scientists needed to better understand the terrain on which they were being drawn to in the climate struggle between reality based and ideology based world views. John Ashton has already called out the issue with the framing of this World at One item in his Guardian piece but the extra additional twist in the uneven terrain here is that the BBC did not play me what Carter had said.
115–“Mightn’t we should just let natural selection run a few stretches of disaster to reduce the carrying load, wash away the residue, pretty up the sea shores? Then we can look around for new things to do with all that room and resource, shared out among those important enough to survive. Petroleum dollars can buy a lot of security and insulation from risk (e.g. Paraguayan mountain valley).”
Please tell me this was a sarcastic and heartless joke.
CASSE3:
I’m pretty sure the majority of RCers are on board with that. The problem is that the “we” reading and commenting on this blog are a tiny subset of the “we” that has to get serious about transitioning to a steady-state economy. That’s a political problem, obviously, thus better discussed elsewhere. Nobody here needs reminding, though, that wonga on the scale of Ray’s “$41.3 billion per Koch bro” buys a lot of political inertia.
What Is to Be Done? I don’t know, but clearly nothing that’s been tried so far.
Peter Stott referred to John Ashton, which led me to some interesting (and to me, believe it or not, soothing – it’s been that kind of day) material. I see Gavin Schmidt was also at that Royal Society event.
http://royalsociety.org/events/2013/climatescience-next-steps/
http://www.e3g.org/people/john-ashton
This is a tremendous indictment of the BBC program:
http://www.theguardian.com/commentisfree/2013/oct/01/bbc-betrayed-values-carter-scorn-ipcc
I didn’t find the Royal Society talk, but I did find this:
http://www.e3g.org/docs/Speech_by_John_Ashton_September_2013.pdf
a “top climate diplomat” indeed. There is a lot of passionate and gorgeous language that expresses much that I worry about but which may be perceived as excessively metaphysical and a tad optimistic in these difficult times. But beautiful use of English is always welcome.
—
Lauri, my apologies for overreacting. It’s such a minefield, or to mix metaphors, walking on the razor’s edge of the need for limits versus expediency in communication with people who find those limits unacceptable.
Kevin McKinney, I don’t think that was straight-up humor, I think it was intended to express outrage (and perhaps frustration at our powerlessness to prevent misuse of precious human and other resrouces as this all plays out), fwiw. Our generation and onwards have learned to use black humor for relief when things get dark.
I copy below my email to Fox News, responding to their “Wall Street Journal Report” of this Sunday.
“Two points made in your 10/6 coverage of the IPCC report were unacceptably distorted: 1) Mr. Gogot’s citation of the “no warming in 15 years” meme; & 2) his guest’s assertion implying that the sole basis for believing that warming may prove highly problematic is the (now presumably challenged) models. Last first, for well over a decade, the stronger basis for believing in mid- to high range sensitivities (natural amplification of direct, spectroscopic CO2 warmth) is not in fact from modeling, but rather from growing paleoclimatic evidence. While technically not a factual error, Mr. Gigot ought think about the following detail. Using global data from the Hadley Center, the coolest five years in the past century and a half, were centered upon 1907, @ 59 hundredths F. below mean. Ninety years later, the five years centered upon 1997 registered as: 72, 54, 76, 106, & 61 hundredths F. warmer than mean. Tens of millions of observations are super-compressed into each of these two-digit summaries. They average +74 hundredths F., which yields a rate of warming across the bulk of the last century of 1.5 hundredths F. per year (+74 – -59 = 133/90 = 1.48). The most current similar interval centers upon 2010: 81, 103, 115, 94, & 97, which averages 98 hundredths F. Since 98 exceeds the 1997 five-year average by 24 hundredths, this 13 year interval’s warming rate was 1.85 hundredths F. per year, or a 25% INCREASE in the rate which prevailed from 1907 through 1997. Note that that 1998 value of 106 exceeds the 1996 value by 52 hundredths F., or 35 years worth of warmth, at the gradual rate of average warming of our world (1.5 hundredths per year). One can deceive an audience through selecting, without their awareness, the single most extreme outlier in the entire instrumental record, to assert that there has been “no warming in 15 years,” but one cannot inform.”
#128–Thanks, Susan. I was likely in a bad mood myself when responding… black humor, indeed. Been re-reading “Six Degrees” and the Technical Summary of AR5, and am disheartened by the way AR5 has been dropped from the news cycle.
Mal Adapted wrote: “The problem is that the ‘we’ reading and commenting on this blog are a tiny subset of the ‘we’ that has to get serious about transitioning to a steady-state economy.”
For one thing, each and every one of “we” can vote with each and every dollar we spend (or DON’T spend) for the transition to a steady-state economy, by purchasing only goods and services that are produced by sustainable, steady-state means (and those of us in the rich countries, especially the USA, can learn to live well and happily with less consumption).
And we can also, of course, lobby the government to enact policies that enable and facilitate sustainable practices and discourage unsustainable practices.
And we can also, of course, refrain from reproducing.
If enough of us do that, the steady-state economy will arise from within the growth-oriented economy.
“Whatever you do may seem insignificant, but it is most important that you do it.” — M.K. Gandhi
SA:
Uhmm, which “us” are you thinking of? Are you saying that there are enough RC readers to bring about the steady-state economy by voluntary action? That would suggest that you don’t regard AGW and other external costs of growth as a Tragedy of the Commons.
If the “us” you’re thinking of is the global (or even just the U.S) consumer population, the question remains “So why don’t enough of us do that?”
Again, further discussion is probably off-topic at RC.
wanted to tap the authors and readers thoughts on why this supposed ‘hiatus’is given importance – a question that climate negotiators i was told were found asking through 2012-13: if we are not certain of how short term temperature rises will play out would it be correct to hinge the 2015 agreement on a two degree rise cap or a carbon threshold cap? what is the ultimate goal and how does one find a formula that is equituous in terms of carbon space for all while giving a temperature cap instead of an emission cap in an agreement.
upon which i make a small observation. as a journalist in a developing world (India), I speak to both negotiators/policymakers and scientists: the former pick on the rhetorical and political significance of the lines in IPCC reports(which can easily deviate from the facts underlying the lines picked) while the scientists too often do not realise the way terms are used in the negotiating and geo-political arena.
Nitin Sethi (#133) asked authors and readers: “would it be correct to hinge the 2015 agreement on a two degree rise cap or a carbon threshold cap?”
This is a WG3 (yet to be published) topic.
But it dosn’t take a very subtle understanding to realize both these approaches would lead nowhere. The 2 degrees cap is of course a joke (as you say, we are not certain how temperatures will play out) but even the seemingly more reasonable carbon cap would likely achieve nothing in practice.
That’s because no one can possibly be held responsible for adherring to some kind of global cap. Everyone will simply point fingers at others.
It is my view that enforceable agreements prescribe specific policies with a view to holding specific persons responsible for enacting and enforcing them.
If governments commit to long-term goals without committing to timetables and specific ways to achieve these goals, they will be sorely tempted to stick to window-dressing and to let the next government deal with the real problems.