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What ocean heating reveals about global warming

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The heat content of the oceans is growing and growing.  That means that the greenhouse effect has not taken a pause and the cold sun is not noticeably slowing global warming.

NOAA posts regularly updated measurements of the amount of heat stored in the bulk of the oceans.  For the upper 2000 m (deeper than that not much happens) it looks like this:

heat_content2000m

Change in the heat content in the upper 2000 m of the world’s oceans. Source: NOAA


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AGU Chapman Conference on Climate Science Communication

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A couple of weeks ago, there was a small conference on Climate Science communication run by the AGU. Both Mike and I attended, but it was very notable that it wasn’t just scientists attending – there were also entertainers, psychologists, film-makers and historians. There were a lot of quite diverse perspectives and many discussions about the what’s, why’s and how’s of climate science communication.

There were a couple of notable features: the conference had a lively twitter hashtag (#climatechapman), and almost the entire proceedings were webcast live (schedule). The video from this has now been posted on YouTube in more bite-sized chunks.

While our own presentations (Mike here and Gavin here) are available, it is worth watching the presentations from people you might not have heard of, as well as a few from more established people. We’ll embed a few here, but please point out some of the other ones of interest in the comments.
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A new experiment with science publication

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A while ago, I received a request to publish a paper on a post that I had written here on RealClimate, exposing the flaws in the analysis of Humlum et al., (2011).

Instead of writing a comment to one paper, however, I thought it might be useful to collect a sample of papers that I found unconvincing (usual suspects), and that have had a fairly high public profile.

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References

  1. O. Humlum, J. Solheim, and K. Stordahl, "Identifying natural contributions to late Holocene climate change", Global and Planetary Change, vol. 79, pp. 145-156, 2011. http://dx.doi.org/10.1016/j.gloplacha.2011.09.005

Yamal and Polar Urals: a research update

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Guest commentary from Tim Osborn, Tom Melvin and Keith Briffa, Climatic Research Unit, UEA

Records of tree-ring characteristics such as their width (TRW) and density (usually the maximum density of the wood formed towards the end of the growing season – the “maximum latewood density” – MXD) are widely used to infer past variations in climate over recent centuries and even millennia. Chronologies developed from sites near to the elevational or latitudinal tree lines often show sensitivity to summer temperature and, because of their annual resolution, absolute dating and relatively widespread nature, they have contributed to many local, continental and hemispheric temperature reconstructions. However, tree growth is a complex biological process that is subject to a range of changing environmental influences, not just summer temperature, and so replication, coherence and consistency across records and other proxies are an important check on the results.

Tree-ring records have greater replication (both within a site and between nearby sites) than other types of climate proxy. Good replication helps to minimise the influence of random localised factors when extracting the common signal, and it also allows the comparison of information obtained from different independent sets or sub-sets of data. If independent sets of data – perhaps trees with different mean growth rates or from different sites – show similar variations, then we can have greater confidence that those variations are linked to real variations in climate.

In a new QSR paper (Briffa et al., 2013), (BEA13) we have used these approaches to re-assess the combined tree-ring evidence from the Yamal and Polar Urals region (Yamalia) of northern Siberia, considering the common signal in tree-growth changes at different sites and in subsets of data defined in other ways. Together with our Russian colleagues and co-authors, we have incorporated many new tree-ring data, to increase the replication and to update the chronology to 2005 and have reassessed the inferences about summer temperature change that can be drawn from these data. The paper is published as an open-access paper (no paywall) and supplementary information including the raw tree-ring and instrumental temperature data are available from our website.
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References

  1. K.R. Briffa, T.M. Melvin, T.J. Osborn, R.M. Hantemirov, A.V. Kirdyanov, V.S. Mazepa, S.G. Shiyatov, and J. Esper, "Reassessing the evidence for tree-growth and inferred temperature change during the Common Era in Yamalia, northwest Siberia", Quaternary Science Reviews, vol. 72, pp. 83-107, 2013. http://dx.doi.org/10.1016/j.quascirev.2013.04.008

Should regional climate models take the blame?

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Kerr (2013) recently provided a critical review of regional climate models (“RCMs”). I think his views have caused a stir in the regional climate model community. So what’s the buzz all about?

RCMs provide important input to many climate services, for which there is a great deal of vested interest on all levels. On the international stage, high-level talks lead to the establishment of a Global Framework for Climate Services (GFCS) during the World Climate Conference 3 (WCC3) in Geneva 2009.

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References

  1. R.A. Kerr, "Forecasting Regional Climate Change Flunks Its First Test", Science, vol. 339, pp. 638-638, 2013. http://dx.doi.org/10.1126/science.339.6120.638

Movie review: SWITCH

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This year, the Geological Society of America is rolling out their SWITCH Energy Awareness campaign . The centerpiece of the campaign is a documentary film, SWITCH, which purports to be about the need for a transformation in the world’s energy systems. Recently, I attended the Chicago premier of the film, presented as part of the Environmental Film Series of the Lutheran School of Theology. I had high hopes for this film. They were disappointed. Given the mismatch between what the movie promises and what it delivers, it would be more aptly titled, “BAIT AND SWITCH.”
Switch Still
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Climate change and consequences on the ground

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The link between extreme weather events, climate change, and national security is discussed in Extreme Realities, a new episode in PBS’ series Journey To Planet Earth hosted by Matt Damon.

The video features a number of extreme weather phenomena: hurricanes, tornadoes, floods, wild fires, and flooding. The discussion is about climate change and the consequences on the ground – or, how climate change may affect you.

It is important to ask what is the story behind the assertions made in the video. What scientific support is there for the link between such extremes and climate change?

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Sea-level rise: Where we stand at the start of 2013 — Part 2

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This is Part 2 of my thoughts on the state of sea-level research. Here is Part 1.

Sea-level cycles?

A topic that keeps coming up in the literature is the discussion on a (roughly) 60-year cycle in sea level data; a nice recent paper on this is Chambers et al. in GRL (2012). One thing I like about this paper is its careful discussion of the sampling issue of the tide gauges, which means that variability in the tide gauges is not necessarily variability in the true global mean sea level (see Part 1 of this post). I want to add some thoughts on the interpretation of this variability. Consider this graph from my Response to Comments in Science (2007):


Fig. 1: Fifteen-year averages of the global mean temperature (blue, °C, GISS data) and rate of sea level rise (red, cm/year, Church&white data), both detrended.
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References

  1. D.P. Chambers, M.A. Merrifield, and R.S. Nerem, "Is there a 60‐year oscillation in global mean sea level?", Geophysical Research Letters, vol. 39, 2012. http://dx.doi.org/10.1029/2012GL052885
  2. S. Rahmstorf, "Response to Comments on "A Semi-Empirical Approach to Projecting Future Sea-Level Rise"", Science, vol. 317, pp. 1866-1866, 2007. http://dx.doi.org/10.1126/science.1141283

AGU time again…

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This week is Fall AGU, the biggest climate-related conference around. Not everything is related to climate – there is a lot of other geophysics and astrophysics, but it is generally the place to go if you want to see and be seen (and incidentally, be crushed, be excited, be friendly and be frustrated that you can’t be in three places at once).

If you are not going, you should check out the improvements in the ‘Virtual meeting‘, which will offer live streaming of some big sessions, and for those and many additional sessions there is video-on-demand (VOD) after the fact. Many posters will also be available via ePoster. The twitter hashtag is #AGU12.

And if you are going to be there, here is a limited selection of sessions that will discuss issues that often come up here (more details in the scientific program).

Monday, Dec 03:

PP11F. The Climate of the Common Era I + II
8:00 AM – 12:30 AM; 2010 (Moscone West) (including Kevin Anchukatis, Philip Brohan, Eric, and many others).

12:30 PM – 01:30 PM: San Francisco Marriott Marquis – Salon 10 Brown Bag Lunch Workshop with Michael Gerrard on “Legal Duties to Preserve and Disclose Scientific Data and Personal Communications” (note that anyone who wants a private one-on-one session with a lawyer related to these or related issues, can email lawyer(at)climatesciencedefensefund.org to set up a meeting).

PA13B. Countering Denial and Manufactured Doubt of 21st Century Science
1:40 PM – 3:40 PM; 302 (Moscone South)

6:30 PM – 8:30PM; Open Mike Night hosted by Richard Alley. Jillian’s, 175 4th Street, Suite 1070.

Tuesday, Dec 04:

PA21B. Communication of Science Through Art: A Raison d’Etre for Interdisciplinary Collaboration
8:00 AM – 10:00 AM; 104 (Moscone South) (VOD)

GC22B. Communicating Climate Science—Seeking the Best of Old and New Paradigms
10:20 AM – 12:20 PM; 3014 (Moscone West) (including Mike, Richard Alley, Dan Kahan, Richard Somerville and Naomi Oreskes)

PA23B. PA23B. Facebook, Twitter, Blogs: Science Communication Gone Social—The Social Media 101
1:40 PM – 3:40 PM; 302 (Moscone South) (Including Mike, Michael Tobis, Peter Sinclair, and Zeke Hausfather)

Bloggers Forum: Science on the Web:
5:00 pm – 6:00 pm: 3000 (Moscone West)

Wednesday, Dec 05:

Session Title: A32D. New Atmospheric Sciences Fellows Presentations I + II
8:00 AM – 12:20PM; 3002 (Moscone West) (including Tony DelGenio, Mike, Ron Stouffer, Dave Neelin… ) (VOD)

PP31D. Continental Archives of Past Climate and Seismic Events II
8:00 AM – 10:00 AM; 2006 (Moscone West) (including Ray B. discussing this)

PP32A. Emiliani Lecture
10:20 AM – 11:20 AM; 103 (Moscone South)
“No future without a past” or “History will teach us nothing”? (Invited) Richard E. Zeebe (VOD)

12:30 PM – 1:30 PM; Brown Bag lunch with Pete Fontaine “An inside look at the Michael Mann case”. 226 (Moscone South)

GC33F. Construing Uncertainty in Climate Science
2:40 PM – 3:40 PM; 3003 (Moscone West) (including Naomi Oreskes, Gerard Roe)

GC44B. Links Between Rapid Arctic Change and Midlatitude Weather Patterns
5:00 PM – 6:00 PM; 3001 (Moscone West) (including Steve Vavrus, Judah Cohen)

Thursday, Dec 06:

GC43I. Tyndall History of Global Environmental Change Lecture:
2:40 PM – 3:40 PM; 2022-2024 (Moscone West): “Successful Predictions” (Invited), Raymond Pierrehumbert (VOD)

U44A. Dissolving Boundaries Between Scientists, Media, and the Public
4:00 PM – 6:00 PM; 102 (Moscone South) (Including Eric as speaker and panelist).

Friday, Dec 07:

C54B. The Ice Core Record of Carbon Cycle History and Processes
4:00 PM – 6:00 PM; 3007 (Moscone West)

Feel free to advertise other sessions/talks that might be of interest in the comments. Hopefully we’ll get some reports of interesting sessions to share with you (and if anyone wants to send us anything, we’ll post it up that evening).

Don’t estimate acceleration by fitting a quadratic…

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… if your data do not look like a quadratic!

This is a post about global sea-level rise, but I put that message up front so that you’ve got it even if you don’t read any further.

The reputable climate-statistics blogger Tamino, who is a professional statistician in real life and has published a couple of posts on this topic, puts it bluntly:

Fitting a quadratic to test for change in the rate of sea-level rise is a fool’s errand.

I’d like to explain why, with the help of a simple example. Imagine your rate of sea-level rise changes over 100 years in the following way:
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