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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.
[Read more…] about Yamal and Polar Urals: a research update

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.

[Read more…] about Should regional climate models take the blame?

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?

[Read more…] about Climate change and consequences on the ground

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.
[Read more…] about Sea-level rise: Where we stand at the start of 2013 — Part 2

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:
[Read more…] about Don’t estimate acceleration by fitting a quadratic…

Stronger regional differences due to large-scale atmospheric flow.

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A new paper by Deser et al. (2012) (free access) is likely to have repercussions on discussions of local climate change adaptation. I think it caught some people by surprise, even if the results perhaps should not be so surprising. The range of possible local and regional climate outcomes may turn out to be larger than expected for regions such as North America and Europe.

Deser et al. imply that information about the future regional climate is more blurred than previously anticipated because of large-scale atmospheric flow responsible for variations in regional climates. They found that regional temperatures and precipitation for the next 50 years may be less predictable due to the chaotic nature of the large-scale atmospheric flow. This has implications for climate change downscaling and climate change adaptation, and suggests a need to anticipate a wider range of situations in climate risk analyses.

Although it has long been recognised that large-scale circulation regimes affect seasonal, inter-annual climate, and decadal variations, the expectations have been that anthropogenic climate changes will dominate on time scales longer than 50 years. For instance, an influential analysis by Hawking & Sutton (2009) (link to figures) has suggested that internal climate variability account for only about 20% of the variance over the British isles on a 50-year time scale.
[Read more…] about Stronger regional differences due to large-scale atmospheric flow.

References

  1. C. Deser, R. Knutti, S. Solomon, and A.S. Phillips, "Communication of the role of natural variability in future North American climate", Nature Climate Change, vol. 2, pp. 775-779, 2012. http://dx.doi.org/10.1038/nclimate1562
  2. E. Hawkins, and R. Sutton, "The Potential to Narrow Uncertainty in Regional Climate Predictions", Bulletin of the American Meteorological Society, vol. 90, pp. 1095-1108, 2009. http://dx.doi.org/10.1175/2009BAMS2607.1

ClimateDialogue: Exploring different views on climate change

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This is a guest posting from some Dutch colleagues on a new online experiment in fostering dialogue on climate change. Bart Verheggen has asked us to host this quick introduction. We are interested to hear if you think this is a good idea.

Guest Commentary by Bart Strengers (PBL)

ClimateDialogue.org offers a platform for discussions between invited climate scientists on important climate topics that have been subject to scientific and public debate. The goal of the platform is to explore the full range of views currently held by scientists by inviting experts with different views on the topic of discussion. We encourage the invited scientists to formulate their own personal scientific views; they are not asked to act as representatives for any particular group in the climate debate.

Obviously, there are many excellent blogs that facilitate discussions between climate experts, but as the climate debate is highly polarized and politicized, blog discussions between experts with opposing views are rare.

Background


The discovery, early 2010, of a number of errors in the Fourth IPCC Assessment Report on climate impacts (Working Group II), led to a review of the processes and procedures of the IPCC by the InterAcademy Council (IAC). The IAC-report triggered a debate in the Dutch Parliament about the reliability of climate science in general. Based on the IAC recommendation that ‘the full range of views’ should be covered in the IPCC reports, Parliament asked the Dutch government ‘to also involve climate skeptics in future studies on climate change’.

In response, the Ministry of Infrastructure and the Environment announced a number of projects that are aimed to increase this involvement. ClimateDialogue.org is one of these projects.


We are starting ClimateDialogue with a discussion on the causes of the decline of Arctic Sea Ice, and the question to what extent this decline can be explained by global warming. Also, the projected timing of the first year that the Arctic will be ice free will be discussed. With respect to the latter, in its Fourth Assessment Report in 2007, IPCC anticipated that (near) ice free conditions might occur by the end of this century. Since then, several studies have indicated this could be between 2030-2050, or even earlier.

We invited three experts to take part in the discussion: Judith Curry, chair of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology; Walt Meier, research scientist at the National Snow & Ice Data Center (NSIDC) in Boulder, Colorado; and Ron Lindsay, Senior Principal Physicist at the Polar Science Center of the University of Washington in Seattle.

Future topics that will be discussed include: climate sensitivity, sea level rise, urban heat island-effects, the value of comprehensive climate models, ocean heat storage, and the warming trend over the past few decades.

Our format


Each discussion will be kicked off by a short introduction written by the editorial staff, followed by a guest blog by two or more invited scientists. The scientists will start the discussion by responding to each other’s arguments. It is not the goal of ClimateDialogue to reach a consensus, but to stimulate the discussion and to make clear what the discussants agree or disagree on and why. 
To round off the discussion on a particular topic, the ClimateDialogue editor will write a summary, describing the areas of agreement and disagreement between the discussants. The participants will be asked to approve this final article, the discussion between the experts on that topic will then be closed and the editorial board will open a new discussion on a different topic.

The public (including other climate scientists) are also free to comment, but for practical reasons these comments will be shown separately.

The project organization consists of an editorial staff of three people and an advisory board of seven people, all of whom are based in the Netherlands. The editorial staff is concerned with the day-to-day operation of researching topics, finding participants for the discussion and moderating the discussions between the experts. The main task of the advisory board is to guard the neutrality of the platform and to advise the editorial staff about its activities

The project leader is Rob van Dorland of the Royal Netherlands Meteorological Institute (KNMI), a senior scientist and climate advisor in the Climate Services section and is often active at the interface between science and society. The second member is Bart Strengers. He is a climate policy analyst and modeler in the IMAGE-project at the PBL Netherlands Environmental Assessment Agency (PBL) and has been involved in the discussion with climate skeptics for many years. The third member is Marcel Crok, an investigative science writer, who published a critical book (in Dutch) about the climate debate.

We welcome comments here and are happy to answer any questions regarding this project. You can also send an email to info [at] climatedialogue [dot] org.