Climate Feedback

Posted by Olive Heffernan on behalf of Paty Romero Lankao

It does make sense to compare the per capita CO2 emissions of Mexico City and Los Angeles (see figure below) to illuminate the debate on shared but differentiated responsibilities on greenhouse gases emissions and show that just as urban centers register different levels and paths of economic development, cities do not contribute at the same level to global warming. For instance, the real GDP per capita of Los Angeles (US$40,031) is almost 3 times that of Mexico City (US$13,470). The paradox here is that many of those urban centers with almost negligible contributions to the greenhouse gases in the atmosphere are more vulnerable to the negative impacts of climate change are. One reason of this relates to the local level of expenditures per capita in Mexico City, which are similarly tiny when compared with those of Los Angeles. In such conditions, the binding constraint for this and other cities of the developing world is the lack of economic resources from peoples’ taxes and of economic growth to deal with any component of the climate agenda.

Continue reading "Does it make sense to compare cities’ per capita emissions?" »

Posted by Olive Heffernan on May 12, 2007
Categories: Climate Science, GHG emissions, Paty Romero Lankao | Permalink | Comments (0) | TrackBacks (0)

(Posted by Olive on behalf of Roger)

Even the venerable New York Times is prone to completely botching a discussion of the science of climate change. In a front page article today, the NYT reports on how the National Arbor Day Foundation has updated plant hardiness maps to reflect recent changes in climate. (A plant hardiness map presents the lowest annual temperature as a guideline to what plants will thrive in what climate zones.) The NYT misrepresents understandings of variability and trend and in the process confuse more than clarify.

The new map updates a 1990 USDA map based on 1974-1986 data, and replaces it with data from 1990-2006. In most places the range of increased average minimum temperature has moved north as can be seen from a difference map between the two time periods. The difference map, shown here, has the horizontal lines because the zones used are so broad -- 10 degrees -- that the differences are only noticeable at the margins of the zones.

The New York Times reports that these differences can all be attributed to human-caused climate change, using the case of Atlanta as an illustration:

Using data from the National Oceanic and Atmospheric Administration, the Arbor Day map indicates that many bands of the country are a full zone warmer, and a few spots are two zones warmer, than they were in 1990, when the map was last updated.

Atlanta, which was in Zone 7 in 1990, is now in Zone 8, along with the rest of northern Georgia. That means that areas in the northern half of the state where the average low temperature was zero to 10 degrees Fahrenheit are now in a zone where the average low is 10 to 20 degrees. A scientific consensus has concluded that this warming trend has largely been caused by the human production of heat-trapping gases.

Because the zones span 10 degrees (or 5 degrees in the case of the 1990 USDA map) and the largest change shown on the difference map is 2 zones (i.e., >10 degrees!, now corrected), then clearly no location has jumped 2
zones! This is just an error.

More important than this simple mistake is the claim in the NYT that the changes in temperature observed in Atlanta can be attributed to human-caused greenhouse gases. In fact, the IPCC argues that it needs 30 years of records to detect trends, much less make attribution. In fact, the IPCC report just out has reported that the U.S. southeast has actually cooled over the period of record as shown below.

The underlying issue has to do with understanding the role of human-caused climate change in the context of climate variability on long time scales.

Continue reading "Confusion on Climate Variability and Trends" »

Posted by Olive Heffernan on May 03, 2007
Categories: Climate Science, Communicating Climate Change, In the News, Roger Pielke, Jr | Permalink | Comments (35) | TrackBacks (0)

(Posted by Olive on behalf of Hans)

In October 2004 we were lucky to publish in Science our critique of the ‘hockey-stick’ reconstruction of the temperature of the last 1000 years. Now, two and half years later, it may be worth reviewing what has happened since then.

The publication in 2004 was a remarkable event, because the hockey-stick had been elevated to an icon by the 3rd Assessment Report of the IPCC. This perception was supported by a lack of healthy discussion about the method behind the hockey-stick. In the years before, due to effective gate keeping of influential scientists, papers raising critical points had a hard time or even failed to pass the review process. For a certain time, the problem was framed as an issue of mainstream scientists, supporting the concept of anthropogenic climate change, versus a group of skeptics, who doubted the reality of the blade of the hockey stick. By framing it this way, the real problems, namely the ‘wobbliness’ of the shaft of the hockey-stick, and the suppressing of valid scientific questions by gate keeping, were left out.

Hopefully, sociology of science will later study this unfortunate period of climate science, but we may conclude now that science itself has indeed corrected claims of premature knowledge. We see now a healthy and broad discussion of the issue. We had the opportunity to respond to no less than four comments on our 2004 Science paper, but unfortunately only two comments were published. Similarly, Michael Mann and his coworkers had to respond to at least 2 comments to their Journal of Climate article in 2005.

At the EGU General Assembly a few weeks ago there were no less than three papers from groups in Copenhagen and Bern assessing critically the merits of methods used to reconstruct historical climate variable from proxies; Bürger’s papers in 2005; Moberg’s paper in Nature in 2005; various papers on borehole temperature; The National Academy of Science Report from 2006 – al of which have helped to clarify that the hockey-stick methodologies lead indeed to questionable historical reconstructions. The 4th Assessment Report of the IPCC now presents a whole range of historical reconstructions instead of favoring prematurely just one hypothesis as reliable.

When looking back we are satisfied with what has been achieved – namely an open, open-minded exciting discussion about the merits and problems related to different methods; an atmosphere where mere claims about the informational content of proxy-data meet a more critical response; an evolving practice of testing the skill of reconstruction methods in the laboratory of millennial forced global climate model simulations, where the formation of proxy-data is simulated in - so far too simplified - models.

Hans von Storch and Eduardo Zorita

Posted by Olive Heffernan on May 03, 2007
Categories: Climate Science, Hans von Storch, Palaeoclimate | Permalink | Comments (27) | TrackBacks (0)

(Posted by Olive on behalf of Heike)

The week before last, I was one of an army of geoscientists travelling to Vienna from Europe and the world for the General Assembly of the European Geophysical Union (EGU). And of course, we are all aware of climate change. There was a talk on “The carbon footprint of academic travelling – assessing the sustainability of different ways of travelling to the EGU Assembly”. Too late, since most of us had already come by plane.

There also was a debate with the title “The carbon footprint of EGU is bigger than necessary”. I didn’t go. I suspect the potentially interesting question in this debate — “What is necessary?” — was not addressed.

Is the EGU assembly itself necessary? Of course it is nice to meet colleagues in person. Yes, when people chat over a glass of wine at the poster session, chances are that new science emerges that would not have come into the world without that poster session (or without that wine). And for me personally, talking to people informally about the launch of my new Journal, Nature Geoscience, is very helpful.

In the end, do 4,200 oral presentations and 6,700 posters justify 8,000 participants’ travel emissions? The bottomline of EGU sounds reasonable. But necessary? No. Necessary it is not.

Heike Langenberg
Chief Editor, Nature Geoscience

Posted by Olive Heffernan on May 03, 2007
Categories: Climate Science, Conferences and Meetings, Heike Langenberg | Permalink | Comments (3) | TrackBacks (0)

Welcome to Climate Feedback, a new blog hosted by Nature Reports: Climate Change to facilitate lively and informative discussion on the science and wider implications of global warming.

Launching in May, Nature Reports: Climate Change is a new online resource from Nature, dedicated to in-depth reporting on global change. In light of the need for greater understanding of and access to information on climate change, the new website will vastly extend Nature’s reporting on this issue of incalculable importance.

As its accompanying blog, Climate Feedback aims to encouarge less formal debate and commentary on climate science featured in our journals and others, in the news, and in the world at large. The blog will host the climate-related musings of editors of Nature and Nature Reports: Climate Change, as well as of a select group of climate scientists and policy experts. For details of our regular contributors, go to ‘Contributors’ on the blog home page. We will also host postings from other contributors outside of the core group from time to time. As Nature’s first exclusive climate blog, Climate Feedback will join the list of existing Nature blogs, which cover a diversity of subjects from neuroscience to science news.

Why the need for another climate blog?

Despite a twenty fold in increase in coverage of global warming over almost two decades in the UK (and a five fold increase in the US over the same period) (see papers by Max Boykoff) , climate change remains a low priority for the mainstream media. More importantly, climate change issues remain poorly understood among even the well-informed public. Mainstream coverage of climate change often leaves readers out in the cold when it comes to separating the known from the unknown, fact from opinion and even fact from fiction. And while the contribution of human activity to climate change is well-established, the extent and timescale of future changes and how to minimise and deal with these changes remain topics of huge debate.

Here at Nature, we have launched Climate Feedback with the aim of providing a forum for authoritative discussion on climate issues, hosting a balance of voices and a diversity of well-informed opinions. We will discuss the broader issues surrounding climate change, as well as cutting-edge climate science. Our goal is to provide a respected and trustworthy source of discussion and debate for a wide audience, from climate scientists to the scientific public.

Why ‘Climate Feedback’?

We have called our blog Climate Feedback as a tribute to the inherently complex feeedback mechanisms in the climate system that can diminish or amplify the effect of initial greenhouse warming, and which remain one of the least well understood components of climate change. Feedback occurs when one processes triggers another that then has a positive or negative influence on the first. Similarly, we hope that postings on this blog will generate feedback to which we can respond, generating dynamic discussions on climate issues.

What will we host on the blog?

-Discussion of the weekly content of Nature Reports: Climate Change and of our monthly podcasts

-Comment and analysis on climate science in our journals, other journals and in the news

-Musings from us on meetings and conferences we are attending

-Details of upcoming events, books, interesting sites, articles etc.

-Notes from climate scientists in the field ….updating us with their in situ observations

-And much more, of course!

We will be posting to the blog frequently, so do check in regularly to see what’s new. Please join in our discussions by leaving comments. If you want to contact us, email climatefeedback at nature dot com. We look forward to hearing from you!

Posted by Olive Heffernan on April 30, 2007
Categories: Climate Science, Communicating Climate Change, Olive Heffernan | Permalink | Comments (4) | TrackBacks (0)