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ICECAP in the News
Dec 03, 2009
Georgia Tech: “50 percent of USA warming that has occurred since 1950 is due to land use changes”

Georgia Tech Press Release as reported on Watts Up With That

Reducing Greenhouse Gases May Not Be Enough to Slow Climate Change according to Georgia Tech press release here.

Georgia Tech City and Regional Planning Professor Brian Stone publishes a paper in the December edition of Environmental Science and Technology that suggests policymakers need to address the influence of global deforestation and urbanization on climate change, in addition to greenhouse gas emissions.

See larger image here.

According to Stone’s paper, as the international community meets in Copenhagen in December to develop a new framework for responding to climate change, policymakers need to give serious consideration to broadening the range of management strategies beyond greenhouse gas reductions alone.

“Across the U.S. as a whole, approximately 50 percent of the warming that has occurred since 1950 is due to land use changes (usually in the form of clearing forest for crops or cities) rather than to the emission of greenhouse gases,” said Stone.  “Most large U.S. cities, including Atlanta, are warming at more than twice the rate of the planet as a whole - a rate that is mostly attributable to land use change.  As a result, emissions reduction programs - like the cap and trade program under consideration by the U.S. Congress - may not sufficiently slow climate change in large cities where most people live and where land use change is the dominant driver of warming.”

According to Stone’s research, slowing the rate of forest loss around the world, and regenerating forests where lost, could significantly slow the pace of global warming.

“Treaty negotiators should formally recognize land use change as a key driver of warming,” said Stone.  “The role of land use in global warming is the most important climate-related story that has not been widely covered in the media.”

Stone recommends slowing what he terms the “green loss effect” through the planting of millions of trees in urbanized areas and through the protection and regeneration of global forests outside of urbanized regions.  Forested areas provide the combined benefits of directly cooling the atmosphere and of absorbing greenhouse gases, leading to additional cooling.  Green architecture in cities, including green roofs and more highly reflective construction materials, would further contribute to a slowing of warming rates.  Stone envisions local and state governments taking the lead in addressing the land use drivers of climate change, while the federal government takes the lead in implementing carbon reduction initiatives, like cap and trade programs.

“As we look to address the climate change issue from a land use perspective, there is a huge opportunity for local and state governments,” said Stone.  “Presently, local government capacity is largely unharnessed in climate management structures under consideration by the U.S. Congress.  Yet local governments possess extensive powers to manage the land use activities in both the urban and rural areas.”

The Environmental Science and Technology article is available here.

For more on land use change in the USA, see this NASA resource.


See response by Roger Pielke Sr. to the kneejerk reaction of Gavin Schmidt, Real Climate to Stone’s finding in the post
Comment On The Inaccurate Response By Gavin Schmidt Of Real Climate On The Role of Land Use Change On Temperature Trends

There is a response by Gavin Schmidt on Real Climate with respect to the role of land use change on the attribution of surface air temperature trends [thanks to Charlie Allen for alerting us to it!]. While Gavin has expertise in global climate modeling, his reply illustrates his lack of expertise on the role of landscape processes within the climate system, and, in this example, with respect to the role of land use/land cover change on long temperature trends.

The text from Real Climate is CCPO @258 - you quoted Gavin as saying “Note. global land use effects result in a cooling because the biggest issue is the chopping down of forest (dark) to make cropland (bright)” Well, that’s not actually true. Here’s a press release for a new paper from Georgia Tech, showing how 50% of the warming across the US is due to land use changes.

Original reference for Gavin’s comment was from Edward’s post @95:[Response: A statement in a press release is not a scientific result and the paper referred to does not show this to be true (and in fact I doubt very much that it is true). There are many papers on the global impacts of land cover change - Pondgratz et al is good, and all such papers show that land use at the global scale drives a cooling. - gavin]

The person who prepared the comment (CCPO) clearly understands the science issue better than Gavin Schmidt. I have already documented his lack of expertise in research topics that he comments on at Real Climate and elsewhere in my post Does Gavin Schmidt Understand Boundary Layer Physics?

A Recent paper of ours which document an increase in surface temperatures due to landscape change include: Fall, S., D. Niyogi, A. Gluhovsky, R. A. Pielke Sr., E. Kalnay, and G. Rochon, 2009: Impacts of land use land cover on temperature trends over the continental United States: Assessment using the North American Regional Reanalysis. Int. J. Climatol., DOI: 10.1002/joc.1996

With respect to the study by Stone Jr, Gavin apparently did not even read it before he commented! In the paper, (Stone Jr., Brian, 2009: Land Use As Climate Change Mitigation, Environmental Science and Technology), it is written [emphasis added in bold face font]

“...the mean decadal rate of warming across the urban stations is significantly higher than that of rural stations. Averaged over the full period, the mean decadal rate of warming for urban stations was found to be 0.08C higher than that of rural stations. This average rate of heat island growths i.e., urban warming in excess of the rural trends rises to 0.20C/decade over the most recent 20 years of observation.” and “The increasing divergence between rural and urban temperature trends in U.S. cities highlights the limitationsof a climate policy framework focused on emissions reductions alone. If land use change is the dominant agent of climate forcing at the urban scale, Kyoto-based emissions trading schemes may fail to sufficiently safeguard human health in the most heavily populated regions of the planet. It is important to emphasize, however, that the phrase “urban heat island effect,” much like the phrase “greenhouse effect,” is a misnomer…The physical mechanisms underlying warming trends in cities are limited neither to urban areas nor to small geographic regions. Rather, changes in surface moisture and energy balances accompanying land conversion processes across large swaths of the planet’s land area are giving rise to changes in climate that may be of the same order of magnitude as changes brought about through the emission of GHGs. As such, the urban heat island effect should be understood to be only the most visible manifestation of a larger phenomenon occurring across multiple geographic scaless a phenomenon better characterized as a “green loss effect” than as something unique to urban areas.”

This reply by Gavin, besides ignoring (e.g. Fall et al 2009) and his trivializing (e.g. Stone Jr 2009) peer reviewed papers that disagree with his perspective, his comment also shows that he has learned little from the exposure of the inappropriate attempt by Phil Jones and colleagues to serve as gatekeepers to climate science issues. Since Gavin Schmidt is not a recognized expert on the role of land use/land cover change, he should have sought a qualified climate scientist to address the comment by CCPO. Instead, he perpetuates the biased and often inaccurate presentation of climate views on Real Climate.

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