Study gives clearer picture of how land-use changes affect U.S. climate
from a Purdue University press release
Researchers say regional surface temperatures can be affected by land use, suggesting that local and regional strategies, such as creating green spaces and buffer zones in and around urban areas, could be a tool in addressing climate change.
A study by researchers from Purdue University and the universities of Colorado and Maryland concluded that greener land cover contributes to cooler temperatures, and almost any other change leads to warmer temperatures. The study, published on line and set to appear in the Royal Meteorological Society’s International Journal of Climatology later this year, is further evidence that land use should be better incorporated into computer models projecting future climate conditions, said Purdue doctoral student Souleymane Fall, the article’s lead author.
“What we highlight here is that a significant trend, particularly the warming trend in terms of temperatures, can also be partially explained by land-use change,” said Dev Niyogi, a Purdue earth and atmospheric sciences and agronomy professor, and the Indiana state climatologist. He is the study’s corresponding author.
Niyogi and Fall say the idea that land use helps drive climate change has been poorly understood compared to factors such as greenhouse gas emissions. But that is changing.
“People realize that land use cover also is an important force and not only at the local but also at the regional scale,” said Fall, whose doctoral research focuses on the impacts of land surface properties on near-surface temperature trends.
The researchers used higher resolution temperature data than previous studies, meaning the data was more detailed, Niyogi said. They also employed dynamic data on land-use changes from 1992-2001, which was derived from satellite imagery.
Niyogi said having an understanding of land use’s affects on climate change could have climatic and other benefits. For instance, creating green spaces and buffer zones in and around urban areas also could be aesthetically attractive, he said.
Among the study’s findings:
* In general, the greener the land cover, the cooler is surface temperature.
* Conversion to agriculture results in cooling, while conversion from agriculture generally results in warming.
* Deforestation generally results in warming, with the exception of a shift from forest to agriculture. No clear picture emerged from the impact of planting or seeding new forests.
* Urbanization and conversion to bare soils have the largest warming impacts.
In general, land use conversion often results in more warming than cooling.
The study took an approach called “observation minus reanalysis,” or OMR. Through this process, the researchers used temperature data from local ground observations, observation and computer modeling, Geographic Information Systems (GIS) and statistical methods. They were able to separate the effects of land use or cover from greenhouse warming and isolate the impact from each land use or cover type. The more detailed data provided a clearer picture of the effects of land surface properties on near-surface temperature trends.
“We showed this quantitatively for the first time,” said University of Maryland atmospheric and oceanic science Professor Eugenia Kalnay, who developed the OMR method with Florida State University Professor Ming Cai. She also is a co-author of the study.
While the effects of greenhouses gases like carbon dioxide are clear, Kalnay said, the study does suggest land use needs to be considered carefully as well.
“I think that greenhouse warming is incredibly important, but land use should not be neglected,” she said. “It contributes to warming, especially in urban and desertic areas.”
Another study co-author, Roger Pielke Sr., said the results indicate that “unless these landscape effects are properly considered, the role of greenhouse warming in increasing surface temperatures will be significantly overstated.” Pielke is a senior research scientist in atmospheric and oceanic sciences at the Cooperative Institute for Research in Environmental Sciences and the Department of Atmospheric and Oceanic Sciences at the University of Colorado in Boulder.
Purdue’s Gilbert Rochon and Alexander Gluhovsky also participated in the study. Rochon is associate vice president for collaborative research for Information Technology at Purdue (ITaP) and director of ITaP’s Purdue Terrestrial Observatory satellite and remote sensing data program. Gluhovsky is a Purdue professor in earth and atmospheric sciences and statistics.
The work was supported by the U.S. Department of Energy Atmospheric Radiation Measurement program, NASA, the National Science Foundation, and the National Oceanic and Atmospheric Administration.
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ABSTRACT
Impact of land use cover on temperature trends over the continental United States: assessment using the North American Regional Reanalysis
We investigate the sensitivity of surface temperature trends to land use land cover change (LULC) over the conterminous United States (CONUS) using the observation minus reanalysis (OMR) approach. We estimated the OMR trends for the 1979-2003 period from the U.S. Historical Climate Network (USHCN), and the NCEP-NCAR North American Regional Reanalysis (NARR). We used a new mean square differences (MSDs)-based assessment for the comparisons between temperature anomalies from observations and interpolated reanalysis data. Trends of monthly mean temperature anomalies show a strong agreement, especially between adjusted USHCN and NARR (r = 0.9 on average) and demonstrate that NARR captures the climate variability at different time scales. OMR trend results suggest that, unlike findings from studies based on the global reanalysis (NCEP/NCAR reanalysis), NARR often has a larger warming trend than adjusted observations (on average, 0.28 and 0.27 °C/decade respectively).
OMR trends were found to be sensitive to land cover types. We analyzed decadal OMR trends as a function of land types using the Advanced Very High Resolution Radiometer (AVHRR) and new National Land Cover Database (NLCD) 1992-2001 Retrofit Land Cover Change. The magnitude of OMR trends obtained from the NLDC is larger than the one derived from the static AVHRR. Moreover, land use conversion often results in more warming than cooling.
Overall, our results confirm the robustness of the OMR method for detecting non-climatic changes at the station level, evaluating the impacts of adjustments performed on raw observations, and most importantly, providing a quantitative estimate of additional warming trends associated with LULC changes at local and regional scales. As most of the warming trends that we identify can be explained on the basis of LULC changes, we suggest that in addition to considering the greenhouse gases-driven radiative forcings, multi-decadal and longer climate models simulations must further include LULC changes.
The peer reviewed paper which this press release discusses is
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.
WattsUpWithThat also featured a land use study done by Morton D. Winsberg of Florida State University.
“With little or no land use change, Winsberg says, areas showing a longer hot season would have followed the general cooling trend seen elsewhere in the Southeast U.S.”
http://wattsupwiththat.com/2009/02/10/floridatrend-its-hot-but-dont-blame-global-warming/
The case for co2 as the controlling factor in weather and climate grows weaker. I have not seen any evidence strengthening it. It’s end is inevitable.
“A study by researchers from Purdue University and the universities of Colorado and Maryland concluded that greener land cover contributes to cooler temperatures, and almost any other change leads to warmer temperatures.”
Umm… plant more trees then… it might soak up some of that (so called ) excess CO2 then… SHEESH!!!
Minor quibble, but the map depicts a swath of the North Cascades in WA as warming. This may be true, but as a Nat’l Park it is not due to conversion. It’s also possible the map scale is a bit off. But that northwest WA red are is prime agricultural land butting up to National Forest and State forest land butting up to Nat’l Park. Looks suspicious.
Back when forest management was a respectable course of study the general conclusion in the West was that soil surface temps on a south facing slope could reach over 140F on a sunny spring day.
Without disputing anything, isn’t albedo the be all and end all of temperature correlation? A dark green forest or cornfield will have a low albedo, but perhaps not as low as dirt. Are there any uses which would increase albedo? Hockey rinks? White pavement and roofs? An icefield or glacier?
“I think that greenhouse warming is incredibly important, but land use should not be neglected,” she said. “It contributes to warming, especially in urban and desertic areas.”
The only thing that is important about “greenhouse warming” is the damage to the global economy the eco-fascists will cause whilst allegedly combatting it.
But this new study is another lttle straw in the wind showing that CO2 ain’t guilty.
Land [mis]use is a far more sensible cause for alarmism than climate change (in our times).
“Among the study’s findings: * In general, the greener the land cover, the cooler is surface temperature.”
Some maple trees are highly regarded and widely planted in urban landscapes and some, an example is the purple leaf Norway maple, have non-green leaves, even in summer. On the other hand, things can be painted green. I wonder if by the phrase “the greener the land cover” they really mean ‘the color green’ or living things that have green colors, or just plants? Would plants with very light colored leaves be the best? Or is it the evapotranspiration process that is the thing to focus on?
Should any plant that has non-green leaves be banned from landscape plantings and sought-out and destroyed in its natural habitat. Should our roofs be colored green or white?
The thing that bothers me about this report is their assumption that greenhouse warming is an established thing — “They were able to separate the effects of land use or cover from greenhouse warming and …”
I wonder if they have read any of the “how not to measure temperature” postings?
Terry Jackson (22:59:01) : re: northern Washington State
I missed this until reading your comment. From 1979 to 2003 I wonder what land cover change could have been contributing to this? I’ve helped widen a few hiking trails, including parts of the PCT in this region. Not much else going on that I noticed!
Slightly O/T. Initially I was searching for ‘coldest october on record’. Now I had found over 100 cities in the U.S. breaking records or near records for coldest temp or snowiest month or record rainfall for october, I also found parts of the U.K. was also experiencing the same thing and N. Z. as well.
But then I stumbled across this little gem.
CLIMATE CHANGE: Temperature readings in rural Australia show no increase in 100 years
by Dr A.L. McClintock
“Weather observatories in Australia, dating back 100 years or more, show cities getting hotter as they get bigger; but country towns have generally not been warming up. Some have actually been cooling down.”
http://www.newsweekly.com.au/articles/2009oct31_c.html
I’m sure (someone) will post about Oct. Temps. , so I’ll leave that alone for now, because this article was a eye-grabber.
It has been my understanding that UHI effect has been largely overlooked by the I.P.C.C. and the UK Met Office because of their alarmist views on AGW. I can understand why now. I don’t know about the rest of you, but I want to dump 1000 copies of this article on a little known office ran by P. Jones.
Then stand out in the parking lot and use a line from an old sitcom, ” Oh Lucy! You have some esplaynin to do!”
I’m not sure the map goes where the press release leads.
martin brumby (23:07:09) : ” … The only thing that is important about “greenhouse warming” is the damage to the global economy the eco-fascists will cause whilst allegedly combatting it.”
Some nice support for this comment, Martin can be found here: Placing My Lance – George Rebane
Like…um…DUH???
I am quite surprised that agricultural land changes lead to cooling. Bare soil is darker and absorbs sun radiation better, warming the air above (everyone who flies gliders knows it). Another case is, when swamps are turned to fields, which has definitely warming effect.
I am also curious, how the authors “separated the effects of land use or cover from greenhouse warming”, since US experiences free fall in temperatures since 2005.
Terry Jackson (22:59:01) :
Minor quibble, but the map depicts a swath of the North Cascades in WA as warming.
The map covers trend from 1979 – 2003. I don’t have the charts of +/- PDO in front of me but if I am remembering correctly there was a +PDO during most, if not all, of that time frame. The effects of a +PDO could be the explanation since Washington is next to the Pacific.
On a trip to Borneo a few years ago I noticed that night temperatures in the inland were far more acceptable than on the coast i.e. cooler. This was despite being away from coastal breezes, surrounded by jungle and no more than 200 ft above sea level. All I could put it down to was the evapotranspiration from the rainforest and the higher rainfall in these forest areas. Every afternoon it used to pour down with rain from towering cumulonimbus clouds, no doubt the rain drops were cooled from their formation high in the clouds. I get the impression that vegetation is an even better airconditioner than the ocean.
OT, but relevant?
Pielke Jnr has thrown down the glove.
http://rogerpielkejr.blogspot.com/2009/11/open-invitation.html
This Blog
This Blog
02 November 2009
Open Invitation
Here is an open invitation to my loudest critics. I’d like to invite Joe Romm, Tim Lambert, the guys at Real Climate, William Connolley and anyone else (apologies to critics not mentioned, no slight intended;-) to engage in a substantive debate on the following 10 conclusions that I’ve reached about the climate issue, based on the fact that the human influence on climate is real, serious and deserving of significant policy attention:
1. There is no greenhouse gas signal in the economic or human toll record of disasters.
2. The IPCC has dramatically underestimated the scale of the stabilization challenge.
3. Geoengineering via stratospheric injection or marine cloud whitening is a bad idea.
4. Air capture research is a very good idea.
5. Adaptation is very important and not a trade off with mitigation.
6. Current mitigation policies, at national and international levels, are inevitably doomed to fail.
7. An alternative approach to mitigation from that of the FCCC has better prospects for success.
8. Current technologies are not sufficient to reach mitigation goals.
9. In their political enthusiasm, some leading scientists have behaved badly.
10. Leading scientific assessments have botched major issues (like disasters).
Here is my guarantee:
Your comments will be allowed here in full, they will not be deleted or snipped. I will delete comments that are off topic much more rigorously than I usually do to keep a clear focus. Anyone can participate, but I will require respectful, substantive discussion at all times. If there is enough interest, I will be happy to spin off unique threads for any of the 10 topics that people want to challenge or debate.
OK guys here is your chance to step up and show the world where I am wrong based on a substantive discussion of issues that really matter. What do you say? All are welcome.
I think my money’s safe, if I popped into the Bookies & wagered that none of his aforementioned critics will engage in the discussion.
I left this in the tips section:
Nice little story in Red State about the effect of urbanisation on local climate:
http://www.redstate.com/neil_stevens/2009/11/02/squirrels-cities-and-climate/
David Alan (00:04:46) :
🙂 A POI.
The Met Office only overlook things when convenient to do so. As Prof John Brignall has pointed out on Number Watch before, Dr Vicki Pope has advised in national newspapers that the UHI will (could/might/may/possibly/potentially/likely) kill 100s by 2100 due to global warming, whereas the likes of Dr Jones (no not hunky heroic Harrison) has implied that the UHI is insignificant & has been accounted for & doesn’t affect the evidence supporting Global Warming!
Another related study about land use vs energy sources used I document on my blog
http://tr.im/DTUg
The more “green” you are the more land you use!
The phrase ‘reinventing the wheel’ comes to mind.
All this was known 50 years or more ago but no one bothered to quantify the effect because it was taken as a given and, moreover, a factor that was too complex to quantify adequately at that time. The best that could be done was to apply very rigorous site standards, so rigorous that I abandoned all hope of contributing to the recording system of the day. As Anthony has proved, those standards were then abandoned wholesale.
It seems that so many AGW proponents have so little real world knowledge that they piled into a wholly speculative and unlikely scenario and in the course of rowing back from it they are now ‘discovering’ stuff that they should have known from their schooldays.
Another area where I find total incomprehension amongst warmlings is the issue of latent heat.
They are genuinely unaware that evaporation has a net cooling effect. I find so many otherwise well informed warmlings insisting that either the process is temperature neutral or that the extra evaporation induced by downward re-radiated infra red energy leaves an energy residue available for warming of the environment.
The more I have looked into this over the past 18 months the more I have found the problem to be that warmlings focus on large numbers of individual bits of data and extrapolate madly from them yet have no idea how the climate system works as a coherent whole so that the proper weighting is never attributed to those bits of data.
I suspect that all the models are similarly replete with nonsensical weightings due to such issues.
Conclusion: Land change use introduces a bias in the surface temperature record.
Green: Cool
Tar Macadam: Warm
Doesn’t this study confirm what most all ready knew?
Roger Carr (00:16:29) :
They will not only damage the economy, they will damage the Climate and the ability of civilization to adapt to the natural cycles of change.
What drives the madness?
Power?
What power can one have if one brings down their own country?
Monetary gain?
What profit can one make if one destroys the very currency accumulated?
Eden?
What garden will one have if the aim is to remove from the Earth all the carbon upon which terrestrial life is based?
But today:
http://www.foxnews.com/politics/2009/11/03/gop-senators-talk-boycotting-climate/%20/?test=latestnews
GOP Senators talk of Boycotting Climate Bill.
Logic. If some land is classed as an unfarmed sand desert, how does this affect the temperature? Presumably, if it has been a sand desert for some centuries, it is more or less in equilibrium and it is not going to produce a trend today that can be substracted from another trend like proposed GHG.
While closely settled countries with active land use changes might show a signal, places like the Antarctic and much of Australia and Africa have insignificant land use changes of a type that would need accounting in the energy balance. In any case it would need to tie in with albedo changes for the whole earth.
Besides, the sea dominates the heat equations. Not the NH, not the USA.
UHI and land use are talked about in this video from 2:23 to 3:33
“Simon Filiatrault (02:09:43) :
Another related study about land use vs energy sources used I document on my blog
http://tr.im/DTUg
The more “green” you are the more land you use!”
I agree with this. All the “greenie” types stating that we grow our own food blah blah blah, lmao, I live in an apartment block (Ever growing “solution” in Australia), where can I grow food, generate power etc etc (Strata bylaw restrictions etc etc)? If I had access to 1 acre block of land within commuting distance to work, I’d need to be wealthier than Al Gore (Thanks to oil for him and soon carbon credits).