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.
Correction..
“I live in an apartment block (Ever growing “solution” in Australia), where can I grow food, generate power etc etc”
Should read..
“I live in an apartment block (Ever growing “solution” in Australia), where *can’t* I grow food, generate power etc etc”
As an architect I need to design with passive solar design principles, such as orientation, heat sinks, wall and roof colour etc. Yet when it comes to the heat island effect on temperatures we are meant to ignore it. So we have a situation where basic solar design principles are required in design to control the temperature of a building but not in recording the temperature.
Robert
Its called climate communism
http://www.twawki.wordpress.com
@Stephen Fisher Wilde (02:43:57) “The phrase reinventing the wheel comes to mind.” Indeed it does, in the course of reading nearly every study, or more precisely, the media take on nearly every study, seen on this blog. Often it’s not just the journalist who hadn’t heard of that before, it’s also the researchers.
With regard to the map accompanying this blog; are the colors reversed? Or are the blues in previously high density areas which just did not change (or got cooler?) in the years covered by the study. Did the southern California desert cool due to land use changes between 1979 and 2003?
What land use changes other than forest fire occurred in the Bitterroot Mountains of east central Idaho and southern Montana? Most of this land is national forest and much of it that is not forested is grassland.
The article is behind a pay wall.
OT, but I thought you might all like this:
http://news.bbc.co.uk/1/hi/england/oxfordshire/8339652.stm
“After the hearing, his solicitor, Shah Qureshi, said: “Essentially what the judgment says is that a belief in man-made climate change and the alleged resulting moral imperative is capable of being a philosophical belief and is therefore protected by the 2003 religion or belief regulations.”
Yes, AGW is a religion, I always knew it was!
The press release (but not the abstract) confuses climate warming with increased (atmospheric) temperatures.
Deforestation generally results in warming
Deforestation results in warmer temperatures. However, this is because forests absorb more solar energy. That is forests result in heat gain to the Earth’s climate system. Remove the forests and some of that heat enters the atmosphere giving warmer atmospheric temperatures. It also of course means that heat will be lost to space, cooling the climate.
Mac (02:49:15) :
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?
Hence my earlier: “Like…um…DUH?” comment. 🙂
Geeks who spend all their time in academia and computerland are clueless about the real world. These “self evident” truths about the natural world escape them.
OT: British courts recognise belief in AGW as a religion.
See this from the bbc.
Does this mean I can get carbon Credits for my 12000 sq ft of lawn?
I suppose I should repeat what I have said before. I live in rural Devon, 15-20 minutes outside the provincial city of Exeter. In the winter evenings, I drive my car out of the driveway, aircon says -3°C. After a few minutes up over the hill & down the other side, aircon reads -2°C. As I approach the outskirts of the city, aircon reads -1°C. In the city centre, aircon reads +1°C. It appears to be the reverse when I return home for some peculiar reason I cannot fathom. Curiously it happens in the summer months too, but a few degrees higher up the scale, (although not the last 3 summers). Not scientific, Peugeot’s electronics may not be the most accurate but the error would be consistent more or less, but it illustrates the point I feel!
How much do these guys get paid for “discovering” all this stuff? I think I need to apply for a research grant as the pension plan looks a little shakey.
This rubbish from Uk Telegraph. http://www.telegraph.co.uk/earth/environment/globalwarming/6486612/Global-warming-ten-most-affected-areas.html
The study is flawed. There is no consideration or mention of the UHI effect putting a warm bias into the temperature record. About all we are really affecting are localized temperatures, not climate.
This is just one more example of agenda-based “science” : creating green spaces and buffer zones in and around urban areas, could be a tool in addressing climate change. How absurd. Sure, they’d be nice to have. But, so would a lot of things.
Until it’s time to try to come up with the money to pay for them.
In Glasgow, Scotland, the clans bequeathed land they owned to the city so that the people of that city – including many “emigrants” of their own – could enjoy it. Seems a better reason than spurious science.
A tree is just a giant “mister.” It’s sucking tons of cool subsurface water up, and expelling it into the atmosphere.
Ask any little kid why he sits up in the tree in the summertime. It’s cooler up there. And, trust me; it’s cooler up in the oak tree than it is in the sweet corn patch.
Until I can read the entire article, I call this one junk. The red bands correspond to exactly what is expected under El Nino conditions, IE the Pacific was in a warm phase. On top of that, I can tell you that the NE corner of Oregon is not exactly what I would call a den of development. If anything can be said, it would be that high desert was turned into green crop circles. Yet the temps remained high. My hunch is that if I were the peer reviewer I would have ripped this article to shreds and recommended it be round filed.
REPLY: The paper is linked below the main article. – Anthony
@terry Jackson The albedo is not the full story. A cornfield may have a low albedo but it uses up a lot of energy in the latent heat of evaporation from the plants.
“I am quite surprised that agricultural land changes lead to cooling.”
Wouldn’t this depend, among other variables, upon latitude and the prevalence of unbroken winter snow cover, and the consequent change in albedo?
New Jersey, for example, the most densely populated state in the U.S., has significantly more tree-cover than it did a century ago–or even fifty years ago– as suburban development has gobbled up farmland, with consequent planting of trees on what used to be cleared fields.
@Alan the Brit In NYC when I was growing up in the 50s, the local temperatures were reported from lower Manhatten. We lived maybe 10 miles away in NJ. The normal adjustment was of the order of 6 degrees F.
We already know what causes climate change and all this “denier” science is designed to purposely confuse the issue. How much oil money funded this study?
Oh, I forgot to mention big tobacco. How much did big tobacco pay for this study? Did the authors take money from big insurance companies?
BTW: This is sarcasm.
For some unknown reason a vision came to mind. Kinda deja vouish, y’know? It’s 2010, we’re flies on the wall in the Oval Office: “Here it is again! Proof positive! As the wierdo Trekees say: ‘It’s all the fault of the Carbon Units infesting planet Earth.’ Wonder what the effect would be of reducing US population levels to those of 1941 (and, of course, the size of the concrete footprints of NYC, LA, Chi-town, Seattle, Philly, etc., etc.). No one wants to face the ugly truth, it’s NOT CO2, it’s over-population. But you know how things are today, it’s not something you can say out loud like a good four letter word, you have to be sensitive to people’s feelings.” When the WH Chief of Staff finished talking, everyone nodded quickly in agreement. (He had a very bad temper. Y’know?)
Doug in Seattle (00:13:44) :
I’m not sure the map goes where the press release leads.
——-
Comparing the map with the Google map, I’d agree. Why no large splotches of dark red in Texas? Why are the large, dark red splotches (CA, WA, CO) in national parks? What land use changes at the Canadian border in MN caused the small splotch of large temp difference?
And from impressions of what’s gone on with land use changes since 1979, shouldn’t there some indication of a bluing in the SE Michigan area at least similar to what is represented in the Buffalo, NY area? Shouldn’t there be more red in FL especially along the Gulf coast?
Does the map only reflect the 1992-2001 land-use changes or did they also take advantage of the plethora of aerial photography that’s been done since 1960 in relation to municipal planning but it is just not mentioned in the Press Release? The 1992-2001 window of land use change seems awfully small to be using to establish a pattern with the preciseness of the temperature changes shown in the legend, especially if it is to also remove natural temperature variations as a contributing variable.
But those concerns aside (and maybe I misread the objective of the work), I can appreciate the effort to establish a rational method for measuring the degree to which land use changes affect surface temperatures to substitute for the memories of those who grew up in cities during the end of the American Elm Era and can tell you how much of a affect trees covering city neighborhoods make to urban temperatures.
Question the data. I suppose that these longish term trends come from surface measurements. surfacestations.org shows exactly how small modifications around a temp probe can change the data for a local area, or region.
If these affects were removed, I suspect there would not be wide spread red regions on the map – just little pin points.
“greener land is cooler”? Who wouldda thunk? My granddad (long since passed away) could have told them that. How much taxpayer dollars did they spend ‘discovering’ what our ancestors have known for millennia?
OT but science related 🙂
Some of you may have recently heard that a chairman of the UK’s Advisory Council on the Misuse of Drugs was sacked by our esteemed (allegedly) Home Secretary due to a difference of opinion that doesn’t warrant identification here. Much embarrassment & anger has risen to the surface (all jolly exciting I must say). However, the interesting point is that Professor Nutt has been most vocal about high quality science & the scientific evidence as opposed to government policy decisions, in this case related to canabis use. The UK’s Chief Scientist has also weighed in about such things & the requirement for government to have top quality science advice provided to it at all times. It will be equally interesting to see if anybody raises the obvious question about AGW & CC! Somehow I think not.
There seems to be a “Latter Day Saints” effect.