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.
###
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.
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.” Bruce Cobb
Actually this is a real boon for farmers in the USA. When the new food safety regs go into effect making growing food too cost prohibitive we can switch to growing trees and being paid by corporate carbon offset dollars.
Now I just have to figure out the marketing and ways around the regulations so I can feed at the public trough too….
Oh yeah I hope you like to eat dead tree leaves since the USA used to grow 25% of the worlds food supply.
This one has me scathing my head:
http://devoidofnulls.wordpress.com/2009/11/03/im-perplexed/
I think this type of study must be considered before we convert 10-20% of the desert southwest into a mirror or other solar collector surface. These large solar farms that have been proposed could have a large regional impact on climate. I have wondered if the removal of such a large amount of solar heating in this area will result in lower nighttime temperatures and what impact that has on local wildlife survival in winter months. Although the solar heating that is being intercepted by the solar farms is small, I would expect the effect to be non-zero and somewhat cumulative over time.
I believe that land use change is the major climate warming vehicle and the larger environmental threat; however, I fail to see how the posted map makes the case.
The areas of Colorado, Utah, Wyoming, and Idaho that show the greatest temperature increases have had little development or land use change. If anything, the BLM leases on public lands have reduced grazing pressures.
The rapidly growing urban areas of Florida and Texas generally show no significant change. Although Minneapolis and Boston show increases, the much faster growing areas of Northern Virginia and Oklahoma City show declines. Coastal Southern California shows a small increase, but the Antelope Valley, an area of massive land use change in the past two decades, shows a significant decline.
To repeat, although I believe that land use change is key to warming – this map doesn’t seem to make much of a case.
The Dust Bowl disaster in Mid-Western States in the 1930’s and 1940’s was the direct result of a change in land use. The hitherto robust grassland, which had been capable of withstanding extended periods of drought, was replaced by crops which did not have this resistance. Consequently, long periods of dry weather caused the crops to wither and die, and the topsoil was then no longer secured. It blew off as fine dust, causing choking black storms. The weather for the whole region was substantially modified, and the drought became even more extended as a result.
The whole process started with a government initiative to provide free land for farmers and encourage change of land use for productive farming.
This well-documented event demonstrates clearly that man can indeed modify local climate to a very significant extent, and emphasises that change of land use is a key component in this process.
In the UK, while the government is proposing to adopt draconian measures to cut CO2, it continues to encroach on substantial areas of green land for housing development, while leaving old industrial city areas barren wasteland.
Gail Combs says:
If growing seasons are affected by “climate change” (and by climate change I mean cooling) then it might still do so (except in California where there will be no water allotted to the Central Valley). However, overall, less food will be grown.
Hold on to your hats. Interesting time ahead.
Finally!
IMO, climate natural variability + sun radiation change + land use change = 100% temperature change.
The cycle of water eats huge amount of sun energy when water is changed into vapor. I think it is something like half a year of sun radiation stored in water cycle.
Deplete the cycle of water and this sun energy has to go somewhere else…heat. And we all can see rivers levels have been decreasing because of land use change, this is a well known fact -> land use change may have a very underestimated influence on temperature.
It’s not only a simple question of albedo…land use change has a long chain of consequences sorry for poor english.
You would think a forest fire and the resulting blackened earth left behind would be an extreme case of land surface change effecting temps.
@Alan the Brit
The Professor Nutt escapade is quite amusing – not least because both the existing Home Secretary Alan Johnson and his predecessor Jacqui Smith (not to mention Brown) both obviously reckoned that they should be able to expect scientific experts to provide backing for whatever fashionable soundbyte they thought would play best with the press and the sheeple.
But there is a difference with AGW. Here both this Government and previous governments for at least 20 years have been avidly stuffing hard line eco fascist AGW worshippers into every possible key “scientific” advisor position. Robert Napier, David McKay, Lord Stern, Lord Turner, David King. The list goes on and on. Plus they have used backdoor influence to make sure that the management boards of NGOs, charities and Scientific Institutions, even the Royal Society are packed with ‘reliable’ people.
Consequently, what kind of “scientific advice” do you think they receive?
A bit like the old fable of the parish church clock which always agreed with the time the village watchmaker showed in his shop window. Every morning when the church warden went to work he set his watch by the clock in the watchmaker’s window, then adjusted the church clock when he arrived. And every lunchtime, the watchmaker set the clock in his window when the parish church clock started to chime.
“Terry Jackson (23:04:50) :
Without disputing anything, isn’t albedo the be all and end all of temperature correlation?”
Albedo is a huge factor, but plants (green or otherwise) which use energy in photosynthesis, soak up and convert the energy into growth, so it’s not available to warm the local climate (until it burns or decomposes). And plants release water into the atmosphere, through evapotranspiration, which cools the local climate.
If not to “address climate change”, because unless you change the Length of the Day you won’t change anything, at least having parks it’s beautiful. They will be colder as we enter the new Maunder like minimum, but nice anyway.
Juraj V. (00:50:16) :
“I am quite surprised that agricultural land changes lead to cooling. ”
Trees reduce wind flow and thus forests will be warmer than open fields due to higher wind chill and evaporation in open fields.
More about land cover change to weather/climate can be found in “Impact of land cover change on the climate of southwest Western Australia”, (Pitman, Narisma, Pielke Snr, Holbrook, 2004).
http://www.waclimate.net/land-clearing.pdf (580kb)
Extract: “We explore an alternative hypothesis that large-scale land cover change explains the observed changes in rainfall and temperature. We use three high-resolution mesoscale model configurations forced at the boundaries to simulate (for each model) five July climates for each of natural and current land cover. We find that land cover change explains up to 50% of the observed warming. Following land cover change, we also find, in every simulation, a reduction in rainfall over southwest Western Australia and an increase in rainfall inland that matches the observations well. We show that the reduced surface roughness following land cover change largely explains the simulated changes in rainfall by increasing moisture divergence over southwest Western Australia and increasing moisture convergence inland. Increased horizontal wind magnitudes and suppressed vertical velocities over southwest Western Australia reduce the likelihood of precipitation. Inland, moisture convergence and increased vertical velocities lead to an increase in rainfall.
… Since we are simulating isolated months (July) we cannot capture trends in soil moisture associated with drying in June, and we therefore probably underestimate the large-scale impact of LCC on the latent heat flux and temperature.”
Temperature data from the 1800s to now (http://www.waclimate.net) suggests a cooling in some towns within the area of southwest Western Australia cleared for agriculture. Averaging temps from the available 32 locations across Western Australia with 100+ year records, the state’s maximum has increased by .6 degrees C and its minimum has increased by 3.9 degrees C when comparing the early 20th C average to the 12 months up to and including October 2009.
AManuel (08:32:14) :
“I think this type of study must be considered before we convert 10-20% of the desert southwest into a mirror or other solar collector surface. These large solar farms that have been proposed could have a large regional impact on climate. ”
As a new resident of Burbank, I’m looking forward to cooler climate in the Mojave keeping the Santa Ana winds blowing cool air downhill for more of the year. Maybe it will help with precipitation as well…
Goreacle Report: Al moves on.
Gore tosses CO2 into the ash heap of his history:
“”Over the years I have been among those who focused most of all on CO2, and I think that’s still justified,” he told the magazine. “But a comprehensive plan to solve the climate crisis has to widen the focus to encompass strategies for all” of the greenhouse culprits identified in the Nasa study.”
“Gore acknowledged to Newsweek that the findings could complicate efforts to build a political consensus around the need to limit carbon emissions.”
…-
“”He is one of the only politicians that takes the time to actually talk to scientists who are producing the cutting-edge stuff and he comes in with questions. He doesn’t ask us how our results impinge on a particular policy he actually asks about science,” said Gavin Schmidt, a climatologist at Nasa’s Goddard Institute for Space Studies, who spoke to Gore along with colleagues four or five times for the book.
>>> “Nobody that we have dealt with has ever taken as much time to understand the subtlety of the science and all the different complications and what it all means as Al Gore.”
Those conversations led Gore to politically inconvenient conclusions in this new book. In his conversations with Schmidt and other colleagues at the beginning of the year, Gore explored new studies – published only last week – that show methane and black carbon or soot had a far greater impact on global warming than previously thought. Carbon dioxide – while the focus of the politics of climate change – produces around 40% of the actual warming.
Gore acknowledged to Newsweek that the findings could complicate efforts to build a political consensus around the need to limit carbon emissions.
“Over the years I have been among those who focused most of all on CO2, and I think that’s still justified,” he told the magazine. “But a comprehensive plan to solve the climate crisis has to widen the focus to encompass strategies for all” of the greenhouse culprits identified in the Nasa study.
The former vice-president has been working behind the scenes to try to nudge the White House and Congress to move forward on a 920-page proposed law to cut America’s greenhouse gas emissions and encourage its use of clean energy sources like solar and wind power.”
“Al Gore’s Inconvenient Truth sequel stresses spiritual argument on climate
Nobel winner adapts fact-based message to reach those who believe they have a moral duty to protect the planet in Our Choice: A Plan to Solve the Climate Crisis”
http://cnews.canoe.ca/CNEWS/Environment/2009/11/03/11617491-reuters.html
Therefore this kind of study clearly shows that the planet’s climatic evolution cannot be inferred from temperatures and that the notion of global warming or cooling derived from surface temperature is a myth.
With the greatest respect to Dr. Pielke, I don’t understand this study at all. Take a look at Figure 9. It shows that:
• when forest is converted to barren, the temperature rises … and when barren is converted to forest, the temperature rises.
• when grass/shrub is converted to barren, the temperature rises … and when barren is converted to grass/shrub, the temperature rises.
• when urban is converted to barren, the temperature drops … and when barren is converted to urban, the temperature drops.
What am I missing here?
The main problem is the huge range of the 95% confidence intervals. Of the fifteen possible pairings, I see only one pair (agriculture to grass/shrub, grass/shrub to agriculture) where the confidence intervals don’t overlap.
In all the rest (as is confirmed by the paradoxical results I quote above), the intervals overlap. It seems to me that the only scientifically sustainable conclusion is that when you go from agriculture to grass/shrub, it warms up, and vice versa.
Clearly, I don’t understand what is going on in the study. Help, anyone?
Politicians won’t want to know about it. Reducing land clearing and deforestation is too political. It is far easier to blame CO2 and win votes by adding new taxes.
Re: Willis Eschenbach (12:40:34)
Willis, you aren’t missing anything (good eye). You have recognized the major inconsistencies with this paper.
What caught my eye in figure 9 were the claims concerning urban areas converted to forest, grass/shrub, agriculture etc. It conjured up in my minds-eye visions of cities being bulldozed to create farmland.
I think the problem is that the land use land cover change was estimated using satellite-based AVHRR data, which is iffy at best. For example, when a new suburban development is built, the trees are freshly-planted and small. As it ages, the trees grow taller, their crowns spread and eventually begin to join. The AVHRR classification then changes from “urban” to “forested”. How “urban” becomes “agricultural” I can’t imagine.
I also agree with your observations of the CI’s in fig 9. There really isn’t much useful information in that figure.
I was also bothered by the authors statements of the reliability of the results in that figure due to sample size, sometimes lesser, sometimes greater, with no mention of what the sample sizes were.
Frankly, I think the Pielke Sr. group has been banging the “land use change” drum a little too loudly, and got a little too carried away with this paper.
Philip_B (05:10:52) : Is there a link to this available, Philip?
Once again I find myself bringing to attention here the Palouse formations http://en.wikipedia.org/wiki/Palouse. The hills of fertile soil are basically silt dust blown in from other regions during times of drought, similar to the dust bowl era but clearly not related to human activity. The dust bowl era has no relation to human activity in that the weather pattern variation that set up the blowing dust had nothing to do with human activity. Some say that farming practices made it worse. I beg to differ. All you have to do is measure the depth of the Palouse soil to know that nature trumps humans. Everytime.
Well it has been confirmed. There is a bias in the surface records of temperature. The bias is towards a greater warming trend than actual, as recorded by satellite records.
New Paper Documents A Warm Bias In The Calculation Of A Multi-Decadal Global Average Surface Temperature Trend – Klotzbach Et Al (2009)
“An Alternative Explanation For Differential Temperature Trends At The Surface And In The Lower Troposphere” By Klotzbach Et Al 2009
the link: http://pielkeclimatesci.wordpress.com/
240 years ago, the great historian, Edward Gibbon appealed to changing land use as the cause of a warming climate.
Part I of Chapter IX: The State of Germany till the
Invasion of the Barbarians, in the Time of the Emperor Decius of The
History of the Decline and Fall of the Roman Empire by Edward
Gibbon originally published in 1776:
Some ingenious writers have suspected that Europe was much colder formerly than it is at present; and the most ancient descriptions of the climate of Germany tend exceedingly to confirm their theory. The general complaints of intense frost and eternal winter, are perhaps little to be regarded, since we have no method of reducing to the accurate standard of the thermometer, the feelings, or the expressions, of an orator born in the happier regions of Greece or Asia.
But I shall select two remarkable circumstances of a less equivocal nature. 1. The
great rivers which covered the Roman provinces, the Rhine and the Danube, were frequently frozen over, and capable of supporting the most enormous weights. The barbarians, who often chose that severe season for their inroads, transported, without apprehension or danger, their numerous armies, their cavalry, and their heavy wagons, over a vast and solid bridge of ice. Modern ages have not presented an instance of a like phenomenon. 2. The reindeer, that useful animal, from whom the savage of the North derives the best comforts of his dreary life, is of a constitution that supports, and even requires, the most intense cold. He is found on the rock of Spitzberg, within ten degrees of the Pole; he seems to delight in the snows of Lapland and Siberia: but at present he cannot subsist, much less multiply, in any country to the south of the Baltic. In the time of Caesar the reindeer, as well as the elk and the wild bull, was a native of the Hercynian forest, which then
overshadowed a great part of Germany and Poland.
The modern improvements sufficiently explain the causes of the diminution of the cold. These immense woods have been gradually cleared, which intercepted from the earth the rays of the sun. The morasses have been drained, and, in proportion as the soil has been cultivated, the air has become more temperate. Canada, at this day, is an exact picture of ancient Germany. Although situated in the same parallel with the finest provinces of France and England, that country experiences the most
rigorous cold. The reindeer are very numerous, the ground is covered with deep and lasting snow, and the great river of St. Lawrence is regularly frozen, in a season when the waters of the Seine and the Thames are usually free from ice.
http://www.nytimes.com/2007/08/14/science/earth/14fenc.html
At Australia’s Bunny Fence, Variable Cloudiness Prompts Climate Study
By SONAL NOTICEWALA
August 14, 2007
A fence built to prevent rabbits from entering the Australian outback has unintentionally allowed scientists to study the effects of land use on regional climates.
The rabbit-proof fence — or bunny fence — in Western Australia was completed in 1907 and stretches about 2,000 miles. It acts as a boundary separating native vegetation from farmland. Within the fence area, scientists have observed a strange phenomenon: above the native vegetation, the sky is rich in rain-producing clouds. But the sky on the farmland side is clear.
Researchers led by Tom Lyons of Murdoch University in Australia and Udaysankar S. Nair of the University of Alabama in Huntsville have come up with three possible explanations for this difference in cloudiness.