Study finds a better way to gauge the climate costs of land use changes

Jan 08, 2012
Tropical rainforests have an even greater climate cooling impact when biophysical attributes, such as evapotranspiration, are included in calculations. Other eco-regions, such as boreal forests, have less climate cooling potential when biophysical attributes are also considered. Credit: Kristina Anderson-Teixeira

Those making land use decisions to reduce the harmful effects of climate change have focused almost exclusively on greenhouse gases – analyzing, for example, how much carbon dioxide is released when a forest is cleared to grow crops. A new study in Nature Climate Change aims to present a more complete picture – to incorporate other characteristics of ecosystems that also influence climate.

"We know that forests store a lot of carbon and clearing a forest releases into the atmosphere and contributes to climate change," said University of Illinois postdoctoral researcher Kristina Anderson-Teixeira, who pioneered the new approach with plant biology and Energy Biosciences Institute professor Evan DeLucia. "But ecosystems provide other climate regulation services as well."

The climate effects of a particular ecosystem also depend on its physical attributes, she said. One such attribute is its reflectivity, a quality climate scientists call albedo.

"If you think of an open snow-covered field or bare sandy soil, that ground acts somewhat like a mirror, reflecting solar radiation back to space," Anderson-Teixeira said. "In contrast, a forest is dark and absorbs a lot of solar radiation. In that sense, any type of vegetation is going to warm the land surface to some extent."

Another factor that should be considered is an ecosystem's ability to release heat through the evaporation of water. The more water available in an ecosystem, the more it cools itself by evapotranspiration or, as DeLucia puts it, "planetary sweating."

"It takes a great deal of energy to convert liquid water to vapor, and this transition cools the soil and the surface of leaves as water evaporates, in the same way that sweating cools your skin," said DeLucia, who also is an affiliate of the Institute for Genomic Biology at Illinois.

Scientists have known about biophysical effects for a long time, Anderson-Teixeira said. "But the challenge has been to incorporate them into a single metric that will help us design land-use policies that are going to help mitigate – and not exacerbate – climate change."

To tackle this problem, Anderson-Teixeira and DeLucia teamed with University of Minnesota professors Peter Snyder and Tracy Twine; professor Santiago Cuadra, of the Federal Center of Technological Education in Rio de Janeiro; and professor Marcos Costa, of the Ministry of Science, Technology and Innovation in Brazil. The researchers compiled data to calculate the "greenhouse gas value" of 18 "ecoregions" across North and South America, and also modeled the ecoregions' biophysical characteristics. They looked at several types of forest, as well as grassland, tundra, tropical savanna and agricultural crops, such as soy, sugarcane, corn, miscanthus and switchgrass. (Please see graphic.)

"The challenge of combining the with the biophysical effects is that they operate over very different spatial and temporal scales," Anderson-Teixeira said. To integrate the two, the researchers first divided the local biophysical effects by the global land surface area. They then combined the measures and converted the values into carbon dioxide equivalents, a common currency in the world of climate mitigation.

The researchers found that biophysical attributes make a tropical rainforest even more valuable for protection against climate warming, but lessen the climate value of boreal (evergreen) forests in Canada.

Any forest provides a climate service by storing carbon, the researchers said, but forests also absorb more solar radiation than bare ground. Tropical forests cool the land by evapotranspiration, but northern boreal forests have much lower evapotranspiration and are dark in comparison to open spaces. These factors give Amazon forests "the highest climate regulation value of all the ecoregions we studied," Anderson-Teixeira said.

Crops also have an enhanced climate-regulating value when their biophysical attributes are considered, DeLucia said.

"When considering only their effect on greenhouse gases, annually tilled row crops like corn tend to have a warming effect by contributing large quantities of nitrous oxide and carbon dioxide to the atmosphere," he said. "But when you factor in the ability to reflect solar energy and high rates of evapotranspiration, the net effect (compared with bare ground) is cooling."

Ecosystems perform a lot of other services of importance to humans and the planet, DeLucia said.

"While the climate-regulating value that we propose in this paper captures how ecosystems affect climate, it is important to note that this is only one of many services ecosystems provide," he said. "Ultimately the value of any given ecosystem to society must include these other services, including biodiversity, water purification and the production of food and fiber, to name just a few."

The researchers note that theirs is not the only valid way to quantify the climate services various ecosystems offer. But it captures more of the picture than previous methods have.

"We hope that this approach will help to design land-use policies that protect the ," Anderson-Teixeira said.

Explore further: Dead floppy drive: Kenya recycles global e-waste

More information: "Climate Regulation Services of Natural and Agricultural Ecoregions of the Americas," Nature Climate Change (2012).

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JDoddsGW
1 / 5 (5) Jan 08, 2012
Another example of scientists looking at the trees and not seeing the forest. Why do you guys look at land use while ignoring the amount of energy coming into thr Earth? Are you that nearsighted?
How can you look at only solar insolation (E/M) radiation while ignoring the energy from decay heat (short & Long forces) and energy from gravity variations (eg the moon causes tidal energy, Venus & Jupiter cause gravity variations etc, and you guys look at how energy moves around from land to water etc. We are talking about GLOBAL WARMING. not how much it moves from land to water etc. When we talk about global temp increase, and the FACT OF PHYSICS that the EArth is in equilibrium as forced by the Stefan-Boltzmann Law, why in hell are you blaming land use changes which can NOT change the GLOBAL temperature. Why are you wasting research resources? on something that physically can NOT impact the equilibrium temperature?
Vendicar_Decarian
4 / 5 (10) Jan 08, 2012
JDoddsGW is clearly innumerate.

All of the energy "sources" that he yammers about are minuscule compared to solar radiation, and he is too stupid to be able to estimate them for himself.

Solar radiation accounts for essentially 100% of the surface heating of the earth. Geothermal energy on the other hand accounts for only 0.025 percent of that heating. Tidal energy accounts for 0.002 percent.

Denialist Dodds is so mind-numbingly stupid that he can't even begin to estimate the relative magnitude of the various sources of Earth's surface temperature, and yet he is certain that he knows more about the science than Climate Scientists and Geologists who have spent their lives studying their respective scientific fields.

Davecoolman
1 / 5 (5) Jan 08, 2012

JDoddsGW

Another example of scientists looking at the trees and not seeing the forest. Why do you guys look at land use while ignoring the amount of energy coming into the Earth? Are you that nearsighted?

JD. well put I couldn't agree with you more.

Also the warmist have promoted land clearing and forest removed. Murdered villagers in Africa to grow biofuel crops. Palm oil plantations.Food products like Corn = biofuels = less efficiency / mile = EPA bogas miles/gallon rating etc.. etc...
Davecoolman
1 / 5 (6) Jan 08, 2012
The IPCC tells us in no uncertain terms, that the sun is much to constant to influence climate.

Humans are driving climate change.

The Minoan caused the Minoan Optimum. The Romans caused the Roman Optimum. The fall of Rome caused the Dark Ages. The Vikings caused the Medieval Optimum and the Renaissance caused the Little Ice Age. Now the Industrial Age has caused the Modern Optimum.
Oh the Horror, nothing like this as ever happened before, History is full of lying sceptics!!!!
Pull the other leg!
FrankHerbert
3.4 / 5 (15) Jan 08, 2012

[paranoia]
It is a notorious fact that the UN's IPCC and Al Gore are at this very moment plotting our destruction and threatening the extinction of our political, civil, and religious institutions. We have the best reasons for believing that corruption has found its way into our Executive Chamber, and that our Executive head is tainted with the infectious venom of AGW.
[/paranoia]

That was written in 1855 with VERY FEW modifications.

"The Paranoid Style in American Politics"
http://karws.gso....yle.html