Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Landcover changes may rival greenhouse gases as cause of climate change

01.10.2002


These simulations are examples of how global land-use changed from 1700 to 1990. The human-disturbed landscape includes intensive cropland (red), and marginal cropland used for grazing (pink). Other landscape includes, for example, tropical evergreen and deciduous forest (dark green), savanna (light green), grassland and steppe (yellow), open shrubland (maroon), temperate deciduous forest (blue), temperate needleleaf evergreen forest (light yellow), and hot desert (orange). Of particular importance in this paper is the expansion of the cropland and grazed land between 1700 and 1900. Credit: from Klein Goldewijk, K., 2001: Estimating global land use change over the past 300 years: The HYDE Database. Global Biogeochemical Cycles, 15, 417-433


Global Land Use in 1990
Credit: from Klein Goldewijk, K., 2001: Estimating global land use change over the past 300 years: The HYDE Database. Global Biogeochemical Cycles, 15, 417-433


While many scientists and policy makers have focused only on how heat-trapping gases like carbon dioxide are altering our global climate, a new NASA-funded study points to the importance of also including human-caused land-use changes as a major factor contributing to climate change.

Land surface changes, like urban sprawl, deforestation and reforestation, and agricultural and irrigation practices strongly affect regional surface temperatures, precipitation and larger-scale atmospheric circulation. The study argues that human-caused land surface changes in places like North America, Europe, and southeast Asia, redistribute heat regionally and globally within the atmosphere and may actually have a greater impact on climate than that due to anthropogenic greenhouse gases combined.

The study also proposes a new method for comparing different human-influenced agents of climate change in terms of the redistribution of heat over land and in the atmosphere. Using a single unit of measurement may open the door to future work that more accurately represents human-caused climate change.



"Our work suggests that the impacts of human-caused landcover changes on climate are at least as important, and quite possibly more important than those of carbon dioxide," said Roger Pielke, Sr., an atmospheric scientist at Colorado State University, Fort Collins, Colo., and lead author of the study. "Through landcover changes over the last 300 years, we may have already altered the climate more than would occur associated with the radiative effect of a doubling of carbon dioxide." If carbon dioxide (CO2) emissions continue at current rates, atmospheric CO2 concentrations are expected to double by 2050. Land surface changes will also continue to occur.

Types of land surface strongly influence how the Sun’s energy is distributed back to the atmosphere. For example, if a rainforest is removed and replaced with crops, there is less transpiration, or evaporation of water from leaves. Less transpiration leads to warmer temperatures in that area. On the other hand, if farmland is irrigated, more water is transpired and also evaporated from moist soils, which cools and moistens the atmosphere, and can affect precipitation and cloudiness.

Similarly, forests may influence the climate in more complicated ways than previously thought. For example, in regions with heavy snowfall, reforestation or afforestation would cause the land to reflect less sunlight, and more heat would be absorbed, resulting in a net warming effect despite the removal of CO2 from the atmosphere through photosynthesis during the growing season. Further, reforestation could increase transpiration in an area, putting more water vapor in the air. Water vapor in the troposphere is the biggest contributor to greenhouse gas warming.

Local land surface changes can also influence the atmosphere in far-reaching ways, much like regional warming of tropical eastern and central Pacific Ocean waters known as El Niño. El Niño events create moist rising air, thunderstorms and cumulus clouds, which in turn alter atmospheric circulations that export heat, moisture, and energy to higher latitudes. Tropical land surface changes should be expected to play a greater role on global climate than El Niño, given that thunderstorms prefer to form over land, and the fact that the large area of tropical land-use changes far exceeds the relatively small area of water responsible for El Niño. Impacts of land use changes are harder to detect because they are permanent, as opposed to El Niño, which comes and goes.

Pielke Sr., and colleagues propose a new method for measuring the impacts of both greenhouse gases and landcover changes by using a formula that quantifies all the various anthropogenic climate change factors in terms of the amount of heat that is redistributed from one area to another. This heat redistribution is stated in terms of watts per meter squared, or the amount of heat associated with a square meter area. For example, if a flashlight generated heat of one watt that covers a square meter, then the heat energy emitted would be one watt per meter squared.

By using a measure based on the spatial redistribution of heat to quantify the different human influences on climate, including landcover changes and greenhouse gases, the researchers hope to achieve a more accurate portrayal of all of the anthropogenic influences on climate change in future research.


*** The paper was published in a recent issue of the Philosophical Transactions of the Royal Society of London. The research was funded by grants from NASA and the National Science Foundation. ***

Krishna Ramanujan | EurekAlert!

More articles from Ecology, The Environment and Conservation:

nachricht Scientists produce a new roadmap for guiding development & conservation in the Amazon
09.12.2016 | Wildlife Conservation Society

nachricht Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>