Study Gives Clearer Picture of How Land-use Changes Affect U.S. Climate

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.

land-use-graphic

This map shows observation minus reanalysis (OMR) trends in the continental United States from 1979-2003. The trends are associated with land use and land-use changes. Researchers from Purdue and the universities of Colorado and Maryland conducted a study that showed land use can affect surface temperatures locally and regionally. Units are in degrees Celsius per decade. (Image courtesy of Souleymane Fall)

“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.

[Source: Purdue news release]

Writer: Greg Kline, 765-494-8167, gkline@purdue.edu

Sources: Souleymane Fall, 765-494-9138, sfall@purdue.edu

Dev Niyogi, 765-494-6574, climate@purdue.edu

African Desert Rift Confirmed as New Ocean in the Making

rift

Photo: University of Rochester

Geologists Show that Seafloor Dynamics Are at Work in Splitting African Continent

In 2005, a gigantic, 35-mile-long rift broke open the desert ground in Ethiopia. At the time, some geologists believed the rift was the beginning of a new ocean as two parts of the African continent pulled apart, but the claim was controversial.

Now, scientists from several countries have confirmed that the volcanic processes at work beneath the Ethiopian rift are nearly identical to those at the bottom of the world’s oceans, and the rift is indeed likely the beginning of a new sea.



The new study, published in the latest issue of Geophysical Research Letters, suggests that the highly active volcanic boundaries along the edges of tectonic ocean plates may suddenly break apart in large sections, instead of little by little as has been predominantly believed. In addition, such sudden large-scale events on land pose a much more serious hazard to populations living near the rift than would several smaller events, says Cindy Ebinger, professor of earth and environmental sciences at the University of Rochester and co-author of the study.

“This work is a breakthrough in our understanding of continental rifting leading to the creation of new ocean basins,” says Ken Macdonald, professor emeritus in the Department of Earth Science at the University of California, Santa Barbara, and who is not affiliated with the research. “For the first time they demonstrate that activity on one rift segment can trigger a major episode of magma injection and associated deformation on a neighboring segment. Careful study of the 2005 mega-dike intrusion and its aftermath will continue to provide extraordinary opportunities for learning about continental rifts and mid-ocean ridges.”

“The whole point of this study is to learn whether what is happening in Ethiopia is like what is happening at the bottom of the ocean where it’s almost impossible for us to go,” says Ebinger. “We knew that if we could establish that, then Ethiopia would essentially be a unique and superb ocean-ridge laboratory for us. Because of the unprecedented cross-border collaboration behind this research, we now know that the answer is yes, it is analogous.”

Atalay Ayele, professor at the Addis Ababa University in Ethiopia, led the investigation, painstakingly gathering seismic data surrounding the 2005 event that led to the giant rift opening more than 20 feet in width in just days. Along with the seismic information from Ethiopia, Ayele combined data from neighboring Eritrea with the help of Ghebrebrhan Ogubazghi, professor at the Eritrea Institute of Technology, and from Yemen with the help of Jamal Sholan of the National Yemen Seismological Observatory Center. The map he drew of when and where earthquakes happened in the region fit tremendously well with the more detailed analyses Ebinger has conducted in more recent years.

Ayele’s reconstruction of events showed that the rift did not open in a series of small earthquakes over an extended period of time, but tore open along its entire 35-mile length in just days. A volcano called Dabbahu at the northern end of the rift erupted first, then magma pushed up through the middle of the rift area and began “unzipping” the rift in both directions, says Ebinger.

Since the 2005 event, Ebinger and her colleagues have installed seismometers and measured 12 similar—though dramatically less intense—events.

“We know that seafloor ridges are created by a similar intrusion of magma into a rift, but we never knew that a huge length of the ridge could break open at once like this,” says Ebinger. She explains that since the areas where the seafloor is spreading are almost always situated under miles of ocean, it’s nearly impossible to monitor more than a small section of the ridge at once so there’s no way for geologists to know how much of the ridge may break open and spread at any one time. “Seafloor ridges are made up of sections, each of which can be hundreds of miles long. Because of this study, we now know that each one of those segments can tear open in a just a few days.”

Ebinger and her colleagues are continuing to monitor the area in Ethiopia to learn more about how the magma system beneath the rift evolves as the rift continues to grow.

Additional authors of the study include Derek Keir, Tim Wright, and Graham Stuart, professors of earth and environment at the University of Leeds, U.K.; Roger Buck, professor at the Earth Institute at Columbia University, N.Y.; and Eric Jacques, professor at the Institute de Physique du Globe de Paris, France.

[Source: University of Rochester news release]

Adaptive Classification Using Self Organizing Maps

v1…from V1 Magazine

“As humans, we have an innate and natural tendency to establish patterns and associations in our environment. Consider for a moment, the capability of the human brain to “process millions of visual, acoustic, olfactory, tactile, and motor data, and…the astonishing ability to learn from experience, generalize from learned rules, recognize patterns, and make decisions”. The ability to recognize patterns allows us to distinguish objects one from another; to interpret sound waves as speech; and to understand the unique patterns of individual letters that collate to form words and sentences.

“These skills provide meaning, knowledge, and experience to the observer. It is difficult to mimic this type of pattern recognition and establishment of data relationships in a computational context.

“In other words, how do you train a computer to evaluate disparate datasets in order to recognize the difference between desert and forest conditions or understand the type of complex relationships that the human mind can resolve after many years of experience?”

Call for Papers: GIScience Research Track at the 2010 ESRI User Conference

esriCall for Papers:

GIScience Research Track
ESRI International User Conference
12-16 July, 2010
San Diego, California

ESRI invites you to present a peer-reviewed paper in a GIScience Research Track for the 2010 ESRI International User Conference and Educational User Conference. Papers in this special track must focus on cutting-edge research in GIScience. Full papers will be included in a special issue of Transactions in GIS to be distributed at the 2010 Conference. Abstracts (500 words) must be submitted to Dr. John Wilson, University of Southern California, by 15th December, 2009.

The Transactions in GIS editorial team will review abstracts based on their GIScience content and select nine abstracts to become full papers. Notice of acceptance will occur by 22nd December, 2009. Full papers (maximum 6,000 words plus figures, tables, and references in appropriate format for publication) must be submitted to Dr. Wilson for independent review by 15th February, 2010. Reviewed papers will be returned to authors by 15th March, 2010 and final manuscripts must be returned by 8th April, 2010, to be included in the special issue of Transactions in GIS.

For questions or guidelines on this GIScience Research Track, please contact Michael Gould at mgould@esri.com.

Abstracts should be submitted via email with a subject line “ESRI GIScience Abstract, Authors Last Name” no later than 15th December, 2009 to:

Dr. John Wilson, jpwilson@college.usc.edu

A Scan Statistic for Continuous Data Based on the Normal Probability Model

International Journal of Health Geographics 2009, 8:58

Martin Kulldorff, Lan Huang, Kevin Konty

Temporal, spatial and space-time scan statistics are commonly used to detect and evaluate the statistical significance of temporal and/or geographical disease clusters, without any prior assumptions on the location, time period or size of those clusters. Scan statistics are mostly used for count data, such as disease incidence or mortality. Sometimes there is an interest in looking for clusters with respect to a continuous variable, such as lead levels in children or low birth weight. For such continuous data, we present a scan statistic where the likelihood is calculated using the the normal probability model. It may also be used for other distributions, while still maintaining the correct alpha level. In an application of the new method, we look for geographical clusters of low birth weight in New York City.