Environment

Polychlorinated diphenyl ethers (PBDEs), common in flame retardants, have shown steady increases in the environment. These compounds accumulate through the food chain, reaching high levels in top predators. A new study published in the latest issue of Environmental Toxicology and Chemistry provides the first evidence of the harmful effects of these contaminants to a mammalian top predator, the mink.

The 11,000 members of three scientific societies with its roots in agriculture have been closely watching the reports coming out of the Intergovernmental Panel on Climate Change (IPCC).

It is the IPCC’s 4th Assessment Report released on April 6, "Climate Change 2007: The Physical Science Basis" that points to the direct consequences of climate change. Leading scientists from all over the world contributed to the latest installment of this report that attributes ecosystem changes to human-induced global warming. Following the release of the report, the presidents of the American Society of Agronomy (ASA), Crop Science Society of America (CSSA), and Soil Science Society of America (SSSA) issued this statement today:

Planting and protecting trees—which trap and absorb carbon dioxide as they grow—can help to remove carbon dioxide from the atmosphere. But a new study suggests that, as a way to fight global warming, the effectiveness of this strategy depends heavily on where these trees are planted. In particular, tropical forests are very efficient at keeping the Earth at a happy, healthy temperature.

The researchers, including Ken Caldeira of Carnegie’s Department of Global Ecology and Govindasamy Bala at Lawrence Livermore National Laboratory, found that because tropical forests store large amounts of carbon and produce reflective clouds, they are especially good at cooling the planet.

The nonnative invasive grass Microstegium vimineum may hinder the regeneration of woody species in southern forests. Chris and Sonja Oswalt (Forest Service Southern Research Station) and Wayne Clatterbuck (University of Tennessee) set up experiments on a mixed-hardwood forest in southwest Tennessee to study the growth of the invasive grass under different levels of forest disturbance. Study results were published online in the journal Forest Ecology and Management on March 27, 2007.

A new study coordinated by the New York-based Wildlife Conservation Society and other groups found that Central Africa’s increasing network of roads – which are penetrating deeper and deeper into the wildest areas of the Congo Basin – are becoming highways of death for the little known forest elephant. The study, which appears in the journal Public Library of Science, concludes that forest elephants are severely impacted by ivory poachers who use roads to gain access into their remote jungle home. In addition, roads serve as conduits of advancing human settlement fragmenting previously intact forests where elephants live.

It is a natural history tale that every third grader knows: The dinosaurs ruled the Earth for hundreds of millions of years, until an asteroid struck the Yucatan Peninsula and triggered a mass extinction that allowed the ancestors of today’s mammals to thrive.

The asteroid part of the story may still hold true, but a new study challenges the notion that a mass extinction of dinosaurs 65 million years ago played a major role in the dominance of today’s mammals.

The success of science based management in Alaska is emphasized in a newly released report. “Conserving Alaska’s Oceans,” was prepared by Natural Resources Consultants, a research organization based in Seattle, Washington and released by the Marine Conservation Alliance. The report outlines 30 years of improved ocean conservation in the waters off Alaska with recommendations for future action. The “Alaska Model” has been cited as a leading example of science-based management. In Alaska catch limits do not exceed the harvests recommended by science advisers, and there are no overfished stocks of fish. Alaska produces more than 50% of the nation’s seafood.

Over a span of two decades, warming temperatures have caused annual losses of roughly $5 billion for major food crops, according to a new study by researchers at the Carnegie Institution and Lawrence Livermore National Laboratory.

From 1981-2002, warming reduced the combined production of wheat, corn, and barley—cereal grains that form the foundation of much of the world’s diet—by 40 million metric tons per year.

Researchers at the Smithsonian Environmental Research Center report the results of a six-year experiment in which doubling the atmospheric greenhouse gas carbon dioxide (CO2) in a scrub oak ecosystem caused a reduction in carbon storage in the soil.

The scientists said this response suggests a limited capacity of Earth’s ecosystems to stabilize atmospheric CO2 and slow global warming. These findings add a new perspective and a measure of caution suggesting that elevated CO2, by altering microbial communities, may turn a potential carbon sink into a carbon source.

Previous studies have shown that plants will respond to higher CO2 by increasing growth and taking up much of the excess carbon.

The French Intergovernmental Panel on Climate Change (IPPC, or GIEC in French) has just announced the conclusions of its 4th report, which restates that global warming has increased the average temperature by 0.74°C over the last century. However, there is very little information about some parts of the planet, such as central Asia.