Climate change science

The water cycle amplifies abrupt climate change

Phys.org

19 January, 2014

During the abrupt cooling at the onset of the so-called Younger Dryas period 12680 years ago changes in the water cycle were the main drivers of widespread environmental change in western Europe. Thus, the regional impacts of future climate changes can be largely driven by hydrological changes, not only in the monsoonal areas of the world, but also in temperate areas.

The role of the hydrological cycle during abrupt temperature changes is of prime importance for the actual impact of climate change on the continents. In a new study published in Nature Geoscience online (January 19, 2014) scientists from the University of Potsdam, Germany and the GFZ German Research Centre for Geosciences show that during the abrupt cooling at the onset of the so-called Younger Dryas period 12,680 years ago changes in the water cycle were the main drivers of widespread environmental change in western Europe. The team of scientists analyzed organic remains extracted from Meerfelder maar lake sediments from the Eifel region, western Germany, to reconstruct changes in precipitation patterns in unprecedented detail. They were able to show that the intrusion of dry polar air into western Europe lead to the collapse of local ecosystems and resulted in the observed widespread environmental changes at that time.

Organic remains of plants from lake sediments as molecular rain gauges

The exact sequence of events during abrupt climate changes occurring over only a few years is one of the great unknowns in paleoclimate research. The new results presented here were obtained by using a novel method, where molecular organic remains derived from plant fossils were extracted from precisely dated annually laminated lake sediments. The ratio of the heavy Deuterium to the light Hydrogen isotopes in these biomarkers can be used to reconstruct changes in precipitation regime and moisture sources with unprecedented detail.

Aerial view of Lake Meerfelder Maar in the Eifel region (Western Germany). The lake covers the northern part of the maar crater while the village Meerfeld and agricultural land is seen in the southern part of the crater. Credit: Achim Brauer, 

The Younger Dryas period was the last major cold period at the end of the last glaciation with a duration of about 1100 years, when an abrupt change in the pathway of westerly wind systems over Europe lead to massive environmental change within a few years, as GFZ scientists showed in an earlier study. Dirk Sachse, the head of the workgroup at the Institute of Earth and Environmental Sciences of the Potsdam University explains: "In our new study we can show for the first time that this change in the pathway of westerly wind systems brought dry polar air into western Europe and this was the ultimate cause for the widespread disappearance of forests in the area."

Soil Microbes Alter DNA in Response to Climate Change

EcoNews

20 January, 2014

A 10-year study of soil ecosystems has determined that microbes alter their genetic code in response to a warming climate so they can process excess carbon being absorbed by plants from the atmosphere, a team of U.S. researchers reports in the journal Applied and Environmental Microbiology.

New research shows soil microbes can alter their DNA to adapt to the warming climate. Photo courtesy of Shutterstock

A two degree Celsius temperature increase spurred microbes in soil ecosystems to—over many generations—tweak their DNA, amping up their respiratory systems and converting extra organic carbon in the soil to carbon dioxide.

The soil contained extra carbon because the two degree temperature increase made plants grow faster and higher; when those plants began to die, the carbon in their leaves, stems, and roots was added to the soil and taken up by the microbial community. Understanding the “black box” of carbon’s fate in soil ecosystems holds important clues for better forecasting an ecosystem’s response to climate change, says Georgia Institute of Technology researcher Kostas Konstantinidis, an author of the study.

“One reason that models of climate change have such big room for variation is because we don’t understand the microbial activities that control carbon in the soil,” Konstantinidis said.