Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Alaskan lakes are drying up, signal of warming climate

13.10.2006
Shrinking Ponds Signal Warmer, Dryer Alaska; 50 Years of Images Show Dramatic Change

Between 1950 and 2002, more than 10,000 Alaskan lakes have shrunk in size or completely dried up, according to a newly published study. Over this period, Alaska has experienced a warming climate with longer growing seasons, increased thawing of permafrost, and greater water loss due to evaporation from open water and transpiration from vegetation; yet there has been no substantial change in precipitation.

Three scientists at the University of Alaska Fairbanks' Bonanza Creek Long-Term Ecological Research Program studied 50 years of remotely sensed imagery and conclude that these landscape- level changes in Arctic ponds are associated with recent climate warming in Alaska and may have profound effects on climate and wildlife.

The shrinking of these closed-basin ponds may be indicative of widespread lowering of the water table throughout low-lying landscapes in Interior Alaska, write the authors. A lowered water table negatively affects the ability of wetlands to regulate climate, because it enhances the release of carbon dioxide by exposing carbon in the soil to aerobic decomposition. Their report appeared 10 October in the Journal of Geophysical Research-- Biogeosciences.

"No one has done a state water-body inventory of this magnitude, said Brian Riordan, lead author of the study. "It will allow land managers to stop speculating about possible water body loss and begin to address the implications of this loss."

"Alaska is important in terms of waterfowl production, and if you have a lowering of the water table, that could have a potentially huge impact on waterfowl production," said David Verbyla, a co- author of the study.

"This is an issue relevant to flyway management, in terms of all the ducks that might use the Yukon Flats National Wildlife Refuge and overwinter elsewhere, and this is something that goes beyond the refuges in Alaska," said David McGuire, the third member the research team.

National Wildlife Refuges cover more than 31 million hectares [77 million acres] in Alaska comprising 81 percent of the national refuge system. These refuges provide breeding habitat for millions of migratory waterfowl and shorebirds that overwinter in more southerly regions of North America.

Using black and white aerial photographs from the 1950s, color infrared aerial photographs from 1978-1982, and digital Landsat satellite images from 1999-2002, Riordan outlined each pond by hand. "With automated classification, your accuracy goes down," he said.

Cloud shadows can look like water, and Alaska rarely experiences a cloudless day, said Verbyla. The most difficult part of the four- year project, said Riordan, was "having the patience to circle 10,000 ponds for each time period."

The main study area was the subarctic boreal region of Interior Alaska, which spans more than five million square kilometers [two million square miles] bounded on the north by the Brooks Range and on the south by the Alaska Range. To contrast the semi-arid, subarctic sites of discontinuous permafrost in Interior Alaska, the authors also selected study areas in the Arctic Coastal Plain, where the temperatures are much colder, the growing season much shorter, and the permafrost is continuous, as well as a more maritime site south of the Alaska Range.

All ponds in the study regions in subarctic Alaska showed a reduction in area of between four and 31 percent, with most of the change occurring since the 1970s. The ponds in the Arctic Coastal Plain showed negligible change.

The research project was funded in part by NASA, the National Science Foundation, and the U.S. Department of Agriculture.

Harvey Leifert | American Geophysical Union
Further information:
http://www.agu.org
http://www.uaf.edu

More articles from Earth Sciences:

nachricht Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>