I mentioned this earlier

but here is a release of information from a different source. I can’t yet find the photos.

In the meantime, here are illustrations from the Kuskokwim Delta (click on the images to go to where you can see larger sizes.)





Public release date: 12-Oct-2006

Shrinking ponds signal warmer, dryer Alaska
50 years of remotely sensed images show dramatic change

FAIRBANKS, Alaska–A first-of-its kind analysis of fifty years of remotely sensed imagery from the 1950s to 2002 shows a dramatic reduction in the size and number of more than 10,000 ponds in Alaska. The analysis, by University of Alaska Fairbanks scientists and published this week in the Journal of Geophysical Research, indicates 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.

Over the past 50 years, Alaska has experienced a warming climate with longer growing seasons, increased permafrost thawing, an increase in water loss due to evaporation from open water and transpiration from vegetation, and yet no substantial change in precipitation.

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 soil carbon to aerobic decomposition.

“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,” …

“No one has done a state water-body inventory of this magnitude,”said Brian Riordan, lead author and data manager for the Bonanza CreekLong-Term Ecological Research program at UAF. “It will allow landmanagers to stop speculating about possible water body loss and begin to address the implications of this loss.”

Using black and white aerial photographs from the 1950s, color infrared aerial photographs from 1978-1982, and digital images from the Landsat satellite from 1999-2002, Riordan outlined each pond by hand. …

The main study area was the subarctic boreal region of Interior Alaska, which spans more than 5 million square kilometers 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 a study area in the Arctic Coastal Plain where the temperatures are much colder, the growing season much shorter, and the permafrost is continuous, and 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 4 and 31 percent, with most of the change occurring since the 1970s. The ponds in the Arctic Coastal Plain showed negligible change….

Blogged with Flock

but Flock has problems with multiple posts while claiming errors. I had to tidy up by hand.

Technorati Tags: , , , , , ,
Site Search Tags: , , , , , , , , , ,