Quickly melting ice and Arctic permafrost is changing the tundra in Alaska, Canada and Russia. Now, scientists are taking a closer look at this degradation in order to better understand its effects.
The Arctic tundra can be seen as a string of interconnected polygon shapes that are about 15 to 30 meters wide. These polygons are actually shaped by frozen ice wedges located beneath the earth in the permafrost. These ice wedges formed over hundreds or even thousands of years as water seeped into permafrost cracks.
In this latest study, the researchers examined high resolution remote sensing imagery in several Arctic sites. Scientists then analyzed and compared these results with field data and climate observation to understanding how degradation of ice beneath the earth affects the surface of the land.
More specifically, the researchers compared historical aerial photo and satellites images from 1948 to 1990 with recent images taken from 2005 and 2012.
"The analysis clearly shows dramatic changes to this landscape, especially during relatively short periods in unusually warm summers in recent years," Marius Necsoiu, a principal scientist in SWRI's Geosciences and Engineering Division, said.
More specifically, the researchers found that deep troughs have formed in the region as the tops of these ice wedges melted due to warmer temperatures. Without these ice wedges, small shallow ponds don't form in the summer because deep troughs create channels for the water to run off.
This degradation didn't happen slowly, either. It turns out that ice-wedge degradation can occur in less than a decade. In fact, in some cases a single warm summer was enough to cause more than 10 centimeters of surface subsidence, which can cause pooling and runoff.
While these regions contain permafrost with an average temperature of just 7 degrees Fahrenheit, thawing still occurred at all of the study sites.
The findings show that these melting ice wedges could be a serious issue from the Arctic tundra. More specifically, they can completely change the surface of this tundra, causing run-off with some areas becoming wetter and some drier. Already, researchers have found that native vegetation is changing due to this phenomenon.
The findings are published in the journal Nature Geoscience.
