terra central

April 14 Fireball

Last Wednesday’s fireball, meteorite, or space junk, whatever it was, lit up the sky over Iowa. At the time, I was standing in front of the AmercInn in downtown Ottumwa talking to a collegue who was outside chain-smoking in anticipation of spending the night in a non-smoking hotel.

The fireball’s leading edge was red-rimmed grading to orange, then yellow. The tail was green with yellowish white “sparks” at the very end. It was beautiful, lasting around four or five seconds – much bigger and slower-moving than other meteorites I’ve seen. When I first saw it, I didn’t say anything to Keith, figuring it would be gone by the time he looked up. Then I pointed to the sky. It flew behind a gothic church steeple, then reappeared on the other side brighter than ever. Keith saw it, too.

Coast of Alaska: Accelerated Erosion 2002-2007

Alaskan coastal erosion (USGS).

A five-year study in Alaska led by the U.S. Geological Survey (USGS) found that shoreline erosion along a 40-mile stretch of the Beaufort Sea has been accelerating from about 20-feet per year fifty years ago, to 45-feet per year by 2007. The research makes obvious the importance of considering the specific properties of the earthen materials exposed to erosive forces. In this case, the land contains permafrost, a consituent of the soil order called Gelisol.

An excerpt:

The authors proposed that these recent shifts in the rate and pattern of land loss along this coastline segment are potentially a result of changing arctic conditions, including declining sea ice extent, increasing summertime sea-surface temperature, rising sea level, and increases in storm power and corresponding wave action.

“Taken together, these factors may be leading to a new era in ocean-land interactions that seem to be repositioning and reshaping the Arctic coastline,” wrote (Benjamin) Jones and his colleagues. “And any increases in the current rates of coastal retreat will have further ramifications on Arctic landscapes – including losses in freshwater and terrestrial wildlife habitats, and in disappearing cultural sites, as well as adversely impacting coastal villages and towns. In addition, oil test wells are threatened.”

Alaskan permafrost erosion (USGS)

For most of us who live on the relative “terra firma” of the mid-latitude continents, global warming may seem like a fairly benign process, one that might result in better weather to play golf. The Arctic and Antarctic environments, by contrast, are very different, very fragile worlds. The authors are careful with their words, using the standard qualifiers, but it’s pretty clear they think climate change is a factor as the waves pound that coast.

Research Paper:
Jones, B.M., Arp, C.D., Jorgenson, M.T., Hinkel, K.M., Schmutz, J.A., and Flint, P.L. Increase in the rate and uniformity of coastline erosion in arctic Alaska. Geophysical Research Letters, February 14, 2009. http://www.agu.org/journals/gl/gl0903/2008GL036205/.

Photos source: USGS

A Look at Rivers from Space

The above photo is a false-color image taken from the Landsat 7 satellite in 2000. The Lena River Delta is frozen most of the year but, during the summer, thaws into an enormous wetland complex of about 11,000 square miles. It’s a wildlife refuge.

The Lena River flows into the Laptev Sea, on the north coast of Russia.

Here’s a view of the Lena River Delta taken near the ground.

Photo source: Ramsar Convention on Wetlands

Wired Science has a gallery of other rivers observed from satellites and the International Space Station. Just click on the thumbnails or some impressive views.

Tip: Ike Union and his grandpa.