Arctic Melt Season Lengthening, Ocean Rapidly Warming says NASA
The length of the melt season for Arctic sea ice is growing by several days each decade, and an earlier start to the melt season is allowing the Arctic Ocean to absorb enough additional solar radiation in some places to melt as much as four feet of the Arctic ice cap’s thickness, according to a new study by National Snow and Ice Data Center (NSIDC) and NASA researchers.
Arctic sea ice has been in sharp decline during the last four decades. The sea ice cover is shrinking and thinning, making scientists think an ice-free Arctic Ocean during the summer might be reached this century. The seven lowest September sea ice extents in the satellite record have all occurred in the past seven years.
"The Arctic is warming and this is causing the melt season to last longer," said Julienne Stroeve, a senior scientist at NSIDC, Boulder and lead author of the new study, which has been accepted for publication in Geophysical Research Letters. “The lengthening of the melt season is allowing for more of the sun’s energy to get stored in the ocean and increase ice melt during the summer, overall weakening the sea ice cover.”
To study the evolution of sea ice melt onset and freeze-up dates from 1979 to the present day, Stroeve’s team used passive microwave data from NASA’s Nimbus-7 Scanning Multichannel Microwave Radiometer, and the Special Sensor Microwave/Imager and the Special Sensor Microwave Imager and Sounder carried onboard Defense Meteorological Satellite Program spacecraft.
Zebras’ bold striped patterns have puzzled scientists for nearly 150 years. Researchers have offered a lengthy list of possible explanations, from confusing predators by creating a distracting dazzle when a herd gallops away, to helping the animals avoid biting flies. Support for the dazzler hypothesis comes from computer tests using people, who have trouble tracking striped, moving objects on a computer; while other studies have shown that the flies prefer to land on uniformly colored, not striped, surfaces. Now, a team of scientists reports online today in Nature Communications that it has tested these hypotheses—as well as suggestions that the stripes might cool zebras down or make them more attractive to mates—to see which one makes the most ecological sense. The winner: those pesky, blood-sucking, disease-carrying (such as parasitic trypanosomiasis) biting flies. The team discovered that the ranges of the horse fly and tsetse fly species and the three most distinctively striped zebra species (Equus burchelli, E. zebra, and E. grevyi) overlap to a remarkable degree. They did not find a similar ecological match for any of the other hypotheses, not even those involving predators. Instead, the researchers argue that biting flies are the most likely reason that zebras, such as those shown above grazing in Tanzania’s Katavi National Park, evolved their distinctive ornamentation. The insects, they note, harass the equids almost year-round, and are known to torment domesticated horses in these areas. The zebras’ black-and-white patterns, which others have shown seem to interfere with the flies’ vision, at least give them a bit of a break. Why equids are so susceptible to the flies’ attacks remains mysterious, but, as the researchers found, the zebras’ short coats may make them particularly vulnerable, and the diseases the flies carry are often fatal.
It never ceases to amaze me that every second of every day, more than 6,000 billion neutrinos coming from nuclear reactions inside the sun whiz through my body, almost all of which will travel right through the earth without interruption.