On the September 13 edition of NBC's Nightly News, host Brian Williams claimed that "[s]cientists can't say yet whether global warming is the culprit" for the recent reported ice melt in the Arctic. In a segment on “the health of our planet,” Williams showed recently released NASA images of the Arctic from 2004 and from 2005 and said that the difference between the two demonstrated “an abrupt shrinkage ... equal to an area about the size of the state of Texas.” Williams stated that the ice is not “shrinking that much every year,” adding that "[s]cientists can't say yet whether global warming is the culprit." However, according to the scientist and author of the September 13 NASA study on the Arctic ice meltdown to which Williams was presumably referring in citing the Arctic images, new data show “the strongest evidence of global warming in the Arctic so far.”

In contrast to Williams's report, recent articles by the Associated Press and The Washington Post, as well as a report posted on the NASA website, all note that NASA senior research scientist Josefino Comiso, who authored the September 13 study, clearly links global climate change to his findings that the Arctic sea ice is rapidly melting. According to a September 14 AP report, Comiso stated: “It is alarming. ... This winter ice provides the kind of evidence that it is indeed associated with the greenhouse effect.” A September 14 Washington Post article similarly reported that “Comiso yesterday called the new data from satellite imaging of ice formation and temperatures 'the strongest evidence of global warming in the Arctic so far,' ” while a September 13 article on NASA's website quoted Comiso stating: “What's remarkable is that we've witnessed sea ice reduction at six percent per year over just the last two winters, most likely a result of warming due to greenhouse gases.”

According to NASA, Comiso's paper will be published this month in the Geophysical Research Letters.

From the September 14 AP article:

Arctic sea ice in winter is melting far faster than before, two new NASA studies reported Wednesday, a new and alarming trend that researchers say threatens the ocean's delicate ecosystem.

Scientists point to the sudden and rapid melting as a sure sign of man-made global warming.

“It has never occurred before in the past,” said NASA senior research scientist Josefino Comiso in a phone interview. “It is alarming. ... This winter ice provides the kind of evidence that it is indeed associated with the greenhouse effect.”

[...]

Scientists and climate models have long predicted a drop in winter sea ice, but it has been slow to happen. Global warming skeptics have pointed to the lack of ice melt as a flaw in global warming theory.

The latest findings are “coming more in line with what we expected to find,” said Mark Serreze, a senior research scientist at the National Snow and Ice Data Center in Boulder, Colo. “We're starting to see a much more coherent and firm picture occurring.”

“I hate to say we told you so, but we told you so,” he added.

Serreze said only five years ago he was “a fence-sitter” on the issue of whether man-made global warming was happening and a threat, but he said recent evidence in the Arctic has him convinced.

From the September 14 Washington Post article:

The amount of ice being formed in the Arctic winter has declined sharply in the past two years, a finding that NASA climate researchers say significantly increases their confidence that greenhouse gases created by autos and industry are warming the Arctic and the globe.

For years, scientists have reported a steady decrease in summertime Arctic ice, but they had never before found a similar reduction in the amount of ice being created during the frigid and dark Arctic winter. This lack of effect on the Arctic winter was one flaw in the scientific models of global warming, which predicted a steady decrease in ice formation.

But a new paper by Josefino Comiso, a senior research scientist at NASA's Goddard Space Flight Center in Greenbelt, found precisely the reduction in wintertime ice over the past two years that the model had predicted. The past two winters each produced 6 percent less ice than the average amount measured for almost three decades.

[...]

Comiso yesterday called the new data from satellite imaging of ice formation and temperatures “the strongest evidence of global warming in the Arctic so far.”

The drop in wintertime ice tracks a similar drop in sea ice detected in the warmer months. According to Mark Serreze, senior research analyst with the National Snow and Ice Data Center, the amount of ice in the Arctic at the end of the 2005 summer was the smallest seen in 27 years of satellite imaging, and probably the smallest in 100 years. He said this year's summer ice cover started out even smaller but is not another record.

Serreze, in a teleconference with Comiso yesterday, said the new information on wintertime ice increases his confidence that greenhouse gases, and not other variables of weather and climate, are causing the warming.

“There a growing consistency here, with our observations in line with what our models project,” said Serreze, whose group is part of the University of Colorado and does contract work for NASA.

From the September 13 article posted on the website of the NASA Goddard Space Flight Center:

“This amount of Arctic sea ice reduction the past two consecutive winters has not taken place before during the 27 years satellite data has been available,” said Joey Comiso, a research scientist at NASA's Goddard Space Flight Center, Greenbelt, Md. “In the past, sea ice reduction in winter was significantly lower per decade compared to summer sea ice retreat. What's remarkable is that we've witnessed sea ice reduction at six percent per year over just the last two winters, most likely a result of warming due to greenhouse gases.”

[...]

Computer simulations of the climate warming effect of greenhouse gases had predicted that winter sea ice would decline faster than summer sea ice Satellite data has shown otherwise until two years ago, when record low winter ice cover and warmer temperatures have prevailed.

[...]

Adding to the plight of winter sea ice, previous research has shown a trend in which the melt period lasts about two weeks longer per year annually due to summer sea ice decline. This means that the onset of freeze-up is happening later in the fall season. As a result, the ice cover in winter never gets as extensive as it would have been if the freeze-up had begun earlier. More than that, the ice reflects the sun's radiation much more efficiently than the ocean's surface. As a result, as the ice cover declines, the ocean's surface warms, causing in turn, further decline of the ice.

[...]

According to Comiso, if the winter ice retreat continues, the effect could be very profound, especially for marine animals. “The seasonal ice regions in the Arctic are among the most biologically productive regions in the world,” he said.

From the September 13 edition of NBC's Nightly News with Brian Williams:

WILLIAMS: The health of our planet is making news tonight. NASA today released these satellite images. The white area here is what's called 'the perennial," or year-round ice mass. This image shows what there was of it in 2004. Then we jump to a year later, 2005. This was the ice mass. That's an abrupt shrinkage -- 14 percent less of it. That's equal to an area about the size of the state of Texas. It's not like it's shrinking that much every year. There's no official explanation. Scientists can't say yet whether global warming is the culprit here or not.