Wednesday, February 10, 2010

All Tomorrow's Snowpocalypses

Image credit: TragicHipster

Weather Underground meteorologist Dr. Jeff Masters explains why those who point to the Snowpocalypse, Snowmageddon, etc. as evidence against global warming have it exactly backwards. Climate change models predict that certain areas of the world will receive even more massive snowstorms in the future, with changes patterns in air currents, air moisture, etc.
According to the National Climatic Data Center, the return period for a 22+ inch snow storm is once every 100 years--and we've had two 100-year snow storms in Philadelphia this winter. It is true that if the winter pattern of jet stream location, sea surface temperatures, etc, are suitable for a 100-year storm to form, that will increase the chances for a second such storm to occur that same year, and thus the odds have having two 100-year storms the same year are not 1 in 10,000. Still, the two huge snowstorms this winter in the Mid-Atlantic are definitely a very rare event one should see only once every few hundred years, and is something that has not occurred since modern records began in 1870. The situation is similar for Baltimore and Washington D.C. According to the National Climatic Data Center, the expected return period in the Washington D.C./Baltimore region for snowstorms with more than 16 inches of snow is about once every 25 years. This one-two punch of two major Nor'easters in one winter with 16+ inches of snow is unprecedented in the historical record for the region, which goes back to the late 1800s....

[I]f climate change is simultaneously causing an increase in ratio of snowstorms with very heavy snow to storms with ordinary amounts of snow, we could actually see an increase in very heavy snowstorms in some portions of the world. There is evidence that this is happening for winter storms in the Northeast U.S ....

Global warming theory predicts that global precipitation will increase, and that heavy precipitation events--the ones most likely to cause flash flooding--will also increase. This occurs because as the climate warms, evaporation of moisture from the oceans increases, resulting in more water vapor in the air. According to the 2007 Intergovernmental Panel on Climate Change (IPCC) report, water vapor in the global atmosphere has increased by about 5% over the 20th century, and 4% since 1970. This extra moisture in the air will tend to produce heavier snowstorms, assuming it is cold enough to snow. Groisman et al. (2004) found a 14% increase in heavy (top 5%) and 20% increase in very heavy (top 1%) precipitation events in the U.S. over the past 100 years, though mainly in spring and summer. However, the authors did find a significant increase in winter heavy precipitation events have occurred in the Northeast U.S. This was echoed by Changnon et al. (2006), who found, "The temporal distribution of snowstorms exhibited wide fluctuations during 1901-2000, with downward 100-yr trends in the lower Midwest, South, and West Coast. Upward trends occurred in the upper Midwest, East, and Northeast, and the national trend for 1901-2000 was upward, corresponding to trends in strong cyclonic activity."
(Weather Underground)

Looks like I will be missing out on a lot of snow days. For Southern California, the climate change models predict historic droughts and a dramatic rise in extremely hot days and months.

Tuesday, February 9, 2010

Garbage Patch Twice the Size of Texas Grows in Pacific Ocean

The Great Pacific Garbage Patch, also known as the Pacific Trash Vortex, floats 1000 miles off the coast of California, and is estimated to be twice the size of Texas:
The patch is characterized by exceptionally high concentrations of suspended plastic and other debris that have been trapped by the currents of the North Pacific Gyre. Despite its size and density, the patch is not visible from satellite photography because it consists of very small pieces, almost invisible to the naked eye and most of its contents are suspended beneath the surface of the ocean.

The patch contains "approximately 3.5 million tons of trash," including "[s]hoes, toys, bags, pacifiers, wrappers, toothbrushes, and bottles too numerous to count ...." (GarbagePatch.Org) The operative word is Plastic:
Plastic constitutes 90 percent of all trash floating in the world's oceans .... The United Nations Environment Program estimated in 2006 that every square mile of ocean hosts 46,000 pieces of floating plastic .... In some areas, the amount of plastic outweighs the amount of plankton by a ratio of six to one. Of the more than 200 billion pounds of plastic the world produces each year, about 10 percent ends up in the ocean .... Seventy percent of that eventually sinks, damaging life on the ocean floor .... The rest floats; much of it ends up in gyres and the massive garbage patches that form there, with some plastic eventually washing up on a distant shore.

Climate Change and Western Australia's Worst Drought in 750 Years

Photo Credit:The Age

New studies suggest a link between Antarctic climate patterns and the epic drought in Western Australia:
Researchers from the Australian Antarctic Division and Antarctic Climate and Ecosystems Co-operative Research Centre have identified a link between the drought, which began in the early 1970s, and snowfall at a site in East Antarctica over the same period.

In research published in Nature Geoscience, they say the relationship is inverse - high snowfalls at the Law Dome site correlate with low rain in the South-West.

That is as a result of the atmospheric circulation pattern that brings dry, cool air to Australia, while sending warm, moist air to East Antarctica.

However, the high snowfall at Law Dome was unlike any other in the past 750 years, and led the researchers to believe the drought was similarly unusual....

"It also suggests ... that if the mix of factors that influence [South-West] rainfall over the past century reflects that of the longer term, then the recent drought ... may be similarly unusual," the researchers say.
The Age

The recent studies suggest that humans have influenced the feedback loop that is helping to create the drought in Western Australia. The drought, they conclude, "lies outside the envelope of natural variability and supports the hypothesis of anthropogenically (man-made) induced climate shift."