Later On

A blog written for those whose interests more or less match mine.

Climate change: again, reality worse than models

with 2 comments

One of the criticisms that climate change deniers make is that many of the projections are based on computer models, which are fallible—as indeed they are. So far, though, as scientists check the actual observations against the models, the reality is consistently worse than predicted. For example, the Arctic ice has melted much faster than projected, and the Greenland ice cap is melting faster than predicted. And now the extreme weather events are worse than predicted:

Climate models have long predicted that global warming will increase the intensity of extreme precipitation events. A new study conducted at the University of Miami and the University of Reading (U.K.) provides the first observational evidence to confirm the link between a warmer climate and more powerful rainstorms. One of the most serious challenges humanity will face in response to global warming is adapting to changes in extreme weather events. Of utmost concern is that heavy rainstorms will become more common and more intense in a warmer climate due to the increased moisture available for condensation. More intense rain events increase the risk of flooding and can have substantial societal and economic impacts.

To understand how precipitation responds to a warmer climate, researchers in this study used naturally-driven changes associated with El Niño as a laboratory for testing their hypotheses. Based on 20 years of satellite observations, they found a distinct link between tropical rainfall extremes and temperature, with heavy rain events increasing during warm periods and decreasing during cold periods.

“A warmer atmosphere contains larger amounts of moisture which boosts the intensity of heavy downpours,” said Dr. Brian J. Soden, associate professor at the University of Miami Rosenstiel School of Marine & Atmospheric Science.

The report, “Atmospheric Warming and the Amplification of Precipitation Extremes,” previewed in Science Express this Thursday, August 7, and published in an upcoming issue of Science, found that both observations and models indicated an increase in heavy rainstorms in response to a warmer climate. However, the observed amplification of rainfall extremes was found to be substantially larger in the observations than what is predicted by current models.

“Comparing observations with results from computer models improves understanding of how rainfall responds to a warming world” said Dr. Richard P. Allan, NERC advance fellow at the University of Reading’s Environmental Systems Science Centre. “Differences can relate to deficiencies in the measurements, or the models used to predict future climatic change”

Source: University of Miami Rosenstiel School of Marine & Atmospheric Science

Written by Leisureguy

8 August 2008 at 8:30 am

2 Responses

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  1. Hmmm – funded science?

    The Arctic loses a load of sea ice every summer, but loads less this year.

    You will not see this trumpeted in the media. It is too much like good news.

    The world is heading for cold and our grandchildren will be amazed that we carbon cycle based lifeforms thought that CO2 was anything other than the life giving gas that it is. Playstation science needs this awakening before trillions of dollars are committed to a phantom menace.

    Like

    Henry Galt

    11 August 2008 at 7:14 am

  2. I appreciate your efforts to do climatological studies and make climate change predictions, but really I don’t think you’ve made a good argument Your evidence consists of a pair of photos, and those who study the problem in greater depth have much more evidence that the problem is real and growing.

    The problem with the Arctic ice cap is not merely the area of ice, but also the thickness: the total volume of ice in the Arctic is dwindling, which leads to faster (and more extensive) melting. Take a look at this note from last January:

    A new study by University of Colorado at Boulder researchers indicates older, multi-year sea ice in the Arctic is giving way to younger, thinner ice, making it more susceptible to record summer sea-ice lows like the one that occurred in 2007.

    The team used satellite data going back to 1982 to reconstruct past Arctic sea ice conditions, concluding there has been a nearly complete loss of the oldest, thickest ice and that 58 percent of the remaining perennial ice is thin and only 2-to-3 years old, said the lead study author, Research Professor James Maslanik of CU-Boulder’s Colorado Center for Astrodynamics Research. In the mid-1980s, only 35 percent of the sea ice was that young and that thin according to the study, the first to quantify the magnitude of the Arctic sea ice retreat using data on the age of the ice and its thickness, he said.

    “This thinner, younger ice makes the Arctic much more susceptible to rapid melt,” Maslanik said. “Our concern is that if the Arctic continues to get kicked hard enough toward one physical state, it becomes increasingly difficult to reestablish the sea ice conditions of 20 or 30 years ago.”

    A September 2007 study by CU-Boulder’s National Snow and Ice Data Center indicated last year’s average sea ice extent minimum was the lowest on record, shattering the previous September 2005 record by 23 percent. The minimum extent was lower than the previous record by about 1 million square miles — an area about the size of Alaska and Texas combined.

    The new study by Maslanik and his colleagues appears in the Jan. 10 issue of Geophysical Research Letters. Co-authors include CCAR’s Charles Fowler, Sheldon Drobot and William Emery, as well as Julienne Stroeve from CU-Boulder’s Cooperative Institute for Research in Environmental Sciences and Jay Zwally and Donghui Yi from NASA’s Goddard Space Flight Center in Greenbelt, Md.

    The portion of ice more than five years old within the multi-year Arctic icepack decreased from 31 percent in 1988 to 10 percent in 2007, according to the study. Ice 7 years or older, which made up 21 percent of the multi-year Arctic ice cover in 1988, made up only 5 percent in 2007, the research team reported.

    The researchers used passive microwave, visible infrared radar and laser altimeter satellite data from the National Oceanic and Atmospheric Administration, NASA and the U.S. Department of Defense, as well as ocean buoys to measure and track sections of sea ice.

    The team developed “signatures” of individual ice sections roughly 15 miles square using their thickness, roughness, snow depth and ridge characteristics, tracking them over the seasons and years as they moved around the Arctic via winds and currents, Emery said. “We followed the ice in sequential images and track it back to where it had been previously, which allowed us to infer the relative ages of the ice sections.”

    The replacement of older, thicker Arctic ice by younger, thinner ice, combined with the effects of warming, unusual atmospheric circulation patterns and increased melting from solar radiation absorbed by open waters in 2007 all have contributed to the phenomenon, said Drobot. “These conditions are setting the Arctic up for additional, significant melting because of the positive feedback loop that plays back on itself.”

    “Taken together, these changes suggest that the Arctic Ocean is approaching a point where a return to pre-1990s ice conditions becomes increasingly difficult and where large, abrupt changes in summer ice cover as in 2007 may become the norm,” the research team wrote in Geophysical Research Letters.

    Like

    LeisureGuy

    11 August 2008 at 7:27 am


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