Archives for August 10, 2007

Rural climate change sceptics shock kayaker

From ABC Rural Thursday, 09/08/2007

A man paddling and pulling his kayak from Brisbane to Adelaide to promote the need for action on climate change says he is disappointed with the sceptical nature of outback Australians.

Steve Posselt, who is pulling his kayak along the Darling River road due to a lack of water, says that many rural people do not believe in climate change.

He says he did not expect so many people to doubt what the majority of climate scientists agree on.

“I’ve been astounded by the actual lack of belief on this trip,” he said.

“Many people want to argue the issue about whether there is such a thing as global warming.

“You can talk to blokes in the pub and they say yep winters aren’t what they used to be, they’re a lot shorter.

“And you say, ‘well do you believe in climate change? No, mate its just a cycle’.”

An interesting new paper has been published:

Spencer, Roy W.; Braswell, William D.; Christy, John R.; Hnilo, Justin (2007)
Cloud and radiation budget changes associated with tropical intraseasonal oscillations
Geophys. Res. Lett., Vol. 34, No. 15, L15707

Abstract
We explore the daily evolution of tropical intraseasonal oscillations in satellite-observed tropospheric temperature, precipitation, radiative fluxes, and cloud properties. The warm/rainy phase of a composited average of fifteen oscillations is accompanied by a net reduction in radiative input into the ocean-atmosphere system, with longwave heating anomalies transitioning to longwave cooling during the rainy phase. The increase in longwave cooling is traced to decreasing coverage by ice clouds, potentially supporting Lindzen’s “infrared iris” hypothesis of climate stabilization. These observations should be considered in the testing of cloud parameterizations in climate models, which remain sources of substantial uncertainty in global warming prediction.

Received 15 February 2007; accepted 16 July 2007; published 9 August 2007.

The UAH press release is here.

Cirrus disappearance: Warming might thin heat-trapping clouds

The widely accepted (albeit unproven) theory that manmade global warming will accelerate itself by creating more heat-trapping clouds is challenged this month in new research from The University of Alabama in Huntsville.

Instead of creating more clouds, individual tropical warming cycles that served as proxies for global warming saw a decrease in the coverage of heat-trapping cirrus clouds, says Dr. Roy Spencer, a principal research scientist in UAHuntsville’s Earth System Science Center.

That was not what he expected to find.

“All leading climate models forecast that as the atmosphere warms there should be an increase in high altitude cirrus clouds, which would amplify any warming caused by manmade greenhouse gases,” he said. “That amplification is a positive feedback. What we found in month-to-month fluctuations of the tropical climate system was a strongly negative feedback. As the tropical atmosphere warms, cirrus clouds decrease. That allows more infrared heat to escape from the atmosphere to outer space.”

The results of this research were published today in the American Geophysical Union’s “Geophysical Research Letters” on-line edition. The paper was co-authored by UAHuntsville’s Dr. John R. Christy and Dr. W. Danny Braswell, and Dr. Justin Hnilo of Lawrence Livermore National Laboratory, Livermore, CA.

“While low clouds have a predominantly cooling effect due to their shading of sunlight, most cirrus clouds have a net warming effect on the Earth,” Spencer said. With high altitude ice clouds their infrared heat trapping exceeds their solar shading effect.

In the tropics most cirrus-type clouds flow out of the upper reaches of thunderstorm clouds. As the Earth’s surface warms – due to either manmade greenhouse gases or natural fluctuations in the climate system – more water evaporates from the surface. Since more evaporation leads to more precipitation, most climate researchers expected increased cirrus cloudiness to follow warming.

“To give an idea of how strong this enhanced cooling mechanism is, if it was operating on global warming, it would reduce estimates of future warming by over 75 percent,” Spencer said. “The big question that no one can answer right now is whether this enhanced cooling mechanism applies to global warming.”

The only way to see how these new findings impact global warming forecasts is to include them in computerized climate models.

“The role of clouds in global warming is widely agreed to be pretty uncertain,” Spencer said. “Right now, all climate models predict that clouds will amplify warming. I’m betting that if the climate models’ ‘clouds’ were made to behave the way we see these clouds behave in nature, it would substantially reduce the amount of climate change the models predict for the coming decades.”

The UAHuntsville research team used 30- to 60-day tropical temperature fluctuations – known as “intraseasonal oscillations” – as proxies for global warming.

“Fifteen years ago, when we first started monitoring global temperatures with satellites, we noticed these big temperature fluctuations in the tropics,” Spencer said. “What amounts to a decade of global warming routinely occurs in just a few weeks in the tropical atmosphere. Then, as if by flipping a switch, the rapid warming is replaced by strong cooling. It now looks like the change in cirrus cloud coverage is the major reason for this switch from warming to cooling.”

The team analyzed six years of data from four instruments aboard three NASA and NOAA satellites. The researchers tracked precipitation amounts, air and sea surface temperatures, high and low altitude cloud cover, reflected sunlight, and infrared energy escaping out to space.

When they tracked the daily evolution of a composite of fifteen of the strongest intraseasonal oscillations they found that although rainfall and air temperatures would be rising, the amount of infrared energy being trapped by the cloudy areas would start to decrease rapidly as the air warmed. This unexpected behavior was traced to the decrease in cirrus cloud cover.

The new results raise questions about some current theories regarding precipitation, clouds and the efficiency with which weather systems convert water vapor into rainfall. These are significant issues in the global warming debate.

“Global warming theory says warming will generally be accompanied by more rainfall,” Spencer said. “Everyone just assumed that more rainfall means more high altitude clouds. That would be your first guess and, since we didn’t have any data to suggest otherwise …”

There are significant gaps in the scientific understanding of precipitation systems and their interactions with the climate, he said. “At least 80 percent of the Earth’s natural greenhouse effect is due to water vapor and clouds, and those are largely under the control of precipitation systems.

“Until we understand how precipitation systems change with warming, I don’t believe we can know how much of our current warming is manmade. Without that knowledge, we can’t predict future climate change with any degree of certainty.”

Spencer and his colleagues expect these new findings to be controversial.

“I know some climate modelers will say that these results are interesting but that they probably don’t apply to long-term global warming,” he said. “But this represents a fundamental natural cooling process in the atmosphere. Let’s see if climate models can get this part right before we rely on their long term projections.”

This article is from The Times (London). Not sure what to make of this, other than perhaps a ‘green’ attack on meat eating:

Walking to the shops ‘damages planet more than going by car’

Walking does more than driving to cause global warming, a leading environmentalist has calculated.

Food production is now so energy-intensive that more carbon is emitted providing a person with enough calories to walk to the shops than a car would emit over the same distance. The climate could benefit if people avoided exercise, ate less and became couch potatoes. Provided, of course, they remembered to switch off the TV rather than leaving it on standby.

The sums were done by Chris Goodall, campaigning author of How to Live a Low-Carbon Life, based on the greenhouse gases created by intensive beef production. “Driving a typical UK car for 3 miles [4.8km] adds about 0.9 kg [2lb] of CO2 to the atmosphere,” he said, a calculation based on the Government’s official fuel emission figures. “If you walked instead, it would use about 180 calories. You’d need about 100g of beef to replace those calories, resulting in 3.6kg of emissions, or four times as much as driving.

“The troubling fact is that taking a lot of exercise and then eating a bit more food is not good for the global atmosphere. Eating less and driving to save energy would be better.”

Mr Goodall, Green Party parliamentary candidate for Oxford West & Abingdon, is the latest serious thinker to turn popular myths about the environment on their head.

Full article here.

Enjoy!