Saturday, November 10, 2012

Climate change: worse is more likely

Climate is changing faster than we’ve been told, and it’s going to get worse than the consensus estimates.

That’s a conclusion of a new report from the National Center for Atmospheric Research (NCAR).

Much of the science industry has been understating its science, perhaps because the most dire scenarios seem so outrageous, perhaps because they’re reeling from the denier attacks.

The Intergovernmental Panel on Climate Change’s 2007 report says its projections “do not include uncertainties in climate-carbon cycle feedbacks nor the full effects of changes in ice sheet flow, therefore the upper values of the ranges are not to be considered upper bounds for sea level rise.” 

Translation: We left out the really scary stuff.

For Hawai`i, where climate change predicts significantly reduced rainfall and coastal flooding from higher sea levels, it’s also important stuff.

Even so, IPCC in 2007 projected contracting snow cover, disappearance of Arctic summer sea ice, increase of extreme hot weather, increased hurricane intensity, less rainfall in subtropical land areas and more. Sound familiar? Let’s see. Glaciers are melting, you can now run ships over the north sides of both the Americas and Asia, Hurricanes Katrina and Sandy, the expanding Sahara and Gobi deserts.       

NCAR, in an article in this week’s issue of Science, is suggesting that the more severe estimates of global warming are more likely to be the accurate estimates.

“Our findings indicate that warming is likely to be on the high side of current projections,” say NCAR scientists John Fasullo and Kevin Trenberth.

The two researchers come to their conclusion based on global humidity patterns. Many earlier studies have tried to link climate change to cloud patterns, but clouds are notoriously ephemeral and difficult to model. On the other hand, humidity is well researched and provides a useful tool for analysis of climate patterns, they said.

They looked at relative humidity figures for cloud-free subtropical areas, which they said are “easier to observe than the cloud properties themselves.”

Why the subtropics? “The dry subtropics are a critical element in our future climate. If we can better represent these regions in models, we can improve our predictions and provide society with a better sense of the impacts to expect in a warming world,” said Fasullo.

“Because we have more reliable observations for humidity than for clouds, we can use the humidity patterns that change seasonally to evaluate climate models,” says Trenberth. “When examining the impact of future increases in heat-trapping gases, we find that the simulations with the best fidelity come from models that produce more warming.”

NCAR’s press release on the study says it “could provide a breakthrough in the longstanding quest to narrow the range of global warming expected in coming decades and beyond.”

© Jan TenBruggencate 2012

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