Note Dr. Andrew Glikson’s remarks on this item , together with supporting scientific reports.
It has been my view for a long time, in particular following James Hansen, Hans Schellnhuber and other, that the scale and rate of climate change have been underestimated.
I enclose relevant papers.
My best wishes
From: Neville Gillmore [mailto:email@example.com]
Sent: Monday, March 26, 2012 11:52 PM
To: Andrew Glikson
Cc: JOHN JAMES; W. Shawn Gray
Subject: Impact of climate chamge may be underestimated.
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Impact of climate change may be underestimated
A new study suggests climate scientists may have underestimated the effect of greenhouse gases, with global temperatures now predicted to rise by between 1.4 and 3 degrees Celsius by 2050.
The study was published in the journal Nature Geoscience by a team of international scientists who ran 10,000 computer simulations of climate models in an attempt to explore the range of global warming predictions made by climate scientists.
The researchers found that while their results matched the predictions made by the Intergovernmental Panel on Climate Change (IPCC) at the lower end, they were higher than earlier predictions at the higher end.
One of the certainties about predicting climate change is uncertainty, which is why climate change professor David Frame and 26 of his colleagues from around the world have tried to narrow things down.
“We set out to look at how a large range of climate models could try to span a range of uncertainties to try to get a better handle on the sort of range of plausible climates we might see in the next half century and beyond,” said Professor Frame, who works at the Victoria University of Wellington.
“Generally people build a model and they spend a lot of resources on doing so and they try to make it as good as they can. But when everybody tries for their best-shot model, it doesn’t necessarily mean that you systematically explore all the possible uncertainties.”
When it comes to climate change, there many variables including cloud cover, ocean temperatures and land temperatures. So Professor Frame and his colleagues took one of the world’s best-known climate models and tweaked some of the parameters.
They then asked 10,000 people around the world to run these new models through their home computers, assuming nothing is done to reduce greenhouse gas emissions.
“If people keep emitting fossil fuels in the way we expect, with no price on carbon or no future policy initiatives, we expect a range of 1.4 to 3 degrees by 2050,” he said.
Those numbers are based on average temperatures between 1960 and 1990.
At the bottom end it is similar to the last prediction made by the IPCC, but it exceeds that group’s prediction at the higher end.
“What we’ve kind of got is just a broader sweep of that uncertainty range,” Professor Frame said.
“So it’s not just about the headline result numbers, it’s actually about the physical understanding we can get to with this sort of approach.”
He says the world is most probably somewhere in the middle range rather than at the extremes.
“But it makes me think that people who are thinking about real-world problems, farmers, wine growers in Australia, people managing river catchments for instance, might want to have a look at some of these models to think about what … might plausibly happen, what sorts of changes they might plausibly have to manage for,” he said.
“So one of the real purposes of this is to give planners a chance to … think about scenarios for the future that are physically plausible, are internally consistent, which is an important property and potentially quite practical.”
The paper comes just three days after the World Meteorological Organisation published its latest Status of the Global Climate Report, which found that 2011 was a year of climate extremes and the 11th warmest year on record.
The journal has also published a paper which states that extreme weather events over the past decade have increased and were “very likely” caused by man-made global warming.