Morgan BellClimate change deniers using inappropriate statistics?
May 27th 2008 02:53
Most scientists seem to be in agreement that they've actually underestimated the amount of climate change, and we're seeing that greenhouse gas emissions are increasing much faster than we thought.
There are still a few out there, though, that would look at the numbers and tell you that it's all a myth.
Good Math, Bad Math takes a look at one study that claims that global warming stopped in 2002, but a deeper excavation of their methods reveals shoddy statistics.
In Sydney's own Morning Herald, Michael Duffy claims that global warming stopped six years ago:
"Hadley expresses temperature changes in terms of deviations from the 1961 to 1990 average. In 2002 the rounded global temperature for land and sea was 0.46 above that average. In the next five years it was: 0.46, 0.43, 0.48, 0.42, and 0.40. The figures for the date centre are calculated slightly differently, but they too show no trend over the period in question.
What does this mean? Some global warming sceptics say these figures disprove the basic hypothesis of global warming, that rising greenhouse gas emissions automatically produce rising temperatures. Some have looked back to 1998, an unusually hot year (0.52 on Hadley's list) and said that global warming actually stopped back then. They conclude that after 10 years we can now say global warming is over, and we face the possibility of global cooling."
What does this mean? Some global warming sceptics say these figures disprove the basic hypothesis of global warming, that rising greenhouse gas emissions automatically produce rising temperatures. Some have looked back to 1998, an unusually hot year (0.52 on Hadley's list) and said that global warming actually stopped back then. They conclude that after 10 years we can now say global warming is over, and we face the possibility of global cooling."
Good Math, Bad Math suggests that Duffy took the raw data and calculated six-year trends. Unfortunately, taking trends selectively allows the statistician to create erroneous results.
From the article:
"Proper statistical analysis relies on a kind of blindness."
By taking six-year trends, it's argued, Good Math, Bad Math suggests that Duffy looked for a trend that would show that there's no real warming occuring. Using 7-year or 8-year trends, and the global warming is apparent. From the article:
"What Duffy did is look at his data, and try to find a way of presenting it that appeared to support his pre-selected conclusion. And he managed to find one. He didn't show a complete analysis - he couldn't, because a complete analysis would have refuted his argument. So he selectively chose a way of analyzing the data that would produce the desired results: he looked at the data to find the longest period where trend analysis would show what he wanted - and he stopped there."
Read more anger at Deltoid, which examines his article in the Sydney Morning Herald.
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Comment by Louie
randomthoughts
Phil's Wellness Tips
thanks for this Cib.....
P.S. love the pic. I am jealous
Comment by Cibbuano
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Techbreak
Whenever I read a news article that quotes a scientific paper as a source, I'm skeptical. You've really got to take a critical look at the paper's methods.
Comment by Louie
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