An article in from Investors.com (hat tip Luboš Motl) illustrates how choosing a time scale and framing the data are both scientific and political choices. 2006 is both the sixth- warmest year recorded and probably the coldest year in the last five years.
“… it appears that 2006 will be the sixth-warmest year recorded. But let’s remember two significant facts before we fall into the depths of global warming depression.
First, accurate temperature records based on modern instruments don’t go back much further than 100 years. Given that Earth has been around quite a bit longer than a century, such a small sample of data is virtually meaningless.
Second, 2006 will actually be cooler than the previous four years and cooler, as well, than 1998, which was the peak year of global warming — if there is such a thing.
So why didn’t the headlines trumpet this obvious trend toward cooler temperatures rather than shriek about the “sixth-warmest year”?
Are journalists in the business of alarming the public or informing it?
Just like our fathers would have said about the shrinking differences in the appearances of young men and women in the late 1960s: It’s getting hard to tell these days.
We won’t blame the media too much, though. They were simply following the lead of the United Nations’ World Meteorological Organization. Its news release opens thusly: “The year 2006 is currently estimated to be the sixth-warmest year on record.”
Why bother with the tedious exercise of critical thinking — such as rooting out the cooling trend and pointing it out to the public — when the narrative is already written by the WMO?…”