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Originally Posted by Arragonis
From the article above
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One often hears the statement in the media that global warming stopped in 1998, or that there has been no global warming for the past 16 years. Why pick 16 years? Why not some nice round number like 20 years? Or better yet, 30 years, since the climate is generally defined as the average weather experienced over a period of 30 years or longer?
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NOAA did - they chose the start and the period. |
So it comes down to simple math. You have a rising trend of X fraction of a degree per year, underlying an annual variation from other causes (which you could model as a gaussian random). Therefore, given any fairly short period, there is some probability that the start value will be higher than the end value. It's just statistics, and it doesn't make the underlying rising trend go away.
The same math applies to other things, like the stock market. If we look at index values over a few decades, we can find lots of periods in which the starting value is less than the end value (2007-09, for one). But we still see a long-term rising trend, and those of us with sense invest in the market, and don't panic and sell at every downturn because "The economy is going to collapse!"