". . .the earth has been cooling now for the last 15 years, while CO2 is still rising."This is a common meme among the skeptics: that there has been no warming recently despite increasing CO2, therefore global warming has stopped.
The main problem with this argument is that 15 years is too short a period to make any definitive statements about long-term trends. It also fails to take into account other forcings, such as solar intensity (down), ENSO (more La Nina lately) and increased aeresols from Chinese coal burning (study here).
For today, though, I want to show this:
LOOK!! Declining trend. And this one goes back all the way to 1982; 30 years. What could it mean? Whatever this represents, clearly it's evidence of a long-term decline.
So what is this a graph of? This graph shows the annual best long-jump distance by a man during the outdoor track season. And this decline seems to be occurring even during a time of better training, computer-aided physiological modeling, etc. Our athletes must be getting fatter and slower.
If we go back to 1960, though, we get this:
Note the unusual outlier in 1968, Bob Beamon's remarkable jump at the Mexico City Olympics. Even if we start with that year, we still get a positive trend:
(Think of Bob Beamon's jump like the 1998 El Nino, an exceptional outlier that eventually supports the trend rather than refutes it)
So, no, our athletes are not getting fatter and slower. Undoubtedly, the long-term trend will re-emerge and eventually Mike Powell's record from 1991 will also be broken. If I were to offer a bet that long jumpers will be better 30 years from now than they are now, I doubt anyone would bet against me.
So it is with global temperatures. As long as we continue to add heat-trapping gases to our atmosphere, the long-term trend will be up. Short- and medium-term trends may not be, but I'll bet anyone that temperatures 30 years from now will, on average, be higher than they are now. Perhaps someone will take me up on that bet, but they would be as foolish as someone betting on long jumpers jumping shorter and shorter distances.