Sunday, 4 January 2009

Sorry, Global Warming Hasn’t Stopped

Apparently 2008 was a cooler year than 2007, which is predictably leading to the denial lobby screaming that this whole “global warming” thing is obviously a scaremongering crock.

Of course no-one ever said that global warming means we will have year-on-year warming.

This graph shows the average global temperatures over the course of the late 19th and 20th centuries:


The year-on-year changes in temperature jump all over the place, but the trend is ever upward.

In fact, out of the last 50 years there were 22 that were cooler than the year that preceded them: 1959, 1960, 1963, 1964, 1970, 1971, 1974, 1976, 1978, 1982, 1984, 1985, 1988, 1989, 1991, 1992, 1996, 1999, 2000, 2004, 2006 and 2007.

So it’s not surprising at all that 2008 was a cooler year than 2007. Based on recent history the probability of that happening was about 44%.

You’ll also hear the common refrain that global warming stopped 10 years ago and the Earth hasn’t warmed since.

Warning: this is just a convenient selection of statistics.

In 1998 we experienced the peak of the El Niño cycle (see the spike in the graph above) which caused a drastic one-off increase in global temperature. So of course it’ll take a little while for the trend of rising temperatures to get back to that point.

The same argument could have been made the whole period between the years 1944 and 1980. It wasn’t valid then and it isn’t valid now.

There’s nothing at all to indicate that the earlier trend has stopped.

In fact, with the continued increase of CO2 in the atmosphere, there’s every indication that we’ve got quite a way to go yet.


Sarah said...

I'm quite worried about "the commitment". Even if we stopped carbon emissions now, we still have to deal with the not yet felt effects of the stuff that we've already put there.