The Island of Doubt

Now you can say that I've grown bitter but of this you may be sure
The rich have got their channels in the bedrooms of the poor
And there's a mighty judgment coming, but I may be wrong
You see, you hear these funny voices ... In the tower of song
— Leonard Cohen

Predicting the future is rarely a wise move, even for a scientist whose job it is to come up with ways of doing just that, if one cares about a public reputation. Fortunately, there are some courageous researchers out there willing to take a stab. The emerging consensus in climatology is that 2008 will be...

... nothing special.

A couple of months back, the good people responsible for climate models at England's Hadley Centre came up with a set of predictions for the next ten years. Their highly regarded short-term climate forecast emerged from the new Decadal Climate Prediction System, which was widely praised because it "starts from the real observed status of the ocean and the atmosphere," according to study leader Doug Smith.

For the immediate future, Smith and his team expect "the influence of natural climatic variations were likely to dampen the effects of emissions from human activities between now and 2009." Essentially, 2008 isn't going to be anything special, at least not much warmer than the past couple of years:

Global temperature for 2008 is expected to be 0.37 °C above the long-term (1961-1990) average of 14.0 °C, the coolest year since 2000, when the value was 0.24 °C.

Supporting the British prophecy is NASA's Goddard Institute for Space Studies. Its chief, Jim Hansen, yesterday released their predictions for the year.

Hansen's summary points to two factors that should keep 2008 off the record books. First, there's La Niña, the irregular phenomenon that tends to keep things cool by redistributing oceanic heat, and second is the fact that we've just hit the low point in a solar cycle -- the one associated with sunspots in which the amount of heat energy reaching the Earth rises and falls roughly every 11-years. These are the natural climate variables that the Hadley gang also says will counter the warming effect of anthropogenic greenhouse gas emissions. Hansen's conclusion is

it is unlikely that 2008 will be a year with an unusual global temperature change, i.e., it is likely to remain close to the range of (high) values exhibited in 2002-2007.

But both Hansen and Hadley agree that 2008 or possibly 2009 could the last year for a while in which we enjoy a break from rising temperatures. As La Niña winds down and the solar cycle ramps upward again, though, the trends towards something that would break the 2005/1998 record returns. First the future according to Hadley:

Over the 10-year period as a whole, climate continues to warm and 2014 is likely to be 0.3 °C warmer than 2004. At least half of the years after 2009 are predicted to exceed the warmest year currently on record

And now Hansen's vision:

... when the next El Niño [the opposite of La Ni˜a] occurs it is likely to carry global temperature to a significantly higher level than has occurred in recent centuries, probably higher than any year in recent milennia. Thus we suggest that, barring the unlikely event of a large volcanic eruption, a record global temperature clearly exceeding that of 2005 can be expected within the next 2-3 years.

There is a political consequence to such scenarios, of course. It means that 2008 and much of 2009 could be unremarkable to the extent that public pressure to do something about climate change wanes a bit. This would be a bad thing, as we can't afford to let a couple more years pass.

On the other hand, these are global predictions, and there is no reason to assume they will hold true at the regional level. We could still have an unusually warm summer in the U.S., for the umpteenth year in a row. The thing to keep in mind are: a normalish 2008 would not undermine the consensus on climate change; if anything it would lend support to the the science.