Get ready for the climate change pseudoskeptics to exploit to their own disingenuous ends the inevitable disagreement among climatologists over just where the latest 12 months falls in the list of warmest years on record. See? they'll argue, the science can't be trusted. Depending on the record, 2007 is either...
What those in denial probably won't want to focus on is the fact that two natural cycles that have nothing to do with anthropogenic climate change -- the solar minimum/maximum associated with sunspots and the El Niño/La Niña, or Southern Oscillation phenomenon -- had the effect of cooling the planet over the last few months. Which means that without those effects, it is extremely likely that 2007 would have stolen the title of warmest year on record from 2005 (or 1998 depending, again, on who's counting).
As Jim Hansen and his colleagues at the GISS point out:
If the sun should remain 'stuck' in its present minimum for several decades, as has been suggested
in analogy to the solar Maunder Minimum of the seventeenth century, that negative forcing would be balanced by a 5-year increase of greenhouse gases. Thus such solar variations cannot have a substantial impact on long-term global warming trends.
The natural variations of the Southern Oscillation and the solar cycle thus have minor but not entirely insignificant effects on year-to-year temperature change. Given that both of these natural effects were in their cool phases in 2007, it makes the unusual warmth this year all the more notable. It also suggests that, barring the unlikely event of a large volcanic eruption, a record global temperature exceeding that of 2005 can be expected within the next 2-3 years.
And don't forget that "11 of the 12 years from 1995 to 2006 were among the 12 warmest years on record," according our friends at the IPCC.
I am a big advocate of let's face the facts about global warming and work on an all out campaign to remedy what we can!
Since it seems to me that you can accomplish soooo much more by getting people to agree and work on common goals, I would like to see more of a push to include talking about pollution and global warming at the same time.
The gasses and chemicals coming out of power plant smoke stacks and vehicles are toxic, poisonous and not healthy for children or other living things!
If we push for solutions that will combat CO2, pollution and our dependence on foreign oil all at the same time, everybody wins. I have a post on my blog about plug in hybrid vehicles that is this kind of solution. There are many others too I am sure.
If someone is on the other side of the fence from you about if man or nature is warming the whole place up, they still are probably in agreement about wanting to decrease pollution and foreign oil consumption so you can still work together while trying to convince them man has a bigger part in it than they believe.
Dave Briggs :~)
What a fine article! It certainly puts a lot of material in a well writ summary for now. This suggests an explanation for the phase differences between maxima and CO2 observations in the ice cores. With some data juggling we'll get an estimate for the anthropogenic component that is right now.
The psudoskeptics will have a Polyanna reply when they figure it out. Meanwhile, husband the resources: all of 'em.
Wouldn't it be safe to say now that 12 of the last 13 years have been the warmest on record?