Back in October 2009, my post “A Cherry-Picker’s Guide to Temperature Trends” examined the many different statements that could be made to describe the tendencies of global temperatures over the past 20 years. I concluded that anything from rapid cooling to a faster than expected warming could be supported by carefully picking through the available data.
Now, more than a year later, and after one of the “warmest years on record,” I’ve updated my analysis so that any new statements characterizing global temperature can be evaluated against the complete set of recent observations.
In general, I find that statements such as “global warming has stopped” should be tempered, at least for the time being. But I conclude that my original article’s summary remains applicable:
What I can say for certain, is that the recent behavior of global temperatures demonstrates that global warming is occurring at a much slower rate than that projected by the ensemble of climate models, and that global warming is most definitely not accelerating.
I say “more or less” because one could argue from the data (as we’ll see below) that the warming rate during recent years has upticked with the warmth in 2010 indicating a warming that is occurring faster than projected and is accelerating. But, I think that this represents a temporary condition.
In due course (say over the next several months), the warmth in 2010 will continue to subside as the cooling influence from a Pacific La Niña event supplants the warming influence of last year’s El Niño (see here for example). This will have the effect of flattening out recent temperature trends and returning them once again to lower-than-projected values. I imagine that we’ll see such an impact when it comes time again for me to produce an update to this update.
But until that time, I’ll describe the situation as it presents itself data available through December 2010.
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I recommend that you read the entire article at Master Resource