Weatherdem's Weblog

Bridging climate science, citizens, and policy

Warmest Year on Record Likely For US in 2012

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As readers of this blog are likely aware, 2012 was brutally hot across most of the U.S. in the spring and summer.  All-time records at hundreds of stations fell, monthly records were shattered, and seasonal records were similarly set.  These conditions led to speculation that 2012 would be the U.S.’s warmest.

That speculation is likely to be borne out as true.  Even though October was the first month in seventeen in which average contiguous U.S. temperatures were below average instead of above average, the January-October average temperature continued to track well above the previous record-setting year – 1998 – as the following graph demonstrates.


Figure 1. 2012 observed and projected contiguous U.S. temperature anomalies compared to previous top-5 anomalous years.

The current record holder is, of course, 1998 – the year which saw the strongest El Nino event of the 20th century end.  2012’s anomaly are therefore very important in context: a moderate La Nina event ended in 2012.  La Nina is typically characterized as a cooling event while El Nino is typically characterized as a warming event.  Now, those characterizations are global in nature, so interpreting their effects for the U.S. only gets more complex.  The point of this is the following: as the globe as a whole continues to warm and future El Ninos occur, the U.S. is likely to see warmer years than 2012.

The graph also contains the following information.  November and December would have to be among the ten coldest months on record in order for the 2012 average to dip below 1998’s record.  Well, November has been warmer than average so far through the first couple of weeks.  That trend is forecasted to continue for the next couple of weeks (not record-setting hot, just warmer than the 20th century average).  Therefore, the trend would have to absolutely reverse itself in December in order for 2012 to not set the new record.  Simply put, the chances of that happening are incredibly remote.

I haven’t blogged about it yet, but Hurricane Sandy’s landfall and subsequent widespread destruction might start small-scale conversations regarding the state of our infrastructure in today’s world.  Without even considering the potential future effects of anthropogenic global warming, it is clear to more and more people as weather disasters strike that we are not equipped as a society to adequately handle today’s climate.  Conditions have largely been beneficial to benign throughout the 20th century.  That wasn’t always the case prior to that and it’s likely that it won’t be the case in the future.  We have to have honest conversations about this and make hard decisions about what to build where and what industries our society should be built on.  What aid do we provide to farmers in areas that are drought-prone?  What aid do we provide to homeowners that live in high-risk areas?  What do our building codes and zoning laws allow today and should those same things be allowed in the future?  These are just a small sample of the kind of policy questions we have to ask when we see the above graph and many others like it.


On another topic, I’m almost done with classes this semester.  I’ll get back to much more frequent posting in another month.


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