A Single Data Point!

Every winter it seems that the climate denialists bring out the but it's cold argument and while I have covered it before (see here, here, and here) I wanted to point out why it is not a valid argument against global climate change. I was inspired to do this based on a recent post over at Conservapedia which said the following [source]:

Global Warming Update: Cooling Trend Continues. March 2011 is on record as the coldest in 15 years. [14]

I saw that post and said, "so?" but I realized that many people who read Conservapedia, then again I doubt many people who read Conservapedia read my blog, might not realize that one month being colder isn't important.

The problem with one cold month is that it is only one data point. Global climate change is based on a build up of data that spans decades of research. One or two colder than normal months out of decades do not influence the data to a great degree nor should they be considered proof of the end of climate change, these are what are typically referred to as weather. What Conservapedia and the climate change denialists are doing are cherry picking data. I can do the same thing, as a resident of Lubbock, TX I know last month was hot in fact there was a least one day that we set a new record high. What is more is that the National Weather Service agrees with me and therefore that link that conservapedia posted is completely wrong March was one of the top 15 warmest months on record for the area and therefore their view that global warming is not happening is wrong, and the fact that Texas is in a severe drought means that the whole state is going to run out of water forever (sorry I wanted to find a way to get that link in a post somewhere).

It doesn't work that way, in fact even 2010 being tied for the warmest on record isn't, by itself, important. What is important is the long term trends like the graph to the left which shows over the long term the temperatures have been increasing globally, from Wikipedia. If you go to NASA's climate change website you can see all of the data accumulated thus far showing that climate change is in fact happening. Climate scientists might even actually expect 2011 to be much cooler than 2010 (I don't know that they do this was more just an example), but this will not pronounce climate change dead but will in fact just say that temperatures will vary year to year in the same way that temperature varies day to day. These individual variations are not important again it will always be colder in January than in July in the northern hemisphere and some places will always see snow. What is important is the long term trend, this is what scientists are interested in and this is what they look at. As summarized here, yes I know it is Wikipedia but the summary is good, you can see that of the 20 warmest years the vast majority in the upper half are in the last decade, and here you can see that the last 3 decades have been the warmest decades with each being warmer than the last. That sort of information is important and how climate change is decided not, well it was cold today we should stop worrying.