I heard someone mention the other day that the current drought and heat is just like the 1930s. I think that is taking things bit too far. We tend to have short memories and the 1930s are a long time ago as compared to the normal human lifespan. A quick look at this wikipedia page or this youtube video will remind you of how dry, hot, and devastating the 1930s were in the U.S. In Wausau, 9 of the top 20 warmest Summers we have recorded in the last 115 years or so occurred during the 1930s. Only 1935 failed to make it into the top 20. It ranks number 31 on the list of warm Summers. So it was not only hot back then, it was hot EVERY Summer for a decade. I shudder to think of the media coverage, intense anthropogenic global warming (AGW) discussions, and political machinations that would occur if the U.S. suffered a multi-year drought and heat wave like the 1930s. It is such a distressing thought, I want to block the image out of my mind and stop writing right now. Alas, we should not be surprised if such a pattern did develop because multi-year and even multi-decade droughts were much more common in North America prior to the 20th century.
That is not to say that there are NO comparisons to the 1930s. 1936 had the warmest July and 1933 had the warmest Summer (June-July-August) we have ever recorded here in Wausau (going back to the late 1800s). This year we are on pace to break both of those records. The mean temperature so far this July is 77.3. In 1936 the mean temperature was 76.7. It looks like we are going to be close to breaking that record. Current extended forecasts indicate a more substantial cool down could hit the area for the last few days of the month. If it does materialize, then we will probably not break the record. Otherwise, we are in the running.
For the warmest Summer record, at this point we are certainly in good shape to break that one, but we still have about a month and a half to go, which means a lot could happen. In 1933 the mean Summer temperature was 71.3. So far this year we are at 72.8. What is interesting to note is that our temperatures this year have not been as extreme as the 1930s, with multiple days at 100 or above (at least not in Wausau) but it has been persistently warm. Every day so far this July we have experienced high temperatures in the 80s or 90s. I forget what the 70s feel like.
Which brings me back to our “short-term memories”. Just remember that the last time we had a high of 98 in Wausau was 2006. After 2006, high temperatures in the 90s were very sparse. In 2009 we didn’t even get close to 90 in July (85 was the warmest). It wasn’t until last year (2011) when multiple 90 degree days become more prominent again. I also remember back to last year when on first weekend of May, there was still a large ice flow on the bank of the trout stream I was fishing. That is only 14 months ago when we were emerging from an abnormally long & snowy Winter.
For more on how the heat this year compares to past years in the U.S. as a whole check out this graphic.
Of course, it is common sense that the drought is linked to the heat wave, but it is one of those things that science sometimes needs to confirm, and it was confirmed in this recent study.
And going back further in the past, there is more evidence to indicate that the time of the Roman civilization and the Medieval Warm period were warmer than we are experiencing now. This does not mean that AGW is not happening, or at least a part of what is going on now, but it does help put the longer term climate in perspective and help us frame possible challenges going forward.
Have a good Tuesday! Meteorologist Justin Loew.