Global ChangeIntersection of Nature and Culture

Say so long to your furnace and hello to a new air conditioner

Thursday, October 29th, 2009

Last summer’s sizzling heat in Texas and the Pacific Northwest saw temperatures soar into the triple digits for what seemed like weeks.

As Yale 360 indicated in June, a new report by the United States Global Change Research Program suggests that we are in store for many more summers like 2009. Their projections of daily temperatures show that much of the South will be hotter than 90 degrees F for almost half of the year.  As temperatures warm, we can expect to set more record high temperatures.

In a forthcoming article in Geophysical Research Letters,^1,2 Gerald Meehl and colleagues asked a simple question: What is the ratio of record high temperatures to record low temperatures, and how will this change over time with climate warming?

Based on temperature data from across the U.S. between 2000-2009, they found that the current ratio is about 2:1, meaning that we are breaking twice as many record high temperatures as we are record low temperatures.  Using climate models to predict U.S. temperatures over the coming century, they estimate that the ratio will increase to 10:1 by 2025, 20:1 by 2050, and 100:1 by 2100.

Because this is a ratio, we need to be a bit careful how we interpret these data.  You can increase this ratio two ways:  by high temperature records outpacing low temperature records (increase the numerator), or by dramatically reducing the number of low temperature records without many new high temperature records (decrease the denominator).

Either way, we’re in for hotter weather.  This kind of study will hopefully influence climate adaptation efforts now, especially in helping cities deal with heat issues among elderly populations.   The heat waves in Chicago (1995) and France (2003) are vivid reminders.  As I mentioned in an earlier post on adaptation, no more Hurricane Katrina responses.

Related posts:

• Chicago 1995: How social disparities lead to environmental disasters
• Climate adaptation: We have no choice, and it’s not enough

¹ Meehl, G.A. et al. (2009) The relative increase of record high maximum temperatures compared to record low temperatures in the U.S. Geophysical Research Letters (paper in press).

² Bowdoin people can access the article here.

photo credit:  http://www.flickr.com/photos/rosh/ / CC BY-NC-SA 2.0

Tags: heat, record temperatures
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