How This Latest Heatwave Isn't Like Ones We've Had In The Past: Context & Nature

פורסם: 25 ביולי 2011, 22:45 על ידי: Sustainability Org   [ עודכן 29 ביולי 2011, 3:24 ]
by Matthew McDermott, New York, NY on 07.22.11

heatwave photo
photo: Dennis Jernberg/Creative Commons

Let's take as given that there have always been weather extremes, both hot and cold, throughout history and there is indeed a component of natural variability at play. But that's far from the whole story. If you're wondering what makes the latest heatwave different from those that have occurred before, has a pretty good summary (h/t Climate Progress). In short, the nature and context of this summer's situation is what sets it apart. senior meteorologist Stu Ostro writes,

This time, the extreme drought, heat, and wildfires are occurring along with US extremes this year in rainfall, snowfalls, flooding, and tornadoes, and many other stunning temperature and precipitation extremes elsewhere in the world in recent years as well as, as I posted on my TWC Facebook "fan" page, record-shattering 500 millibar heights in lattitudes. And all of this is happening while there's an alarming drop in the amount of Arctic sea ice.

The nature and context of the extremes is the difference between the 1930s and now.

Global Land-Ocean Temprature Index

palmer drought index june 2011 image

palmer drought index june 1936 image

palmer drought index june 1934 image
Images: NOAA

In more concrete examples, Ostro explains how alongside areas receiving record amounts of rain, the dry soil conditions are contributing to record high temperatures and how these are contributing to how hot it feels.

Rather than some of the sun's enery going into evaporating soil moisture, it gets efficiently converted into quickly-rising temperatures each day. And in turn, the soil dries out even more, worsening the drought. ...

Soil and crop moisture evaporating will boost the dewpoint, which translates to how humid the air feels.

Read more, it's pretty fascinating stuff, especially considering these sort of conditions are likely to become more usual in coming years and decades: The ridge, heat, humidity, drough, and Dust Bowl