It’s HOT Out There!

A severe heat wave that has kept a tight grip on the Midwest and Eastern United States that has resulted in the deaths of at least 20 people  is perceived by many as a sign of the impact of global warming.  Excessive heat watches, warnings and heat advisories were in effect in more than 30 states, in what the weather service described as “a large portion of the central U.S. and Ohio River Valley, as well as portions of the mid-Atlantic and northeastern states.  Temperatures will feel like 100 to 110 degrees or higher during the afternoon hours.”

The heat wave has brought heat index values — which measure how hot it feels — to as high as 131.  Heat indices reached 129 in Newton, IA; 121 in Taylorville, IL; 122 in Gwinner, ND, and 123 in Hutchinson, MN.  Minneapolis recorded its highest dew point ever, 82 degrees.  The dew point measures atmospheric moisture.

“This is completely out of whack for the Upper Midwest,” said Chris Vaccaro, a spokesman for the National Weather Service.  The heat wave toppled existing peak records for electricity usage.  Xcel Energy, which serves 1.64 million customers in North Dakota, South Dakota, Wisconsin and Minnesota, broke a demand record on Monday with 9,504 megawatts of power used, according to Tom Hoen, a company spokesman.  The old record set in August 2010 was 9,100 megawatts.  Utility companies in Iowa reported record usage.

In Chicago, the National Weather Service is warning that the heat wave could be the most intense since July 1999, with highs flirting with the record of 101 degrees set 31 years ago.  In the downtown area, which the weather service characterizes as an “urban heat island,” the index is likely to remain above 100 degrees late into the evening and probably will not fall below 90 all night.  More than a dozen heat-related deaths have been reported in the Midwest.

A “combination of very hot temperatures and high humidity will create dangerous heat indices over the central US”, said the National Oceanic and Atmospheric Administration (NOAA).  The National Weather Service said a stagnant air mass on the central plains is the cause of the extended heat wave.  NOAA data affirm that temperatures have risen across the United States by roughly 1.5° F over the past 30 years.

This naturally leads to the subject of global warming.  According to Public Radio International’s “The Takeaway”,  Chicago’s 50-year forecast: lethal and extreme weather, a termite invasion and a 1 ½ foot drop in Lake Michigan’s depth.”

According to Aaron Durnbaugh, the deputy commissioner of Chicago’s Department of Environment, the forecast is based on fact, not fiction.  “We worked closely with the best scientists we could find to put forward our forecast, both in a best-cast and worst-case scenario — looking towards the middle of the century and 2100, the end of the century — and identifying different impacts related to precipitation and temperature, and then a follow on impact from those changes.”

Chicago’s city planners have a plan to redesign the city to accommodate the 50-year forecast.  The plan, according to an article in the New York Times, includes everything from what types of trees to plant, to more permeable roads and water-storage tanks.  The city is preparing for “sun” days: “We’re expecting many more days above 90 or 95 degrees, with heat spiking potentially to 117 degrees in the summer,” Durnbaugh said.  “And we have a history, unfortunately, of heat-related disasters in Chicago.  Cities adapt or they go away.  Climate change is happening in both real and dramatic ways, but also in slow, pervasive ways.  We can handle it, but we do need to acknowledge it. We are on a 50-year cycle, but we need to get going.”

According to a study published in the journal Environmental Health Perspectives, global climate change could, by 2081 to 2100, drive that average number of yearly heat wave-related deaths to between 166 and 2,217.  “Our study looks to quantify the impact of increased heat waves on human mortality,” said lead author Roger Peng, associate professor of biostatistics at Johns Hopkins University. “For a major U.S. city like Chicago, the impact will likely be profound and potentially devastating.  It’s very difficult to make predictions, but given what we know now — absent any form of adaptation or mitigation — our study shows that climate change will exacerbate the health impact of heat waves across a range of plausible future scenarios,” Peng concluded.