Global warming may be causing US heat waves

Global warming may be responsible for the heat wave currently gripping the US. This is the second year of intense weather in North America, where last spring and summer temperatures soared for weeks on end in many states. However, the latest stifling weather is breaking even previous records.

Since March 12, more than 7,000 warm temperature records have been equalled or broken. This has caused scientific researchers to remark in email conversations that global warming has increased the likelihood of such events, though they admitted natural variability has also had an impact.

Global warming increases the chances for such extreme heat events to take place, claim previous scientific studies. Though each individual event cannot be directly attributed to climate change, studies suggest that greenhouse gas emissions mean that conditions are in place to increase the likelihood and severity of heat waves.

The US in particular has seen more common and more extreme heat waves in recent years. To examine the extent to which global warming has played a role in this, scientists need to observe different scenarios and compare the entire climate system to see how it reacts. This will allow them to investigate how often an extreme heat event takes place under certain conditions. Such a study was carried out on the Russian heat wave of 2010 and on the European heat wave of 2003. Both found that changes in greenhouse gases increased the odds of unusually hot weather.

However, there is also the view that meteorology is playing a larger role than climate change. Such views were voiced during the March 2011 US heat wave. Martin Hoerling, research meteorologist at ESRL, claimed meteorology was the “main ingredient” in the last spring’s weather in the US.

“[Climate change’s] contribution to the magnitude of current conditions (30 degrees Fahrenheit above average) is quite small (but not zero) indeed,” he added.

Time is needed for scientists to evaluate the role of global warming on recent events in the US more extensively. One thing is for certain, however, and that is that the US is hotting up. The overnight temperature in Rochester, Minnesota, was, on March 18 this year, hotter than even the record high daily temperature. In Chicago, March temperatures have exceeded even April’s record highs, according to the National Weather Service.

Image: dewittn | flickr