Heat Waves Rising in Urban Areas

Over the last 40 years, the number of heat waves that occur in urban areas worldwide have been steadily rising, these sweltering temperatures more prominent in recent years, according to new research.

Of the five hottest heat waves on record, four of them occurred just within the last several years, no less, from 2009 to 2012.

Heat waves are defined, at least in this study, as periods when the daily maximum temperature was hotter than 99 percent of days for the period 1973-2012, for a consecutive period of six or more days.

According to these latest findings, such prolonged periods of extreme hot days have significantly increased in over 200 urban areas across the globe between 1973 and 2012. In addition, during this time the number of individual extreme hot days increased in over half of the studied areas, while nearly two-thirds experienced more individual extreme hot nights.

"Over half of the world's population now live in urban areas; hence, it is particularly important to understand how the climate and climate extremes, in particular, are changing in these areas," lead researcher Vimal Mishra said in a statement.

The study is among the first to focus on the extent of extreme weather on a global scale, and how it differs between urban (over 250,000 people) and non-urban areas. They relied on data from the National Climatic Data Center to reach their conclusions.

In addition to the increase in heat waves for urban areas, they also found that some 60 percent of these regions experienced less windy days and overall a general decline in cold waves. Not to mention about 17 percent and 10 percent of urban areas saw, respectively, a significant surge in daily precipitation extremes and annual maximum precipitation.

According to Mishra, paying close attention to climate change and its affect on urban areas is of particular importance considering they are "centers of wealth," and could result in severe economic losses should extreme weather like heat waves cause any significant damage.

The findings were published in the journal Environmental Research Letters.

For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).