The World Meteorological Organization (WMO) and the World Health Organization (WHO) have issued new joint guidance on Heat–Health Warning Systems to address the health risks posed by heatwaves, which are becoming more frequent and more intense as a result of climate change. Heatwaves are a dangerous natural hazard, and one that requires increased attention. They lack the spectacular and sudden violence of other hazards, such as tropical cyclones or flash floods but the consequences can be severe. Over the past 50 years, hot days, hot nights and heatwaves have become more frequent. The length, frequency and intensity of heatwaves will likely increase over most land areas during this century, according to the Intergovernmental Panel on Climate Change. In addition to the health impact, heatwaves also place an increased strain on infrastructure such as power, water and transport. In recent weeks alone, both India and Pakistan have been hit by deadly heatwaves, killing hundreds of people. The European heatwaves in the northern hemisphere summer of 2003 was responsible for the deaths of tens of thousands of people, as were the Russian heatwaves, forest fires and associated air pollution in 2010.