United Nations issues first-ever guidance to combat heat waves

Geneva: For the first time, on Wednesday, the United Nations issued a new joint guidance for countries to address the health risks posed by heat waves that have become more frequent and deadlier over the last 50 years, recently killing over 3,000 people in India and Pakistan.

The World Health Organisation (WHO) and World Meteorological Organisation (WMO) joined forces to issue guidelines on Heat-Health Warning Systems that will help contain the heat waves that have turned out to be more hazardous due to climate change.

"This is a product which has been in development for quite a number of years. Why do we need it? The reason is because heat waves are becoming more frequent.

"We expect them to become more intense as a result of climate change, so we need to improve our responses to save lives," said Clare Nullis, the spokesperson for WMO.

"And it's quite timely because in recent weeks we obviously saw the heatwave in India which killed hundreds of people. We saw the heat wave in Karachi last week which killed more than a 1,000 people," Nullis added.

"Of principal concern in an HHWS (Heat Health Warning System) is how to assess the level of heat stress associated with the meteorological or climate forecast, translate this into an estimate of a likely health outcome and identify a critical heat-stress threshold for a graded plan of action," a report released by the UN said.

"Cities are growing fast, and they tend to be considerably hotter than surrounding areas. Populations are also ageing, with more people suffering pre-existing conditions which exacerbate heat stress.

"So, it is becoming more and more important for countries to address the growing problem. This report will take them through the process," said Dr Diarmid Campbell-Lendrum, Team Leader, Climate Change and Health of WHO.

"The definition of a heatwave is very location-specific. For instance, 32 to 34 degrees celsius may be extremely hot for Geneva but might not be so for Delhi. The WMO-WHO guidance document gives a range of approaches to assess heat stress and identify heatwave conditions.

"The product also gives a range of definitions for heatwaves which can be tailored to a specific city," said Dr Rupa Kumar Kolli, Chief, World Climate Applications & Services Division at WMO.

"There are sophisticated models also available which can estimate, if temperature in a particular location exceeds heat wave thresholds, what additional number of deaths one might expect, what the associated health outcomes could be, etc," Kolli added.

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.

Currently, there is no universally-accepted definition of a heatwave and no absolute universal value, such as a given temperature that defines what is extreme heat.

"Our work in the future will be to support national agencies to work together to give better protection to their populations," Campbell-Lendrum said.

"Heatwaves are a dangerous natural hazard, and one that requires increased attention," said Maxx Dilley, Director of WMO's Climate Prediction and Adaptation Branch, and Maria Neira, Director of WHO's Department of Public Health, Environmental and Social Determinants of Health. "They lack the spectacular and sudden violence of other hazards, such as tropical cyclones or flash floods but the consequences can be severe."

In addition to the health impact, heat waves also place an increased strain on infrastructure such as power, water and transport, the report said.