Extreme heat in South Asia threatens millions of people
By Gracie Pearsall
Pervasive climate-based heat affects all corners of the globe, even places that normally have hot, tropical climates. One place already experiencing some of the devastating effects of rising temperatures and heatwaves is South Asia. The region’s rapid urbanisation and poverty rates are among the most important factors when it comes to heat and general climate vulnerability. However, solutions like green and reflective roofs are emerging as heat adaptation measures.
South Asia is already a hot and humid region and it’s getting even hotter. The average temperature there is rapidly approaching 37° C, which is the operating temperature of the human body. When the apparent temperature approaches body temperature, the body’s capacity to function properly is greatly diminished. This type of heat-stress leads to heat-related illnesses such as heat-stroke, exhaustion, and dehydration.
In the Ganga Plains, there are regularly days where the temperature exceeds 37° C, which puts residents highly at risk for heat-related illness. Climate projections for this area suggest that by 2050 there will be 152 out of 200 days between April and October where temperatures exceed 37° C. Because of these extended periods of extreme heat, the residents of the Ganga Plains will experience even more heat-related illnesses.
Heat stress in rural areas
Millions of families in rural South Asia depend on livelihoods that expose them to extreme heat, such as farming. These families are usually low-income and do not have access to cooling systems that offer relief from the heat. Extended periods of manual labor in the heat make farmers and other manual laborers distinctly vulnerable to heat-related illnesses.
The heat also decreases agricultural productivity because the heat harms crops and livestock. For example, Terai, Nepal’s most productive agricultural region, is in jeopardy because projections show temperatures increasing by 2.8° C by 2060. This heat will likely reduce the arability of the land, limit water for irrigation, and pose a deadly threat to the farmers’ health.
Urban heat island effect
The Urban Heat Island effect caused by the rapid urbanization and population growth in South Asia is adding heat to the already warming climate. Urbanization modifies land cover and replaces natural heat sinks, such as trees, lakes, and wetlands, with pavement and buildings that absorb a lot more heat. Because of this phenomenon urban areas in South Asia are significantly warmer than their rural counterparts.
This phenomenon is even present in typically cooler hill cities such as Kathmandu. As of 2016, a study estimated that the Kathmandu’s average heat index per month is 20 percent higher than that of each corresponding month 30 years ago. Currently, Kathmandu’s metropolitan center is 1° C warmer than the outskirts. The increased heat makes city residents vulnerable to heat-related illnesses and exposes them to respiratory harm from the high concentrations of air pollutants that usually accompany urban heat islands.
Beating the heat
To cope with the heat, South Asian communities use a variety of cooling techniques. The most popular technique is to install reflective material or vegetation on roofs to minimize heat absorption. Reflective roofs are especially critical in combating heat in urban areas where roofs make up the majority of surfaces hit by solar radiation. In Pakistan, a National Center for Atmospheric Research and Institute for Social and Environmental Transition study found that at night houses with reflective roofs were 3° C cooler inside than outside. Furthermore, in Bangladesh reflective roofs have been shown to reduce the indoor heat index by 77 percent during peak heat times.
South Asia’s overall ability to limit heat stress depends on reliable delivery of basic services such as clean water, sanitation, healthcare, and energy to run cooling technology. These services will help communities stay cool and treat heat-related illnesses. However, to provide these services, there must be significant investment in infrastructure. South Asian governments must also implement policy measures to preserve natural heat sinks, such as parks and lakes, and limit human activities that contribute to climate change, in order to brace for rising temperatures.