Down To Earth
By Shreeshan Venkatesh
A study published in the journal Environmental Research Letters on October 16, for the first time, gives us an estimate of the human impact of increasing frequency of heat waves as we proceed into the 21st century. The study reveals that under a business-as-usual scenario regarding emissions, frequency of heat waves could increase by about 75 times. Adherence to the Paris Agreement and limiting global mean temperature rise below 2 degrees may cause a 30-fold increase in severe heat wave frequency by the end of the century. By 2100, the population affected under an unhindered emissions scenario could be as much as 200 times the current affected population, according to the study.
Under the current emissions scenario, the study shows that the entire stretch from Uttar Pradesh in the north to the southern peninsular tip is likely to be badly affected by the increase in heat wave frequency. In comparison to heat wave frequency between 1971 and 2000, authors estimate that the frequency will increase by 3-9 events in the next 30 years. This increase is projected to be as high as 18-30 events by the final quarter of the century.
Researchers used multiple climate models and heat wave frequency between 1971 and 2000 as a reference to illustrate the difference in heat wave frequency, duration and distribution between different scenarios for both mid- and end-century time frames. Dependent on daily magnitudes of heat waves (dependent on temperature profiles of individual places on the days of the heat waves), researchers create a benchmark for “severe heat waves”.