Humans have an impact on the world’s climate. Since the pre-industrial era, Human-made climate change has increased the global average surface temperature by about 2°C. The frequency, severity, and weather effects, such as heat and cold waves, have worsened due to climate change. Both heat waves and cold waves have adverse impacts on industrial production, human health, and agriculture. There is a climate emergency or a new normal all over the globe.
According to several studies, summer heat waves have increased in frequency while winter waves have decreased over the decades in India. A study at the University of Hyderabad examined the trend of hot and cold waves over various climatic regions of India using daily maximum and minimum temperatures recorded from 1970 to 2019.
India has roughly four primary climatic zones:
The alpine climate of the northern states of Ladakh, Jammu & Kashmir, Himachal Pradesh, and some areas of Uttarakhand, Sikkim, and Arunachal Pradesh is referred to as “montane.”
Arid and semi-arid
It includes the dry Rajasthan and the semi-arid Gujarat climate.
Most of the Indo-Gangetic basin, including Bihar, Jharkhand and Chhattisgarh, Uttar Pradesh and West Bengal, and certain portions of Madhya Pradesh and north-eastern tropical mountains of Assam and Nagaland, which are subjected to hot summers with high humidity and plenty of rainfall during monsoon season.
The tropical wet and dry climate
It refers to the southern peninsula of India, the majority of which has a tropical wet and dry climate.
It is observed that the number of days with abnormally high temperatures rises during the summer every year while the number of days with abnormally low temperatures decreases.
Trends in heat waves
Based on the maximum temperature variability, there are two different types of heat waves. The first type of heat wave over north-central India is linked to a change in the zonal atmospheric circulation. In contrast, the second heat wave type was reported over coastal eastern India. In a heat wave event, abnormally high temperatures continue for three or more consecutive days. Scientists discovered that the frequency of heat waves rises by 0.6 times every decade.
A world with a global mean temperature of 2°C above is expected to have a 30 times increase in severe heat waves by the end of the twenty-first century.
Trends in Cold waves
A cold wave event is three or more days with abnormally low temperatures. The researchers discovered that the frequency of cold waves is dropping by 0.4 times every decade. There is a different pattern of heat and cold waves all over India. For instance, heat waves are more frequent across arid and semi-arid climatic regions, whereas cold waves are less frequent.
To increase their effectiveness and impact, it is essential to include minor scale heat vulnerability and hotspot mapping assessments in heat action plans.
It is associated with mapping heat-sensitive zones based on land use, vegetation proportion, built-up areas, adaptive ability, and demographic characteristics. Furthermore, forecast models must be recalibrated to region-specific energy and water demand, agricultural, and health importance thresholds to offer impact-based heat forecast notifications. The forecast will facilitate decision-makers for proactive planning to deal with the issue of climate emergency.
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