As climate models become more refined, we get a better sense of the fundamental ways in which climate change is altering the world’s weather patterns. According to a new study published in Nature Climate Change on 18 January, researchers have found that monsoon rainfall over the course of the century will get even more severe for southern India. And the reason for this is global heating.
The study, Zonally Contrasting Shifts Of The Tropical Rain Belt In Response To Climate Change, states that the intertropical convergence zone (ITCZ), a narrow band of tropical heavy rainfall, is moving steadily north. The researchers looked at 27 different climate models to conclude that by the end of the century, the ITCZ will migrate towards eastern Africa and the Indian Ocean, even as the atmosphere in Earth’s northern hemisphere heats up.
This will have a varied impact, including “future increases of drought stress in south-eastern Africa and Madagascar, intensifying flooding in southern India and greater drought stress in Central America—large hydrological hotspots of global change that will have considerable impacts on food security and biodiversity.” The report further states that this will result in an increase in India’s monsoon rainfall, as well an increase in extreme rainfall events.
How will the position of the Earth's tropical rain belt be affected by #climatechange in different parts of the world? Read our new #research, published with @SpringerNature in @NatureClimate to find out!https://t.co/auSD6JXSf9— Antonios Mamalakis (@AntoniosMamala2) January 18, 2021
A few key points below (1/6). pic.twitter.com/QXWI68GHXj
The link between the shift in the ITCZ rain belt and climate change is very clear. The northern hemisphere is heating up more than the southern hemisphere. Part of the reason is that due to the loss of Arctic sea-ice and Himalayan glaciers, there has been a reduction in the albedo effect, i.e. less of the sun’s energy is being reflected back into the atmosphere due to a loss in white ice. The northern hemisphere, thus, is becoming more heated. The ITCZ is migrating slowly towards the hotter, northern zone, bringing about a disruption in normal weather patterns. “In Asia, projected reductions in aerosol emissions, glacier melting in the Himalayas and loss of snow cover in northern areas brought on by climate change will cause the atmosphere to heat up faster than in other regions,” says James Randerson, one of the co-authors of the study.
The southern parts of India have been experiencing both severe flooding and extreme rainfall events annually for a few years now. Kerala, for instance, experienced catastrophic flooding in both 2018 and 2019. The northward shift of the tropical rain belt adds another dimension to the climate impacts that India will have to adapt to very soon.