Climate change to impact monsoon in India

Sea level rise of several meters and major disruption to monsoon rains and river flows in India are among the biggest global economic risks from climate change, a policy report by leading economists and scientists has said. 

 “Climate change is likely to mean monsoon system affect larger areas over longer time scales, and rainfall during monsoon season is likely to intensify while becoming less predictable. The largest effect which is being observed today, is an increase in the year-to-year variability of the monsoon trends and the associated extremes of rainfall” said the report. 

Called ‘The missing economic risks in assessments of climate change impacts report’, the report was released two days ahead of the UN Climate Summit in New York. It underlined that policy makers have been receiving economic assessments that omit the biggest risk from climate change. These include periodic assessments by the inter-governmental panel on climate change (IPCC). 

 The Earth Institute in Colombia University, Grantham Research Institute on Climate Change and the Environment and the Potsdam Institute for Climate Impact Research represented by economist Nicholas, climatologist Hans and others who authored the report highlighted that the cascading impacts on destabilization of ice sheets; stronger tropical cyclones; extreme and frequent heat waves and flood; collapse of eco systems are not being reported or analyzed accurately. 

For example, IPCC reports have mismatches between physical and economic impacts on climate change. IPCC’s summery for policy makers for its 5th assessment report published in 2014 muted the impact on economy saying “aggregate global economic losses accelerate with increasing temperature but global economic impacts from climate change are currently difficult to estimate…” Or the summary for policy makers of IPCC’s special report on global warming of 1.5⁰ said risks to global aggregated economic growth due to climate change impact are projected to be lower at 1.5⁰ C than 2⁰ C by the end of the century and that impacts refer to gross domestic product but impacts like loss of lives are difficult to monetize. 

Analyzing current climate science and future models the team concluded that exceeding a threshold may trigger another which could lead to “unstoppable” and “irreversible” impact. “For instance, the loss of ice from the Greenland ice sheet could trigger a critical threshold in the Atlantic Meridional Overturning Circulation (a system of ocean current), causing a rise in the sea level and heat accumulation in the Southern Ocean, which would accelerate ice loss from the East Antarctic from the ice sheet,” the report explained. 

 This cascading impacts are omitted because they can be difficult to predict and to capture in simulations using current models. Models also often cannot represent compound events such as sea level rise and storm surge impacts on exposed coastal population, heat waves, pest and disease outbreaks. Some economic impacts are down played by economist if they are forecast not to occur imminently. 

Those in the tropics will face a combination of extreme heat and humidity. For example, at a “wet bulb temperature” of 35⁰ C or more, sweat no longer evaporates from the skin surface and the body cannot cool down. Parts of South Asia, Eastern China, Arabian Gulf have exceeded a WBT of 31 degrees. “Scientific literature has highlighted that global monsoon systems will be impacted, monsoon rain will increase with monsoon variability,” said climate scientist at IIT Delhi.