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Climate change to impact monsoon in India: Report

Hindustan Times, New Delhi | ByJayashree Nandi
Sep 21, 2019 02:54 AM IST

Called the “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.

Sea-level rise of several metres 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 systems affect larger areas over longer timescales, and rainfall during monsoon season is likely to intensify while becoming less predictable. The largest effect, which is already being observed today, is an increase in the year-to-year variability of the monsoon strength and the associated extremes of rainfall,” said the report.

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Called the “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.

The report underlined that policy makers have been receiving economic assessments that omit the biggest risks from climate change. These include periodic assessments by the Intergovernmental Panel on Climate Change (IPCC).

The Earth Institute in Columbia University, Grantham Research Institute on Climate Change and the Environment and the Potsdam Institute for Climate Impact Research represented by economist Nicholas Stern, climatologist Hans Jaochim Schellnhuber and others who authored the report highlighted that the cascading impacts of from destabilisation of ice sheets; stronger tropical cyclones; extreme and frequent heat waves and floods; collapse of ecosystems are not being reported or analysed accurately.

For example, recent IPCC reports have mismatches between physical and economic impacts of climate change. IPCC’s summary for policy makers for its fifth 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 1.5 degrees said risks to global aggregated economic growth due to climate change impacts are projected to be lower at 1.5 degree C than 2 degree C by the end of the century and that impacts mainly refer to gross domestic product but impacts such as loss of lives, ecosystem services and cultural heritage are difficult to value or monetize.

“The vague statements about the economic risks in the IPCC reports reflect the limitations of published studies that are based on analyses that exclude the largest potential impacts of climate change,” the report said.

Analyzing current climate science and future models, the team concluded that exceeding one threshold may trigger another which could lead to “unstoppable” and “irreversible” impacts. “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 currents), together causing a rise in sea level and heat accumulation in the Southern Ocean, which would accelerate ice loss from the East Antarctic ice sheet,” the report explained.

These cascading impacts and risks are omitted because they can be difficult to predict precisely 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 populations, heat waves and droughts, pest and disease outbreaks. Some economic impacts are downplayed by economists if they are forecast not to occur imminently.

The report gives examples of certain climate impacts or crises led by it already being experienced which include the Syrian crisis and exodus, disappearance of Lake Chad in the Sahelian region and related conflict. It adds that over 600 million people live on land which is 10 metres or less above sea level which will be exposed to storm surges. Those in the tropics will face a deadly combination of extreme heat and humidity. For example at a “wet bulb temperature” of 35 degree 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.

“The IPCC and other scientific literature has already highlighted that global monsoon systems will be impacted, monsoon rain will increase so will monsoon variability,” said Krishna Achuta Rao, climate scientist at IIT Delhi.

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