Climate change impacts already locked in -- but the worst can still be avoided

https://www.eurekalert.org/pub_releases/2017-11/uoe-cci111617.php

Public Release: 16-Nov-2017
Climate change impacts already locked in -- but the worst can still be avoided
University of Exeter

Some impacts of global warming - such as sea level rise and coastal flooding - are already locked in and unavoidable, according to a major research project.

Global temperatures have already risen by around 1°C, and a further 0.5°C warming is expected. The full impacts of current warming have not yet been seen, since ice sheets and oceans take many decades to fully react to higher temperatures.

But more severe impacts can still be avoided if global greenhouse gas emissions are reduced.

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Even with rapid cuts in global greenhouse gas emissions keeping warming below 2°C, sea levels could rise by 0.5m by the end of the 21st Century, particularly affecting small island states and low-lying countries. HELIX calculations suggest this could impact 2.5 million in Bangladesh.

However, if emissions continue and global warming exceeds 4°C, sea levels will rise further and could impact around 12 million people in Bangladesh if a storm surge from tropical cyclones adds further to the impact.
Increased rainfall is expected to further compound the flooding risk by raising river levels.

"A warmer atmosphere can hold more water, so rainfall would be more intense," said HELIX project leader Professor Richard Betts, of the University of Exeter.

"This would inevitably mean more flooding, and our research suggests the largest increase in flood risk would be in parts of America, Asia and Europe."

At 4°C, the researchers say most countries - nations accounting for 73% of world's population 79% of the global GDP - could experience a five-fold increase in river flood risk and flood damage (compared to a baseline period 1976-2005).

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Professor Beets added: "This wetter climate should also mean fewer droughts in some areas, though droughts could become more common in other areas - for example some parts of Africa and southern Europe."

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"Overall, worldwide food security would be more at risk, not just from changing crop yields but because extreme weather affects the people who grow the crops."

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