Why half a degree change in global warming matters

London, April 22: As the world celebrated Earth Day on Friday, a team of European researchers has found substantially different climate change impacts on Earth for a global warming of 1.5 degrees Celsius and two degrees Celsius by 2100.

The two temperature limits are included in the Paris climate agreement, researchers said, adding that the additional 0.5 degrees Celsius would mean a 10 cm higher global sea-level rise by 2100, longer heat waves and would result in virtually all tropical coral reefs being at risk.

"We found significant differences for all the impacts we considered," said Carl Schleussner, lead author of the study published in the journal Earth System Dynamics.

"We analysed the climate models used in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report focusing on the projected impacts at 1.5 degrees Celsius and two degrees Celsius warming at the regional level," Schleussner added.

The team considered 11 different indicators including extreme weather events, water availability, crop yields, coral reef degradation and sea-level rise.

With researchers from Germany, Switzerland, Austria and the Netherlands, they identified a number of hotspots around the globe where projected climate impacts at two degrees Celsius are significantly more severe than at 1.5 degrees Celsius.

In tropical regions, the half-a-degree difference in global temperature could have detrimental consequences for crop yields, particularly in Central America and West Africa.

On average, local tropical maize and wheat yields would reduce twice as much at 2 degree Celsius compared to a 1.5 Celsius temperature increase.

On a global scale, the researchers anticipate sea level to rise about 50cm by 2100 in a two degrees Celsius warmer world, 10 cm more than for 1.5 degrees Celsius warming.

"Sea level rise will slow down during the 21st century only under a 1.5 degrees Celsius scenario," noted Schleussner.

"Our study shows that tropical regions -- mostly developing countries that are already highly vulnerable to climate change -- face the biggest rise in impacts between 1.5 degrees Celsius and two degrees Celsius," added William Hare, senior scientist at Climate Analytics, a non-profit climate science and policy institute.

IANS