Two degrees target to limit global warming may not be met

Geneva: The plan to limit global warming to below two degrees Celsius may not be met in many regions of the world, and could even lead to a six degree temperature rise in the Arctic, a new study has warned.

At the recent COP21 climate conference in Paris, delegates reached an agreement that plans to limit global warming to "well below" two degrees Celsius.

"However, this climate target is abstract and invites misunderstanding," said Sonia Seneviratne, a professor at ETH Zurich.

Seneviratne noted that many people will interpret two degrees globally as two degrees of warming in their region and, accordingly, will not be proactive enough about reducing carbon dioxide (CO2) emissions in their countries.

According to various climate models, the temperature will rise more sharply over land than over oceans. The big question is therefore how a maximum of two degrees global warming will affect individual regions of the world, researchers said.

Scientists from Switzerland, Australia and the UK led by Seneviratne have calculated the levels of extreme and average temperatures, as well as of heavy precipitation, that will occur in individual regions if the average global rise in temperature is taken as a reference.

The researchers based their calculations on several existing climate scenarios, as well as on the assumed and effective development in atmospheric CO2 concentration.

Graphical depictions of the calculations show at a glance how average temperatures respond to the overall quantity of CO2 emitted and in relation to average global warming in major geographical regions.

The depictions are easy to interpret - the graphical representation is like a type of ruler on which the envisaged target value - such as the global two-degree target - can be set; a linked warming value can then be identified in the corresponding region.

The scientists tested their new model using four examples - the Mediterranean, the US, Brazil and the Arctic.

For each of these regions, the researchers computed a separate graphical representation.

For the Mediterranean, the results show that if the global average temperature increases by two degrees Celsius, the region will see mean temperatures increase by 3.4 degrees Celsius on average. If, however, our aim is to limit warming in the Mediterranean to two degrees Celsius, then the global temperature must rise by no more than 1.4 degrees Celsius.

The most extreme changes could be seen in the Arctic - with global warming of two degrees Celsius, the average temperatures in the far north increased by six degrees Celsius, researchers said.
The two degrees Celsius target for the Arctic had already been exceeded when global warming reached 0.6 degrees Celsius on average (this figure is now approximately 1 degrees Celsius), they said.

The research was published in the journal Nature.