CHINA SANDSTORM
A tourist gestures as she poses for a photograph at Tiananmen Square during a recent sandstorm in Beijing. Extreme weather events are unavoidable now despite efforts to reduce emissions, because of the amount of greenhouse gases already accumulated in the atmosphereReuters/China Daily

Highlighting major implications of subtle global temperature increases, a new study shows that a 2C warming will spur five times as many hot extremes than today, and two times as many hot extremes as with a 1.5C warming.

It further shows that more than half of the hot extremes worldwide and nearly a fifth of heavy rainfall can be attributed to global warming.

These events are not the direct result of warming, but it increases their frequency. The less common and more extreme of these events can be attributed to man-made warming.

The study published in Nature Climate Change analyses and compares climate model simulations for the pre-industrial era and present-day conditions.

In pre-industrial times hot extremes occurred once in three years, but today is 0.85C warmer, extreme hot days occur on average about four to five times in three years.

"Therefore we attribute 3 - 4 events of the 4 - 5 events to the warming and the one that would have occurred without human influence to natural variability," says Erich Fischer, author of the ETH Zurich study.

There has been an increase in more frequent and intense hot extremes since the 1950s, as also increases in heavy precipitation.

The authors however warn against the idea that all weather phenomena are becoming increasingly extreme.

Climate models that quantify the heat and precipitation extremes have their weaknesses in simulating high pressure systems, they say taking the example of convection which is not resolved in these models.

Studies on extreme events, such as hail storms or tornadoes, do not find a significant increase attributable to climate change. But a substantial proportion of all globally occurring hot extremes and heavy rainfall events can be attributed to warming primarily caused by humans.

Extreme events are unavoidable now despite any effort to reduce emissions. The only recourse would be to remove these gases from the atmosphere, especially carbon dioxide that has a long lifetime.