BY KATIE - MYGREENPOD, 28 January '16

Recent run of record warm years is ‘almost certainly’ due to human-made climate change

The record warm years we’ve experienced lately are ‘with extremely high likelihood’ caused by human-made climate change, according to a new study by the Potsdam Institute for Climate Impact Research.

Slim odds

Without greenhouse gas emissions from burning coal and oil, the odds are vanishingly small that 13 out of the 15 warmest years ever measured would all have happened in the current, still young century.

According to the research, these odds are between 1 in 5,000 and 1 in 170,000. The data for 2015 came in after the study was completed; when they are included, the odds become even slimmer.

‘2015 is again the warmest year on record, and this can hardly be by chance.’

Stefan Rahmstorf, co-author, Potsdam Institute for Climate Impact Research

The research

The scientists performed a sophisticated statistical analysis, combining observational data and comprehensive computer simulations of the climate system. Their new approach allowed them to better separate natural climate variability from human-caused climate change.

‘Given the recent press interest, it just seemed like it was important to do this right, and address, in a defensible way, the interesting and worthwhile question of how unlikely it is that the recent run of record temperatures might have arisen by chance alone.’

Michael Mann, lead-author, distinguished professor of meteorology and director, Earth System Science Center, Penn State (US)

Explaining the global heat record

The newly computed odds for experiencing the recent runs of record temperatures by chance, without accounting for human-caused greenhouse gases, are greater than odds previously reported in some media – between 1 in 27 million and 1 in 650 million – but they are still incredibly slim.

In contrast, taking human-caused global warming into account makes the recent record temperatures quite likely.

‘Natural climate variations just can’t explain the observed recent global heat records, but man-made global warming can.

‘It has led to unprecedented local heat waves across the world – sadly resulting in loss of life and aggravating droughts and wildfires.

‘The risk of heat extremes has been multiplied due to our interference with the Earth system, as our data analysis shows.’

Stefan Rahmstorf, co-author, Potsdam Institute for Climate Impact Research

Click here to read the full article, The Likelihood of Recent Record Warmth.