Climate change: Don’t blame it on nature, those unbearably hot years are more human-made than natural

Human-made climate change is largely responsible for those warm years that made people sweat like never before. Otherwise, it would never have been possible that 13 out of the 15 warmest years would all be in the current century, an international team of scientists revealed.

Greenhouse-gas emissions from burning oil and coal have greatly contributed to the rise in temperature. Without the emissions, the odds are between 1 in 50,000 and 1 in 170,000. Data for 2015 came after the study was conducted. If considered, the 2015 data will make the odds even thinner.

Scientists at the Potsdam Institute for Climate Impact Research performed a sophisticated statistical analysis where they combined observational data and comprehensive computer simulations of the climate system. This approach allowed the scientists separate human-made climate change from natural climate variability.

“2015 is again the warmest year on record, and this can hardly be by chance,” said co-author Stefan Rahmstorf.

Lead-author Michael Mann, a distinguished professor of meteorology and director of Earth System Science Center, Penn State (US), said that natural climate variability makes temperatures wane over a period of time and not vary erratically year after year. This makes it all the more challenging to pinpoint the chance likelihood of temperature records.

“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,” Mann added.

According to the study, natural climate variations cannot possibly explain the recent global heat records. However, human-made global warming can definitely do so. This human-made climate change has resulted in extraordinary local heat waves across the world resulting in deaths, droughts and wildfires. Human interference with the Earth system has multiplied the risk of heat extremes, the data shows.