The hot potato that is man-induced climate change

Wildfires raging across parts of Canada, Spain and the recent inferno that scorched Maui in Hawaii killing a confirmed 111 are all pointing to the fact that climate change makes heatwaves hotter and more frequent. This is the case for most land regions, and has been confirmed by the United Nations’ global panel of climate scientists, the Intergovernmental Panel on Climate Change (IPCC), a Reuters report said. Greenhouse gas emissions from human activities have heated the planet by about 1.2 degrees Celsius since pre-industrial times. That warmer baseline means higher temperatures can be reached during extreme heat events. Climate change increases hot and dry conditions that help fires spread faster, burn longer and rage more intensely.Every heatwave being experienced today has been hotter and more frequent due to climate change, said Friederike Otto, a climate scientist at Imperial College London who co-leads the World Weather Attribution (WWA) global research collaboration. But other conditions affect heatwaves too. In Europe, atmospheric circulation is an important factor. To find out exactly how much climate change affected a specific heatwave, scientists conduct "attribution studies”. Since 2004, more than 400 such studies have been done for extreme weather events, including heat, floods and drought – calculating how much of a role climate change played in each.This involves simulating the modern climate hundreds of times and comparing it to simulations of a climate without human-caused greenhouse gas emissions. For example, scientists with WWA determined that a record-breaking heatwave in western Europe in June 2019 was 100 times more likely to occur now in France and The Netherlands than if humans had not changed the climate.The global average temperature is around 1.2C warmer than in pre-industrial times. That is already driving extreme heat events. On average on land, heat extremes that would have happened once every 10 years without human influence on the climate are now three times more frequent, according to ETH Zurich climate scientist Sonia Seneviratne. Temperatures will only stop rising if humans stop adding greenhouse gases to the atmosphere. Until then, heatwaves are set to worsen. A failure to tackle climate change would see heat extremes escalate even more dangerously.Countries agreed under the global 2015 Paris Agreement to cut emissions fast enough to limit global warming to 2C and aim for 1.5C, to avoid its most dangerous impacts. Current policies would not cut emissions fast enough to meet either goal. A heatwave that occurred once per decade in the pre-industrial era would happen 4.1 times a decade at 1.5C of warming, and 5.6 times at 2C, the IPCC says.Letting warming pass 1.5C means that most years "will be affected by hot extremes in the future,” Seneviratne said.Without human-induced climate change, the extreme weather experienced across the world this summer would have been extremely rare, according to a study by WWA, which also found that human-induced climate change played an absolutely overwhelming role in the extreme heatwaves that swept across North America, Europe and China in July. Forest management and ignition sources are also important factors. In Europe, more than nine out of 10 fires are ignited by human activities, like arson, disposable barbecues, electricity lines, or littered glass, according to European Union data. But scientists concur that without steep cuts to the greenhouse gases causing climate change, heatwaves, wildfires, flooding and drought will significantly worsen.Unless the world rapidly stops burning fossil fuels, these events will become even more common and the world will experience heatwaves that are even hotter and longer-lasting. A heatwave like the recent ones would occur every 2-5 years in a world that is 2°C warmer than the pre-industrial climate. There is an urgent need for an accelerated roll-out of heat action plans.