There\u2019s a clich\u00e9 that has popped up for years in discussions of climate and weather disasters: You can\u2019t blame any individual event on climate change. Climate is all about trends and statistics, the reasoning goes, so you can\u2019t necessarily draw meaningful conclusions from a single data point, be it a heat wave, a hurricane, or a drought. <\/p>\n
But in recent years, climate scientists have been pushing back against this notion: Bolstered with better data and even clearer trends, they\u2019re no longer reluctant to point the finger back at humanity for worsening these calamities. In the latest report from the Intergovernmental Panel on Climate Change (IPCC), a team of leading researchers convened by the United Nations presented some of the most robust research that connects the dots. It shows how some greater weather extremes can<\/em> be traced back to rising average temperatures, which in turn stem from emissions of greenhouse gases, mainly from countries and corporations burning fossil fuels. <\/p>\n \u201cOn a case-by-case basis, scientists can now quantify the contribution of human influences to the magnitude and probability of many extreme events,\u201d according to the report. <\/p>\n Scientists are not just confident that humans are warming the climate \u2014 that much is \u201cunequivocal.\u201d Now they\u2019ve concluded it\u2019s \u201can established fact\u201d that signals of this warming shine bright in events like the severe heat and torrential rainfall that we\u2019re seeing now, increasing their frequency, severity, or both. That\u2019s why scientists only needed a few days to implicate climate change in recent Pacific Northwest heat waves, for example. <\/p>\n The field of extreme weather attribution has made enormous strides since the last major IPCC assessment in 2013, and it\u2019s one of the most significant components of the new report. \u201cWhat\u2019s new in this report is that we can now attribute many more changes at the global and regional level to human influence \u2014 and better project future changes we will see from different amounts of emissions,\u201d said Ko Barrett, vice chair of the IPCC and senior adviser for climate at the National Oceanic and Atmospheric Administration, during a press conference.<\/p>\n At the same time, the stunning, record-breaking disasters of recent memory have again forced a public discussion about the role of climate change. This year alone, the world has seen extreme fires in California, Siberia, Greece, and Turkey; devastating flooding in China and Germany; and heat waves and record drought across the US West, to name just a few. <\/p>\n<\/aside>\n The question is not whether these individual events were \u201ccaused\u201d by climate change \u2014 such disasters arise from a confluence of factors and could still happen even if humans weren\u2019t spewing heat-trapping gases into the sky. The question is: How has human-caused climate change altered their likelihood and their severity?<\/p>\n \u201cOver the last 10 years, we\u2019ve seen a shift in the ways scientists answer that question,\u201d said Kevin Reed, an associate professor at Stony Brook University who studies climate attribution but was not involved in the IPCC report. Rather than invoking general trends, scientists are now keen to quantify climate change\u2019s role in specific events, and increasingly coming up with estimates while a given disaster is still fresh in people\u2019s minds.<\/p>\n The revolution in attribution research highlights that climate change is not just a problem for the future; it\u2019s being felt right now. As humanity\u2019s role becomes increasingly clear, it could have far-reaching consequences for how we prepare for the future and for the countries and corporations that will shoulder the blame for climate disasters. <\/p>\n The science linking weather extremes to climate change is stronger than ever<\/p>\n The planet has warmed by at least 1.1 degrees Celsius on average, the first installment of the new IPCC report concludes, and the effects are visible now. The report dedicates a whole chapter just to attributing elements of extreme weather to humanity\u2019s actions. <\/p>\n Here are some of the findings in how human influence is playing out now:<\/p>\n \u201cEvidence of observed changes and attribution to human influence has strengthened for several types of extremes … in particular for extreme precipitation, droughts, tropical cyclones and compound extremes,\u201d including fires, the IPCC report says. Much of this is due to emissions of carbon dioxide from burning coal, oil, and gas, but changes in land use and aerosol pollutants play a role as well. And as average global temperatures continue to rise, the magnitude of these impacts will grow.<\/p>\n There are also aspects of extreme weather that don\u2019t exhibit human influence, or haven\u2019t been studied enough to yield conclusions. For example, there does not appear to be a distinct global or regional trend in the number of tropical cyclones, also known as hurricanes and typhoons. However, scientists do expect a trend toward higher wind speeds in these storms over the coming century.<\/p>\n Drought is another complicated phenomenon with different mechanisms at play, so it\u2019s hard to make general conclusions about how climate change is influencing them. But scientists have found droughts that overlap with heat waves have become more frequent, and looking ahead, they have \u201chigh confidence\u201d that drought will get more frequent and more severe in many parts of the world.<\/p>\n Some scientists have taken this research further by calculating the degree of human influence in specific events, often soon after they occur. The World Weather Attribution initiative, an international research consortium founded in 2014, examined the June 2021 heat wave in the Pacific Northwest of North America. Within a week, they concluded that the searing heat in the region \u201cwas virtually impossible without human-caused climate change.\u201d<\/p>\n\n