Devastating wildfires that ravaged Australia in 2019 and 2020 (one pictured) were made at least 30 percent more likely by human-caused climate change. Scientists have similarly tied many other natural disasters to global warming. Climate change is making extreme weather worse. It tripled the risk of Hurricane Harvey’s record rainfall over Texas in 2017. It made Australia’s devastating wildfires in 2019 and 2020 at least 30 percent more likely . And it made a heat wave that ravaged the Pacific Northwest in 2021 at least 150 times more likely . These are all findings of scientific studies. But how do scientists figure out how much climate change is to blame for any given weather event ? A variety of methods can help answer that question. This type of work is known as extreme event attribution . See all the entries from our Let’s Learn About series One common method compares two versions of the world. The first is the real world — where humans burning fossil fuels have caused global warming. The second is what the world would look like without climate change. Scientists estimate what that second world would look like based on historical weather data and climate models . With some clever number-crunching, researchers can see how likely or severe a weather event is in each of those versions of the world. Hundreds of studies have probed the role of global warming in natural disasters. Many have found that climate change made extreme weather worse. In some cases, studies have shown that a specific weather event would have been almost impossible without climate change. One example is a brutal heat wave that struck Siberia in 2020. That year, Siberia saw temperatures around 30° Celsius (86° Fahrenheit). It would usually have been closer to freezing at that time […]