Climate change has added to the lexicon of weather events with scientists identifying five distinct new patterns that are occurring regularly across the planet, posing new threats to regions and cities.
The journal Environment Research: Climate has published a paper reporting that all pose lethal risks for people around the planet.
Scientists drew upon hundreds of “attribution” studies, or research that aims to calculate how climate change affected an extreme event using computer simulations and weather observations.
“We find we have a much better understanding of how the intensity of these events is changing due to climate change,” said study co-author Luke Harrington, a climate scientist at Victoria University of Wellington.
While places such as California and East Africa are undergoing prolonged endemic drought, other regions are facing up to flash versions of the phenomenon, such as China, South Africa and the US. This is a soil moisture, or agricultural, drought that occurs extremely rapidly with little warning. The report cites the situation in Cape Town, as it narrowly avoided “day zero”, when there would have been no water remaining in city pipes.
The worsening wildfires risk is manifest in megafires that burn more than 100,000 acres that have already substantially increased in many regions. Recent blazes in Canada, the US, Australia and other parts of the world have been made much more likely by climate change. Fire raged across the US state of New Mexico in April, after a controlled burn set under “much drier conditions than recognised” got out of control. The fires burnt 341,000 acres, causing deaths, harm to health from air pollution, billions of pounds of damage and harm to wildlife.
Super storms more associated with the tropics are now occurring as high up the planet as Canada. There is also evidence that tropical storms are becoming more intense and even stalling over land, where they can deliver more rain on a single area. A greater fraction of those that do happen are the most intense category four and five “superstorms”, and events such as Hurricanes Katrina and Sandy have been amplified by climate change. While climate change might not have made Cyclone Batsirai any more likely to have formed in February, it probably made it more intense, capable of destroying more than 120,000 homes when it hit Madagascar.
“There have also been several notable events amplified by climate change in recent years, including Hurricanes Irma, Maria, Katrina, Harvey, Florence, Sandy, Typhoons Haiyan and Morakot, and others. Additionally, notable recent seasons of high cyclone activity could not be explained without anthropogenic influence, including in the Arabian Sea in 2015, in the western North Pacific in 2015, and in the North Atlantic in 2017,” the report said.
Scorching heatwaves also bring unprecedented misery. The disasters database shows that of 157,000 documented heat-related deaths from 2000 to 2020, just 6.3 per cent of them occurred in countries — many of them tropical — that are home to 85 per cent of humanity and 60 per cent of Earth’s land. That is a result of poor measurement, not an absence of heatwaves.
In general, a heatwave that previously had a 1 in 10 chance of occurring is now nearly three times as likely — and peaking at temperatures about 1°C higher — than it would have been without climate change.
An April heatwave that saw the mercury climb above 50°C in India and Pakistan was made 30 times more likely by climate change, according to the paper.
Cold extremes are declining while heat extremes are increasing. “Pretty much all heatwaves across the world have been made more intense and more likely by climate change,” said study co-author Ben Clarke, an environmental scientist at the University of Oxford.
Rainfall is also becoming more lethal, more often. A growing number of floods have been made more intense by the effects of rising temperatures on rainfall. Episodes of heavy rainfall are becoming more common and more intense because warmer air holds more moisture, so storm clouds are “heavier” before they eventually break.
“Since the 1950s, heavy rainfall has become more frequent and intense across most parts of the world, which is now known to be mainly due to human climate change,” he said. “It hasn’t strongly decreased in likelihood anywhere,” the paper said. “The general trend is increasingly extreme rainfall resulting in destructive flooding over a large portion of the world’s surface.”