Box 3. Extreme weather events often trigger cascading impacts
Extreme weather events often set off compounding secondary events and risks, such as cascading impacts across borders affecting global supply chains. Since 2012, the American Meteorological Society has published an annual assessment of extreme weather events. Of 146 research findings, a substantial link between an extreme weather event and climate change was identified in 70 per cent of instances between 2011 and 2018.,
An assessment published by GermanWatch in 2020 determined that between 1999 and 2018 nearly half a million people worldwide died as a direct result of over 12,000 extreme weather events, with losses amounting to some $3.54 trillion (at purchasing power parity). It is important to note that almost all economic losses from extreme weather events in low-income countries are uninsured, further compounding the impacts on those populations.
Climate change contributes to the creation of conditions that are more susceptible to wildfires, principally via hotter and drier conditions. In the period 2015–18, measured against 2001–14, 77 per cent of countries saw an increase in daily population exposure to wildfires, with India and China witnessing 21 million and 12 million exposures respectively. California experienced a fivefold increase in annual burned area between 1972 and 2018. There, average daytime temperatures of warm-season days have increased by around 1.4°C since the early 1970s, increasing the conditions for fires, and consistent with trends simulated by climate models. Observations show that during the devastating Australian bushfires of 2019–20, a heatwave 1–2°C warmer than at the beginning of the 20th century was a contributing factor. Property and economic damage resulting from the disaster is estimated to have totalled some US $70 billion., Such heatwaves are now around 10 times more likely than at the beginning of the last century. Projecting forward, similar bushfires are around eight times more likely with 2°C of global warming. In Siberia, a prolonged heatwave in the first half of 2020 caused wide-scale wildfires, loss of permafrost and an invasion of pests. It is estimated that climate change has already made such events more than 600 times more likely in this region.
As with many extreme weather events, attribution of tropical cyclones to climate change is challenging, with many studies demonstrating conflicting results. The large fluctuations in frequency and intensity of tropical cyclones complicates the attribution of their changing nature to climate change. However, future projections based on climate models have indicated the most intense cyclones are likely to substantially increase in frequency due to climate change, with increases in precipitation rate within 100 km of the storm centre increasing by around 20 per cent.