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Heatwaves, droughts, maximum one-day rainfall and extreme wind events will likely become a near-permanent in some 20 countries, even if the world curtails warming to 1.5 degrees Celsius, according to a new study.
These effects can become permanent for 37 countries if the warming reaches 2°C and 85 countries can be impacted if it increases by 3°C compared to the preindustrial era, the findings published in journal Earth System Dynamics stated.
Further, the world will see a disproportionate increase in compound events, which are multiple extremes that occur simultaneously or consecutively. Such extremes could become two to 9.6 times more frequent if warming exceeds 3°C compared to the preindustrial period.
“The impacts associated with compound events are expected to be higher than impacts caused by individual extremes,” the researchers wrote in their paper.
For example, a combined onslaught of extreme wind and extreme precipitation could increase the destruction of infrastructure and economic losses. The researchers studied individual extremes as well as combinations of compound extremes.
The first combination was heatwave and drought. The duo influence wildfire, crops, natural vegetation, power plants and fisheries. The second combination — extreme wind and precipitation — can cause storm surges and flooding.
Several studies have found that heatwave–drought occurrences have increased in the last four to five decades. Their analysis focused on changes in the frequency and timing of individual and combined extremes.
“Amazonia, southern Africa, the Sahel, India and Southeast Asia have been projected as a hotspot for increasing temperatures and are the most vulnerable regions to extreme events,” the paper read.
At the current level of warming, the frequency of heatwaves in mid- and high-latitude and subtropical countries has more than doubled compared to preindustrial levels. It has quadrupled in tropical countries.
At 3°C of warming, the frequency of heatwaves in tropical nations will likely increase by 7.5 times relative to the preindustrial period.
Increased global temperatures will likely decrease isolated drought events, the paper said. This is mainly because drought and heatwave events are likely to strike together with higher global warming levels.
At 1.5°C, 2°C and 3°C, the number of concurrent heatwave-drought events is estimated to increase by 4.5, 5.5 and 6.8 times in tropical countries compared to the preindustrial period, respectively.
At 3°C warming, mid and high-latitude countries will see a 9.6-times increase in concurrent heatwave-drought events and subtropical countries are estimated to face an 8.4-times increase compared to the preindustrial period, the researchers wrote.
The number of concurrent maximum one-day rain and extreme wind events in tropical countries is predicted to rise by 3.3, 4, and 5.3 times at 1.5°C, 2°C and 3°C, respectively, compared to the preindustrial period.
Such compound events could increase 2.3 times in subtropical countries and two times in mid- and high-latitude countries at 3°C warming compared to the preindustrial period.
"With higher global warming levels, we have seen a sharp increase in concurrent heatwave–drought events in three climate regions, with the most dramatic increase in northern mid- and high-latitude countries followed by subtropical countries," the paper read.
In contrast, the maximum one-day rainfall-wind events increase the most in tropical countries, the findings showed.