According to a major global update, as the planet continues to warm, extreme weather events such as heatwaves and heavy rainfall are now more frequent, more intense, and longer.
The update is based on data from more than 36,000 weather stations around the world, reports The Conversation.
The research is based on a dataset known as HadEX and analyses 29 indices of weather extremes, including the number of days above 25℃ or below 0℃, and consecutive dry days with less than 1mm of rain.
This latest update compares the three decades between 1981 and 2010 to the 30 years prior, between 1951 and 1980.
Globally, the clearest index shows an increase in the number of above-average warm days.
For Australia, the team found a country-wide increase in warm temperature extremes and heatwaves and a decrease in most areas in cold temperature extremes such as the coldest nights. Broadly speaking, rainfall extremes have increased in the west and decreased in the east, but trends vary by season.
In New Zealand, temperate regions experience significantly more summer days and northern parts of the country are now frost-free.
Unusually warm days are becoming more common throughout Australia. When 1981-2010 was compared with with 1951-80, substantial increase was found: More than 20 days per year in the far north of Australia, and at least 10 days per year in most areas apart from the south coast. The increase occurs in all seasons but is largest in spring.
This increase in temperature extremes can have devastating impacts for human health, particularly for older people and those with pre-existing medical conditions. Excessive heat is not only an issue for people living in cities but also for rural communities that have already been exposed to days with temperatures above 50℃.
New Zealanders are also experiencing more days with temperatures of 25℃ or more. The climate stations show the frequency of unusually warm days has increased from 8 percent to 12 percent from 1950 to 2018, with an average of 19 to 24 days a year above 25℃ across the country.
Unusually warm days, defined as days in the top 10 percent of historic records for the time of year, are also becoming more common in both countries.
During the summers of 2017-18 and 2018-19, marine heatwaves delivered 32 and 26 (respectively) days above 25℃ nationwide in New Zealand, well above the average of 20 days. This led to accelerated glacial melting in the Southern Alps and major disruption to marine ecosystems, with die-offs of bull kelp around the South Island coast and salmon in aquaculture farms in the Marlborough Sounds.