Levon Azizyan, Director of the Center for Hydrometeorology and Monitoring, SNCO, wrote on his Facebook page:
Summer has lengthened by a month: Scientists have recorded an acceleration of climate change.
An international group of scientists from the University of British Columbia has found that in the middle latitudes of the planet, the summer season is rapidly lengthening and seasonal transitions are becoming increasingly abrupt. The study, published in Environmental Research Letters, is based on an analysis of data from 1961 to 2024.
Since 1990, summer has lengthened by an average of 5-7 days per decade, and in the mid-2020s, summer conditions last approximately 30 days longer than in the 1960s. This is almost twice as fast as the previously recorded 4 days per decade. This trend extends not only to land, but also to coastal areas and oceans, with some cities such as Sydney and Minneapolis experiencing summers that are now longer by more than a day per year.
The researchers also found that temperatures are changing more rapidly, both at the beginning and end of summer, and that seasonal transitions from spring to summer and from summer to autumn are becoming more abrupt. This leaves ecosystems and human activities with less time to adapt.
Cumulative summer heat gain for the Northern Hemisphere has increased by 44°C•days per decade since 1990, more than three times faster than the 14°C•days per decade rate from 1961 to 1990. This increase is non-linear, due to the simultaneous increase in summer length and temperature.
Regional differences are even more significant. Summer in Tokyo is increasing by 2.1 days per decade, in Paris by 7.1 days, in Sydney by 14.8 days, and in Minneapolis by 9.3 days. The oceans are now showing the same rate of summer lengthening as the land.
Scientists warn that the increase in summer heat accumulation could pose problems for human physiological adaptation and lead to greater energy consumption for cooling during both the day and the night. Sharper seasonal shifts could lead to earlier snowmelt, flooding, and more deadly heat waves.
