Summers in Sydney have become hotter for longer, a new study has revealed, with summers stretching out by nearly 50 days over the past three decades.
Researchers from the University of British Columbia analysed the weather stations for 10 countries between the tropics and polar regions, including Sydney, Minneapolis, Tokyo, St Petersburg, Paris, Toronto and Reykjavik.
The study found that summers are getting hotter for a longer period of time – with Sydney leading with the biggest increase in the number of summer days.
Summer wasn’t measured by traditional calenders, but instead by the temperatures that meet seasonal norms.
According to the research, between 1990 and 2013, the average summer cycle grew by six days per decade.
However, Sydney was the leader of the pack, with summers now lasting approximately 130 days, compared to 80 days in 1990.
Lead researcher Ted Scott said the NSW capital was “one the places (that) is changing the most dramatically”.
“Another way to think about that is in 20 years, Sydney has been on average adding a whole month of summer,” he said.
“Now this is up until 2023, so we should be careful and say we don’t know if these trends will continue … but the trends are pointing in one direction.”
Scott said he was inspired to conduct the study after theorising that summers were shorter during his childhood in Minneapolis.
“It feels like they’re longer, it feels like the shoulder seasons on either side just disappear in a hurry and it feels like summers are staying much more intense than I remember them being, we wanted to test that human perception,” he said.
The city is one of the only others that reported a similar increase in summer days to Sydney, growing by an extra nine days every decade since 1990.
He said the findings “challenge what we believe to be the normal cycle of the seasons”.
“When summer happens and how quickly it arrives impact patterns and behaviours in plant and animal life, and human society,” he said.
The study found that not only were summers becoming hotter and lasting longer, the transition between seasons was becoming more abrupt.
“The changes may be very disruptive to a wide range of systems,” he said.
He warned the sudden onset of hot weather could make the population “ill-prepared for earlier heat”.
