A new shows unprecedented temperatures could regularly hit the globe by as early as 2020.
Researchers from the University of Hawaii in the United States have pinpointed the year temperatures will hit historic highs in different parts of the world, including Australia.
University of Hawaii researcher Abby Frazier says Sydney would hit its new extreme climate in 2038 and Brisbane four years after that.
"The global average under the business-as-usual, we-don't-do-anything [scenario] is 2047, and if we are able to take aggressive action now to mitigate our CO2, that year gets pushed back to 2069," she said.
The University of Hawaii study used nearly 40 different climate-modelling systems to work out when the world's temperatures will surpass those recorded over the past 150 years.
Ms Frazier says it is the first research of its kind and the findings were a surprise.
"We took a very conservative approach to this whole study by using, the absolute min and max values and using all the possible models that are out there," she said.
"We didn't even think that this date [would] happen in the next century so we were really surprised that the 2047 [deadline] was so early. I mean this is within our lifetimes.
"[We were] even more surprised that even if we take action now, the 2069 is still happening within this century."
The study found countries in the tropics like Indonesia and Jamaica could experience changes in climate, or what are termed climate departures,by as early as 2020.
Ryan Longman, who was also part of the research team, says climate change in the tropics will have a ripple effect across the globe.
"Everybody will be affected if the biodiversity in the tropics is affected," he said.
"That's where a majority of the world's biodiversity exists and that includes coral reefs which are basically the habitat for fish populations," he said.
"So in a country that depends on fishing, if the reefs are in jeopardy and they can no longer be suitable habitats for fish, then you would definitely see those rippling effects on land."
The study also revealed efforts to reduce greenhouse gas emissions could push back the temperature change by more than 20 years in some places.
Ms Frazier has outlined the potential difference in Australian cities.
"In Perth we expect under the business-as-usual scenario, climate departure by the year 2042 and we can push that back to 2072 if we take mitigation action now," she said.
"In Sydney it's expected 2038 and that will get pushed back to 2052 under a mitigation scenario.
"Melbourne is 2045 under the business-as-usual or 2072 if we take action now."
The research will be published in the journal Nature.