When it comes to climate change, there is often confusion as to when one should consider a particular meteorological event to be “just weather” or something more significant in a climatological context. In general, the individual weather and climate events that scientists consider most significant are those that are both at the extremes of — or beyond — our historical experience, and consistent with quantifiable trends….
As far as day-to-day weather goes, numerous individual locations in Australia set daytime records for extreme heat. As far as regional averages go, records were also set for the hottest daytime temperatures averaged over the whole of Australia. Records were set for the duration of extreme heat at both individual locations, and for Australia as a whole. Birdsville experienced 31 successive days above 40°C and Alice Springs had 17.
When it comes to averages over time, January 2013 was the hottest month recorded in the entire observational record for Australia, stretching back to 1910 (the first year for which we can confidently estimate national temperatures).
And as of yesterday, a new record was added to the books. The summer of 2012-13 was Australia’s hottest on record. In fact, the entire six months — from September 2012 to February 2013 — were warmer than the previous high for that period, set in 2006-2007. Average summer temperatures across Australia were 1.1°C above the 1961-1990 average, surpassing the previous record, set in 1997-98, by more than 0.1°C. Daytime maximum temperatures also set a record; they were 1.4°C above normal, and 0.2°C above the 1982-83 record….
Australia has warmed by nearly a degree Celsius since 1910. This is consistent with warming observed in the global atmosphere and oceans. And it’s going to keep getting hotter. Over the next century, the world will likely warm by a further 2 to 5 degrees, depending on the amount of greenhouse gases emitted into the atmosphere. Under mid-to-high emissions scenarios, summers like this one will likely become average in 40 years time. By the end of the 21st century, the record summer of 2013 will likely sit at the very cooler end of normal.
Indeed, an interesting feature of the heat this summer is that it occurred during a “neutral” period in the El Niño-Southern Oscillation (that is, it was neither La Niña nor El Niño). Up until this year, six of the eight warmest summers, and the hottest three summers on record, occurred during El Niño years. This essentially means that the record was consistent with warming trends, and achieved without an extra push from natural variability associated with El Niño.