An inconvenient hot summer in Australia

With record high temperatures across much of the continent, smashing the previous record; with record rainfall in North Queensland and 500,000 cattle lost; with extreme drought in many locations, including the death of millions of fish in the Menindie Lakes; it has been a summer well beyond past experience.  Bushfires have caused loss of property in Tasmania, Victoria, and New South Wales.

With such an extreme summer being closely followed by a federal election, denial of climate change; claiming that Australia should do nothing as we are a small emitter of greenhouse gasses on a global scale; and token policies will not resonate well with the majority of the electorate.  As Australia is being damaged by climate change, and the damage will escalate, it is time to consider what action we can take which is of greater influence on global greenhouse gas emissions than our proportion of emissions.

Australia’s 2018-19 summer was very hot compared with all previous summers, dating back to 2010-11 (Chart 1).

Chart 1
hottestsummer01

The record mean temperature in 2018-19 was 0.86 degrees C hotter than the previous record set in 2013.  This margin is the greatest on record, exceeding the margin of 0.52 degrees C by which the summer of 1972-73 was hotter than the previous record in 1938-39 and 1925-26.

The only comparable extreme is the very low mean temperature in 1916-17.  That was during an extreme La Nina, but there was no extreme El Nino in 2018-19.

The temperatures shown in Chart 1 are relative to the average of the period 1961 to 1990 (27.5 degrees C).

The upwards trend is 1.3 degrees per century (Chart 2) and has accelerated to 2.2 degrees per century from 1970 (the last seven summers have been hotter than the 109 year trend).  These trends are highly statistically significant.

Chart 2
chart2

The trend mean temperature anomaly for 2019-20 is predicted to be 0.64 degrees, with a 95% confidence interval of 0.45 to 0.83.

The mean temperature anomaly relative to 1961 to 1990 across Australia in the summer of 2018-19 is shown in Chart 3.  Much of the continent was more than one degree hotter than the 1961 to 1990 average, many locations had a mean temperature more than 2 degrees hotter, and some places were more than 3 degrees hotter (the average was 2.1 degrees across the continent).

Chart 3
hottestsummer03

The record rainfall in much of north Queensland was in marked contrast to a dry summer in most of the rest of the continent (Chart 4).  This chart shows rainfall anomalies relative to the 1961 to 1990 average.

Chart 4
hottestsummer04

The longest continuous tracking of the general public’s level of belief in imminent global warming has been carried out by foreseechange (Chart 5).  The estimated likelihood of clear signs of global warming in the year ahead is a 63% chance, back to the level of 2007 when the electorate last voted the coalition out of office.  The last update of this tracking survey was in November 2018 – since then we have experienced the highly extreme summer of 2018-19, which would have further lifted the level of belief in imminent climate change.

Chart 5
chart5

Previous variations in the level of belief in imminent climate change have been caused, in part, by preceding temperatures and rainfall.

When the general public was asked to rate issues on the basis of the level of concern in the foreseeable future, climate change ranked fifth, ahead of traffic congestion, health, and crime (Chart 6).  The scale was from 0 (will not be at all concerned) to 10 (will be extremely concerned).  This survey was conducted in November 2018 and it is likely that the extreme summer of 2018-19 will have lifted the level of future concern about climate change.

Chart 6
chart6

In the lead-up to the imminent federal election, the electorate will be looking for a credible, urgent plan to mitigate climate change.

Australia must move on from the seemingly endless debate about whether human activity is causing climate change and whether we should do anything at all because our contribution to greenhouse gas emissions is less than 2% of the global total.

Australia can have an impact beyond our share and it is in our interests to do so given the economic and environmental damage we are experiencing and the economic opportunities we can capitalise on.  That will be the subject of a future article.

Charlie Nelson