As extreme hurricanes and extensive wildfires proliferate around the globe, an internet search suggests that, in reporting these events, the words “climate change” are rare. Some exceptions include the SMH and The Guardian, but numerous ABC reports of the Houston floods have neglected to mention climate change at all (for example here, here, here, here and here).
There is no lack of claims on climate denial websites to suggest extreme weather events have no relation to global warming — now about 1.5 degrees Celsius higher than 250 years ago — as exemplified by the Global Warming Policy Foundation, or Dr Roy Spencer, or as reported in Jezebel.
It is often stated that single climate events do not necessarily represent the effect of climate change, and statements such as “once in 50 years” are common. But the incidence of extreme weather events has been rising as the Earth warms, as stated by the IPCC (2012 ):
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“Models project substantial warming in temperature extremes by the end of the 21st century. It is virtually certain that increases in the frequency and magnitude of warm daily temperature extremes and decreases in cold extremes will occur in the 21st century on the global scale. It is very likely that the length, frequency and/or intensity of warm spells, or heat waves, will increase over most land areas. Based on the A1B and A2 emissions scenarios, a 1-in-20 year hottest day is likely to become a 1-in-2 year event by the end of the 21st century in most regions, except in the high latitudes of the Northern Hemisphere, where it is likely to become a 1-in-5 year event ”.
The rise in meteorological and hydrological events is recorded by the Munich-Re institute, as in the figure below:
Up-to-date evidence for developments in the atmosphere is presented by NASA. The physics of this trend are elementary: as global temperatures rise evaporation from the oceans increases, forming migrating cyclonic cells. The moisture needs to be dumped somewhere. Lightning strikes ignite forest fires. As temperatures rise hot air plumes migrate from desert regions into cultivated and forest regions, creating conditions for wildfires.
The rise in land temperatures results in an increased frequency and intensity of heatwaves and fires, at a rate about two to three fold during 1980–2012.
“We find that the number of record-breaking events increases approximately in proportion to the ratio of warming trend to short-term standard deviation. Short-term variability thus decreases the number of heat extremes, whereas a climatic warming increases it.”
Similar anomalies were reported by Hansen et al. in 2012, stating:
“The distribution of seasonal mean temperature anomalies has shifted toward higher temperatures and the range of anomalies has increased. An important change is the emergence of a category of summertime extremely hot outliers, more than three standard deviations (3sigma) warmer than the climatology of the 1951–1980 base period. This hot extreme, which covered much less than 1% of Earth’s surface during the base period, now typically covers about 10% of the land area.”
None of the above appears to trouble law makers in the most heavily carbon polluting nations, including Australia, in the process of opening coal mega-mines and exporting more than twice its domestic carbon consumption, where the total carbon emission from combined domestic use and export is one of the world’s highest.