What if Cyclone Ingrid, as powerful as Cyclone Tracy, had turned south and hit Cairns? Brick-veneer homes built at the northern beach suburbs might have been turned into roofless swimming pools. Would north Queenslanders have blamed global warming, or are severe cyclones a risk we should all plan for more seriously?
Across the world there has been concern that global warming is resulting in more extreme weather events including more cyclones.
For example, as Cyclone Olaf battered the Cook Islands in mid-February, Greenpeace issued a statement asking the global community to "deal with climate change" so Pacific Islanders wouldn't have to suffer increasingly extreme and devastating weather events.
However, the evidence for an increase in extreme weather events globally, including more cyclones, is far from compelling.
Some environmentalists argue this way: Carbon dioxide levels have increased dramatically over the past 40 years as a result of the burning of fossil fuels; this has caused the Earth to warm up; there is thus more energy in the atmosphere, and thus there are more extreme weather events.
This argument is flawed. The overall increase in global temperature of 0.6°C over the past century is mostly the result of warming over middle and high latitudes, particularly in winter.
There has been only slight warming in tropical sea surface temperatures and no general or sustained trend of warming over the western tropical Pacific Ocean.
This is the region where tropical cyclones that affect eastern Australia are formed and intensify and where earlier this week Cyclone Ingrid was born.
Cyclone Ingrid formed during an El Nino event at a time when there have been above-average sea-surface temperatures over the tropical western Pacific Ocean. However, there is no general trend of warming in this area.
El Nino and La Nina events have nothing to do with the recent global warming, but rather are a natural part of the climate system and have been affecting the Pacific Basin for thousands of years.
Over the past week Cyclone Ingrid has been compared with Cyclone Tracy -- the cyclone that destroyed much of Darwin in the Christmas of 1974. Interestingly, however, the wet and cyclonic conditions of 1973 and 1974 have been attributed to the strong La Nina (rather than the present El Nino) conditions that prevailed at that time.
Overall, 1974 was a bad year for cyclones. It was in January 1974 that Cyclone Wanda crossed the Queensland coast near Maryborough resulting in the flooding of 6000 homes in Brisbane. A few weeks later, on February 6, a very large and intense Cyclone Pam passed 500km to the east of Brisbane.
Then, four days later, Cyclone Yvonne struck near Dunk Island, tearing off roofing iron and uprooting large trees. A month later, on March 13, Cyclone Zoe crossed the coast at Coolangatta with more flooding in Brisbane and landslides in northern NSW.
The Bureau of Meteorology in Brisbane has information on 208 cyclones that have affected the Queensland coast dating from the mid-1800s. The first record is a Sydney Morning Herald report about a cyclone that uprooted trees on Green Island (off Cairns) in January 1858.
Worst accounts include two cyclones that devastated north Queensland in January and then March of 1918.
Complete records on tropical cyclones in northern Australia, however, are available only from 1967, the start of routine monitoring by satellites.
According to a CSIRO review, and also an assessment by the United Nations' Intergovernmental Panel on Climate Change, there has been a slight, but not statistically significant, decline in the number of tropical cyclones in the Australian region since 1971 and a slight, but not statistically significant, increase in the intensity of these cyclones.
Environmental activists, however, try to create a popular perception that there has been an increase in extreme weather events, worldwide.
Late last year Greenpeace executive director Stephen Tindale said "no one can ignore the relentless increase in extreme weather events and so-called natural disasters, which in reality are no more natural than a plastic Christmas tree".
This claim was based on a real increase in insurance claims from natural disasters in 2004. This is attributable to a dramatic increase in the number of people living by the sea and, at least in the US, building more expensive homes in hurricane-prone areas -- not an increase in the number or severity of hurricanes.
The interest in global warming (largely driven by environmental campaigning) has distracted governments from what's really happening with climate change and the reality that places such as coastal Queensland have always, and will always, be susceptible to severe cyclones.
Large amounts of money are spent by the Australian Government on its global warming program. Last financial year the Greenhouse Office received $107 million for tasks including "leading the agenda" and "promoting sustainable energy" -- as though this might make cyclones go away.
You can be sure that in the future severe cyclones will hit populated centres such as Mackay and Brisbane. Now is the time to think seriously about mitigation -- issues such as drainage management and building codes -- to reduce the risk of homes being flattened and flooded.
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