Of extreme weather and climate change: Part 1

Kia Ora

The world has some amazing extremes in terms of climate around the world, and roles that the local climate plays in the shaping of the landscape, the communities that live there and the ecology. It has extremely wet areas such as the Himalaya’s and the West Coast of New Zealand, but it also has some extremely dry areas such as the east coast of Australia and Death Valley in the United States. And it’s worth noting the speed with which some of these places can swing between extremes. But it is in Australia where the world is getting a taste of these extremes right now.

Perhaps not a better example of that exists in Australia right now. Just a month ago, eastern Australia was facing up to the fact that the summer of 2012-13 could be one of the worst bush fire seasons on record. An extreme heat wave had formed over the continental interior of the country and had over the course of several days progressively intensified. The drying out the land under such intense heat pushed the fire danger to extreme. Coupled with the readily available fuel of tinder dry vegetation, eucalyptus trees loaded with their oil content, afternoon thunderstorms with cloud-ground lightning strikes and – unfortunately the odd deliberate human act of madness – the conditions for bush fires were perfect. As the fires start, if they make quick progress, driven by strong winds, some of them take on aspects of the fire storm by sucking in air creating strong internal winds. Trapped by rapidly moving fire fronts, with choking smoke deaths and property damage are inevitable. In 2009, similar conditions preceded catastrophic bush fires that killed in excess of 200 people in the State of Victoria in what has become known as Black Saturday. On that occasion temperatures reached 46 degrees Celsius in Melbourne. Four years later in 2013, a heat dome formed and at it’s peak there were towns in the interior of Australia which were expected to get close to 50 degrees Celsius. The extreme heat was followed by bush fire outbreaks in Queensland, New South Wales, Victoria and South Australia. Earlier, bush fires had torn through communities in Tasmania.

Whilst it is true that bush fires are a regular feature of Australia, so is flooding. Every year tropical depressions moving down from the Coral Sea and ex-tropical cyclones such as Oswell, which is responsible for the current severe weather, give rise to heavy rain fall events. The relatively flat terrain with its very wide river valleys permits water levels to rise during flood events to heights unheard of in other parts of the world. Earlier today I heard that one river was running at more than 15 metres above normal. In 2011 catastrophic flooding in Toowoomba caused by exceptionally intense down pours caused tens of billions of dollars in damage and numerous lives were lost. Many people were caught by surprise by the suddenness of this flash flood event, but it was actually part of a larger flood event that took days to fully occur. The frequency of these events is evidenced right now by the many flood emergencies in progress across Queensland where some places have had 500mm of rain in the last two days. Just a few weeks ago bush fire warnings were the story of the day across parts of southern Queensland, and New South Wales, where the storm is now headed. Many rivers at the time of writing – too many to remember – are in under major flood warnings. Forced evacuations are in under way in many towns – Gympie, Bundaberg – best renown for its ginger beer – among others.

In Part 2, tomorrow: Is climate change responsible for these events?

Take Care,


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