29 October 2008

Climate change: The reality of now in Victoria

The Great CO2 Enhancement Experiment (~40% and rising!) continues unabated, and looks set to continue for the foreseeable future. Unfortunately, the results are coming in, and the verdict doesn't look good. Numerous lines of evidence from around the globe (as presented previously at planet doom?) support the idea that this is the case.

A recent jaunt across country Victoria prompted some reflection on the effects of climate change closer to home. Much of Australia, the southeastern corner in particular, is experiencing a long-term drought. In Melbourne, the drought is of 'unprecedented severity' – annual rainfall has been below average for 12 consecutive years. And the drought continues, with record-low monthly rain in September, and very little rain thus far in October.

Drought is a regular climatic event in this part of Australia, often corresponding with ENSO – El Nino years are dry, while La Nina years typically bring relief. Unfortunately, the recent La Nina brought little precipitation to the region. This may in part be related to the unprecedented events observed in the Indian Ocean; a third consecutive positive Indian Ocean Dipole (and apart from El Nino two years in a row, too). Historically, the positive IOD does show a negative relation with rainfall over this part of the continent.

The impacts of the drought are widespread, with concerns continuing to grow over the availability of water resources. The Murray-Darling river system -- southeastern Australia's lifeline – is a particular concern. For a third year running, very little water has been made available for irrigation along the river (also reported last year), with zero allocation in some parts. Nearly 90% of the wetlands in the MD Basin have disappeared. These effects are being exacerbated by human mis-management, with individual states acting on an ad-hoc basis.

Similar impacts are seen throughout Victoria. For much of the state, streamflows in the rivers are currently running below 10% of capacity. In total, water storage across the state is at 22% of capacity. Melbourne, a city of over 3m people, is slightly better off with storage levels at 34%. Water restrictions are in place..

Another consequence of the drought is the threat of wildfire becomes larger. In the current environment, the forested areas of Victoria are a particular are of concern for the upcoming summer. The water catchment areas of Melbourne are a concern; a major bushfire is these regions could increase the difficulty of maintaining an adequate water supply for the future.

The current drought is unprecedented in Australia's recorded history (over 100 years). This is climate change, part of the growing climate instabilities being observed around the globe. An enhancement (a corruption!) of the natural variability. The hysteresis in the Earth system means the effects, from causes long past, are only now becoming apparent. And the causes (i.e. CO2 radiative forcing) continue today, meaning that these events and their impacts are but a foretaste of our future.

Australia and Victoria are among the first -- by no means the last -- to confront the new realities of climate change. Adaptation will be a long, difficult process. Water – vital to human life -- is but one issue among many. Understanding how climate and the hydrologic cycle interact is crucial for the future. As Australian federal and state governments try to manage the current water crisis, the globe will be watching to learn from both our mistakes and successes. Adaptation is an unknown challenge and recent events provide an opportunity to lead the world towards a brighter, greener future.

In both a local and global sense, the time to act is now. Inaction is not an option. Society must adapt to the immediate realities and simultaneously try to minimize future impacts, through both emissions reductions and the development of a less environmentally intense lifestyle. We owe a moral obligation to future generations to accomplish this, a Green New Deal for the 21st century.

Images: 1. Low water levels in Thomson Dam via The Age
2. A nice gum tree in Lake Eildon NP, by me

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