Climate change back in the spotlight

Few of you would have missed the news that the Intergovernmental Panel on Climate Change has released its latest Assessment Report. Only the Summary for Policy Makers has been released thus far, with the unedited version of the remainder of the report due for release on Monday.

The findings are largely unsurprising and are consistent with the last assessment report published in 2007. This latest version strengthens its statement of confidence about the Continue reading

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Thinking outside of the bell curve

Statistical distributions do not usually generate widespread public enthusiasm. Sure, some people spend hours admiring the shape-shifting forms of the beta distribution or the unflappable positivity of the exponential distribution; the limitless potential of the Gumbel distribution or the black-or-white certainty of the Bernoulli distribution. But those people usually reside at the extreme reaches of the societal bell curve.

Until now. The financial crisis has been blamed on numerous factors: inflated house prices, greedy bankers and weak regulation of Wall Street, but a commentator recently Continue reading

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Changes to the temporal distribution of Australian rainfall

The question of how rainfall intensity will change with global warming is an important one, and confidence is building within the scientific community that rainfall extremes will on average become more intense and/or more frequent as global temperatures increase. While this may be true on average, however, what is perhaps less well appreciated is that there are different types of weather systems that produce rainfall, and that these might change in different ways and sometimes even in opposing directions as the climate warms. This substantially complicates efforts to provide robust projections of likely changes to Continue reading

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Calculating the probability of compound events: a risky proposition

The following is a guest post from Dr Michael Leonard, a research associate at the University of Adelaide.

Hurricane Sandy in late October 2012 was widely noted to involve the alignment of a tropical storm with an extra tropical storm, and a cold air mass moving from the northwest helped push the storm onshore in the vicinity of New Jersey. The manner in which all these factors combined to produce the flood impact was strongly emphasized in the media discussions following the event, and here the term ‘compound event’ (following Continue reading

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How good are climate models at simulating sub-daily rainfall patterns?

Climate models are one of our most important tools to help us understand likely changes to extreme rainfall under a warmer climate. These models are complex

Timing of daily minimum rainfall throughout southeast Australia. The colours inside circles represent diurnal cycle of observed rainfall, and remainder of figure shows diurnal cycle from the WRF model.

mathematical representations of the world’s climate system, and simulate the circulation of the earth’s atmosphere and oceans. They are closely related to the numerical weather prediction models which are used to develop weather predictions, except that they are run over longer timescales (often decades at a time) and therefore need to be run at coarser resolutions. Continue reading

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An increase in the intensity of extreme rainfall?

One of the most alarming projections associated with human-induced climate change is the potential for an increase in the intensity and frequency of rainfall extremes. But how much do we really understand about the likely changes to extreme rainfall patterns over the coming decades? Continue reading

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2011: A busy year for global extremes

By all accounts, 2011 was a busy year for climate extremes. Readers from Australia will no doubt remember the year starting with extremely heavy rainfall drenching much of the state of Queensland, followed by the catastrophic flash floods in Toowoomba in the middle of January, the Brisbane floods only a few days later, and cyclone Yasi devastating northern Queensland in early February. Taking a more global perspective, it can be seen in the figure below that this was only one of many major climate disasters which occurred that year, with other notable extremes in Thailand, the Continue reading

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A warm summer in the Arctic

It is around this time every year that I start obsessively checking the National Snow and Ice Data Centre (NSIDC) website to look at the latest measurements of Arctic sea ice. I have no idea why I do this – I’m not an expert on ice, I have never been to the Arctic, and I certainly don’t like the cold. But there is something awe-inspiring about the dramatic changes taking place in this region, and I cannot help being struck by the idea that humans may play a dominant role in transforming this most hostile of environments. What is more, this year is already breaking the record for the lowest observed sea ice extent, and Continue reading

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Why blog about hydrology?

The hydrological cycle has fascinated humanity for millennia, with a diversity of ancient civilisations known to manipulate river systems for agricultural purposes, and adapt – although not always successfully – to periodic floods and droughts. It was not until seventieth century, however, that hydrology (literally, the study of water) was born as a quantitative science, with some of the first ‘hydrologists’ taking measurements of both rainfall and river flows in catchments in France, and showing that the former was sufficient to cause the latter. Since that time, continued research and developments in Continue reading

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Welcome to The Hydro Files!

We all know that water is one of the most important substances required for life to exist on earth. But how well do we really understand this remarkable substance? For example when it rains do we actually know where the water has come from, and what happens to it once it has reached the ground? Why some regions experience water scarcity and yet others experience abundance? Why alternating droughts and floods seem to occur almost constantly in some places but not in others? And perhaps most importantly: how we can best harness our understanding of water to maximise our societal well being? Continue reading

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