Literature on natural hazards has repeatedly shown that socioeconomic, cultural, and political processes shape the way people respond and cope with extreme weather events like the flooding in New Orleans. This vulnerability is socially constructed; its underlying causes are more social than biophysical, and they are rooted in socio-political processes that allocate resources within a society. We may experience frequent extreme events due to anthropogenic climate changes or natural variability, but we should not focus only on mitigation.
It is important to address the deeper issues that lead to social vulnerability, i.e., unequal access to resources and political, social, and cultural inequalities, that determine how people and communities will be affected and their capacity to cope with those impacts. Climate adaptation plans are being developed at both the national and international levels, but funding is lacking for these initiatives. It is especially relevant when we consider the social justice aspects of climate change. Many of the communities and countries that will be most affected by extreme events live in developing countries or are indigenous communities living on the margins. They have also contributed the least to global emissions and are therefore facing double exposure, i.e., the interaction of climate change with other globalization processes such as urbanization and poverty. The issue of climate change must be reframed in a way that is more humane and socially just, as increased extreme weather events will affect the lives of many people.
A landslide that occurred in 2009 in the Philippines killed around 200 people. The landslide in the Philippines was caused by Typhoon Pepeng, also known as Parma, outside of the Philippines.
Climate is a series of weather events that we all experience. In fact, climate can be understood as a collection of weather events – or the probability density function in technical terms. Climate change will be felt as a shift in the weather. It includes “mean” and extreme weather. Extreme weather is rare by Nature – it’s at the extremes of the weather distribution. Due to this, detecting climate change-induced changes in extreme weather events is much more difficult than seeing climate-change-induced changes in average climate. This requires longer and more comprehensive data records. The uncertainty in establishing a link between climate changes and extreme events is, therefore, greater. It does not mean that climate change is not occurring or that extreme events will not be affected by it. The greater uncertainties when observing and predicting the future of severe weather around the world highlight the importance of continuing research into the relationship between climate change and extreme weather.
Associate Prof. Stewart Franks School of Engineering, University of Newcastle
Australia has a rich and detailed history of climate variability. However, there is a new threat: anthropogenic climate changes caused by CO2 emissions. There is a danger, despite the long history and extremes of climate, that we will now see every drought or flood as a CO2 climate shift. As a hydrological scientist, I can confirm that there are no signs of “change” regarding the frequency of extreme hydrological events. It is sad to say that natural disasters are a common occurrence. Extreme events are real, but they’re not always our fault. No published research shows otherwise. However, those who ignore history often make this claim.
The security forces took few risks when they evacuated New Orleans residents after Hurricane Katrina in 2005, which caused the levees of the city to fail. AAP/EPA/Larry W. Smith
Dr Stuart Corney is a climate systems modeler at the University of Tasmania.
It’s difficult to tell the difference between the frequency of extreme events and the likelihood they will increase in the future. The IPCC supports the idea that extreme events are changing in frequency and will be more frequent. Some studies have shown that recent extreme weather events can be partially attributed to human-induced climate change. For example, a report published by Nature in 2010 attributes the change in flood risk in England & Wales to climate changes. The IPCC Special Report on extreme weather, which has not yet been released, will likely discuss the difficulties in detecting and attributing such low-probability events.
Climate change will continue to be a major issue, and extreme weather events will increase in frequency. On the east coast, a rainfall event that occurs once every 50 years (for the climate of today) will see approximately 125mm of rainfall in 24 hours, while an event that happens only once every 1000 years would see about 175mm of rainfall in one day. Recent research by the Climate Futures for Tasmania Project states that by 2050, a 1-in-50-year rainfall event will have 175 mm in a day. Many studies, like the IPCC Special Report on extreme weather, which will be released soon, indicate that extreme events such as excessive rain, fire weather, or heat waves are likely to increase in frequency.
It is difficult to link an individual event with climate change. This process, known as detection and attribution, can be challenging. If we go back to the East Coast of Tasmania, is 175 mm of rainfall on a single day a one-in-1000-year event, or will this be more common due to climate change? Statisticians cannot distinguish between very rare events (1 in 1000 years) and those more common (but still rare) 1 in 50 years until a large number of them occur.
In summary, every single weather event – no matter how unlikely or extreme – has a chance to happen in today’s climate. (Even events that are expected to only occur once in 10000 years in this climate can still happen, but it is very unlikely they will appear twice in the coming century). Only by carefully examining the patterns of past events over many years or decades can we begin to attribute our changing weather pattern to climate change. In the soon-to-be-released IPCC Special Report, Extreme Weather, states that extreme weather events will become more frequent. However, at this point, it is difficult to say with confidence that we’ve already seen an increase in extreme events of low probability. It will be easier to prove that extreme weather events are occurring more frequently if we don’t change our emission behavior. But this is not the path we want to take.