The Need For Change: Extreme Weather

In terms of cost, the average annual amount spent following the impacts of natural disasters have been as follows...

1950s: $4B per year
1970s: $13B per year
1990s: $65B per year

... and these costs have been mainly attributed to weather-related hazards. (McBean, 2004) Most of the time the weather doesn't try and kill us. Global warming? Hey, we're having a few warmer summers over in England and that's great! But sometimes the weather can kill us and these are the events of which this blog post is about. We're talking about extreme, high impact weather - hurricanes, tornadoes and the other forms that manifest as droughts, floods, snow slides and the like! Back to the rising cost, McBean (2004) identifies three main reasons for the increasing cost...

1. Social and demographic characteristics - increasing population, increased exposure to hazards
2. Changes to built and commercial environment - ageing infrastructure and commercial activities becoming more independent and vulnerable
3. Changing physical environment, specifically climate change

The IPCC (2001) report notably identified the irrefutable increase in CO2 and methane gases but for the sake of this blog post we can skim over that and focus on what it said about extreme weather conditions. It agrees with McBean (2004) and does attribute increases in 'historical disaster losses' to socioeconomic factors in addition to climatic changes and states that "Many of the observed upward trends in weather-related losses are consistent with what would be expected under human-induced climate change". Thus attributing the increases in extreme weather events to climate change in the report.

McBean 2004 - Original Table taken from IPCC (2001a)

The above table originally taken from the 2001 IPCC report shows estimates for increases in extreme weather, it shows a summary of predictions based on modelling and statistics. The predictions show that an increase in cyclones and drought are likely (90-99%) to increase over the coming century and more intense precipitation events are likely (66-90%) to increase. The prediction clearly shows change in these events is predicted to happen with the projected. Several severe weather conditions are not included in the table such as tornadoes or hail, simply because these are not resolved in climate models.

As a general prediction the future climate can be said to be warmer and contain more moisture. This tends to be of most concern in mid-latitude's (US) as these wetter and warmer conditions tend to be more energetic - tornadoes and thunderstorms are much more likely to occur on these warmer and wetter days. Rising sea-levels increase the likely hood of damage to coastal areas through storm surges and the additional melting of sea ice will leave more exposed water for moisture and heat sources in storm generation. (McBean, 2004)

It's not always the frequency of these events that are changing. To take the example of cyclones, Zwiers (2002) used modelling to predict cyclone frequency between two separate time periods - 1900-1910 and 2091-2100. He found that between the first time interval and the predicted second time interval the number of cyclones decreased by around 10%. However the severity of the cyclones did increase; the number of severe cyclones per year increased from 11 to 15 over the same time gap. (Zwiers, 2002)

Cyclone! Source: Giphy

The McBean (2004) paper concludes with strategies to deal with this information regarding investments into preventative strategies and calculating the cost of investment against the cost of damage that would be caused if things were just left how they are. The increased cases of severe weather events does pose a threat to society and it is important we try to limit the changes in climate so we limit the chances of being killed by the weather!