Climate Change and Cyclone Damage

Satellite Image of Cyclone Yasi from Feb 2011 (Image Source)

A very belated Happy New Year - it's been a while since I last blogged! Earlier today I was kindly pointed in the direction of a new paper which was released in Nature this week (the article can be found here).

The paper ties in nicely with some of the latest cyclone research that I blogged about in December. The purpose of the research was to assess future damages caused by cyclones and climate change. They are clear in their introduction that future scenarios with cyclone models are sketchy at best and that despite increases in cyclone numbers in the past 40 years, they are still well within natural variability. The paper is also quick to note that increasing damages in the last few decades are largely down to the increasing population and more assets in harms way rather than as a result of anthropogenic warming. However, they have taken the scientific viewpoint further by modelling cyclones in separate ocean basins, taking into account frequency, intensity and regional location changes (rather than just wind speeds and sea surface temperatures as seen in previous studies and models). The figure below shows the global storm tracks and their intensity (minimum pressure). It clearly indicates that the storms are more frequent over the warmer equatorial waters, and most occur in the Western Pacific.

The present annual global damage from tropical cyclones is US$26 billion and is used as a baseline for scenario comparisons up to 2100. The results in this paper, reveal (as would be expected) that the distribution of climate-change damage is not even across the world. The figure below shows the estimated projected damage caused by climate change in each region. North America has the highest average damage of US$26 billion yr-1, which is half of the global damage. East Asia and Central America Caribbean average damages of US$15 and US$10 billion yr-1 respectively.

There are some limitations with this study and its projections, which largely revolve around economics and countries GDP and growth rate. Damages vary a great deal if a storm hits a city versus a rural area, but this is not yet captured in this analysis. Moreover, increases in income and population along the coast, relative to the rest of the country, will cause more damage. There is also no account of any adaptation policy that could be put in place. Despite these limitations it is a nice to see an initial attempt at quantifying costs of cyclone damage associated with climate change.

Is Strange Weather in the Air or just On Air?

I came across this clip from NBC news last week which is probably one of the most one-sided reports on climate change causing extreme weather I've seen in recent weeks. It doesn't even try to balance the argument, or even suggest "on the other hand", which is surprising for a major US news network. It devotes a full 2 and a half minutes to suggesting that extreme weather events will become more likely and are a result of climate change. The video concludes by saying "today, no one can deny that extreme weather is here to stay"!

After doing a bit of digging in some journal archives, I came across this interesting paper. It looks at how extreme weather event coverage on US national television has changed over the past 50 years, and assesses whether news coverage can be used almost as a proxy as to whether extreme events are becoming more discernible.

News archives between 1968 and 1996 were used to track records of heat waves, droughts, hurricanes and floods from ABC, CBS and NBC television networks. A control period was used in order to distinguish between 'climate science' and 'global warming' frenzies that hit news and media in the late 80s. Some of the key findings are displayed on the graphs below:

Annual coverage of heat waves on the network news.

Annual coverage of floods on the network news.

Annual coverage of hurricanes on the network news.

The results show a dramatic increase in the coverage of floods and hurricanes since the 1980s, however, it must be noted that the different types of extreme events do not receive equal coverage: for example, annual peaks for droughts contain about twice as many stories as the peaks for heat waves. 

One of the key findings that the data revealed is that surprisingly there is no association between coverage of climate change and the overall coverage of extreme events. They also discovered that whilst total news coverage of extreme events in the US increases dramatically, coverage devoted to extreme events in other countries remains relatively constant (see image below).

Index of extreme weather coverage on the network news by all events and foreign events.

There are a variety of limitations with using a study such as this to show extreme events are linked to anthropogenic change. Media is always subjective and some news stories can be made at the expense of others. Some stories can often dominate the news, whilst others get left behind. Changes in technology, forecasting and the ability to track extreme weather events has also come a long way in the last 50 years and the ability to cover events and show footage will impact whether an event is covered.

Despite not a lot of concrete evidence coming out of reports such as these, it is pleasing that researchers are trying new and innovative ways of collating evidence for climate change.

In the News: Snowstorm hits US East Coast... in October!?!

Snow fall in New York - 30/10/2011

Record levels of snow were recorded on the East Coast of the US yesterday. According to the National Weather Service, 31.4 inches fell in Jaffery New Hampshire. The storm blanketed New York city's Central Park with 3.3cm (1.3in) of snow, almost doubling an 86-year-old record set on October 30, 1925. The storm caused chaos, killing 9 people and leaving over 3 million homes without power (The full story and news video can be found here).

In trying to find some up to date information on this storm and any links to climate change I came across a blog called 'Weather Underground' which is written by meteorologist Dr. Jeff Masters. It is well worth a look and keeps up to date with all the latest notable weather events across the world.

Jeff states on his blog that the recent snows do not, by themselves, demonstrate anything about the long-term trajectory of the planet. "Climate is, by definition, a measure of decades and centuries, not months or years." But Dr. Masters also re-emphasises that government and academic studies have consistently predicted an increasing frequency of just these kinds of record-setting storms, because warmer air carries more moisture.