With the flooding in New England caused by record-setting precipitation, the near flooding in North Dakota, concerns over the volcano in Iceland, and the earthquakes in Haiti and Chile all occurring in just three months, my blog has been inundated with people wanting to know why there are so many natural disasters lately. The answer to that question is threefold.
1. Some disasters are no more frequent nor severe than before but appear that way because they receive more news coverage
Earthquakes may seem more frequent because there are more stations set up to monitor earthquakes, and because we are now able to quickly receive news from all over the world. This means that earthquakes which might have gone unnoticed or unreported before, may now make the news just minutes after they occur. This creates the impression that there are more earthquakes than ever before.
According to the U.S. Geological Survey (USGS)
Although it may seem that we are having more earthquakes, earthquakes of magnitude 7.0 or greater have remained fairly constant throughout this century and, according to our records, have actually seemed to decrease in recent years.
2. Some natural disasters are no more frequent nor severe than before, but cause far more damage due to population growth and urban migration
The more people who are in the area, the larger the number of people that will be affected by a disaster. Higher population densities mean that even if the strength of an earthquake is no greater than before, the people and property impacted will be far greater.
Overpopulation as well as urban migration may force people to live in marginal areas such as on unstable hillsides, in flood plains, on top of fault lines, or in shabbily constructed buildings. All of these factors increase the odds that more lives and livelihoods will be severely affected by a natural disaster. Again from the USGS:
The population at risk is increasing. While the number of large earthquakes is fairly constant, population density in earthquake-prone areas is constantly increasing. In some countries, the new construction that comes with population growth has better earthquake resistance; but in many it does not. So we are now seeing increasing casualties from the same-sized earthquakes.
3. Some natural disasters are more frequent and more severe than ever before due to environmental degradation and climate change
Deforestation, over-grazing, river channelization, hardscaping (covering large swaths of landscape with asphalt and concrete), and many other activities impact the frequency and severity of natural disasters. Deforestation or overgrazing on hillsides increases the probability of landslides after heavy rains. Deforestation and overgrazing in marginal lands can lead to dustbowls or desertification. Straightening and channelizing rivers decreases the total volume of water a river can hold and speeds the flow of the water. Hardscaping large areas decreases the amount of land available to absorb and slow the flow of water. Both of these factors lead to increased flooding.
Although the tsunami was caused by an earthquake, the destruction it caused was greatest in areas where the mangrove swamps had been destroyed. Mangroves act as a sponge absorbing much of the force of the waves. In Thailand, the places with the greatest destruction were those with sandy beaches where the waves could travel kilometers inland, unimpeded.
Climate change is raising sea levels and changing weather patterns in many parts of the world. As sea levels continue to rise, low-lying coastal areas become more prone to damage by wave surges, tropical storms and other coastal issues. Areas with increased rainfall risk flooding and landslides, while areas with decreased rainfall face crop failure, desertification, wild fires and other serious issues.
Preparing for natural disasters
While not all types of natural disasters are increasing in frequency or severity, there is an overall increase in the rate and impact of natural disasters. The better prepared individuals and governments are before a natural disaster strikes, the more lives and structures will be saved.