A wide variation in the number and intensity of natural hazards is normal and to be expected. What we have witnessed over the past decades, however, is not nature's variation but a clear upward trend caused by human activities. There were three times as many great natural disasters in the 1990s as in the 1960s, while disaster costs increased more than nine-fold in the same period. Most disaster victims live in developing countries, where poverty and population pressures force growing numbers of people to live in harm's way. We know why the trend is upward.
Unsafe buildings compound the risks.
The vulnerability of those living in risk-prone areas is perhaps the single most important cause of disaster casualties and damage. Second, we know that unsound development and environmental practices exacerbate the problem. Massive logging operations and the destruction of wetlands reduce the soil's ability to absorb heavy rainfall, making erosion and flooding more likely. It is not just the costs of natural disasters that are exacerbated by human action. Many scientists believe that the recent upsurge of weather-related natural disasters is the product of increased global warming, much of which is caused by human activity.