The tragic earthquake in Greece and the enormous devastation and suffering wrought by the recent earthquake in Turkey are reminders of one of the most pressing challenges of our time: the extraordinary increase in the number and extent of natural disasters.

The facts are startling. The costs of weather-related disasters in 1998 exceeded the costs of all such disasters in the decade of the 1980s. Tens of thousands of mostly poor people died during the year, tens of millions have been temporarily or permanently displaced.

In the Caribbean, hurricanes designated George and Mitch killed more than 13,000 people, with Mitch being the deadliest Atlantic storm in 200 years. A much less-publicized cyclone in India in June caused damage comparable to Mitch and an estimated 10,000 deaths.

Major floods hit India, Nepal, Bangladesh and much of East Asia, with thousands killed. Two-thirds of Bangladesh was inundated for months, leaving millions homeless. More than 3,000 died in China's catastrophic Yangtze River flood, millions were displaced, and the financial cost is estimated at an astonishing $30 billion.

Fires ravaged tens of thousands of square kilometers of forest in Brazil, Indonesia and Siberia, with devastating consequences for human health and local economies. In Afghanistan earthquakes killed more than 9,000 people, while the exact toll of the horrific earthquake in Turkey is still unknown.

We know that human communities will always have to face natural hazards, whether floods, droughts, storms or earthquakes. But today's disasters owe as much to human activities as to the forces of nature. Indeed the term ‘natural’ is an increasingly misleading.

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.

We know why the trend is upward. Ninety per cent of disaster victims worldwide live in developing countries, where poverty and population pressures force growing numbers of poor people to live in harm's way -- on flood plains, in earthquake-prone zones and on unstable hillsides. 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. While the earth has always experienced natural cycles of warming and cooling, the 14 hottest years since measurements first began in the1860s have occurred in the past two decades. 1998 was the hottest year on record.

Given that the pressures of poverty and population growth continue to increase, the disaster trend is likely to worsen if we do not take disaster prevention more seriously.

More effective prevention, as the dedicated staff of the UN International Decade of Natural Disaster Reduction have tirelessly argued, requires better early warning of impending disasters to give vulnerable populations time to move out of harm's way. It also requires more effective disaster response policies. But above all it requires that we reduce the vulnerabilities that cause the damage in the first place.

Our tasks are clear. Development, land use and habitation policy must be informed by a thorough understanding of the scientific and technical requirements of prevention.

Disaster reduction legislation is crucial, but not sufficient. The best laws are useless if not effectively and impartially enforced.

Above all we must never forget that it is poverty, not choice, that drives people to live in risk-prone areas. Equitable and sustainable economic development is not only a good in its own right, but also one of the best forms of disaster insurance.

There are some reasons for optimism. Radical improvements in wide-area satellite surveillance is revolutionizing disaster early warning, while the Internet can provide instant dissemination of the satellite and other warning data. These developments have been particularly important with respect to weather-related natural disasters.

But successful disaster prevention is not dependent on access to advanced technologies. Last year in one Honduran village, the hurricane designated Mitch claimed more than 150 lives. In an equally exposed village nearby, where a disaster reduction pilot programme was in place, there were no deaths.

In China, where extensive disaster control policies have been introduced over the years, the death toll from floods has fallen dramatically. Flooding cost more than 3,000 lives in China in 1998, but similar floods in 1931 and 1954 cost 140,000 and 33,000 respectively. Prevention strategies saved tens of thousands of lives.

While much can be done at the local level with modest financial resources, some major risk reduction and disaster prevention programs require levels of funding that many poor countries simply cannot afford. International assistance is both critical and cost-effective here.

We now know what has to be done, what is needed is the political will to do it.