PARIS - In the space of a year, a tsunami, an earthquake, brutal storms and floods have claimed more than 300,000 lives and cost at least 100 billion dollars in damage. Humans prefer to view these catastrophes as the result of misfortune, of randomness, of the unfathomable forces of Nature, of the whim of gods or of God. But the exceptional disasters of the past 12 months raise a far more difficult question. Could mankind be to blame? For many scientists, the deep pain from this year's string of disasters is to a very large degree man-made.