Isn't it sad that you can tell people that the ozone layer is being depleted, the forests are being cut down, the deserts are advancing steadily, that the greenhouse effect will raise the sea level 200 feet, that overpopulation is choking us, that pollution is killing us, that nuclear war may destroy us - and they yawn and settle back for a comfortable nap. But tell them that the Martians are landing, and they scream and run.