COPENHAGEN — When it comes to global warming, extreme scare stories abound. Al Gore, for example, famously claimed that a whopping 6 meters of sea-level rise would flood major cities around the world.

Gore's scientific adviser, Jim Hansen from NASA, has even topped his protege. Hansen suggests that there will eventually be sea-level rises of 24 meters, with a 6-meter rise happening just this century. Little wonder that fellow environmentalist Bill McKibben states that "we are engaging in a reckless drive-by drowning of much of the rest of the planet and much of the rest of creation."

Given all the warnings, here is a slightly inconvenient truth: Over the past two years, the global sea level hasn't increased. It has slightly decreased. Since 1992, satellites orbiting the planet have measured the global sea level every 10 days with an amazing degree of accuracy — 3-4 mm. For two years, sea levels have declined. (All of the data is available at sealevel.colorado.edu.)