I was trying, the other day, to explain global warming to an online colleague in an email, in simple terms. Finally, I settled on something like; "...the temperate zones are moving north in the northern hemisphere, and south in the southern hemisphere, towards the poles, decreasing the amount of ice at the poles and increasing the desert areas around the equator."

Sounds simple, right? But it's not. Some areas in the Arctic and Antarctic are cooling, whilst most are warming, and are predicted to warm further this century. Ocean "ice pack" coverage is rapidly declining, and the large Arctic and Antarctic continental ice shelves are melting at the edges, an ominous sign.

How serious is this stuff? Well, look at it this way. If the sea level rises 100cm within this century, as thousands of climate scientists have predicted, due to melting ice at the poles, Florida will be inundated. The red areas in the map below indicate the areas in Florida that will be under water.

Now the science gets complicated. Melting ocean ice will not effect the sea level dramatically, as floating ice is already part of the sea level. But, once the ice melts, it can no longer reflect light away from the earth, and this will warm the ocean. A warming ocean will accelerate the melting at the edges of the major continental ice shelves, and the major glaciers, which will lead to rising sea levels.

So, the scientists can't be sure that what they predict will not worsen. There is just no single computer model, at this time, that can predict the effects of multiple accelerated trends in climate change successfully. Dennis Quaid can't help us here :)

Below is a graphic that depicts the reduction in sea ice expected this century in the Arctic. Greenland stands exposed as the last refuge of Arctic ice cover, with its massive continental ice shelf.

If the major Greenland and Antarctic ice sheets melted, we would really be in trouble; a respected NASA scientist recently told a U.S. Senate panel that the melting of the two major Antarctic ice sheets could raise sea levels by around 18 foot (that's around 6 metres).

In addition to this rapid melting of ice at the poles, CO2 emissions have been rising gradually, but relentlessly, for the past half a century. This has accelerated the pace of global warming beyond "historic norms" into an entirely new scenario.

Unfortunately, no-one knows exactly what that scenario will be, as the situation we face now has no historical precedent. But the science becomes better every day, and models are being developed to help us predict the future of this fragile planet.

One thing is for sure. Major climate changes are under way, and more are to come. We will have to embrace serious lifestyle changes within the next decade to slow this global warming, or we may just perish. The 3 NASA scientists who spoke to the U.S. Senate panel were unanimous --- global warming is here, now, and we must act immediately.

The frightening thing is, even if we were to act today, the effects of global warming will continue for years anyway. As the scientists say; "...there is already heat in the pipeline" and it will continue regardless of our actions.

Species extinction

Now, let's take a quick look at the increasing incidence of "melt" in Greenland's ice shelf... over just the past 10 years... This is having a dramatic effect on the Arctic species that rely upon the ice cover to survive.

According to the ACIA; "Polar bears are unlikely to surrvive as a species if there is an almost complete loss of summer sea-ice cover, which is projected to occur before the end of this century by some climate models." -- ACIA Report, Impacts of a Warming Arctic.

Now, you might believe that we have no moral responsibilities towards the planet and its species. But I believe that we do, deep in our historical past and deep in our collective future.

Global warming (such a cuddly phrase, really) is a misnomer. If our CO2 emissions are accelerating the trend towards rising temperatures, as the majority of the world's climate scientists are claiming, things can only get worse...

I'm concerned about our affect on the planet. Our lack of responsibility could bring us low .. and soon. Osama bin Laden and Saddam Hussein may have simply distracted us from the truth ... that the human race, as advanced as it claims to be, is an unworthy steward of such a beautiful planet.

It's past time we really started worrying about "...the day after tomorrow". According to the scientists, we're there now.

Sources:

• Impacts of a Warming Arctic -- Arctic Climate Impact Assessment -- ACIA
• Carbon emissions reach record high -- Lester Brown
• Report to the U.S. Senate Committee on Global Climate Change (C-SPAN broadband -- RealPlayer).