I'VE been talking about doomsday scenarios for the last two weeks or so and it turns out that the one that many people are trying to deny is getting worse, much worse. I’m talking, of course, about global warming.

Researchers from the Potsdam Institute for Climate Impact Research have recently published a paper stating that the Greenland ice sheet is much more vulnerable to global warming than previously thought. The best estimate of the temperature threshold for melting the ice sheet completely is 1.6ºC above pre-industrial levels. Since temperatures have already risen 0.8ºC above pre-industrial levels, this is a little scary.

The scientists achieved their insights by using a computer simulation of the Greenland ice sheet and the regional climate. The model performs calculations using data from many physical systems, like climate feedback associated with changes in snowfall and melting rates. The simulation correctly calculated both the observed ice sheet of today and its evolution over previous glacial cycles, thus increasing the confidence that it can properly assess the future. All this makes the new estimate of Greenland temperature threshold more reliable than previous ones.

And on the other side of the planet, a new study that examined nearly 40 years of satellite imagery has revealed that the floating ice shelves of West Antarctica are steadily losing their grip on adjacent bay walls, potentially amplifying an already accelerating loss of ice to the sea.

The most extensive record yet of the evolution of the floating ice shelves in West Antarctica shows that their margins, where they grip onto rocky bay walls or slower ice masses, are fracturing and retreating inland. As that grip continues to loosen, these already-thinning ice shelves will be even less able to hold back grounded ice upstream, according to researchers at the University of Texas at Austin's Institute for Geophysics (UTIG).

The UTIG team found that the extent of ice shelves in the Amundsen Sea Embayment changed substantially between the beginning of the Landsat satellite record in 1972 and late 2011. These changes were especially rapid during the past decade.

The shear margins that bound these ice shelves to the land are now heavily rifted and they look like a cracked mirror in satellite imagery. Eventually the cracks widen entirely and the ice shelves calve massive icebergs that drift north and melt.

So ... what does this all mean for us? (We live about as far away as it’s possible to get from either Greenland or Antarctica.) Well, according to a study by scientists at Rutgers University, even if we manage to limit global warming to 2ºC (3.6ºF), future generations will have to deal with sea levels 40 to 70 feet higher than present levels.

The scientists studied rock and soil cores taken from Virginia, Eniwetok Atoll and New Zealand and looked at the late Pliocene epoch, 2.7 million to 3.2 million years ago. That was the last time atmospheric carbon dioxide were at current levels, and temperatures were 2ºC higher than they are now.

The difference in water volume between then and today is the equivalent of melting the entire Greenland and West Antarctic Ice Sheets, as well as some of the marine margin of the East Antarctic Ice Sheet. The sea level rise would swamp the world's coasts and affect as much as 70 percent of the world's population.

Releasing this much water won’t happen overnight, but when I lived in Ipan, I always said my house was on the bottom of what had once been a beautiful half moon bay below Talofofo. Ladies and gentlemen, it looks like it will be a beautiful half moon bay again in the not-so-distant future!