"We do not have good models that include all of the relevant physics for the ice sheets," said James Hansen, a top climate scientist at NASA's Goddard Institute for Space Studies in New York. But Hansen said that if humans continue to heat the atmosphere in a business-as-usual fashion — and the Greenland or Antarctic ice sheets start to collapse — all bets are off.
"Once a collapse starts, things can happen very rapidly," Hansen said. "I would expect that it's almost certain that before the end of the century we would have sea level rise measured in meters. At least one or 2 or 3 meters [ 6 to 9 feet] this century if we follow business as usual."
With so many people around the world living within several meters of sea level, the implications could be catastrophic.
"A large fraction of people live within several meters' elevation of sea level," said Hansen. "So we would be talking about hundreds of millions of people being displaced if sea level goes up a few meters. So we really can't afford to go down that path."
Mazria, like Hansen, believes humans must act now to dramatically reduce the use of coal. The Architecture 2030 report claims that any other measures proposed to fight global warming are almost futile. Consider the following statistics, which were calculated by Architecture 2030 using government data.
"Wal-Mart is investing a half billion dollars to reduce the energy consumption and CO2 emissions of their existing buildings by 20 percent over the next seven years," the report stated. "If every Wal-Mart Supercenter met this target, the CO2 emissions from only one medium-sized coal-fired power plant, in just one month of operation each year, would negate this entire effort."
"California passed legislation to cut CO2 emissions in new cars by 25 percent and in SUVs by 18 percent, starting in 2009. If every car and SUV sold in California in 2009 met this standard, the CO2 emissions from only one medium-sized coal-fired power plant, in just eight months of operation each year, would negate this entire effort."
Grim figures, for sure, But Mazria doesn't want anyone to lose hope, either.
"The American public is exceptional at taking a hold of a problem and solving it," he said. "If there's a need to do something, we'll do it."
Bill Blakemore contributed to this report.