While climate change is altering the planet, a lead National Aeronautics and Space Administration (NASA) scientist recently stated that the Earth might be beyond the tipping point.

Last year was one of the warmest years on record, with January 2007 the warmest January on record since 1880.

As predicted, climate change is causing weather extremes, including too much rain or droughts — like the ones Atlanta, Ga., and Australia suffered — their worst in a century.

More than 260 all-time record highs and weather anomalies were recorded by weather stations in the United States alone. A tornado struck New York City. Iran and Oman were hit by an equally unusual cyclone. More than 8,000 new heat records were set during the year.

“We’re having an increasing trend of odd [weather] years,” said Michael MacCracken, chief scientist at the Climate Institute in Washington, D.C., in an Associated Press article. “Pretty soon odd years are going to become the norm.”

Individual events like these are not directly attributable to global warming, but the combination is alarming many scientists. More worrisome than weird weather is the unprecedented melting of the Arctic and Antarctic ice cover.

Recent legislation in Bali, Indonesia and Washington were modest attempts to address the problem.

But a “mind-blowing bottom-line” given by Dr. James Hansen, a top U.S. climatologist, might render those modest gains “quaint and nearly irrelevant,” wrote environmentalist Bill McKibben in The Washington Post.

The latest research by Hansen and his colleagues indicates that the Earth cannot sustain more than 350 parts per million (ppm) of carbon dioxide without dire consequences. We are already at 383 ppm and the planet is reacting strongly.

Experts warn this upper limit is the best estimate of avoiding the “runaway greenhouse effect,” or abrupt climate change due to positive feedback mechanisms — factors not taken into account in the most recent Intergovernmental Panel on Climate Change (IPCC) report.

“The evidence indicates we’ve aimed too high [for acceptable levels of carbon dioxide],” Hansen said, and if we are to prevent catastrophic consequences, drastic changes need to take place sooner rather than later.

Other researchers point to uncertainties in the modeling process but agree with Hansen’s call for urgent action.

“There are different tolerances for risk,” Gavin Schmidt, a climate modeler at the NASA Goddard Institute for Space Studies in New York, wrote in an e-mail. “Three hundred and fifty [ppm] is safer than 450, which is safer than 550, but no one really knows where the dangerous point is. All we know is that we are going towards one.”

The report urges the United States to play a stronger national and international role in mitigating the effects of climate change, and it acknowledges that risks from climate change will undoubtedly get worse the more we delay.

“Without realizing it, we have begun to wage war on the Earth itself. Now, we and the Earth’s climate are locked in a relationship familiar to war planners: mutually assured destruction,” Al Gore said when he accepted the Nobel Prize.

Even so, climate change remains a low priority in the United States — even as the 2008 elections draw near.

“The inconvenient truth of the 2008 election year is that climate change is still way down the dance card of most-talked-about topics,” syndicated columnist Ellen Goodman said. “It’s ranked No. 12 among Democratic candidates and No. 15 among Republicans.”

Physicist Joseph Romm, author of Hell and High Water, veteran of the Department of Energy, and founder and director of the Center for Energy and Climate Solutions, isn’t convinced by Hansen’s dire figures, although admittedly he has not reviewed his latest paper.

Romm maintains, along with many top climatologists, that 450 ppm is still the upper bound of ‘acceptable’ atmospheric carbon dioxide.

“Staying below 450 ppm is technologically doable, but [it] would be the greatest achievement in the history of the human race, by far,” Romm said. “It would require a global effort sustained for decades.”

Seventy-nine percent of Americans said lifestyles in the United States will need to change, and 65 percent are willing to accept higher energy costs and taxes in order to tackle climate change, according to a University of Maryland/BBC poll released in November.

Not only should people be concerned with the rhetorical “war on Earth,” but analysts believe there is an increasing danger of more conflicts around the world. So alarming is the threat that 11 retired generals and admirals published a 2007 report titled “National Security and the Threat of Climate Change.”

“Projected climate change poses a serious threat to America’s national security,” according to the report, and climate change will act as a “threat multiplier in the most volatile regions of the world.”

[Reach columnist Aditya Ganapathiraju at news@thedaily.washington.edu.]