Report: Climate change may trigger ‘abrupt’ worldwide consequences

Human-caused climate change is real, and so is the chance that abrupt and irreversible changes could have a devastating impact on the world in a matter of decades, or even years, a new report by an association of American scientists warned Tuesday.

“As scientists, it is not our role to tell people what they should do or must believe about the rising threat of climate change,” the American Association for the Advancement of Scientists (AAAS) wrote in its report.

“But we consider it to be our responsibility as professionals to ensure, to the best of our ability, that people understand what we know: human-caused climate change is happening, we face risks of abrupt, unpredictable and potentially irreversible changes, and responding now will lower the risk and cost of taking action.”

The AAAS warned of “massively disruptive consequences to societies and ecosystems,” adding that scientists do not know exactly what degree of warming would lead to such changes. Even a relatively small change in one element of the climate can lead to abrupt changes in the system as a whole, according to the report.

These changes can occur over periods as short as decades, or even years, the scientists warned. Some of the planetary systems that could trigger those abrupt changes, if pushed beyond their limits, include large-scale ice sheet melting, collapse of the Gulf Stream, destruction of the Amazon rain forest and coral reef die-off.

Scientists can’t predict what temperature will cause that red line to be crossed, the report added. Once the climate has been pushed across that line, “even if we do not add any additional CO2 to the atmosphere, potentially unstoppable processes are set in motion.”

In September 2012, Arctic summer ice melting reached record highs, the report said. In a worst-case scenario, the world could experience a sea level rise of 6 to 7 feet by the end of the century, or 16 feet in the distant future if emissions continue unabated.

“About 7 to 8 million people in the U.S. live within 6 feet of the local high tide line, and storm surge can extend flooding far beyond the high tide line, as witnessed in Hurricane Sandy,” the AAAS report said.

Extreme weather events — such as floods, droughts, wildfires and storms — are becoming more frequent, the scientists noted, with ”100-year” events becoming the annual norm. Such events have a 1-in-100, or 1 percent, chance of occurring in any given year.

“Greenhouse gases from man-made sources such as smokestacks and tailpipes have … supercharged the climate just as steroids supercharged hitting in Major League Baseball," the report said. "We can think of this as sudden climate brake and steering failure where the problem and its consequences are no longer something we can control."

More than half of Americans doubt the reality of climate change, according to the report, but for some communities in the world it's an undeniable fact.

In early March the Marshall Islands, a Pacific Island nation, were devastated by king tides as it prepared to host in April the Cartagena Dialogue — a coalition working to address climate change. Widespread flooding, along with property and agricultural damage, was reported.

“While king tides are not new to the Marshall Islands, their frequency and ferocity are clearly intensifying," Phillip Muller, the country’s foreign minister, said in a statement on March 7. "We know there is only one explanation for this unprecedented phenomenon — climate change has arrived ... Here in the Marshall Islands, at an average of just six feet above sea level, we are at ground zero."

Now is the time to act, the scientists said, adding that the U.S. had already developed solutions to the threats posed by acid rain and the hole in the ozone.

Climate change’s impact on global dynamics could lead to political instability, increased societal tensions and increased resource competition, and could place new burdens on economies and governments, the AAAS report concluded. Large numbers of people will likely be displaced due to famine and drought.

A NASA-funded study released Friday said that global industrial civilization is headed for a collapse in the coming decades, blaming unsustainable resource use and increasing wealth inequality.

The study cited examples of the rise and fall of civilizations throughout history, including the Roman Empire, and said cases of “precipitous collapse — often lasting centuries — have been quite common.”

“The fall of the Roman Empire, and the equally (if not more) advanced Han, Mauryan, and Gupta Empires, as well as so many advanced Mesopotamian Empires, are all testimony to the fact that advanced, sophisticated, complex, and creative civilizations can be both fragile and impermanent,” the report said.

Among the most important factors that explain the decline of civilizations are population, climate, water, agriculture and energy, according to the report. They can lead to collapse when coupled with overuse of resources and economic inequality.

The report said collapse can be avoided if resource use is reduced to sustainable levels and distributed in an equal fashion.