Of all the failures of American government over the past decade, the one that is likely to haunt future generations most is the failure to act decisively to lessen the effects of global warming caused by greenhouse gas emissions.

Former President George W. Bush not only failed to act to limit the increasing production of CO2 but vehemently denied U.S. culpability in the rising global temperatures. His ignorance has been compounded by the ineffective, even lukewarm, efforts of the Barack Obama administration and the continued denial and refusal of Congress to acknowledge the looming crisis. President Obama's proposed caps on carbon emissions by American industry went nowhere, and now it seems, in the face of their intransigence, he has given up trying to persuade legislators to do anything.

The United States, more than any nation on Earth, will be held accountable, and should be, for what scientists now say are the inescapable consequences of putting fossil-fuel industry interests above the interests of the planet's inhabitants. The U.S. and China are the primary contributors. While emerging nations India and China are not held to the goals of the Kyoto agreement of 1997, the United States has simply failed to use the technology available to reduce emissions. Europe, Russia and Japan, meanwhile, have nearly met the goals set by the pact. The U.S. Senate never ratified it.

Scientists say now, after the record-setting temperature increases of 2010 when the global carbon dioxide emissions increased by the highest one-year amount ever, we may have gone beyond the point when we can help ourselves. And the United States is leading the way to global catastrophe.

The growth in warming has accelerated every decade, well beyond what scientists predicted two decades ago. According to the National Oceanic and Atmospheric Administration, since 1990 the heat-trapping force from all the major greenhouse gases has increased by 29 percent.

We have, perhaps, already reached the "tipping point," when the melting of the Earth's ice sheets is irreversible. If that is true, sea levels will rise by several feet, inundating coastal nations, many of them in some of the world's poorest places. Refugees from those places will escape to higher-ground nations, creating societal problems the world has not yet seen. Extreme weather events are already beginning and will bring severe floods, droughts and storms.

World leaders will meet this week in South Africa to once again try to formulate plans to cut emissions and lessen the coming crisis. The United States has an obligation to, at least, admit it has a role to play.