CHARLESTON, W.Va. -- Delegates from nearly 200 nations are meeting in Qatar for another U.N. attempt to curb the peril of global warming. Fear of climate disasters like Hurricane Sandy has been voiced repeatedly. Blame for worsening weather calamities is heaped on carbon dioxide pollution that forms a "greenhouse" layer in the sky, heating the planet.

In a surprise twist, 140 corporations -- including Exxon Mobil, Shell and BP -- signed a "Climate Price Communiqué" agreeing to a $20-per-ton tax for CO2 emissions. Why would they willingly tax themselves? The Global Warming website explained:

"The most obvious reason why big oil and gas companies would support a huge new tax on their own products is that it would kill coal first. Burning coal emits roughly twice as much carbon dioxide as producing the same amount of energy by burning natural gas. A $20-a-ton CO2 tax would roughly double the current price of coal used for producing electricity. That would provide a huge incentive for utilities to switch to natural gas. Exxon Mobil owns the world's largest privately owned reserves of natural gas. Shell and BP also own huge gas reserves."

Nobody can predict whether a carbon pollution tax will be adopted by large industrial nations. Meanwhile, delegates in Qatar heard dire warnings of increased weather danger. Secretary-General Ban Ki-moon declared:

"No one is immune to climate change, rich or poor. It is an existential challenge for the whole human race ... a crisis, a threat to us all, our economies, our security and the well-being of our children."

The secretary-general said humanity is "in a race against time" to prevent global temperatures from rising 2 degrees Fahrenheit, which would melt polar ice, raise sea levels, trigger more monstrous storms, cause horrific droughts, decrease food crops, make some seashores uninhabitable, cause ever-worse floods and bring other costly evils.

Ban Ki-moon added: "Let us avoid all the skepticism. Let us prove wrong all these doubts on climate change."

On the "PBS NewsHour," Coral Davenport of the National Journal warned that "the 2-degree critical mark" is "sort of the point we can't go past; it's kind of a point of no return ... that will set off a lot of rapid and potentially catastrophic chain reactions."

However, Davenport noted sourly that world authorities "have been talking about it for 18 years," with little solid action to curtail carbon pollution -- so it's doubtful that a U.N. effort can prevent planet Earth from exceeding the 2 percent heat-up.

Worse hurricanes, tornadoes, floods and droughts already are costing America billions in damage, plus many deaths. It's a terrible price to pay for failure to face the reality of what humanity is doing to its home planet.