One day, our children's children will ask us, "What did you know about global warming, and when did you know it?"

Inaction on global climate change has shown politics at its worst — ducking difficult choices, giving into big contributors, substituting words for deeds, postponing the reckoning until the day after tomorrow. If you offend no one, you change nothing.

If nothing changes, we will be forced to answer that we saw a crisis approaching and did nothing to avert it. No explanations or excuses will matter if we continue to debate a scientific consensus and fail to protect the planet. Here's the bottom line: Within the next decade, if we don't deal with global warming, our children and grandchildren will have to deal with global catastrophe. It is time to stop debating fiction writers, oil executives and flat-earth politicians and take on climate change.

The time to act is now. We cannot allow industry-funded doubters to freeze us into inaction as Earth heats up. For too long, flat-earth politicians have distorted the debate as sea levels rise and mileage standards don't.

The good news is there is another way. A recent Business Week article asked Americans to "Imagine a world in which socially responsible and eco-friendly practices actually boost a company's bottom line." The tag line was "it's closer than you think," but the truth is, it's already here.

Wal-Mart is selling "green" light bulbs, and green companies small and large are popping up across the country. Say what you will about Wal-Mart, but nobody has yet accused it of ignoring its bottom line.

Business leaders will tell you: This crisis presents an economic opportunity to create technologies that lower emissions and reverse the damage. Every American schoolchild knows our history of innovation — from the Wright Brothers to Henry Ford to Bill Gates, from the Model T to the iPod. Why would we stop now?

The real crisis will come if we fail to seize the opportunities global warming presents — for renewables, efficiency breakthroughs and clean technologies. We can create millions of jobs and vast markets, slow global warming, save tax money, earn the world's respect and strengthen our long term outlook — all by making a commitment to solve global warming.

Thankfully, people are finally waking up, and the result is a new environmentalism. For anyone who ever ridiculed environmentalists as elitist "tree huggers," it's time to meet the new face of the environmental movement: ranchers out West; CEOs of 10 major companies urging mandatory carbon emissions caps, evangelicals who believe in "creation care" and parents wondering what's in the water their kids drink.

The new environmentalists reject the lazy dodge that caring about the environment means caring less about security or the economy because they understand that, in the long run, these issues are inseparable.

This is a matter of life and death. It is a matter of keeping our children safe and of respecting God's creation. It is a matter of preserving species and protecting the bottom line.

Last fall, Nicholas Stern, the head of Britain's Government Economics Service, issued a comprehensive analysis concluding that "the benefits of strong and early action far outweigh the economic costs of not acting" and that as a result "prompt and strong action is clearly warranted."

And yet U.S. oil use over the past decade has increased by nearly 2.7 million barrels a day — more than India and Pakistan together use daily. By 2025, will depend on imports for 70 percent of our oil use.

And yet we are allowing carbon dioxide concentrations in the atmosphere to rocket past levels that are safe and sustainable.

And yet we have allowed worldwide temperatures to heat up an average of 1.4 degrees in the last six years alone. Earth is hotter today than at any time in at least the past thousand years.

Talk is not enough: We must lead the worldwide race for new energy sources that do not empower our enemies, pollute our skies and waters and imperil our future.

We need to take bold steps — investment in renewable fuels, a carbon emissions cap, and a dramatic hike in fuel efficiency standards — if we hope to contain this growing threat. Science suggests we have about ten years to get this right before CO2 in the atmosphere reaches potentially catastrophic levels.

Unless we act decisively, we will have no answer to the question our children's children will surely be left to ask us: Why didn't we do more?