The landmark Paris climate agreement opened a new chapter in confronting an enormous challenge to our planet. I believe that it also gave new life to a Clean Air Act provision that traces its roots to Presidents Kennedy and Johnson when my father was Interior Secretary. And as communities in New Mexico and across the globe increasingly battle the impacts of climate change - while congressional gridlock prevents the United States from taking significant action - this provision offers new avenues for action.
My father, Stewart Udall, was determined to make science a cornerstone of federal decision-making. The person he hired as the Department's first science adviser was a distinguished oceanographer, Roger Revelle, who recognized even then the looming dangers of climate change. Revelle collaborated with Johnson's top science advisers on a prescient report entitled "Restoring the Quality of Our Environment."
This 1965 report from the President's Science Advisory Committee devoted a chapter to "Carbon Dioxide From Fossil Fuels - The Invisible Pollutant." The scientists wrote, "Man is unwittingly conducting a vast geophysical experiment" that "may be sufficient by the year 2000 to produce measurable and perhaps marked changes in climate," as well as sea level rise "a hundred times greater than present worldwide rates."
The scientists' concerns clearly influenced Johnson who warned in a special message to Congress in 1965, that "this generation has altered the composition of the atmosphere on a global scale through ... a steady increase in carbon dioxide from the burning of fossil fuels." He called on Congress to strengthen the Clean Air Act to permit the federal government to investigate and prevent air pollution.
Members went to the floor of the House and the Senate to echo Johnson's alarm. One even testified before the House Commerce Committee about the "unnerving" risk that "the increase in carbon dioxide ... may in time melt the polar ice caps" and "greatly raise the level of the oceans, thus dangerously shrinking the earth's land surface area."
That same year, Congress adopted what many of the nation's top environmental law professors now say may be the key to an economy-wide, market-based climate policy in the United States - the international air pollution provision of the Clean Air Act. The provision is surprisingly straightforward: if a pollutant meets an endangerment test and there is reciprocity with other nations, the Environmental Protection Agency can set emission reduction targets for the states, which they can meet using "economic incentives, such as fees, marketable permits, and auctions of emission rights."
The congressional drafters wrote that their goal was "to adopt a procedure whereby we can cooperate with foreign countries in cases involving endangerment of health or welfare." Legal experts maintain that after Paris, we can use this authority to tackle the ultimate international air pollutant: greenhouse gases.
The Clean Power Plan and the other actions contemplated in President Obama's Climate Action Plan are vital to the battle against climate change. But even if we implement all of them, there will still be a gap between the emissions reductions we will achieve and the level we have pledged to meet. The international clean air provision can unlock market mechanisms that will secure the additional reductions at the lowest possible cost.
Predictably, there are already critics of this approach and a bill has even been introduced to repeal it. Some argue that no one ever contemplated climate change when the provision was adopted. Of course, history tells us otherwise.
Others will say that Congress should pass legislation. I certainly hope Congress will act because a carefully crafted bill can address the myriad nuances climate change raises. But our country and the planet should not be held hostage to congressional inaction.
If legislation is not forthcoming, we need to rely on existing law, and none is more promising than the international clean air provision.
In 1969, when former Senator Patrick Moynihan was serving in the Nixon administration, he sent a remarkable memo to John Ehrlichman, writing: "It is now pretty clearly agreed that the CO2 content will rise 25 percent by 2000. This could increase the average temperature near the earth's surface by 7 degrees Fahrenheit. This in turn could raise the level of the sea by 10 feet. Goodbye New York. Goodbye Washington."
Despite these warnings, we've put off action for decades and now the consequences - fiercer storms and wildfires, rising sea levels, more severe droughts - are happening all around us.
Our generation can rise to this challenge. The work of visionary scientists and legislators from my father's era provides the legal foundation on which we can build an economically efficient climate policy for the United States.
Senator Tom Udall (D-N.M.) serves on the Senate Foreign Relations Committee and is the Ranking Democrat on the Senate Appropriations Subcommittee on Interior, Environment and Related Agencies.