I found this highly entertaining: In 2007, Obama claimed that CO2 "threatens our very existence"; claimed that "no business will be allowed to emit any greenhouses gases for free"

The full text of Obama’s energy remarks | Grist

Monday, October 8th, 2007

[Obama] ...maybe the planet’s only superpower would finally lead the world — or at the very least, follow it — in taking on the planet’s greatest threat.
...I believe that when it comes to the issue that will determine the very future of life on this Earth, we are still Earth’s best hope.
...I’ve filled up at a biodiesel pump at UNH, where this year students and faculty will remove over 200 tons of carbon dioxide from the atmosphere...Back then global warming was just the theory of a few scientists. Now it is a fact that threatens our very existence.
...I passed a law that will fuel the research needed to develop a car that will get 500 miles to the gallon...Global warming is not a someday problem, it is now....We are already breaking records with the intensity of our storms...The polar ice caps are now melting faster than science had ever predicted. And if we do nothing, sea levels will rise high enough to swallow large portions of every coastal city and town.
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The first step in doing this is to phase out a carbon-based economy that’s causing our changing climate. As President, I will set a hard cap on all carbon emissions at a level that scientists say is necessary to curb global warming — an 80% reduction by 2050. To ensure this isn’t just talk, I will also commit to interim targets toward this goal in 2020, 2030, and 2040....
In addition to this cap, all polluters will have to pay based on the amount of pollution they release into the sky. The market will set the price, but unlike the other cap-and-trade proposals that have been offered in this race, no business will be allowed to emit any greenhouses gases for free...I’ve been a champion for ethanol...I will launch a Clean Technologies Venture Capital Fund that will provide $10 billion a year for five years to get the most promising clean energy technologies off the ground...The federal government will lead by making all of its buildings carbon neutral by 2025. And I will set a national goal of making all new buildings in America carbon neutral by 2030.
...I will not be outlining these goals in my State of the Union and then walk away when they become too difficult. I will report to the American people every year on the State of our Energy Future, and let you know the progress we’ve made toward an 80% emissions reduction by 2050, toward replacing over a third of our oil consumption by 2030, and toward improving our energy efficiency 50% by 2030.
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From the moment I take office, I will invite the world back to Washington and let it be known that the United States of America is ready to lead again.
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I will personally reach out to the leaders of the biggest carbon emitting nations in both the developed and developing world and ask them to join America in creating a new Global Energy Forum that will lay the foundation for the next generation of climate protocols.