While climate change has not historically been a politically divisive issue until recent years, the fiercely partisan divide as it currently exists makes garnering the support necessary for meaningful change very challenging.
Despite Congressional stalemates to produce meaningful, broadly-scoped legislation to address greenhouse gas emissions, President Obama utilized executive authority to regulate emissions under the Clean Air Act based on the landmark 2007 Supreme Court ruling that categorizes carbon dioxide as a threat to human health. In doing so, he directed the EPA to establish rules for both new coal-fired power plants, and perhaps more controversially, for existing coal-fired power plants (in what became known as the Clean Power Plan). The former was viewed by environmentalists as a bit of a lame duck policy, since you could argue that in 2014, it seems silly to be building ANY new coal-fired power plants. But to regulate the 600+ existing facilities in the country - this could have wide-reaching implications for not only emissions themselves, but also how we as a nation view and value the carbon cost of our energy generation.
The Trump Administration rolled back the Clean Power Plan and implemented the Affordable Clean Energy Plan, which significantly neutered the original legislation. This afforded states more authority to choose to regulate (or not regulate) the emissions from their power plants, citing executive overreach of the Clean Power Plan's structure. As we know, the main federal climate policy since then is the Inflation Reduction Act, though the Infrastructure Investment Act also addresses emissions.
But what did the rollback really mean for overall emissions reductions?
It depends on where you are.
This NY Times summary provides an excellent overview (and these great maps!) of what the rollback (and eventual repeal) would really mean. Remember, a lot of actions were already set into motion before the Trump Administration rolled back the requirements. So for some states, moving forward regardless of the current political winds just makes good economic sense based on recent investments.
You can learn more about the Greenhouse Gas Tailoring Rule that lays out the specifics for regulation under the Clean Air Act, as well as a brief history timeline of this action. EPA went on to structure the proposed rules to afford states the flexibility to meet their emission standards through the employment of a cap and trade system or carbon tax. And while these efforts would have certainly been smaller in reach than an economy-wide system, because these stationary sources are such a big part of the emissions profile, the potential GHG reductions are profound.
The Center for Climate and Energy Solutions offers this list (required) of ways in which Congress can work to achieve GHG emissions reductions without necessarily explicitly crafting climate policy.
This C-SPAN video is from the Senate Environment and Public Works Committee hearing at the time of the Supreme Court Endangerment finding in 2007. That finding opened the door for EPA to regulate carbon dioxide under the Clean Air Act, resulting in the Clean Power Plan proposed rules mentioned above. It's two hours long and quite old now, but it might be something you're interested to have playing in the background while you work on something else - this is footage of our lawmakers in action. Senator James Inhofe (R-Oklahoma), might be one of the most vocal climate change deniers in the entire Congress, so that keeps things interesting. And if you remember, he then chaired this committee in the Senate.