I see this idea thrown around a lot, the idea that somehow we're killing the planet. It's rather egotistical and misses the entire point of climate change and all it's doing is making us more ill-prepared. The Earth will be fine, but we will not.
The Actual Truth
Earth has had mass extinctions on much larger scales and in shorter periods of time. The climate is always changing and goes into a constant ebb and flow of heating and cooling. We're just at the tail-end of the cooling stage and starting the heating.
All the species on Earth that are going extinct from climate change (not pollution) were 100% going to go extinct. The more specialized a species is, the more susceptible it is to changes in the environment, and in their stead you'll see the expansion of other species. Right now it's highly expected we'll see Jellyfish go crazy in the next 100 years.
What man did was just put the pedal to metal on how fast we get to that end-point. Instead of taking 5,000 years; humans made it happen in just 200. The planet won't die, the ecosystems won't all collapse, and the general mass of life will remain largely the same, it's just the diversity of life that's going to get pounded.
So this raises the question of "Well what do we do?" because instead of worrying about reversing what is the inevitable, we've not prepared ourselves for a future of food shortages, water shortages, and mass human migration as coastlines give-way to become more ocean.
How to Advert Crisis
Investments in things such as solar and wind energy are a start, but they alone are not what's going to stop the impending mass human casualties looming ahead. We need to invest both time and resources into GMOs that can grow larger amounts of food, using less water. We need to construct wells in poor villages. We need to start investing in cheap housing for the massive amounts of immigration and migration when coastal areas become nothing but the next generation's Atlantis.
GMOs have been a huge staple in our farming practices since pretty much the very beginning. It's how we went from a mustard plant to a cabbage, but there's going to be a massive demand for seed which is able to reproduce, is pest resistant, produces bountiful foods, and at a fraction of the water usage. We had a major breakthrough in the 20th century thanks to Norman Borlaug who dedicated his life to making a better wheat for humans and giving it out for free to the poorest of the world. We will need these breakthroughs again, and we can't put trust in Monsanto to make that happen, that's for damn sure. Here's a charity where you can donate: Danforth Plant Science Center
Here's their Charity Navigator page
Water will become a very serious issue, especially with the salination of aquifers. Warmer oceans don't just bring with them higher waters, but also warmer air. Warm air tends to create large amounts of wind when it moves to cooler, lower-pressure zones, but this also brings erosion with it. A lot of inland areas that are adjacent to colder areas will desertify, leading to less rain-fall, and eventually dried lakebeds and less flowing fresh water. Constructing wells now, and investing in better technology will help ensure the poorest of the earth can still have the means to their own water, without having to rely on a government to provide it for them. This helps keep strain off foreign gov'ts providing aid, and it helps prevent corruption in the areas most struck. Here's a charity where you can donate: The Water Project Inc
Here's their Charity Navigator page
The last major thing to consider is not what America can do to reduce our foot-print, but on how we can use our influence to exert pressure onto other countries to seek more green solutions. Vote for people who you believe have your best interests in mind, and tell them you want China to shut down their coal plants, and express interest in only trading with countries that take steps to reduce their pollution. Is it the most ridiculous long-shot possible? Absolutely, but what else can one person really do? Link on how to find your congress person.