The debate about global warming -- or as it's better known now, climate change -- has consumed everything from political theater, to corporate board rooms, to the dinner table around America. There's no debate -- in the scientific community at least -- about whether there's climate change going on, but there's a spirited debate about what's caused it, the extent to which humans are the problem, and what to do about it now.

No matter what your belief is on what is causing climate change or who is responsible there's really only one thing within our control that will fix it. The good news is that the solution is becoming more of a reality every day from the automobiles on the streets of the U.S. to the power plants in China. And as investors we can profit from the companies making a positive impact on the environment.

There's one big driver of a solar boom in California. It's cheaper than electricity from the grid. Image source: SolarCity.

The only way we'll ever impact climate change
Let's face it, people around the world love to drive and we're addicted to energy consuming devices like air conditioners, TVs, and smartphones. We're not going to change the world by telling people to use less energy. Even using energy more efficiently is proving to be a tough sell for most people (see the incandescent light bulb debate). It's also disingenuous to put the environmental onus on the developing world where electricity is scarce to begin with and the middle class is just starting to enjoy the benefits of modern technology.

But what we can do from the developed world to the developing world is get the energy we consume from cleaner sources. I'm not talking about "clean coal" or natural gas; I'm talking about wind and solar energy, which produce no carbon dioxide. They're truly renewable energy sources so you might be asking: Why aren't we building wind and solar plants as fast as we can if they're the solution?

Why wind and solar has been held back in the past
Wind and solar electricity generators have been around for decades but they still only produce a fraction of the energy the world consumes every year. The reason is that they've been too expensive to compete with coal or natural gas. You may want cleaner energy but when faced with the option of dirty energy or clean energy for double the price you may reconsider just how important clean energy is to you.

The good news is that wind and solar have both experienced massive cost reductions in the past decade and they're not only competitive with fossil fuels today, in many locations they're actually the cheapest energy option.

In a recent article I highlighted a study by the investment bank Lazard that showed how solar energy is now cheaper than building a new coal plant and competitive with a new natural gas plant in the U.S . Wind energy is actually cheaper than natural gas and coal in most scenarios.

Data source: Lazard. Chart by the author.

This is key because the cost trajectory for wind and solar is declining rapidly while fossil fuel energy production costs are flat at best.

As utilities around the country begin contemplating replacing aging coal plants with new electricity generation it's now renewable energy that's the lowest cost option. Even consumers can get in on the action by installing solar panels on their homes.

But this is also key for developing countries, who have growing energy needs around the world. As they're building out new capacity they're finding that it's lower cost and lower risk to build wind and solar farms rather than building a new coal or natural gas plant. Countries like China, India, South Africa, and Chile are experiencing some of the fastest renewable energy growth in the world.

It's this cost shift that will have an impact on climate change more than any policy or environmental debate. If renewable energy isn't cost effective it's not going to be installed, that's just a fact of life in energy right now.

First Solar has built some of the biggest solar plants in the world, like this one in Canada. Image source: First Solar.

How you can make money off companies impacting climate change
If renewable energy is now cost competitive and having a positive impact on CO2 emissions, there has to be a way to make money of it. And there is.

Wind suppliers are generally large conglomerates where wind is just a small percentage of their portfolio. Companies like General Electric and Siemens dominate this market along with a few manufacturers in China. That makes wind a tough investment today, but solar is another story. 

First Solar (NASDAQ:FSLR), SunPower (NASDAQ:SPWR), and SunEdison (OTC:SUNEQ) are three of the largest solar power plant builders in the world. Just this week SunEdison announced that it had won a bid to build 5 gigawatts of solar plants in India -- enough to power 820,000 U.S. households -- as part of a 25 gigawatt expansion of solar in the country. 

First Solar and SunPower are both solar panel makers who have huge pipelines of utility scale solar projects. They're the two profitable companies in this group and if you're just getting your start in solar they're two companies to keep an eye on. 

The last one I'll mention is SolarCity (NASDAQ:SCTY.DL), which has taken the residential solar industry by storm and is now building its first solar panel manufacturing facility. Elon Musk, the company's chairman, thinks that before long SolarCity will be building 10 gigawatts or more in panel manufacturing to keep up with demand. 

The economics of wind and solar will drive the future climate change debate
There won't be significant progress made in fighting man-made climate change without transitioning from fossil fuels to clean sources of energy. But that transition will never happen if renewable energy isn't economically viable. 

The good news is that today it is economically viable to build wind and solar power plants instead of natural gas or coal plants. Momentum is just beginning to build in wind and solar and before long it will be a paradigm shift in energy that few people saw coming. It's time to get in now and enjoy the ride.