By reporter Marjorie Sun.

I got interested in this story after hearing Silicon Valley venture capitalist Vinod Khosla speak at a conference this fall in Sausalito. He explained how he decides where to invest in green tech and it was fascinating. He and other top venture capitalists think they can help stop global warming and make a ton of money at the same time. You can listen to Khosla's talk on a webcast and listen to all sorts of entrepreneurs and v.c.'s talk about the latest renewable energy projects.

Khosla says to achieve a huge reduction in greenhouse gas emissions fast, we have to think about solutions that make big cuts in emissions and will be widely adopted. Buying a Prius is fine, he says, but it's really just "fashion." We need solutions that people in India and China will buy, Khosla says. To him, the key issues that guide his investments are cost, scale, and adoption. If a renewable solution isn't cheaper than coal, forget it, he says. Geothermal "is nice, but it doesn't scale."

Same with wind. It's "a great technology, but it's a toy." As for hydrogen fuel, the adoption risk is too high. Again, forget it, he says. The focus should be a war on coal, oil, and the manufacturing of cement and steel, which are huge emitters of carbon dioxide. (He's a major investor in Calera, an alternative cement maker in Silicon Valley.)

One more area for potentially huge gains is to improve energy efficiency, such as lighting. Another legendary venture capital company, Kleiner Perkins, is also racing to develop renewable energy solutions and make a fortune. (Khosla is a former partner there.) Kleiner's efforts were profiled in a cover story in The New York Times Sunday Magazine recently

With the Obama administration, it will be interesting to see what new federal policies– tax, economic and regulatory– will be adopted to accelerate solutions and spur more investment during a double whammy of crises: the economic meltdown and climate change.

Listen to the Building Blocks Go Green radio report online.

The new FOCE experimental chamber being developed by MBARI scientists.

The scientists at the Monterey Bay Aquarium Research Institute (MBARI) are already well-known for uncovering some of the most extreme marine animals in the deep sea, like the incredible vampire squid. But recently, they're using their unique blend of biology and engineering to study one of the least-discussed impacts of climate change: ocean acidification.

When we hear about climate change, we tend of think of the atmosphere – and for good reason. But as MBARI scientists describe, the oceans are a key part of the process. The ocean acts like a giant sponge, absorbing carbon dioxide emissions from the air. And as we add more and more CO2 to air by burning fossil fuels, the ocean is absorbing it. On one level, it's done us a big favor. Scientists say that we would be experiencing much more extreme climate change were it not for the ocean's ability to remove the heat-trapping gas.

However, the carbon dioxide that the ocean absorbs is making the water more acidic. This isn't the first time that the oceans have become more acidic. But as is the case with many impacts of climate change, it's the rate at which acidification is happening that worries scientists the most.

As you can probably guess, the ocean is an incredibly complex system. So ocean acidification poses an interesting question to scientists: what will the impacts be on marine species and ecosystems? What they know already is that there will be winners and losers in more acidic waters. Some creatures may do fine, while others won't be able to adapt in time. Either way, food webs may feel the effects – including webs involving species that humans depend on , like salmon.

Another major concern has to do with marine animals with certain kinds of shells – known as "calcifiers." Corals, clams and others all use carbonate in the water to build their shells out of calcium carbonate. But ocean acidification reduces the amount of carbonate in the water, making it more difficult for them to make shells. That could be devastating for coral reefs, who are already facing a number of stresses.

Even if you're an animal without a shell, ocean acidification could make things difficult. Scientists are studying how much stress this could put on animals that can't regulate their internal pH, or how it could affect the larvae or reproduction of certain species. MBARI scientists are hoping that the flume they are developing to conduct FOCE experiments will help researchers answer some of these questions.

Check out the whole story – watch the "Acidic Seas" audio slide show online.