Microsoft co-founder Bill Gates has broken from philanthropic work fighting poverty and disease to take on another threat to the world's poor -- climate change.

"Energy and climate are extremely important to these people," Gates told Friday a TED Conference audience packed with influential figures including the founders of Google and climate champion Al Gore.

"The climate getting worse means many years that crops won't grow from too much rain or not enough, leading to starvation and certainly unrest."

Gates said he is backing development of "terrapower" reactors that could be fueled by nuclear waste from disposal facilities or generated by today's power plants.

He broke down variables in a carbon-dioxide-culprit formula, homing in on a conclusion that the answer to the problem is a source of energy that produces no carbon.

"The formula is a very straight forward one," Gates said. "More carbon dioxide equals temperature increase equals negative effects like collapsed ecosystems. We have to get to zero."

To dramatize his point, Gates pulled out a large jar of fireflies in playful flashback to when he unleashed mosquitoes on a TED audience a year earlier while discussing battling malaria.

"They won't bite," Gates joked of the fireflies. "As a matter of fact, they might not even leave this jar."

Gates touted terrapower as more reliable than wind or solar, cleaner than burning coal or natural gas, and safer than current nuclear plants.

"With the right materials approach it could work," Gates said. "Because you burn 99 percent of the waste, it is kind of like a candle."

Nuclear waste fed into a terrapower reactor would potentially burn for decades before being exhausted.

"Today we are always refueling the reactor so lot of controls and lots of things that can go wrong," Gates said. "That is not good. With this, you have a piece of fuel, think of it like a log, that burns for 60 years and it is done."

Researching and testing terrapower will cost hundreds of millions of dollars, with the building of a test reactor likely to cost in the billions. Once the technology is proven, market forces will drive down costs, Gates predicted.

Work on terrapower hos been done in France and Japan, and there has been interest in India, Russia, China and the United States, according to the famed philanthropist.

Gates said that if he were allowed a single wish in the coming 50 years, it would be a global "zero carbon" culture.

"If I could pick a president or a vaccine, which I love, this is the wish I would pick," he said.

"We need energy miracles. The microprocessor and Internet are miracles. This is a case where we have to drive and get the miracle in a short time-line."

Gates dismissed climate change skeptics, saying terrapower would render arguments moot because the energy produced would be cheaper than pollution-spewing methods used today.

"The skeptics will accept it because it is cheaper," Gates said. "The might wish it did put out CO2, but they will take it."

The world is at "an extraordinary moment" in the struggle to save the climate balance, according to former US vice president Gore.

A vital step will be to put a price on carbon dioxide emissions so the cost of polluting the air gets factored into the global economy.

Legislation to do that has cleared the US House of Representatives and must fight its way through the Senate, where it needs only a few more supporters to send the law on to the willing pen of President Barack Obama, Gore said.

"A price on carbon dioxide emissions can help us make the right decision, not only on nuclear, solar, and wind but on the gamut of energy alternatives available to us," Gore said.

Gore's Alliance for Climate Protection has organized groups in 22 US states with "swing senators" in the hope getting the legislation passed "before the political season gets completely wild."

"These next few months represent the last feasible political window for quite some time to get this done," Gore said. "So much is at stake we have to double down."