EDITOR’S NOTE: Greentech Media Editor Jennifer Kho first fell in love with the cleantech beat as a reporter at Red Herring, a California-based magazine that covers the business of technology. This is the last story she wrote for the publication, which ran as a cover story in August titled "Will Technology Be Enough?" We thank Red Herring for graciously allowing us to republish the story.

A United Nations committee on climate change is expected to release a report in November that paints a dire portrait of the world. The Intergovernmental Panel on Climate Change forecasts floods, heat waves, storms, fires and drought, leading to severe food and water shortages for millions of people, as well as the spread of disease.

While sustainable development can reduce the world’s vulnerability to climate change, it’s not enough to keep greenhouse gases at 2000 levels, according to a draft of the report. "Even the most stringent mitigation efforts cannot avoid further impacts of climate change in the next few decades," it says. "Unmitigated climate change would, in the long term, be likely to exceed the capacity of natural, managed and human systems to adapt." In other words we need to make drastic changes now to avoid complete disaster.

Frightening as things look, the doomsday scenario could be a boon for greentech. According to a Clean Edge report in March, the clean energy market - including revenue from the biofuels, wind,solarand fuel-cell industries - jumped 39 percent to $55 billion in 2006.

But clean-energy technologies still make up a small fraction of the trillion-dollar worldwide energy market, and an even smaller fraction in terms of percentage of megawatts produced. Can the technologies grow quickly enough to reverse climate change? Can technology save the world?

At least a few greentech insiders suggest the answer might be yes. Vinod Khosla, founder of Khosla Ventures, suggests building new electricity-generating capacity with solar-thermal plants. Lester Brown, president of the Earth Policy Institute, thinks we should focus less on ethanol and more on gasoline-electric hybrids that can be plugged into electric outlets for better performance in terms of miles per gallon (MPG). And Susan Eustis and Susie Eustis, the president and senior technical architect at WinterGreen Research, respectively, think the answer is advanced batteries that can support a secondary electrical system of solar and wind power.

All of the scenarios have exciting potential. But while the science is nearly there, the business challenges for each is daunting. They require government policy support and new business models to make them profitable.

And as many in the industry point out, these aren’t competing visions. "The answer, as far as I can tell, is, ’Yes to all of the above’," says Rob Day, a principal at the venture-capital firm @Ventures. "People may have different visions in the specifics, but these all seem to be technologies people are actually pursuing and driving down the costs to make them all viable."

And while any of the scenarios might be right, they won’t succeed on their own. Many new technologies are needed, including energy-efficiency systems to slow the growth of energy generation and related emissions, Day says. "The best way to make a kilowatt-hour is not to use it in the first place.".

Peter Fusaro, head of the Global Change Associates, agrees that energy efficiency - and many other technologies - is missing from these scenarios. Energy efficiency alone could cut energy demand 20 percent by 2020, he says. But to make a difference, the world "really needs to look at about 25 technologies."

Many new ideas are needed to save the world. Maybe these three suggestions will spark more.

Vinod Khosla thinks solar-thermal will slow global warming.
Lester Brown says that we should look to hybrids and wind.
Advanced batteries could reduce reliance on carbon.
VCs invested record amounts in cleantech last year. Will the large deals keep coming?