Honda Motor of Japan has launched the world’s first hydrogen-powered fuel-cell vehicle intended for mass production.

Although it will make just 200 of its FCX Clarity vehicles over the next three years, Honda plans eventually to increase production, especially as hydrogen filling stations become more common.

And even the small initial run represents progress toward a clean-burning technology many have rejected as too exotic and too expensive to gain wide acceptance.

Two new Exchange Traded Funds, filed within days of each other with the U.S. Securities and Exchange Commission, will focus on companies that provide products and services to the wind-energy industry, such as turbine makers and utilities with wind farms.

Wind energy reduces carbon dioxide emissions and cuts natural gas and water use. Of particular interest to investors, wind power is unaffected by price swings in natural gas, coal and uranium — all of which soared this year.

The new filings reflect the deepening role of wind in the battle against climate change.

The most interesting aspect of the 1,700 prominent signatories urging U.S. politicians to make immediate, deep reductions in greenhouse-gas emissions is that so many of them are economists.

Predictably, the statement by the Union of Concerned Scientists, issued on the eve of U.S. Senate debate on the Lieberman-Warner climate bill, affirms the long-standing scientific evidence for global warming.

But what was unusual, and surprising, was the prominent role of economists as measured by the statement that acting quickly to cut emissions “would be the most cost-effective way to limit climate change.”

After virtually abandoning the issue for three decades, the environmental movement got a bold reality check this week from a new book highlighting relentless human population growth as a driving force behind global warming.

This wouldn’t have raised eyebrows in the 1970s, when the modern environmental movement had its genesis and Paul Erlich’s “The Population Bomb” was on just about everybody’s bookshelf.

Since then, however, overpopulation has dropped from the vocabulary of most environmentalists despite a near doubling of the world’s numbers to an estimated 6.8 billion people today.

In sharp contrast to denier’s claims that action against global warming will trigger economic catastrophe, a new study has concluded it would actually be cheaper to cut greenhouse-gas emissions than to suffer the consequences of a changing world.

In fact, the report by economists at Tufts University warns, “The longer we wait, the more painful and expensive the consequences will be.”

A Canadian scientist says university research should be added to the list of human activities that contribute to global warming.

Professor Hervé Philippe of University of Montreal has found that his own research produces 44 tons of carbon dioxide a year.

The average American citizen, in contrast, produces 20 tons of carbon dioxide annually.