writes with this story about the possible elimination of tariffs on environmental goods between the world's largest economic powers. The United States, the European Union, China and 11 other governments began trade negotiations this week to eliminate tariffs on solar panels, wind turbines, water-treatment equipment and other environmental goods. If they are able to reach an agreement, it could reduce the cost of equipment needed to address climate change and help increase American exports. Global trade in environmental goods is estimated at $1 trillion a year and has been growing fast. (The United States exported about $106 billion worth of such goods last year.) But some countries have imposed import duties as high as 35 percent on such goods. That raises the already high cost of some of this equipment to utilities, manufacturers and, ultimately, consumers. Taken together, the countries represented in these talks (the 28 members of the E.U. negotiate jointly, while China and Hong Kong are represented by separate delegations) account for about 86 percent of trade in these products, which makes the potential benefit from an agreement substantial. Other big countries that are not taking part in these talks, like India, South Africa and Brazil, could choose to join later.