A joint working group of the state’s Climate Action Team hopes to have a health impacts study on the California Air Resources Board’s proposed carbon cap-and-trade program ready by the end of the month. The group is planning to examine how cap-and-trade may affect emissions of co-pollutants--toxics and smog-forming contaminants emitted in addition to carbon dioxide when fossil fuel is burned. However, the group appears to be zeroing in on only the impact of cap-and-trade on co-pollutants at refineries and cement plants, giving power plants a pass. Power plant emissions would only be captured in the group’s plan to look at larger communities that are home to many industries. The group includes staff members from both the Air Board and state Department of Public Health. * * * * * A recent California Solar Energy Industries Association study says solar water heaters can reduce gas use in some homes by up 50 percent and cut greenhouse gas and smog-forming emissions accordingly. If solar water heaters were installed in 1.75 million California homes, it would save 1.2 billion therms a year of natural gas, cutting annual greenhouse gas emissions by a million tons. The report comes as the state is implementing AB 1470, which provides incentives to install 200,000 residential solar hot water systems. * * * * * A University of California, Davis, ecological forecaster warns in a paper that predicting sudden shifts in natural systems is more difficult than many say. In short, shifts can occur with no warning, according to U.C. Davis theoretical ecologist Alan Hastings. Among the potential climate change shifts that could occur “precipitously,” according to Hastings, are complete disappearance of Arctic sea ice in summer, leading to drastic changes in ocean circulation and climate patterns across the northern hemisphere; acceleration of ice loss from Greenland and Antarctica, driving rates of sea-level increase to 6 feet or more per century; and ocean acidification from carbon dioxide absorption, causing massive disruption in ocean food webs. The paper is published in the February 9 online edition of the journal Ecology Letters.