The National Conference of State Legislatures has released a study that examined the economic effect of climate change on Georgia industries, from timber to tourism. Carbon dioxide and other "greenhouse gases" help trap heated air within the earth's atmosphere and are thought to be slowly warming global temperatures, potentially causing more extreme weather and rising sea levels. The Intergovernmental Panel on Climate Change, made up of 2,000 scientists recognized as experts in their fields, agreed last year that global warming is a problem partly caused by people. Humans add carbon dioxide to the atmosphere from cars, power plants and industries such as paper and oil. The recent study of effects on Georgia, co-produced by the University of Maryland and released last week, was based on changes that could be expected if the state's average winter temperature increased 4.5 degrees and the summer temperature increased 5.4 degrees, as predicted by the Intergovernmental Panel on Climate Change. Among key findings: Sea level rise and intense hurricanes would leave Georgia's coast very vulnerable, with potential harm to the tourism and real estate industries as well as the transportation system. On the flip side, increased carbon dioxide in the atmosphere could promote growth of trees for the forest products and paper manufacturing industries, creating an estimated 6,531 new jobs and contributing nearly $350 million to the economy by 2040. Global warming likely would reduce farm yields and farm income, the report indicated, but not enough information is available to assess the impact on particular crops. After reviewing the study, Marilyn Brown, a professor with Georgia Tech's School of Public Policy, said it's the first one she's seen that pinpoints impacts at the state level. "Really creditable sources have been used. It's very good," she said. "State governments can get motivated by this information." The study, one of eight that examined global warming's potential effect on specific states, was partly funded by the Environmental Defense Fund. Glen Andersen, program principal for the National Conference of State Legislatures, said the states were chosen to represent a variety of regions and types of industry. The National Conference of State Legislatures is a sort of advocacy, resource and professional group for state representatives and senators. Andersen said the state climate change reports were created to help state policymakers make more informed decisions about climate change policy and to enable them to balance the immediate costs of reducing greenhouse gases with the long-term costs of climate change. All but 12 states have climate action plans. Six of them have enacted mandatory greenhouse reduction laws, and 13 others set voluntary targets. An additional 26 states passed renewable energy portfolio standards. Georgia has taken none of these steps, although this year the state Legislature created a tax incentive to encourage renewable and energy-efficient building. During the past year, committees in the state Senate and House have held a few hearings on the question of whether global warming exists and whether it's caused by people.