Future Pennsylvanians may need to stow their snow skis and fly rods and break out umbrellas and farm tractors.

A new Pennsylvania State University climate change study done for the state's Climate Impact Assessment project is predicting hotter temperatures, wetter weather, significantly less snow and a longer growing season by the middle of the century.

The report, mandated by the state Climate Change Act of 2008, contains conclusions about the effects of changes likely in the state's climate, and will be used to formulate a state Climate Action Plan that must be submitted to the state Legislature by Oct. 9.

"This report presents an assessment of how climate change could potentially affect such things as human health, wildlife, recreation, agriculture, tourism and the economy in Pennsylvania for the rest of the 21st Century," said DEP Secretary John Hanger. "It is a resource intended to inform and educate decision makers on climate change impacts, which in turn will help shape mitigation strategies."

The study, by Penn State's Environment and Natural Resources Institute in the College of Agricultural Sciences, predicts that depending on how much greenhouse gas emission levels are reduced, temperatures will rise an average of 3 to 7 degrees and annual precipitation will increase, especially in winter, but most of it will fall as rain, not snow.

The changes will produce "winners and losers" across the state and complex consequences, said James Shortle, distinguished professor of agricultural and environmental economics, director of the institute and co-author of the report.

For example, the warmer temperatures will lead to a growing season that is three to five weeks longer and increase the yield of crops like corn and soybeans. But they will also lead to a decrease in the yield of cool-temperature adapted fruits and vegetables like apples and potatoes.

He said winter sports that depend on snow -- snowshoeing, snowmobiling, skiing -- will be "greatly diminished," and hotter weather will reduce the number of stream miles that can support brook trout and other wild trout populations.

The hotter climate also will cause higher smog levels in metropolitan areas and negative impacts on respiratory health. Building cooling costs will increase but home heating costs will decline. There are likely to be significant changes in the state's forests, with northern hardwood species unlikely to survive.

Precipitation patterns and storms will become more extreme, with longer dry periods between storms that will be fewer but more severe.

Actions to reduce greenhouse gas emissions, which trap heat from the sun causing climate change, will show few short-term results but have important long-term effects, Dr. Shortle said.

"Climate change over the next few decades will be driven mostly by emissions that have already occurred," Dr. Shortle said. "But changes now will have a large impact on the climate we experience in the second half of this century, and those decisions need to be made today."

Last year's state Climate Change Act established the Climate Change Advisory Committee, which is developing a climate change action plan that will include an inventory and forecast of greenhouse gas emissions in Pennsylvania and develop a series of strategies to reduce those emissions.

The report is based on the best available data on climate change, scientific literature and quantitative analyses. To view the assessment report or for additional information, visit www.depweb.state.pa.us, keyword Climate Change.