Merkel said that climate change had been unambiguously proved by science to be happening and Germany must act on emissions.
"Obviously Germany will make its contribution to achieving the targets," she said, adding that the basic target was to cut CO2 emissions by 20 percent by 2020.
Only if other nations joined in would Germany expand the cut to 30 or 40 percent. Merkel said she could not promise that before negotiations were finished.
Incentives to save energy
The chancellor also told reporters that Economics Minister Michael Glos and Environment Minister Sigmar Gabriel, who attended the meetings, would jointly work on a concept for a new energy and climate change policy to reach Germany's target to cut CO2 emissions.
Gabriel said that the government's proposals would be finalized by the fall and decided on before the UN climate conference in December.
He added that incentives to improve insulation and heating systems in buildings were under consideration. Germans would also be encouraged to use waste heat from power stations and buy power-saving home appliances, he said.
Industry representatives, meanwhile, expressed their concerns about the government's plans, saying that the goal to lower CO2 emissions by 40 percent was unrealistic.
Merkel said she expected annual climate-change talks with industry from 2010 onwards would review if the targets were feasible.
She also criticized energy providers for rising prices at the earliest opportunity after price caps expired on July 1.
The energy "summit" in Berlin was the third and last of a series of meetings on how energy-poor Germany can keep the wheels of industry turning and electrical appliances running while reducing emissions.
The electricity industry in Germany mainly burns fossil fuels to generate power. Some companies are experimenting with sinking carbon dioxide in deep rock instead of sending it up the chimney.
Rethinking nuclear power
The talks also reignited Germany's old debate about nuclear power. Under legislation, all the country's 17 nuclear power stations are to be scrapped by 2021, but some center-right figures favor keeping them operating longer.
Economics Minister Glos, a member of the Christian Social Union, the sister party of Merkel's Christian Democratic Union, favors keeping nuclear power longer so as to hold down CO2 emissions.
Glos said Tuesday that debate about this would continue until the next election in 2009. Gabriel, a Social Democrat, flatly rejected any change in policy.