A delegate rests his head after a 24-hour period of plenary sessions Saturday at the U.N. Climate Summit in Copenhagen. U.N. Secretary-General Ban Ki-moon said “we have a deal” after a climate conference in Copenhagen decided to recognize a political accord brokered by President Barack Obama with China and other emerging powers. Despite round-the-clock efforts, the deal is being called “not enough” by environmental activists and poorer nations.

Copenhagen ? Around the world, countries and capitalism are already working to curb global warming on their own, with or without a global treaty.

In Brazil more rainforests are being saved, and in Chicago there’s a voluntary carbon pollution trading system. People recycle, buy smaller and newer cars, and change lightbulbs.

But the impact of such piecemeal, voluntary efforts is small. Experts say it will never be enough without the kind of strong global agreement that eluded negotiators at the U.N. summit this past week in Copenhagen.

Emissions of greenhouse gases keep rising and so do global temperatures.

Dozens of countries — including the top two carbon polluters, China and the United States — came to the climate talks with proposals to ratchet down pollution levels.

But analysis by the United Nations and outside management systems experts show that those voluntary reductions will not keep temperatures from increasing by more than 2.3 degrees Fahrenheit compared with now. That’s the level that scientists, the United Nations, the European Union and the Obama administration have said the world cannot afford.

Good intentions aren’t enough. The deal forged by President Barack Obama with China and several other countries sets up the first major program of climate aid to poorer nations to help them deal with climate change. But it offers few specifics and goes no farther than emissions curbs already pledged. More negotiations are planned for next year.

“It just underlines the heroic effort here that the science says needs to be done; it’s not easy,” said Alden Meyer, policy director at the Union of Concerned Scientists. “If it were easy, it would have been done. This is a daunting effort.”

And no one knew that more than a weary Obama, who 14 hours after arriving in Copenhagen, unveiled the political agreement by saying “more aggressive” emission cuts were needed and so were still-unseen scientific breakthroughs.

“But this is going to be hard,” Obama said in a news conference late Friday. “This is hard within countries; it’s going to be even harder between countries.”

“Hard stuff … requires going ahead and making the best of the situation that you’re in at this point, and then continually trying to improve and make progress from there,” Obama added.

‘Not enough’

Upon announcement of the deal, a team of experts led by an MIT professor made quick calculations: The average global temperature is likely to rise 5.7 degrees F. above current temperatures.

So the response from many, but not all, environmental activists and poorer nations was “not enough.”

That’s not for lack of trying.

The U.S. private sector has invested hundreds of billions of dollars to cut emissions, and that is probably just the beginning no matter what happened in Copenhagen.

Between 2007 and 2008, energy-related carbon dioxide emissions in the U.S. fell 2.8 percent, though part of that was related to the recession.

A study this year by McGraw Hill Construction said between $36 billion and $49 billion of eco-friendly buildings are under development. That figure is expected to triple by 2013.

The owners of New York’s Empire State building spent $13.2 million on environmental retrofits to draw new tenants.

Wal-Mart Stores Inc. retrofitted about 500 buildings this year. Part of the project included installing skylights with the goal of cutting up to 75 percent of the energy used to light stores.

In Chicago, a company started a voluntary commodities market to trade credits for reducing carbon pollution. It has reduced carbon dioxide pollution by the equivalent of 400 million metric tons in the six years since 2003. That sounds like a lot, but the U.S. emitted 7.05 billion metric tons of carbon dioxide equivalent last year alone.

But the broad range of voluntary carbon reductions falls far short of what’s needed to address climate change, energy experts emphasize. To approach anything near the 17 percent reduction in emissions by 2020 that the Obama administration has targeted, a price must be put on carbon emissions, most energy experts acknowledge.

“If there was an easy answer, the countries could agree on it,” said Gregg Marland who keeps track of worldwide carbon dioxide emissions at the Oak Ridge National Lab. “There is no easy answer. And there is not a cheap answer. I don’t see people going very far voluntarily without incentives to do it, and that comes from government.”

In much of the developing world, the biggest carbon problem is destruction of forests. Brazil, a top 10 carbon dioxide polluter, is also one of the leading countries in losing forests, which suck carbon dioxide out of the air.

Mostly by slowing deforestation, Brazil has already pledged to reduce carbon emissions by about 36 to 39 percent by 2020. Last month, Brazil reported its biggest annual decline in deforestation in two decades.