Johannesburg: Rio 10 years later

World leaders at the Johannesburg summit will check on progress made since Rio

(CNN) -- Facing rising temperatures, melting ice caps and swelling sea levels, world leaders at the first Earth Summit 10 years ago in Rio de Janeiro, Brazil, joined in a united response to global warming.

They signed the U.N. Framework Convention on Climate Change, an agreement to limit emissions of greenhouse gases -- many of them contained in automobile exhaust and industrial pollutants -- that are widely blamed for climate change.

Yet in the last decade, global emissions of greenhouse gases have continued to increase, and many environmentalists said they regard the attempts at change as a failure.

In the last 10 years, greenhouse emissions increased at an average rate of 1.3% per year in the United States. But, with the recent robust economy driving an increase in demand for electricity and fuel, combined with cooler winters, the levels of use have risen at an even greater rate in the last few years.

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"It has been a failure because the big industrial polluters, led by the United States, have failed to clean up our act," said Dan Becker, director of the Sierra Club's global warming and energy program.

Critics also argue the agreement set unrealistic goals for industry without providing adequate guidance on how to achieve them.

"It set a goal to prevent dangerous human intervention with the climate system, but no one could define what that was," said William O'Keefe, former chairman of the industry-supported Global Climate Coalition. "So you have an objective to achieve something that no one could define."

The 1990 agreement called for voluntary efforts to reduce emissions. However, it wasn't legally binding, and there were no measures for enforcement. Critics described it as an ineffective method of control.

But it did provide a framework for limits on emissions. Leading to a follow-up conference on global warming in Kyoto, Japan, in 1997. That conference resulted in the creation of a treaty called the Kyoto Protocol, requiring all industrial countries to cut their emissions to levels below those of 1990 in the next 10 years.

To date, nearly all-major industrial nations have ratified the protocol, including the European Union and Japan. The United States signed the treaty but recently withdrew.

The Bush administration rejected the Kyoto Protocol last year, describing it as "fatally flawed in fundamental ways" saying it would harm the U.S. economy without guaranteeing that it would have an effect on climate change.

The administration argues that the treaty would place undue restrictions on the US economy by restricting emissions of industrialized countries without placing similar restrictions on large developing countries like China.

O'Keefe said of the requirements placed on the US, "To meet our obligations, we would have to reduce energy use in this country by 30 percent. That's the equivalent of shutting down all manufacturing or taking all cars off the road."

Supporters of the Kyoto agreement say that since the United States is the world's largest producer of greenhouse gases, its decision not to be part of the treaty will effectively ruin any chance of global enforcement.

"If the United States had taken a leading role in trying to make this a meaningful agreement ... then I think the whole world would have turned around," Sierra Club's Becker said. "Unfortunately, it has been a big disappointment and creates a real threat for our children's future."

Scientists continue to disagree about the link between greenhouse gas emissions and climate change. But there is general agreement that the Earth's temperatures are rising and that human activity has pumped enough greenhouse gases into the atmosphere to exceed levels higher than any in the last half million years.

If a few more countries ratify, the Kyoto Protocol will go into effect by the end of 2002. But with world leaders heading to a new Earth Summit in late August in South Africa, the absence of the United States in the climate talks may severely handicap the measure.