As countries around the world mark World Environment Day Friday, members of the U.S. Congress are preparing to debate new legislation aimed to slow global warming. This report examines how  actions in the United States may influence the international debate on combating climate change.

Blocks from the U.S. Capitol building, John Mulqueen navigates a bicycle rickshaw through the traffic on a rainy Washington street.

Mulqueen is one of many drivers in a growing fleet of bicycle taxis that carry tourists, and sometimes business people, around the capital. He says his customers enjoy the open-air ride, and feel good they are not polluting.  "There are definitely people you get who are doing it because they don't want to take a car, or they want to take it because it's eco-friendly," Mulqueen observed.

Eco-conscious tourists are not the only ones worried about the environment. U.S. President Barack Obama has made combating climate change a top priority. He laid out his goals in an address to Congress earlier this year.

"I ask this Congress to send me legislation that places a market-based cap on carbon pollution and drives the production of more renewable energy in America. That's what we need," announced President Obama.

The U.S. House of Representatives' Energy and Commerce Committee approved a bill last month that works towards Mr. Obama's goals.

Manik "Nikki" Roy of the Pew Center on Global Climate Change says it is the first time Congress has seriously considered legislation to reduce the gases that scientists say trap heat in the atmosphere and cause the Earth's temperature to rise.

Roy continued, "the most significant part of the legislation is the requirement that all oil companies, electric utilities, large manufacturers have to submit an allowance for each ton of greenhouse gas emissions that they release in a given year. The U.S. is one of the world's biggest polluters.  The legislation would try to curb that by requiring industries to cut emissions of carbon dioxide and other greenhouse gases by 17 percent from the 2005 levels by 2020.

The full House of Representatives and the Senate must still consider the bill. House members from the ruling Democratic Party have put it on a fast-track for debate this month or next.

Rafe Pomerance, the president of the U.S. environmental group Clean Air-Cool Planet, says the bill is critical to protecting the Earth.  Pomerance explained,  "this is a global problem, but the world will have a very difficult time moving forward in a meaningful way without strong U.S. participation. And for the United States to participate, we absolutely need domestic emission control legislation that is meaningful."

Pomerance was a member of the U.S. negotiating team for the Kyoto treaty on global warming in the 1990s. He says the environmental measures the U.S. takes now will influence the international debate on what should replace the Kyoto Protocol when it expires in 2012.

"Any treaty that's negotiated will have to accommodate what the United States does as a domestic manner. If it doesn't, we won't sign it," he stated.

Delegates from 182 nations are holding talks on the treaty in Bonn, Germany this week and next. They only have six more months to reach an agreement before they must present their final text at a United Nations climate change conference in Copenhagen in December.

Pomerance says the U.S. has not yet shown the political will to lead international efforts to stop global warming. He says this has to change, "because the climate system itself, particularly at high latitudes in the Arctic, for example, is coming apart, to put it mildly. I mean, we're losing the Arctic sea ice. Greenland is shrinking."

The proposed U.S. climate law and U.N. treaty face fierce debate on how to balance environmental protection with economic  growth. Until official measures are taken to further cut emissions, eco-conscious citizens remain a first defense to protect the planet.