The question of how to address global climate change is one of the most confounding on the planet. Experts and world leaders plan to wrestle with the scientific, political and social issues surrounding the topic at an upcoming conference in the Danish city of Copenhagen next week. Here's what you need to know.
What is the meeting and what is its goal?
Officially called the United Nations Climate Change Conference, the summit is being held in Copenhagen, Denmark, from Dec. 7 to Dec. 18.
It's also known as the 15th Conference of the Parties (COP 15) to the United Nations Framework Convention on Climate Change (UNFCCC) and the 5th Meeting of the Parties (COP/MOP 5) to the Kyoto Protocol. To break that down, this is the 15th meeting of the participants who attended the UNFCCC, a convention called the Earth Summit held in Rio de Janeiro in 1992. A treaty, also referred to as the UNFCCC, was created at that conference.
It's also the 5th meeting of the participants who met in 1997 to update that treaty, which produced an agreement to reduce greenhouse gas emissions called the Kyoto Protocol.
The stated goal of the Copenhagen meeting is to come up with a successor to the Kyoto Protocol, which effectively expires in 2012.
What's the Kyoto Protocol?
The Kyoto Protocol is an international treaty aimed at curtailing emissions of four key greenhouse gases — carbon dioxide, methane, nitrous oxide, sulphur hexafluoride — and two groups of gases — hydrofluorocarbons and perfluorocarbons.
Man-made emissions of these heat-trapping gases are blamed for the average rise in the temperature of Earth's atmosphere over the last few decades, as well as the associated consequences, such as ice melt and sea level rise.
The stated target for reduction of greenhouse gases under the Kyoto Protocol was an average of 5.2 percent below 1990 levels by 2012 for 37 industrialized countries, including the United States. The methods countries use to reduce emissions were left open to several options and are at the discretion of each country, though the treaty allowed for development of a cap-and-trade emissions system.
What's happened since Kyoto?
As of this year, 186 countries had ratified the Protocol. The European Union ratified the treaty in 2002, Russia in 2004 and Australia in 2007. The most notable country missing from this list is the United States.
Russia's ratification effectively brought the treaty into force, because it was written so it wouldn't take effect until countries accounting for at least 55 percent of 1990 greenhouse gas emissions had approved it. That means that no countries who originally signed the treaty were actually required to abide by it until it had gained that critical mass of supporters. Currently about 64 percent of 1990 emissions are accounted for by ratifying countries.
And plenty of other climate negotiations have been going on, both within individual countries and between the nations of the world. Some countries have set their own emissions reductions targets, some of which are higher than required by the Kyoto Protocol.
The Copenhagen meeting is effectively the deadline to come up with a new set of binding requirements after 2012. Nations have begun hashing out an agreement since a meeting in Bali in 2007, with follow-up meetings in Poznan, Poland, in 2008 and Bonn, Germany, earlier this year.
What will be discussed?
One major item on the agenda will be agreeing on a new emissions reduction target and deadline. Climate scientists have said that the emissions cuts will have to be much more aggressive (between 25 and 40 percent of 1990 values) than those in the Kyoto agreement, because greenhouse gas levels have risen so rapidly in recent years.
Countries also plan to discuss how to make cleaner technologies more available to developing countries, as well as how to factor the effects of deforestation into the climate equation and reduce the trend of dwindling forest reserves in some areas.
One big question is whether the meeting in Copenhagen will actually "seal the deal" on a new agreement. While that was the original intention of the meeting, negotiations between countries aren't as far along as anticipated and there is far from a consensus on how to meet the conference's objectives. Both President Obama and Secretary of State Clinton have referred to Copenhagen as a stepping stone in the path to a new agreement.
How do developing nations fit in?
This is a key part of the new negotiations since China and India, two developing countries, are rapidly increasing their pollution levels. China and India have both ratified the UNFCCC and the Kyoto Protocol.
In addition to making clean technologies more available to developing countries, a key aim of the meeting is to balance emissions reduction requirements between industrialized and up-and-coming countries.
Negotiators have to consider that while countries like China produce a significant amount of greenhouse gases now, their per-capita emissions are still very low. Developing countries also point out that industrialized countries are largely responsible for the emissions that have caused global warming up to now.
How is an agreement enforced?
An enforcement branch is supposed to monitor the compliance of countries that have ratified the agreement, and each nation submits an annual greenhouse gas inventory to the United Nations.
The emissions of most countries have increased since 1990, with just a few exceptions, such as Denmark, Germany, the United Kingdom, Russia and several former Eastern Bloc nations, which have already begun to cut their carbon dioxide output.
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Andrea Thompson is an associate editor at Scientific American, where she covers sustainability, energy and the environment. Prior to that, she was a senior writer covering climate science at Climate Central and a reporter and editor at Live Science, where she primarily covered Earth science and the environment. She holds a graduate degree in science health and environmental reporting from New York University, as well as a bachelor of science and and masters of science in atmospheric chemistry from the Georgia Institute of Technology.