Singapore, a Southeast Asian city-state with high per-capita emissions, will head to global climate talks next week with a pledge to cut carbon pollution by 16 percent versus projected business-as-usual levels by 2020.

The announcement is the latest in a series of pledges to lower carbon emissions made in the run-up to the United Nations Dec 7-18 Copenhagen talks on a broader global climate deal.

Top emitters China, the United States and India have all announced preliminary reduction targets in recent weeks, while New Zealand has passed the world's second formal emissions trading scheme and politicians in Australia have become embroiled in a struggle over a similar scheme.

Here is a timeline showing how countries' pledges and carbon reduction schemes stand ahead of the Copenhagen conference.

* Jan 2005 - The European Union begins what is still the world's largest multi-country, multi-sector greenhouse gas emission trading system (EU ETS).

The scheme fails to have much impact on emissions in its first trading phase from 2005-07 after the EU hands out too many emissions permits, causing a carbon price crash.

* Feb 16, 2005 - Kyoto Protocol comes into force, introducing mandatory targets for 37 developed nations, excluding the United States. The present round of Kyoto expires in 2012 and the world has committed to sign a new pact in Copenhagen in December.

* Dec 2005 - Seven U.S. states agree to implement the Regional Greenhouse Gas Initiative (RGGI), the first mandatory, market-based CO2 emissions reduction program in the United States. In 2007, Massachusetts, Rhode Island and Maryland join Connecticut, Delaware, Maine, New Hampshire, New Jersey, New York, and Vermont, taking the total to 10 states in the eastern United States. * Jan-Feb 2007 - California legislature passes California Global Warming Solutions Act. The governors of Arizona, California, New Mexico, Oregon and Washington agree to develop a regional target for reducing greenhouse gas emissions.

-- The scheme, the Western Climate Initiative (WCI), expands to include other U.S. states and later Canadian provinces in a regional greenhouse gas emissions trading system.

* Jan 23, 2008 - The EU commits to reducing its overall emissions to at least 20 percent below 1990 levels by 2020.

* Oct 2008 - Japan launches a voluntary carbon market, which allows companies exceeding voluntary targets to buy carbon allowances. It approves its first domestic carbon credits in June 2009.

* March 16, 2009 - The Maldives says it will shift entirely to renewable energy and become the first carbon-neutral country, to fight the climate change that threatens the low-lying archipelago's existence.

* Nov 11 - A group of developing countries pledge to green their economies, but stop short of committing to carbon neutrality at a summit hosted by the Maldives.

* Nov 25 - New Zealand passes a revised emissions trading plan, the second to pass into law after Europe's began in 2005.

On the same day, the White House says the United States will pledge in Copenhagen to cut greenhouse gas emissions roughly by 17 percent below 2005 levels by 2020, a drop of about 3 percent below the 1990 benchmark year used in U.N. treaties.

* Nov 26 - China pledges to reduce its carbon intensity -- the amount of carbon dioxide emitted for each unit of GDP -- by 40 to 45 percent by 2020, compared with 2005 levels. It says the target is voluntary and domestic, rather than an international commitment.

* Nov 30 - A draft text written by Copenhagen host Denmark says the world should agree to halve greenhouse gas emissions by 2050 from 1990 levels as part of a U.N. climate pact.

The text, which Denmark says is not a formal proposal, says rich countries should account for 80 percent of global emission cuts by 2050.

* Dec 2 - Australia's parliament rejects laws to set up a sweeping carbon emissions trade scheme.

On the same day India reveals a target to cut its carbon intensity by 24 percent by 2020 compared with 2005 levels.

* Dec 3 - Singapore says it will head to Copenhagen with a pledge to cut carbon pollution by 16 percent versus projected business-as-usual levels by 2020.

(Compiled by Gillian Murdoch, Editing by Sugita Katyal)

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