BRUSSELS (AP) — The new U.S. effort to curb greenhouse gas pollution sees Washington rallying behind the European Union in the fight against global warming and might also help spur emerging economies like China to take action.

Climate change can only be tackled at a global level and chief responsibility lies with the biggest polluters: China, the U.S. and the EU. In 2012 China accounted for 29 percent of global carbon dioxide emissions and its output keeps growing, according to the Netherlands Environmental Assessment Agency. The U.S. stood for 16 percent, the EU for 11 percent of all CO2 emission.

Governments have set a goal of signing an agreement late next year in Paris to curb emissions of greenhouse gases. Here's a look at how their current targets to reduce emissions compare:

REDUCING THE ECONOMY'S CARBON FOOTPRINT

—The U.S. has pledged to reduce its total greenhouse gas emissions by 17 percent by 2020 compared with the level in 2005. That translates to a reduction of about 4 percent compared with 1990 levels.

—The 28-nation European Union says it has already reduced its emissions by 19 percent compared with 1990. It aims to achieve a reduction of about 25 percent by 2020, and by 40 percent ten years later. Its success in curbing emissions relative to 1990, however, got a boost by the collapse of Communism in Eastern Europe that year, which led to the closure of many polluting plants.

—China has been reluctant to commit to binding targets. But Communist Party plans call for reducing carbon intensity, or emissions per unit of gross domestic product, by 40 to 45 percent from 2005 levels by 2020. While that increases China's efficiency, it would still allow total emissions to rise as the economy grows.

TACKLING POLLUTION FROM POWER PLANTS

—Obama's new plan would reduce carbon dioxide emissions from U.S. power plants by 30 percent from 2005 levels by 2030. Emissions already came down by 15 percent over the past nine years — partly because of cleaner natural gas replacing coal — so the new target would only mandate a reduction of another 15 percent by 2030.

—Carbon emissions from European power plants have already fallen by about 25 percent since 2005, according to the EU Commission, the 28-nation bloc's executive arm. Unlike the U.S., the EU has no specific target for emissions from its power plants since they are covered by its wider emissions trading system, under which polluters pay per ton of carbon dioxide they release into the atmosphere.

—China has not set specific emission reduction goals for its power plants but has taken some steps to dent its voracious appetite for coal and oil, the most polluting power sources that are also blamed for fostering pollution in cities. China is promoting the use of nuclear energy while also boosting renewable sources like hydro and wind power.