CHINA
The No. 1 carbon polluter is pledging a big energy efficiency drive but has so far resisted setting an overall cap on its fast-rising emissions. It promises to reduce emissions per unit of GDP by 40-45 percent from 2005 levels by 2020. This would bring the total to 14.3 GtCO2e -- pushed beyond levels of about 12 GtCO2e in 2010 by rapid economic growth.

UNITED STATES
The world's No 2 emitter in 2009 pledged to reduce its greenhouse gases by 17 percent to 6.2 GtCO2e by 2020 compared with 2005 levels. The US is unlikely to reach this "inadequate" target on current policies, according to CAT, even considering a new initiative to cut carbon emissions from power plants by 30 percent by 2030 from 2005 levels.

EUROPEAN UNION (EU)
The 28-member bloc aims to reduce average annual emissions from 2013-2020 by 20 percent from 1990 levels -- a pledge it has already all but achieved. This would mean emissions in 2020 of about 4.6 GtCO2e. EU emissions have been on a downward trend since 1990, with a brief spike after the 2010 economic recovery.

INDIA
Fast-growing India, where emissions have been rising steadily since 1990, has pledged to reduce the greenhouse gas intensity of its economy by 20 to 25 percent by 2020 from 2005 levels -- to about 3.5 to 4.0 GtCO2e. The target's ambition is rated "medium," and remains within reach.

BRAZIL
One of the first developing giants to set a greenhouse gas target, Brazil aims to reduce emissions by 36.1 to 38.9 percent in 2020 from what they would have been under a "business-as-usual" scenario (in which no steps are taken to turn the tide). This would come to about 2.0 GtCO2e. Brazil is one of few nations likely to meet its target, according to CAT.

INDONESIA
Indonesia has pledged to reduce emissions by 26 percent from projected business-as-usual levels by 2020 -- or as much as 41 percent with international support -- much of it from halting forest loss. But Indonesia is likely to decrease 2020 emissions only by about 11 percent, to some 2.5 GtCO2e.

RUSSIA
Moscow aims to reduce emissions by 15-25 percent by 2020 from 1990 levels -- a target rated "inadequate" for being "substantially higher" than business-as-usual projections. Estimated 2012 emissions were 1.75 GtCO2e, projected to reach 2.5 GtCO2e in 2020.

AUSTRALIA
Australia has pledged to reduce emissions by five percent by 2020 from 2000 levels, but has since scrapped a key tool, the world's biggest carbon tax.  The pledged 2020 emissions level of 569 MtCO2e now looks more likely to be about 595 MtCO2e, says CAT. Emissions in 2010 were 558 MtCO2e.