Factbox: What climate deal may be agreed in Cancun?

(Reuters) - Countries in talks at Mexico’s Cancun beach resort are split over how to toughen existing pledges to cut carbon emissions, made at last year’s Copenhagen summit which ended in a brief, non-binding agreement.

Issues that hinge on a deal on emissions include long-term climate aid for developing countries and payments to tropical nations to protect their forests.

Following are areas of possible agreement at the November 29-December 10 talks:

- Decide whether to continue the protocol, as favored by developing countries. Its first round of targets ends in 2012

- Decide on the length of commitment period of the next round of targets, for example whether to 2017 or 2020

- Decide whether to cancel surplus, tradable emissions credits owned by countries that are well below their 2008-2012 Kyoto targets. Credits are called assigned amount units (AAUs) * Emissions targets

- Decide new national targets either under the 1997 Kyoto Protocol or the 1992 U.N. climate convention, or both

- Some industrialized countries do not like Kyoto, as so far it has only controlled the emissions of developed countries. A way out may be to note new targets in an appendix to Kyoto and the convention

- Refer to a long-term goal, for example to limit warming to less than 2 degrees Celsius (3.6 degrees F)

- Mention the widely held scientific view that emissions targets pledged so far are too weak

- Review in 2013-2015 whether targets need strengthening * Measurement

- Also called measurement, reporting and verification (MRV)

- Agree to measure developed country emissions, for example annually, and also their contribution to climate aid funds

- Agree to measure developing countries greenhouse gases and their actions to slow emissions growth, perhaps every two to four years

- Agree common accounting standards, for example on measuring carbon emissions from forests * Protecting rainforests

- A political agreement to pay tropical countries not to chop down natural forests, called reduced emissions from deforestation and degradation (REDD)

- Launch a program to set rules

- Delay decision on whether to include the scheme under an existing market in carbon offsets called the clean development mechanism (CDM)

- Agree safeguards for wildlife and indigenous peoples * Green fund

- A political commitment to establish a new long-term fund to help especially the least developed countries cut carbon emissions and prepare for climate change

- The fund would dovetail with a commitment countries made in Copenhagen last year to raise $100 billion annually by 2020

- Launch a program to decide the board structure including the split between developed and developing countries * Adaptation

- Adaptation means preparing for climate change

- Link new sources of financing, including the proposed new green fund, as well as “fast-start” funding of $30 billion from 2010-2012 agreed last year in Copenhagen

- Create a disaster relief mechanism, to help countries which have suffered extreme weather events * Technology

- Launch a “technology mechanism,” including establishing regional technology centers in developing countries in Asia, Latin America and Africa

Reporting by Gerard Wynn, Editing by Eric Walsh