Each of the 197 signatories to the United Nations Framework Convention on Climate Change (UNFCCC) has its own concerns and interests, which can make consensus-building extremely difficult.
The United Nations climate conference (COP27) begins on in Sharm el-Sheikh, Egypt. Listed below are some of the key stakeholders and negotiating blocs involved.
CHINA
This year, China, the world's largest emitter of greenhouse gases, experienced its warmest summer on record. In a national plan for climate adaptation, extreme weather was identified as a growing threat.
In spite of energy security risks, China is increasing its coal consumption, and President Xi Jinping stated in October that China would continue to support "the clean and efficient use of coal."
Climate issues are also overshadowed by geopolitics. Beijing cancelled bilateral climate talks with the United States due to a diplomatic dispute regarding Taiwan.
China is not expected to make any new commitments at COP27, with officials stating that the summit's focus should be on securing climate finance for developing nations.
UNITED STATES
The second-largest emitter in the world, after China, attends COP27 following the passage of domestic legislation that should unleash trillions of dollars in investments in clean energy and transportation.
The provisions of the Inflation Reduction Act (IRA), which was signed by President Joe Biden in August, are anticipated to triple the amount of clean energy on the electricity grid and reduce carbon emissions by one billion tonnes annually by the end of this decade.
With U.S. Congressional elections on November 8, the second day of COP27, environmental activists are concerned that a shift to Republican control of Congress could impede the implementation of the IRA.
The United States is also poised to ratify the Kigali Amendment to the Montreal Protocol, which will reduce the use of hydrofluorocarbons (HFCs) - a climate pollutant used in refrigeration - over time. In addition, it intends to announce methane regulations for the oil and gas sector that exceed those proposed by the United States last year.
EUROPEAN UNION
The European Union's greenhouse gas emissions account for about 8% of the global total and have been decreasing for years.
The bloc has enshrined in law goals to reduce net emissions by at least 55 percent by 2030 from 1990 levels, and to zero by 2050, but is still in the process of negotiating implementation policies. The EU has stated that it will increase its climate goal, but only after the approval of new climate laws, which will not occur before next year.
At the U.N. climate talks, the EU intends to exert pressure on other major emitters to increase their targets by negotiating as a single bloc. It is also expected to face pressure at COP27 to soften its long-held opposition to loss and damage compensation.
UNITED KINGDOM
The host of last year's conference has endured months of political turmoil and an energy crisis, which threaten the nation's climate goals. The United Kingdom has pledged to achieve net-zero emissions by 2050 in 2019 and a 78% reduction by 2035 compared to 1990 levels.
However, in October the government announced a new round of oil and gas licencing in the North Sea, insisting that it would not impede its climate goals. It is unknown how Prime Minister Rishi Sunak will approach energy policy. Meanwhile, longtime climate advocate King Charles III announced he will not attend COP27 in Egypt.
'BASIC' NATIONS
Brazil, South Africa, India, and China comprise this bloc of densely populated, rapidly developing, and highly polluting economies.
Each has asked rich countries for more climate financing, and demanded equity through the UNFCCC concept of "common but differentiated responsibilities" – meaning wealthy countries that have contributed the most emissions to the atmosphere historically have a greater responsibility to address the problem.
India has resisted giving up coal, collaborating with China at COP26 last year to prevent stronger commitments to abandoning it.
Brazil is expected to spearhead negotiations detailing rules for carbon credit markets, as it seeks to monetise its vast forests.
South Africa is rushing to finalise a side agreement with the EU, the United States, and other nations that will provide it with $8.5 billion to transition from fossil fuels to renewable energy.
OTHER NEGOTIATING BLOCS: G77 + CHINA
This alliance of 77 developing nations and China upholds the notion that different nations have varying responsibilities. At COP27, Pakistan, which was devastated by floods this year, will lead a group whose members are unified in their demand for a compensation fund from wealthy nations.
UMBRELLA GROUP
This alliance of non-EU developed countries includes the United States, Australia, Japan, and Russia.
AFRICA GROUP
Africa's U.N. representatives will advocate for additional climate financing, arguing that expanding economies require fossil fuels to increase electricity capacity. Many African nations, including Egypt, are eager to develop their natural gas reserves as a transitional fuel and a way to profit from Europe's demand for gas to replace Russian imports.
CLIMATE VULNERABLE FORUM
This group, which represents 58 of the most at-risk nations from climate change, including Bangladesh and the Maldives, heads to COP27 with a central demand: a dedicated fund through which rich polluting nations assist the vulnerable in bearing the costs of "loss and damage." The forum also desires that all nations strengthen their climate objectives.
ASSOCIETY OF SMALL ISLAND STATES
The alliance, also known by its acronym AOSIS, represents nations that are disproportionately susceptible to climate-related effects, especially sea level rise and coastal erosion.
FREE ALLIANCE OF LATIN AMERICA AND THE CARIBBEAN
The AILAC bloc is aligned with other developing nations in their demand for increased climate ambition and funding from wealthier nations.
LEAST DEVELOPED COUNTRY GROUP
This classifies 46 nations as vulnerable to climate change despite their negligible contributions. In addition to requiring that loss and damage be addressed, the LDCs want rich nations to provide twice as much funding for adaptation and to make it more accessible.
POWERING PAST COAL ALLIANCE
Under the leadership of the United Kingdom and Canada, 41 nations and dozens of local governments and businesses have pledged to accelerate their transitions to clean energy. This year, the group criticised plans to burn more coal in response to the energy crisis caused by the conflict in Ukraine.
HIGH AMBITION COALITION
This group, led by the Marshall Islands and composed of Costa Rica, the United States, and the European Union, advocates for more progressive emissions targets and climate policies.