The UK Government’s Committee on Climate Change was created by the Labour Government’s Climate Change Act in 2008. Its mission statement now says it exists to give “Independent advice to government on building a low-carbon economy and preparing for climate change”, which is slightly discouraging, given that its original aim was to advise the UK government on how to prevent climate change. Even so, “building a low carbon economy” is part of the effort to prevent climate change. The CCC is responsible for the advice, which the UK government has adopted, to aim for carbon neutrality by 2050. For comparison, note that the Chinese government has recently announced a plan to reach carbon neutrality by 2060. Warwick District Council has voted unanimously to achieve carbon neutrality by 2030.
The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the science related to climate change. It was created in created in 1988 by the World Meteorological Organisation(WMO) and the United Nations Environment Programme(UNEP). The IPCC exists to provide governments at all levels with scientific information that they can use to develop climate policies, and IPCC Assessment Reports are a key input into international climate change negotiations. The fifth report came out in 2014, and the sixth is expected in 2021 and 2022. In 2018, the IPCC issued a special report on limiting warming to 1.5 degrees. All of these reports have “Executive Summaries” or “Summaries for Policymakers” which you can read in an hour or two.
Although the IPCC is the world’s most authoritative climate organisation, its reports are subject to political pressure, e.g. from the delegations from oil producing nations, and many scientists argue that its recommendations on emissions reductions are too timid.
In 2019, the Special IPCC report on 1.5 degrees was itself banned from being used as evidence in negotiations on emissions reductions, by a bloc of oil producing nations led by Saudi Arabia — see the report in the Independent newspaper. At this scale of events, science has less clout than “national interests”.