[5] They compile key findings into "Assessment Reports" for policymakers and the general public;[4] Experts have described this work as the biggest peer review process in the scientific community.

In August 2021, the IPCC published its Working Group I contribution to the Sixth Assessment Report on the physical science basis of climate change.

[15] It published Working Group III's "mitigation of climate change" contribution to the Sixth Assessment in April 2022.

These were the International Council of Scientific Unions, the United Nations Environment Programme (UNEP), and the World Meteorological Organization (WMO).

The United States Environmental Protection Agency sought an international convention to restrict greenhouse gas emissions.

In 2021, the IPCC's annual budget amounts to approximately six million euros, financed by the 195 UN Member states, who contribute "independently and voluntarily".

[45] The IPCC held an Expert Meeting on Communication in February 2016, at the start of the Sixth Assessment Report cycle.

The Bureau (more precisely, the co-chairs of the relevant working group, with the help of its technical support unit) uses these lists as a basis for appointing authors while retaining the possibility of appointing people who are not on the list, primarily based on scientific excellence and diversity of viewpoints, and to a lesser extent by ensuring geographical diversity, experience within the IPCC and gender.

Lead authors of IPCC reports assess the available information about climate change based on published sources.

This final review of the Summary of Policymakers takes place at sessions of the responsible working group or of the Panel.

[75] The IPCC published the Working Group II report, Climate Change 2022: Impacts, Adaptation and Vulnerability, in February 2022.

[80] Later in 2011, the IPCC released the Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation.

All three IPCC working groups and its Task Force on National Greenhouse Gas Inventories collaborated on the report.

The report found that climate change is adding to the pressures we are putting on the land we use to live on and grow our food.

Parties to the UNFCCC and its Kyoto Protocol use the 1996 guidelines and two good practice reports for their annual submissions of inventories.

[101] David Biello, writing in the Scientific American, argues that, because of the need to secure consensus among governmental representatives, the IPCC reports give conservative estimates of the likely extent and effects of global warming.

[102] Science editor Brooks Hanson states in a 2010 editorial: "The IPCC reports have underestimated the pace of climate change while overestimating societies' abilities to curb greenhouse gas emissions.

"[103] Climate scientist James E. Hansen argues that the IPCC's conservativeness seriously underestimates the risk of sea-level rise on the order of meters—enough to inundate many low-lying areas, such as the southern third of Florida.

He added that "passing through the 1.5C world is a significant milestone because it shows that the story being told by the United Nations, with the acquiescence of its scientific advisory body, the IPCC, is a load of bullshit.

"[105] Roger A. Pielke Sr. has also stated "Humans are significantly altering the global climate, but in a variety of diverse ways beyond the radiative effect of carbon dioxide.

"[106] Stefan Rahmstorf, a professor of physics and oceanography at University of Potsdam, argued in 2007 that the IPCC's tendency to make conservative risk assessments had benefits.

Rahmstorf argued that "In a way, it is one of the strengths of the IPCC to be very conservative and cautious and not overstate any climate change risk".

[108][109] A memo by ExxonMobil to the Bush administration in the United States in 2002 was an example of possible political influence on the IPCC.

The memo led to strong Bush administration lobbying to oust Robert Watson, a climate scientist, as IPCC chair.

[111] For instance governments take part in the review process and work with authors to approve the Summary for Policymakers of reports.

[112] In 2023, it was reported that pressure from Brazil and Argentina, two countries with large beef industries, caused the IPCC to abandon text recommending the adoption of plant-based diets.

The IAC report made recommendations to fortify IPCC's management structure, to further develop its conflict-of-interest policy, to strengthen the review process, to clarify the guidelines on the use of so-called gray literature, to ensure consistency in the use of probabilities for the likelihood of outcomes, and to improve its communications strategy, especially regarding transparency and rapidity of response.

For example, John Christy, a contributing author who works at the University of Alabama in Huntsville, explained in 2007 the difficulties of establishing scientific consensus on the precise extent of human action on climate change.

[126] Christopher Landsea, a hurricane researcher, said of "the part of the IPCC to which my expertise is relevant" that "I personally cannot in good faith continue to contribute to a process that I view as both being motivated by pre-conceived agendas and being scientifically unsound,"[127] because of comments made at a press conference by Kevin Trenberth of which Landsea disapproved.

The two intergovernmental bodies won the prize because they "produce scientific knowledge, alert society, and inform decision-makers to make better choices for combatting climate change and the loss of biodiversity".