Since its establishment in 1988 by the United Nations Environment Programme and the World Meteorological Organization and endorsed by the UN General Assembly, the IPCC has become the world authority for climate change knowledge through its, so far, six assessment reports (AR1 to AR6) as well as numerous reports and technical guidelines. The IPCC came about because of an increased awareness of anthropogenic climate change and assessments by individual agencies along with a 1985 conference in Austria that recognized as important the shift of climate science into the international policy space1. The role of the IPCC is to provide scientific assessments of the climate change literature to inform government at all levels to develop climate policies; the international negotiations that make use of this information is the responsibility of the United Nations Framework Convention on Climate Change (UNFCCC), established in 1994, which coordinates the annual Conference of the Parties (COP).

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Recognition of the contribution by the IPCC to the world has seen the organization being awarded the 2007 Nobel Peace Prize (jointly with Albert Arnold (Al) Gore Jr) for “efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change”, and, in 2022 (jointly with the Intergovernmental Science–Policy Platform on Biodiversity and Ecosystem Services (IPBES)), the Gulbenkian Prize for Humanity — which rewards individuals and organizations who are leading society’s efforts to tackle climate change — for work in highlighting the threats of climate change and biodiversity loss.

But it has not been without controversy or challenges over the years. For example, questions arose about the quantification of Himalayan glacier melt included in AR4, which was later acknowledged as an error. Another example is the body of literature that has arisen studying the IPCC, its processes and outputs, which includes concerns on consistency across Working Groups for dealing with uncertainites2 and that geographic inclusions haven’t broadened viewpoints and cultural understandings3 but celebrates the inclusion of early-career researchers4.

The seventh assessment report (AR7) is expected to be finalized in 2029, and the cycle will include the Special Report on Climate Change and Cities, the Report on Short-lived Climate Forcers, the Methodology Report on Carbon Dioxide Removal Technologies, Carbon Capture Utilization and Storage, and a revision of the 1994 Technical Guidelines on impacts and adaptation. The IPCC planning meeting being held in China in late February (taking place at the time of writing) will agree the outline for AR7 and the Methodology Report, but without US researchers in attendance. News reports state that NASA confirmed that Katherine Calvin, the co-chair of Working Group 3, would not be there, and the future of the US-based Working Group 3 Technical Support Unit is unclear. In the first Trump administration, US scientists contributed to AR6, but none of the co-chairs were from the United States; at this time, it is too early to tell what change there may be to contributions from the wider community of US-based scientists to AR7.

Moving from IPCC to UNFCCC matters, we do know that an Executive Order has been signed early in Trump’s second term to begin the process to withdraw the United States from the Paris Agreement. The United States previously withdrew from the Paris Agreement during President Trump’s first term — effective from November 2020 — but when the announcement was made in June 2017, it was feared that this would lead to others also leaving and to a breakdown in the Agreement. However, in a Comment article at the time, Luke Kemp argued that if the United States had stayed in the Agreement that it would have actually been more detrimental as they could have weakened commitments and eroded the spirit of the Agreement. With the United States outside it, it might embolden other nations, as well as states and business, to push forward into climate leadership roles5, which was seen; however, it was disruptive to international climate diplomacy and relations.

The loss of financial commitments and aid is of course a concern, and previously, Michael Bloomberg, who is UN Secretary-General’s Special Envoy on Climate Ambition and Solutions, committed to support the UNFCCC by covering the financial contributions for 2017–2020 that were the responsibility of the United States. With the January 2025 announcement that the United States intended to again leave the Paris Agreement, Bloomberg has stated that his foundation, Bloomberg Philanthropies, and other US climate funders will ensure that US funding obligations are again met.

Not having the United States committed to the Paris Agreement is a loss, and the same is true for the IPCC. There are challenges ahead, as we see at each COP when the final statement involves concessions to be reached, but these organizations are bigger than one nation, and the strength of the collective can ensure that the AR7 cycle delivers, and can work together to advance climate action.