Menu


Image: IPCC

Home > Climate wiki > Response > IPCC Intergovernmental Panel on Climate Change

Summary

1988 the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) established the Intergovernmental Panel on Climate Change IPCC to provide governments and policymakers around the world with a synthesis of scientific research about climate change.

1990: First Assessment Report (FAR) made it clear that human emissions were changing the climate. The report included scenarios: what our futures might be like depending on which pathways the world chooses to (a) reduce greenhouse gas emissions and (b) drawdown and store carbon dioxide.

1992: Countries joined an international treaty, the United Nations Framework Convention on Climate Change (UNFCCC) to cut emissions to stabilise atmospheric carbon at 354ppm by 2020.

1995: Second Assessment Report (SAR) published. The first annual Convention of the Parties (COP1), the governments that had signed the UNFCCC, met in Berlin to discuss the progress being made to cut emissions.

1997: The 1997 Kyoto Protocol aimed to cut greenhouse gas emissions and establish the Adaptation Fund for developing nations. The general construct was that the faster emissions could be reduced (the most optimistic IPCC pathway to 2100), the less adaptation would be needed.

NOTE: voluntary scientists collate and synthesise the science but governments ultimately must agree on the final wording of keyreports. Captured by fossil fuel interests, for the next 29 years governments/policymakers denied, disputed, ignored, or cherry-picked an extraordinary wealth of scientific evidence and indisputable observed facts. Uncertainty was often interpreted as ‘not going to happen’; subsequent IPCC reports consistently underestimated the speed and impacts of climate change. 

2015: Atmospheric carbon reached 399.4ppm.The Paris Agreement was signed by some but not all COP members to reduce emissions.

2020: Atmospheric carbon: 412.5ppm and rising fast. Promises made in Paris were not being upheld. See the GAP index (updated monthly) and how well Aotearoa was doing.

Recent reports

2021: Sixth Assessment Report I The Physical Science Basis finalized during the 14th Session of Working Group I and 54th Session of the IPCC.

Climate change is widespread, rapid, and intensifying… Many of the changes observed in the climate are unprecedented in thousands, if not hundreds of thousands of years, and some of the changes already set in motion—such as continued sea level rise—are irreversible over hundreds to thousands of years.  – IPCC August 2021

2022: Sixth Assessment Report II Impacts, Adaptation and Vulnerability released February (Video 1).

2022: Sixth Assessment Report III Mitigation of Climate Change (Video 2).

I’ve seen many scientific reports in my time but nothing like this. Today’s IPCC report is an atlas of human suffering and the damning indictment of failed climate leadership. This report reveals that all people on the planet are getting clobbered by climate change. Nearly half of humanity is living in the danger zone. Now. Many ecosystems are at the point of no return. Now. And unchecked carbon pollution is forcing the globe’s most vulnerable on a frog march to destruction. Now. The facts are undeniable. This abdication of leadership is criminal. – António Guterres, Secretary-General of the United Nations introduction to the IPCC Sixth Assessment Report II: Impacts, Adaptation and Vulnerability

2026: Atmospheric carbon: 432ppm and rising fast.
Next IPCC reports:
A Special Report on Climate Change and Cities and a Methodology Report which is scheduled for publication in early 2027. The Report on Short-lived Climate Forcers and the Methodology Report on Carbon Dioxide Removal Technologies, Carbon Capture Utilization and Storage are both also planned for release in 2027. – IPCC Seventh Assessment Report

What’s in this page

What’s on other pages 

Emissions pathways: RCP & SSP

The researchers who developed the RCP scenarios for the earlier IPCC reports describe the pathway in detail here.

In addressing the future impacts of climate change, the IPCC 6th Assessment Report used a set of narratives, ‘Shared Socioeconomic Pathways’ (SSPs) to describe five possible future development pathways for humanity (Fig. 2). The worst-case SSP5-8.5 scenario described a dire future if we continued our ‘business as usual’ extractive, exploitive path. This warning played an important role in developing the Paris Accord and subsequent policies and actions. 

The following explanation is from the 2019: FINAL DRAFT Chapter 1 Supplementary Material IPCC SR Ocean and Cryosphere, Chapter 1: Framing and Context of the Report Supplementary Material (page 7):

Five SSP narratives describe alternative pathways for future society (Figure SM1.1). Each SSP looks at how the different RCPs could be achieved within the context of the underlying socioeconomic characteristics and shared policy assumptions of that world. The SSPs five alternative socio-economic futures compromise: sustainable development (SSP1), middle-of-the-road development (SSP2), regional rivalry (SSP3), inequality (SSP4), and fossil-fuelled development (SSP5) (Kriegler et al., 2016; Riahi et al., 2017). 

Across these five SSP narratives there are a total of 23 ‘Marker’ SSP scenarios….SSP5-8.5 represents the high end of the range of future pathways, corresponding to RCP8.5. SSP3-7.0 lies between RCP6.0 and RCP8.5, and represents the medium to high end of the range of future forcing pathways. SSP4-6.0 corresponds to RCP6.0, fills in the range of medium forcing pathways. SSP2-4.5 represents the medium part of the range of future forcing pathways and updates RCP4.5. SSP5-3.4 (Overshoot) fills a gap in existing climate simulations by investigating the implications of a substantial 21st century overshoot in radiative forcing relative to a longer-term target. SSP4-3.4 fills in the range of low forcing pathways, and there is substantial mitigation policy interest in this scenario that reaches 3.4 W m–2 by \] 2100. SSP1-2.6 is similar to RCP2.6. It is anticipated that it will produce a multi-model mean of less than 2°C warming by 2100.

SSP1-1.9: Sustainability: The world shifts gradually but consistently toward a more sustainable path, with net zero emissions by 2050
SSP1-2.6: Low emissions: Emissions decline to net zero by 2050
SSP2-4.5: Regional rivalry: resurgent nationalism, conflicts, less investment in education and technological development, consumption is material-intensive, and inequalities persist or worsen over time. Emission stay at current levels and fail to reach net zero by 2100
SSP3-7.0: Inequality: increasing conflict and decreasing global co-operation. Social cohesion degrades and conflict and unrest become increasingly common. Investments in both carbon-intensive fuels like coal and unconventional oil, but also low-carbon energy sources. Environmental policies focus on local issues around middle and high income areas. ie, the wealthy are protected. Emissions double by 2100
SSP5-8.5: Fossil-Fueled Development: increasing faith technological ‘fixes’ to manage social and ecological systems, including by geoengineering if necessary. Emissions triple by 2075.

Today, despite considerable backsliding, policies to decarbonise energy systems, identify unavoidable risks, and develop adaptation strategies are underway, and anthropogenic emissions are not rising as fast as they once were. Having achieved its goal to incentivise policies and actions, the SSP5-8.5 and earlier RCP8.5 scenarios are being retired. A new set of scenarios for the IPCC 7th Assessment Report includes a ‘High’ scenario where temperatures could reach 2.5 – 4.3°C by 2100 if decarbonisation policies and actions to reduce emissions are rolled back.  

The proposal also includes plans for long-term extensions (up to 2500 AD) to study long- term impacts, climate change-related processes on long time scales, and (ir)reversibility. – Van Vuuren et al April 2026

Some vocal politicians, policy makers, and climate change deniers now claim that retiring SSP5-8.5 is proof, to quote Donald Trump, scientists were ‘WRONG! WRONG! This was “just admitted” by the UN’s “top climate committee”’.

Wilful ignorance and a deconstruction of history is to be expected in the current political climate. RCP8.5 and SSP5-8.5 achieved their objectives: they warned us to avoid the worst. SSP1-1.9 and SSP1-2.6 have also been retired, as emissions are still rising. How high temperatures continue to climb, their increasingly challenging impacts, and how well we adapt depends on which path we choose: backslide under Trumpian-style policies, or forge ahead with decarbonisation and adaptation plans.

New climate models charting our possible futures will be in the IPCC 7th Assessment Report, the first part due to be published in 2027. See also Carbon Brief Explainer of the next CMIP7 emissions scenarios – and how they explore future climate change.

Background

Back in 1988 when it was clear that the world’s climate was changing, it was also evident that every aspect of life on Earth would be affected. The IPCC was formed to gather research from around the world, evaluate it, and use it to make predictions about the impacts, with the objective of ‘stablising greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic (human-induced) interference with the climate system‘. By gathering research from across all sectors, the IPCC is also able to see where there are gaps in knowledge, which in turn helped direct research.

Each of the six Assessment Reports published since 1988 runs into several million words, are in several parts, and collated over four to five years by scientists and researchers nominated by their respective governments (Fig. 2).

The first report of the sixth cycle for example, was published August 2021. It included peer-reviewed science published prior to January 31, 2021. Research published after that date was not included due to the time it takes to collate and review material. This process ensures that:

  1. All member nations are represented
  2. There is time to include all relevant material
  3. A consensus is reached by all nations prior to each Assessment Report being released 

Thousands of scientists and other experts around the world volunteer their time to write and review the draft reports. As these are long and technical, to ensure the research is robust and comprehensive there is also a summary report for policymakers. Delegates from all participating governments—around 120 including New Zealand—check the summary report line-by-line, and all countries have to agree on the wording before the final report is published. 

And this is the point where to reach consensus, some science or data is sidelined and the wording can be changed to downplay the science, which has led to criticisms that the reports are too conservative, even dangerously optimistic.

Criticisms of reports being too conservative

Some assumptions in the first five assessment cycles (AR1-5) have not come to pass. These assumptions were primarily that:

Some nations still reject aspects of the science and implications of climate change, insisting on language in the summary reports downplay the scale and urgency of the problems. As few policy makers read more than the summary reports, vital nuances are often lost or overlooked.

Supporting evidence: It takes years to gather robust data, write research papers and have that research published. Consequently, some research in IPCC reports is more than a decade old by the time the report is published. 

In research fields such as the process that lead to ice-caps melting, it was (and still is) an evolving field of science. So  summary reports did not include the potential of this to lead to rapid sea level rise, because it was an unknown. Hence, by the time IPCC reports are released, real-world events and discoveries have already taken place.

For example, IPCC predictions about sea level rise and temperatures regarded the ‘worst case scenario’ to be the ‘least likely’ to happen. But on the eve of the Fourth Assessment Report a study was published showing that temperatures were at the top end of the worst case scenario (blue-dotted line) while sea levels were rising much faster that the worst case scenario (grey shaded area) (Fig. 3).

This problem of a lack of data and out-dated research is crucial, given that data in the 2013 Fifth Assessment Report used as the basis of the 2015 Paris Agreement to keep global temperatures under 1.5°C was itself based on research as much as 10 year old. 

In 2021 AR6 WG1 The physical Science presented catastrophic evidence, and yet the modelling of sea level rise still didn’t include rapid melting processes being observed in Greenland and Antarctica as there wasn’t (and still isn’t) sufficient data to calculate exactly how much sea level could rise over what time period.

Adaptation: where’s the promised funding?

The 1997 Kyoto Protocol aimed to cut greenhouse gas emissions and establish the Adaptation Fund for developing nations. The general construct was that the faster emissions could be reduced (the most optimistic IPCC pathway to 2100, see Fig. 2 above ), the less adaptation would be needed.

As developed nations were the least vulnerable, they were assumed to have the capacity and technological knowhow to mitigate and undergo any needed adaptation over decades. The Adaptation Fund wasn’t launched until 2001 at COP7 but didn’t become operational until 2007 at COP13.

In 2010 at COP16 the Cancun Adaptation Framework included setting up an Adaptation Committee to ‘promote the implementation of stronger, cohesive action on adaptation… Governments also agreed to include carbon capture and storage (CCS) in the projects under the Clean Development Mechanism (CDM).’

But by 2012 revenue from CDM crashed, and with it, funding for the Adaptation Fund.

In 2013 COP19 delegates agreed on components of an Adaptation Plan that were so weak that the WWF, Oxfam, ActionAid, International Trade Union Confederation, Friends of the Earth, and Greenpeace walked out due to lack of funding commitments for the ‘poorest /most vulnerable countries’.

In 2014 the IPCC (AR5) introduced the concept of Dynamic Adaptive Policy Pathways (DAPP) and promoted ‘…partnerships with Indigenous peoples and the contribution that indigenous knowledge can make to adaptation.’

A year later the Adaptation Fund came under the wing of the 2015 Paris Accord (Article 6)  ‘…to unlock financial support for developing countries…’ while Article 7 established a global goal to ‘…enhance adaptive capacity, strengthen resilience and reduce vulnerability.’

In 2016 COP22 was criticised as heavy on rhetoric but light on progress with insufficient money for less developed countries to adapt to ‘changes that are already happening because of global warming.’

In 2017 Donald Trump announced the U.S. withdrawal from the Paris Accord, shifting global politics. Since then, successive COPs have failed to deliver meaningful advancement of adaptation, and instead focussed on emissions reduction and CCS/CDM technology.

By 2020 it was evident that major climate tipping points were already being breached.

In 2021, while the U.S. rejoined the Accord it was clear that even the weak Paris pledges had failed to be implemented.

The 2022 IPCC AR6 WGII report: Impacts, Adaptation and Vulnerability again emphasised the role of DAPPs and partnering with indigenous peoples. At COP27 that year a ‘loss and damage fund’ was created to help developing countries mitigate and deal with the impacts (aftermath), ‘ending almost 30 years of waiting by nations facing huge climate impacts.’ No commitment was made to phase out fossil fuels; a refusal that continued up to and including COP30 (2025).

2025: At COP30 adaptation finance was agreed upon until:

In a cruel blow to communities already reeling from extreme climate impacts, richer nations shamefully sought to renege on their commitment to triple adaptation finance for lower income nations that was secured just six months ago at COP30. – Union of Concerned Scientists, 18 June 2026

More information