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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 policy makers around the world with a synthesis of scientific research about climate change.
Since then over 8,000 experts from nearly every country have volunteered to collate material covering scientific, technical, and socio-economic knowledge on climate change, its impacts, future risks, and develop mitigation and adaptation strategies. This 2-page PDF from the IPCC includes links to all the main reports to 2024.
1990: IPCC 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 the excess carbon dioxide in the atmosphere and store it…somewhere using technologies not yet in existence.
1992: 198 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: IPCC Second Assessment Report (SAR) published, collating the science. The governments that had signed the UNFCCC (Convention of the Parties or COP) met in Berlin. This would become an annual event. Delegates agreed that existing commitments to return emissions to 1990 levels by 2000 were inadequate to prevent dangerous climate change.
1997: The 1997 Kyoto Protocol aimed to cut greenhouse gas emissions and establish the Adaptation Fund for developing nations. The rational was that the faster emissions could be reduced the less adaptation would be needed.
2007: Jointly awarded the Nobel Peace Prize for its “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.”
2011: Adopted a Conflict of Interest Policy.
Despite this policy, captured by fossil fuel interests, some governments and policy makers denied, disputed, ignored, or cherry-picked an extraordinary wealth of scientific evidence and indisputable observed facts. Science couldn’t explain why, for example, in 1995 an ice shelf in Antarctica disintegrates in weeks, not hundreds of years. Nor why it happened again to a second ice shelf in 2007. Not knowing ‘why’ was enough to sideline the consequences of more ice shelves collapsing:
2013:
2015: Atmospheric carbon: 399.4ppm. The Paris Agreement to reduce emissions was signed by some but not all COP members.
2020: Atmospheric carbon: 412.5ppm and rising fast. By now it was clear that the promises made in Paris were not being upheld. See the GAP index (updated monthly); this includes how badly Aotearoa was and is doing.
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).
At least a dozen IPCC lead authors are employed by or linked to Saudi Aramco, Saudi institutions and other oil and gas interests…. One IPCC vice-chair, part of the body’s leadership group, also represents the kingdom at global climate negotiations as a government employee. – The Guardian 21 September 2026
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Click the image to be taken to the atlas. This screengrab is an example of how you can enter specific information for regions (here, New Zealand / land only) and check the projected temperature changes over time based on different models and pathways (i.e. if and by how much we reduced emissions).
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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:
- All member nations are represented
- There is time to include all relevant material
- 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.
Explainer: Representative Concentration Pathways RCPs
Warming climate scenarios are based on models for the 2013 IPCC Fifth Assessment Report. These Representative Concentration Pathways or RCPs represent the concentration of greenhouse gases in the atmosphere based on how these gases retain heat.
Heat is measured in watts per metre squared, written as W⋅m−2. In most graphs, the numbers 2.6, 4.5, 6.0, and 8.5 are W⋅m−2 however ‘W⋅m−2 ‘ is implied, and the four units are written instead as four scenarios: RCP2.6 etc. See Figures 2 & 3. In some graphs, this is written without a decimal place: RCP26, RCP45 etc.
For example, Figure 2 shows the estimates rise in sea levels based on different emissions pathways. It’s important to note that the 8.5 ‘worst case scenario’ (dark orange in Fig. 2) doesn’t include any effects from tipping points such as the collapsing Antarctica and/or Greenland ice sheets because at that time (2013) the mechanisms behind rapid melting were either not well understood or lacked sufficient evidence:
The researchers who developed the RCP scenarios for the earlier IPCC reports describe the pathway in more detail here.
Explainer: Shared Socioeconomic Pathways SSPs
In addressing the future impacts of climate change, the IPCC 6th Assessment Report (AR6) used a set of narratives, ‘Shared Socioeconomic Pathways’ (SSPs) to describe five possible future development pathways for humanity (Fig. 3). The worst-case SSP5-8.5 scenario described a dire future if we continued our ‘business as usual’ emissions of greenhouse gases. This warning played an important role in developing the 2015 Paris Agreement 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):
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 (although the planet is no longer absorbing most of the excess, so the energy imbalance is increasing and the planet is warming faster than it did 10 years ago). 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 will also be replaces 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.
Shortcomings and 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:
- Once governments knew the problems that climate change would bring, they would act quickly to replace fossil fuels. This is failing.
- Carbon capture technologies would be invented and installed to remove excess greenhouse gases from the atmosphere. The technology exists but is not cost effective and most tech sells the CO2 as fuel, returning it back into the atmosphere.
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. 4).
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Top: Monthly carbon dioxide concentrations; different colours are from different measuring stations.Middle: annual global-mean surface temperature; the grey area are IPCC projections.Bottom: sea-level data based on tide gauges and satellite altimeter; the grey area are IPCC projections, the top line shows what was actually observed.From: Rhamstorf et al; Recent Climate Observations Compared to Projections Science 316 (5825) :709
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. 3 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.
2001: Adaptation Fund launched at COP7
2007: Adaptation Fund finally operational at COP13.
2010: At: 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).’
By 2012 revenue from CDM crashed, and with it, funding for the Adaptation Fund.
2013: At 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’.
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.’
2015: 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.’
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.’
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.
2021: While the U.S. rejoined the Accord it was clear that even the weak Paris pledges had failed to be implemented.
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
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