The IPCC’s 6th Report Cycle is Ending. Here’s the Latest on the State of Global Climate Science.

The people of Mozambique are paying the high price of climate change. Cyclone Freddy battered the country in February and March 2023, breaking records for the duration and strength of tropical storms in the southern hemisphere. Photo: Alfredo Zuniga / UNICEF

After years of effort by hundreds of scientists, experts, and governments around the world, the Intergovernmental Panel on Climate Change is wrapping up its sixth assessment cycle following the March 2023 release of its Synthesis Report. Drawing important conclusions from across all six reports released in this cycle, the Synthesis Report reflects our deepest understanding of climate science to date – and will become a key input for the Global Stocktake when experts and leaders will assess progress toward limiting global warming to 1.5°C.

This blog post was originally published in April 2022, and has been updated with the Synthesis Report release.


The six major reports published during the sixth assessment cycle of the Intergovernmental Panel on Climate Change (IPCC), known as AR6, have permanently reshaped the global conversation on climate change, and the implications of these reports’ findings continue to reverberate around the world. A methodology report was also released by the IPCC’s Task Force on National Greenhouse Gas Inventories (read more about IPCC’s process).

This table outlines the major reports from the IPCC's 6th assessment cycle

Special Report on Global Warming of 1.5°C

At the request of countries at the conclusion of the UN Climate Change Conference in Paris in 2015 (COP 21), the IPCC undertook this seminal project of examining the implications of 1.5°C of warming above preindustrial levels and the consequences of exceeding it. The report’s findings about the myriad devastating impacts of breaching this warming threshold helped to fundamentally shift global ambition and made 1.5°C the new global marker of adequate climate ambition. This helped create momentum for the proliferation of commitments by state, subnational, and private actors to reach net-zero emissions by 2050 — as that is the only course that can put us on track to 1.5°C.

A joint European fire operation works to contain forest fires in France in August 2022. Photo: European Union

Special Report on Climate Change and Land

This 2019 report found that while climate change had been largely viewed as a future challenge, there were already impacts to people and ecosystems on land. For instance, temperatures on land have increased more than the global average, and this warming has led to more wildfires and heat waves, which in turn have influenced reduced agricultural yields. While climate change affects land, the reverse is also true: Changes to land are driving climate change, responsible for 23% of human-caused emissions.

Special Report on the Ocean and Cryosphere in a Changing Climate

This 2019 report highlighted two major findings: first, oceans have absorbed the majority of heat from global warming, and second, Earth’s coldest regions are warming the fastest. While ocean warming has blunted the experience of climate change on land, it has caused marine acidification and deoxygenation, which in turn have destroyed coral reefs and degraded coastal ecosystems. Meanwhile, the increasing rate of glacial, ice, and permafrost loss has threatened ecosystems as well as livelihoods, especially for the millions of people who live in the Arctic.

Working Group I: Physical Science Basis of Climate Change

The 2021 science report found that the earth is likely to hit 1.5°C of warming within 20 years — with an extremely narrow pathway available to stay below that warming target. Due to advances in attribution science, the report established strong links between human-caused climate change and increasingly frequent extreme weather events. These events will become worse with every fraction of a degree of warming felt across the globe. With climate change now widespread, rapid, and intensifying — and warming trends unprecedented in human history — transformational change across sectors, societies, and countries is required to successfully limit global warming. 

Khursheed Bibi holds her 3-year-old son, Abu Bakar, who is experiencing fever and chest pain. Since devastating floods struck Pakistan in 2022, malaria and other diseases have been on the rise – especially in children. Photo: Saiyna Bashir / UNICEF

Working Group II: Impacts, Adaptation, and Vulnerability

Released just two months ago, this report found that climate change impacts are worse and more widespread than anticipated, affecting billions of people and causing dangerous impacts on nature. The world has not acted at the pace or scale required for meaningful adaptation to current and anticipated impacts of climate change, and both climate adaptation and emissions cuts are needed. Even with immediate action, some climate impacts will continue to worsen, and others are irreversible, so adaptation planning is essential. The most marginalized people in the world — those who are the most exposed to climate impacts — must be at the center of adaptation efforts.

Working Group III: Mitigation of Climate Change

The mitigation report, published in early April, provided a stark conclusion to this cycle. We are running out of time to limit warming to 1.5°C. The last decade saw the highest-ever increase in greenhouse gas emissions, and world leaders are not acting fast enough to secure a sustainable future. If emissions peak before 2025, and are halved by 2030, we stand a chance of meeting our climate goals and avoiding the most harmful outcomes of climate change.


While IPCC reports are released individually, they by no means stand alone. Several overarching themes run through the AR6 cycle, each with important implications for climate policy.

1. Climate change is unequivocally happening and is caused by humans.

We are past the days of tempered language on the levels of certainty around human-caused global warming. The first sentence of the AR6 Working Group I Summary for Policymakers reads: “It is unequivocal that human influence has warmed the atmosphere, ocean and land.” What’s more, society has moved beyond the question of whether or not climate change is real. Climate deniers are increasingly on the fringes, and mainstream politics in nearly every country acknowledge the unavoidable reality of the climate crisis.

A Chinese laborer loads coal into a furnace as smoke and steam rise from an unauthorized steel factory in Inner Mongolia, China. Photo: Kevin Frayer/ Getty Images

2. The world’s goal of limiting warming to 1.5°C is looking increasingly out of reach.

The goal to limit warming to 1.5°C is underscored by the Working Group reports, which explain that climate impacts will be more severe, and mitigation less effective, if warming surpasses this threshold. The reports also show that even 1.5°C will yield serious (and sometimes permanent) impacts on both people and nature. At the same time, our path to limit warming to 1.5°C is increasingly narrow — and looking more and more unlikely. Can emissions peak in the next 2½ years? Can we implement deep cuts to halve emissions by 2030 and reach net-zero emissions by 2050? While technically feasible, this may not be politically possible (see #5 below for more on political will and climate action).

3. Climate change exacerbates existing inequalities. Justice must be a core pillar of climate solutions.

The AR6 cycle underlines that marginalized people bear the brunt of climate change impacts and reveals the extent to which vulnerable people are exposed to climate risk. Marginalized communities live in areas that are more exposed to climate impacts, have fewer resources to enhance their adaptive capacity, and lack financing for implementing mitigation strategies. Climate injustice manifests in multiple ways, such as unequal access to financing and technology in developed and developing economies; greater impacts on marginalized groups like Indigenous peoples, women, and youths; links between climate and racial justice in some countries, especially the United States; and the economic abandonment of people who work in the fossil fuel industry. Climate action must avoid perpetuating these injustices and should actively work to reverse them. The IPCC reports underscore the importance of a “just transition” — all efforts on climate must incorporate justice and ensure that vulnerable groups are meaningfully included in, and positively affected by, climate action.

4. Every issue is a climate issue.

AR6 highlights how climate change has implications for other issues, such as health, equity, and poverty. In fact, action on climate is known to yield positive outcomes for gender equity, biodiversity, jobs, and more. The interconnectedness of the environment and society — long recognized in Indigenous knowledge — has been consistently acknowledged across the AR6 reports. In particular, the reports highlight synergies between addressing climate change and improving sustainable development, as well as identifying areas with potential trade-offs that policymakers will need to navigate (such as if and when land should be used for food, energy crops, or conservation). The Sustainable Development Goals (SDGs) do not exist independently of each other, and climate action can be a unifying force to help deliver a better future for everyone.

The National Renewable Energy Laboratory (NREL) hosted the 2023 JUMP into STEM Final Competition in Golden, Colorado. The national science competition aims to attract students from a variety of majors and backgrounds to the industry. Photo: Werner Slocum / NREL

5. We have solutions to tackle climate change. Weak and irresponsible leadership is holding us back.

The AR6 reports make it clear: We have climate solutions. The IPCC has highlighted strategies to reduce human-caused emissions from land use, analyzed the potential of ecosystem conservation to help nature and humans adapt, and found that every sector has proven solutions that could halve global emissions by 2030. And yet, emissions are increasing, and investments in fossil fuel infrastructure continue. We have the technology, so what is the largest obstacle to combating climate change? The answer, according to the IPCC, is largely a lack of political will. If we can muster political will — something that, so far, many world leaders haven’t done — then the rapid, transformational change that we need is achievable.


The AR6 cycle officially concluded this year with a synthesis that drew from every report in the cycle and which reflected many of the conclusions drawn above. The Synthesis Report will play a major role at COP 28, where countries will be urged to raise their climate ambition once again. With the Working Group III report defining clear, and rapidly approaching deadlines for peaking and reducing emissions, the AR6 reports will be critical inputs as negotiators meet in Dubai, United Arab Emirates, at the end of 2023 to map out a feasible path to 1.5°C.

COP 28 will also be a test of multilateralism at a time of increasing nationalism around the world. Climate action relies on international cooperation, which is strained by such challenges as the war in Ukraine, the COVID-19 pandemic, and increasingly fraught political landscapes at the national level (with climate policy especially contentious in some countries, including Australia, the United States, and other large emitters). While international cooperation is hindered in many areas, the IPCC reports represent a remarkable feat of multilateral success, agreed upon by every government in the world. Can world leaders rise to the same level of cooperation evident in the IPCC process to pursue meaningful action at COP 28?

UN Secretary-General António Guterres speaks at the opening session of COP 27 in Sharm El-Sheikh, Egypt. Photo: Kiara Worth / UNClimateChange

After the climate conference, AR6 will be a main input into the Global Stocktake, measuring progress toward meeting the goals of the Paris Agreement. The first Stocktake will conclude at the end of 2023, and countries’ climate actions will be directly compared with what the IPCC reports have found is necessary to limit global warming to 1.5°C. We know from Working Group III that right now, the world is not on track. There is still time to change course — but not much.

The AR6 cycle comes to an end as the world has already warmed 1.1°C. The IPCC’s next cycle, AR7, will likely conclude around 2030 — and by then, we will already have made the decisions that will determine if we limit warming to 1.5°C, or if we surpass it — and by how much. AR6 provides the main scientific information that world leaders will use to make critical climate choices over the next eight years. As UN Secretary-General António Guterres made clear while laying out his priorities for the year ahead: “2023 is a year of reckoning. It must be a year of game-changing climate action.”

Scientists have done their part. They have laid out the choices in no uncertain terms: drastically reduce emissions now or face insurmountable challenges later. The world’s shared future hinges on whether leaders listen to science and find the political will to act before it’s too late.