IPCC Sixth Assessment Report facts for kids

The Sixth Assessment Report (AR6) is a big report about climate change made by the United Nations (UN) Intergovernmental Panel on Climate Change (IPCC). It's the sixth in a series of reports that gather all the latest scientific information on how our planet's climate is changing.

This report was put together by three main groups of scientists, called Working Groups (WGI, II, and III). Each group focused on a different part of climate change:

• Working Group I looked at The Physical Science Basis, which means the actual science behind how the climate is changing.
• Working Group II studied Impacts, Adaptation and Vulnerability, focusing on how climate change affects us and nature, and how we can get ready for it.
• Working Group III explored Mitigation of Climate Change, which is all about ways to stop or reduce climate change.

The first report came out in 2021, the second in February 2022, and the third in April 2022. The final summary report was ready in March 2023.

The first group's report, published in August 2021, was called Climate Change 2021: The Physical Science Basis. A huge number of scientists, 234 from 66 countries, worked on it. They looked at over 14,000 scientific papers to create a very long report. Then, 195 governments approved it. The main summary for leaders was written by scientists and agreed upon by these governments.

This first report said that to avoid the planet warming by 1.5 degrees Celsius or 2 degrees Celsius, we need to make huge and immediate cuts in the gases that cause global warming, like greenhouse gas emissions. Many news outlets and leaders around the world called this report a very serious warning about big, unavoidable, and lasting changes to our climate.

How the Report Was Made

A Look Back: Previous Reports

In 2016, the IPCC decided on the topics for this new report series. They also worked on some special reports in between the Fifth Assessment Report and this Sixth one. These special reports helped gather more information:

• Special Report on Global Warming of 1.5 °C (SR15) came out in October 2018.
• 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories was published in May 2019.
• Special Report on Climate Change and Land (SRCCL) was released in August 2019.
• Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) came out in September 2019.

The Report's Main Parts

The Sixth Assessment Report is made up of the reports from the three working groups and a final summary report.

• The Physical Science Basis of Climate Change (WGI) in August 2021.
• Impacts, Adaptation and Vulnerability (WGII) in February 2022.
• Mitigation of Climate Change (WGIII) in April 2022.
• Synthesis Report (the final summary) in March 2023.

Understanding Future Paths

For the first time, the report included different ways societies might develop in the future. These are called Shared Socioeconomic Pathways (SSPs). They help scientists guess how climate change might play out depending on how people and countries work together. For example, one pathway, SSP1, is called "Taking the Green Road," imagining a world with strong international cooperation and sustainable growth. Other pathways imagine different futures, like "A Rocky Road" or "Taking the Highway."

These pathways help show that if countries work together and economies grow in a way that helps with climate change, it will be easier to adapt. Some ideas even suggest that if we have enough money and technology from things like fossil fuels, we might be able to adapt even to a 5-degree Celsius temperature rise. However, many experts think a 3-degree Celsius rise is more likely.

Working Group 1 Report: The Science Behind Climate Change

Variation of annual observed global average temperature (1850–2019) compared to the 1850–1900 average.

The first working group (WGI) published its report, Climate Change 2021: The Physical Science Basis, in August 2021. As mentioned, 234 scientists from 66 countries contributed to this massive 3,949-page report. It was based on over 14,000 scientific papers. The main summary for leaders was approved by 195 governments.

The report clearly stated that to keep global warming below 1.5 or 2 degrees Celsius, we need to make huge and immediate cuts in greenhouse gas emissions. News outlets like The Guardian called it the "starkest warning yet" about "major inevitable and irreversible climate changes."

The report also included an interactive atlas. This tool helps people see and understand climate change information for different places and times.

Key Discoveries from Working Group 1

The WGI report focused on the basic science of how human activities cause greenhouse gas emissions and their effects. It gave much more detail on how climate change affects different regions around the world. For example, it looked at how sea-level rise might affect coastal areas. It suggested that by 2100, sea levels could rise by half a meter to one meter, and even two to five meters is possible, though scientists are still learning about how ice sheets melt.

The report also looked at how much the Earth's temperature will rise if carbon dioxide in the atmosphere doubles. The best guess is a 3-degree Celsius rise. All the future scenarios in the report show that the 1.5-degree Celsius warming limit will be reached, at least for a while, in the middle of this century. However, some experts believe it's still possible to avoid warming by 1.5 degrees Celsius if the world cuts emissions by 50% by 2030 and 100% by 2050. If we don't start cutting emissions drastically soon, it might become impossible to prevent 1.5 degrees Celsius of warming.

The report suggests that the most likely temperature rise by the end of the century is around 3 degrees Celsius. It's very likely that the 1.5-degree Celsius warming mark will be reached before 2040. The report also warned about more serious combined impacts, like heat and drought happening at the same time. The famous hockey stick graph, which shows a sharp rise in global temperatures, was updated and extended.

Extreme weather events are expected to increase as temperatures rise. The report also showed that scientists are now much better at linking specific extreme weather events to climate change.

To stay below 1.5 degrees Celsius of warming, the world can only release about 500 billion more tonnes of greenhouse gas. This means the whole world needs to reach net zero emissions before 2050. The report also stressed the importance of quickly reducing methane emissions to gain time while we work on cutting carbon dioxide emissions.

Any future warming will lead to more extreme weather. Even with a 1.5-degree Celsius temperature rise, there will be "an increasing occurrence of some extreme events unprecedented in the observational record." This means events we've never seen before.

The table below shows how much more often and how much stronger extreme events will become with global warming:

Increase in how often extreme events happen with global warming.

Working Group 2 Report: Impacts and Getting Ready

The second part of the report, from Working Group II (WGII), was released in February 2022. It's called Climate Change 2022: Impacts, Adaptation & Vulnerability. This report is all about how climate change affects nature and people. It covers things like losing different kinds of plants and animals (biodiversity loss), people having to move because of climate change (Climate migration), risks to cities and farms, human health, food security, and water shortages.

It also looks at ways to deal with these risks. It shows how building a climate-ready future can be part of making our world more sustainable.

Key Discoveries from Working Group 2

The report found that the effects of climate change are even worse than thought before, and they are affecting every part of the world. At least 3.3 billion people, which is about 40% of the world population, are now in the "highly vulnerable" group. The worst effects are seen in developing countries. For example, if emissions continue as they are, parts of Africa could lose a lot of land used for growing important crops like maize and beans. One billion people could face flooding because of sea level rise. Climate change, along with other factors, also increases the risk of new diseases spreading.

The report also mentioned that China might face the highest financial costs if temperatures keep rising. These impacts could include not having enough food or water, more floods, especially in coastal areas, and stronger storms. Some parts of the country might even become too hot and humid for humans to survive for long periods. Overall, the report found 127 different negative effects of climate change, and some of them cannot be undone.

People can protect themselves from some effects of climate change. This is called adaptation. The report noted that progress has been made in adapting to climate change in many areas. However, this progress is not equal everywhere. Many efforts focus on immediate problems rather than long-term changes. Still, there are good ways to adapt, and many adaptation actions have extra benefits. For example, better water management can help with water risks and also bring economic and environmental benefits. Similarly, things like planting trees on farms or growing food in cities can increase food supply and help the environment.

The report also stressed the need to protect nature to keep different kinds of plants and animals alive (biodiversity) and reduce the effects of climate change. It said that to keep nature healthy globally, we need to protect about 30% to 50% of Earth's land, fresh water, and ocean areas. The report was careful about using only technology to remove carbon dioxide. Instead, it suggested that making cities better could help people use things like public transport and renewable energy. It also warned about high risks from strategies like trying to control sunlight or planting forests in places where they don't naturally grow.

The report also talked about "loss and damage." This means the negative things that happen because of climate change that we cannot avoid, even with adaptation. The report said that these losses and damages are already happening widely. Things like droughts, floods, and heatwaves are becoming more common, and many species are already disappearing. Taking quick action to limit warming to below 1.5 degrees Celsius would greatly reduce future losses, but it can't stop all of them.

The report stated that even a short time above the 1.5-degree limit will harm people and nature. Some impacts will even cause more greenhouse gases to be released, and some will be impossible to reverse. It will be harder to build a climate-ready world if the temperature rises by 1.5 degrees, and it will become impossible in some regions if it rises by more than 2 degrees.

Even though the report's outlook can seem serious, it concludes that there is still time to limit warming to 1.5 degrees Celsius by making big cuts to greenhouse gas emissions. But this action must happen right away. Also, building a climate-ready world can help both with adapting to climate change and reducing it. This needs countries to work together and with local communities.

Working Group 3 Report: Stopping Climate Change

The third report was presented in April 2022. Some people were worried that its conclusions might be made less strong because of how these reports are approved by governments.

Key Discoveries from Working Group 3

This report used new ways to look at climate change, including how different parts of society can help. It talked about the importance of young people (youth), indigenous people, cities, and businesses in finding solutions. It said that "International cooperation is a critical enabler for achieving ambitious climate change mitigation goals." This means countries working together is super important to reach big goals for stopping climate change. For example, many developing countries need more support from other countries to take strong climate action.

The report said that if people change their habits and how they use things, we could reduce greenhouse gas emissions by 40–70% by 2050. To make this happen, these changes should also help improve everyone's basic well-being.

The report concluded that to reach net zero emissions (meaning we remove as much greenhouse gas as we put into the air), we need to use technologies that remove carbon dioxide from the air. It said that all ways to limit warming to 1.5 or 2 degrees Celsius involve quick and big cuts in emissions across all areas. This includes switching from fossil fuels to very low-carbon energy sources like renewable energy, using less energy, being more efficient, and reducing other types of emissions. The report compared different ways to remove carbon dioxide, like planting more trees (reforestation), managing coastal ecosystems (blue carbon), and restoring peatlands.

Cities have a big chance to reduce greenhouse gas emissions. With full efforts, city emissions could almost reach zero. City planning that supports mixed-use areas, public transport, walking, cycling, and sharing vehicles can reduce city emissions by a lot. Green spaces in cities, like urban forests and lakes, can also help reduce emissions directly and indirectly (for example, by reducing the need for air conditioning).

Buildings caused 21% of global greenhouse gas emissions in 2019. The report says that 80–90% of these emissions can be cut while also helping with other Sustainable Development Goals. It introduced a new plan for reducing emissions in buildings: SER = Sufficiency, Efficiency, Renewable. Sufficiency means using simple things like natural ventilation, green roofs, and white walls to reduce energy needs. Reducing emissions from buildings is also linked to sharing things and using a circular economy, where we reuse and recycle more.

The IPCC found that people could have a good quality of life using less energy than previously thought. The report said that to achieve well-being for everyone, the energy needed is much lower than current levels. Fairer income distribution can also lower emissions. Ways to reduce emissions that focus on low demand and high efficiency can lead to a good quality of life for everyone.

The report also noted some good changes in global climate action. For example, the rate of cutting down forests slowed after 2010, and the total forest cover increased in recent years because of tree planting in Europe, Asia, and North America.

Reactions to the Reports

From Scientists

The first report came out during a summer with a lot of extreme weather in the Northern Hemisphere. There was a big heat wave in Western North America, flooding in Europe, heavy rain in India and China, and wildfires in many countries. Some scientists said these events showed that the climate models used for the report might have underestimated how severe things would be.

From Political Leaders

After the first report, the EU Vice President, Frans Timmermans, said it's not too late to stop runaway climate change. UK Prime Minister Boris Johnson said the next ten years will be very important for the planet's future.

Rick Spinrad, who leads the US's National Oceanic and Atmospheric Administration, said his agency would use the report's findings to help communities get ready for and adapt to climate change.

John Kerry, the US special envoy for climate, said about the second report: "We have seen the increase in climate-fuelled extreme events, and the damage that is left behind – lives lost and livelihoods ruined. The question at this point is not whether we can altogether avoid the crisis – it is whether we can avoid the worst consequences."

From Groups and Activists

Swedish climate activist Greta Thunberg said the first report "confirms what we already know from thousands [of] previous studies and reports – that we are in an emergency."

Environmentalist Inger Andersen commented: "Nature can be our saviour... but only if we save it first."

From the United Nations

The Secretary-General of the UN, António Guterres, called the first report a "code red for humanity." After the second report, he called it "an atlas of human suffering and a damning indictment of failed climate leadership." He also said that the third report showed "a litany of broken climate promises [by policy makers]." He urged for more action, saying, "Climate activists are sometimes depicted as dangerous radicals. But, the truly dangerous radicals are the countries that are increasing the production of fossil fuels."

Synthesis Report: The Big Summary

The final summary report, which brings together all the information from the three working groups, was completed in March 2023. It includes a summary for leaders and will be used as a key document for the 2023 United Nations Climate Change Conference (COP28) in Dubai.

This report gives advice for both short-term and long-term actions. It states that the main reason for global warming is the increase in carbon dioxide emissions. It says that it's very likely the world will go above 1.5 degrees Celsius of warming under scenarios with higher emissions.

The panel released a longer report, a summary for leaders, a presentation, and a short "Headline Statements" document. Some key statements include:

• "Human activities, mainly from releasing greenhouse gases, have clearly caused global warming. The global temperature reached 1.1°C above 1850–1900 levels between 2011 and 2020. Greenhouse gas emissions continue to rise, with different countries and people contributing unevenly due to unsustainable energy use, land use changes, lifestyles, and how things are produced and consumed."
• "Continued greenhouse gas emissions will lead to more global warming. The best guess is that we will reach 1.5°C in the near future in the scenarios we looked at. Every bit of global warming will make many dangers worse. Big, fast, and lasting cuts in greenhouse gas emissions would clearly slow down global warming within about twenty years, and also change the air's makeup within a few years."
• "Climate change is a threat to human well-being and the health of our planet. There is a quickly closing window of opportunity to create a livable and sustainable future for everyone."

Society and Culture

Early Information Sharing

During the making of the reports, a small group of scientists shared some information early from the Working Group III report (Mitigation of Climate Change). They did this because they were concerned that governments might make the official summaries less strong. These scientists wanted to make sure the important messages were heard clearly. The early information suggested that humanity needs to cut greenhouse gas emissions by 50% by 2030 and completely by 2050 to limit warming to 1.5 degrees Celsius. This would require big changes in how we live and how our economies work.

Including Diverse Voices

Like other big international science projects, the IPCC has been criticized for not including enough scientists from the Global South (developing countries). For example, there are challenges that make it harder for African scientists to participate, such as requirements for publishing research and being an expert reviewer before joining the main group of contributors.