IPCC 2022: Science and key takeaways from the WGII report

There is a narrowing window of opportunity for us to cut greenhouse gas emissions and adapt to climate change to secure a liveable future, the Working Group II’s (WGII) contribution to the IPCC Sixth Assessment Report states.

Humans must urgently slash greenhouse gas emissions if we are to avoid the worst impacts of climate change. While this is crucial to slow down or prevent the widescale destruction of the natural world, emissions cuts are not enough. Humans and nature must also adapt and do so faster than they have ever done before.

This is according to the WGII’s contribution to the IPCC Sixth Assessment Report (AR6). This instalment of the report, “Climate Change 2022: Impacts, adaptation and vulnerability”, was finalised on 28 February 2022. It outlines how climate change is affecting the world and what we must do to avoid its worst impacts.

The IPCC Working Group I’s (WGI) contribution to the report was published in August 2021. This set out the scientific proof that human activity is unequivocally driving climate change. The United Nations’ Secretary-General, António Guterres, said that report is “a code red for humanity”. Working Group III’s contribution will be released in April 2022.

Bushfires are another extreme weather event that will increase in frequency.

A bushfire rages in a forest

Why is the WGII contribution to the Sixth Assessment Report scientifically significant?

The IPCC 2022 WGII contribution to the Sixth Assessment Report is significant because it is the most comprehensive review of climate change’s impacts on the world to have ever been conducted. It covers the most up-to-date, peer-reviewed science.

Approximately 270 leading scientists from 67 countries worked on finalising the WGII contribution to the IPCC Sixth Assessment Report. They were selected through a rigorous process to ensure a mix of scientists from different parts of the world. The report references over 34,000 scientific papers, and it went through a thorough drafting and review process over the course of several years.

What kind of impacts is climate change already causing?

Human-caused climate change has already had devastating impacts on both nature and people, the WGII contribution to the IPCC Sixth Assessment Report states. This includes more extreme and frequent weather events. Often, this impacts the most vulnerable people and ecosystems, and it is now pushing them beyond their natural adaptation capacity.

Climate change is causing the widespread deterioration of ecosystems, in addition to shifts in seasonal timing. About half of the species assessed in the WGII’s contribution to the IPCC Sixth Assessment Report have moved towards the poles or to higher land, due to changes to ecosystems. Extreme heat is driving the loss of hundreds of species and is causing mass death events. Some losses are irreversible, like the extinction of certain species. Other changes resulting from retreating glaciers and permafrost thaw are almost irreversible.

The impacts of climate change on some ecosystems will be increasingly difficult to reverse if the world warms above 1.5°C during this century. This includes polar, mountain and coastal ecosystems. This, in part, will be due to ice-sheet and glacier melt, and rising sea levels. Warming by 1.5°C will also severely limit humanity’s resilience to climate change. On the other hand, warming of 2°C could make resilience impossible for some regions.

Every fraction of a degree matters, and every bit of warming makes our planet more unsafe. But, every action taken to limit emissions brings us closer to a safer future.

Key findings of the IPCC 2022 WGII report

  • Human-caused climate change has already caused widescale damage to natural ecosystems and people. Climate change is driving more frequent, intense and extreme weather events. These events are affecting people’s physical and mental health. They are also threatening the food and water security for millions of the world’s most vulnerable people.
  • Adaptation to climate change is essential. But some of humanity’s adaptation efforts have not been successful. In fact, some of these efforts have actually reduced our ability to adapt to climate changes. This is happening, in part, through poor planning and weak mitigation efforts. This is also happening due to adaptation plans that are actually damaging nature.
  • Climate and weather extremes, like droughts and fires, have widespread impacts on ecosystems. They are also affecting people, settlements and infrastructure. There has been an increase in heat-related deaths in humans, coral bleaching and dying coral reefs. There has also been a rise in trees dying due to droughts.
  • Human-caused climate change has substantially damaged land, freshwater and marine ecosystems. This has negative socio-economic consequences.
  • Food and water insecurity, caused by extreme weather and other climate impacts, are already causing an increase in malnutrition for vulnerable people. This is especially the case for Indigenous Peoples, pregnant women, children and the elderly. Approximately half of the world’s population is currently experiencing severe water scarcity for at least some part of the year. This is due to climatic and non-climatic reasons.
  • More people are becoming sick from food- and water-borne illnesses, while diseases affecting humans and animals are developing in new areas.
  • Climate change is also affecting infrastructure, cities and settlements. Heatwaves are intensifying in cities, aggravating air pollution and affecting the functioning of infrastructure. Again, this impacts the most economically and socially marginalised in society.
  • Climate change will likely cause humanitarian crises, as climate and weather extremes drive migration and displacement.
Ice-sheet melts are a direct consequence of climate change.

An ice-sheet melts

What are the costs of extreme weather events, as defined by current climate science?

The WGII’s contribution to the IPCC Sixth Assessment Report sets out the costs of warming in the near, medium and long term, should we breach warming of 1.5°C. The costs of this rise in temperature, including increased extreme weather events and hotter weather, will be severe. It will result in economic costs, compromised food and water security, health impacts and loss of biodiversity.

Near term impacts

If we limit warming in the near term, we could substantially limit some of the expected losses and damages attributed to climate change. However, we will not be able to limit them all.

Warming in the near term will increase the frequency, severity and duration of extreme weather events. Extreme climate and weather events impact food and water security. For example, climate change has likely slowed the growth of agricultural production over the last 50 years. Oceanic warming and ocean acidification have also negatively affected food production from fisheries in some regions. This food and water insecurity is compounded by a decrease in diet diversity, especially in vulnerable communities. This means a greater risk of malnutrition.

Furthermore, many water- and land-based ecosystems will be at “very high risk” of biodiversity loss, including forests and undersea ecosystems. Sea levels will rise, encroaching on coastal settlements and increasing the risk of flooding.

There are regional differences in how these impacts will affect people in the near term. Indeed, vulnerable people, coastal and Arctic regions, and the developing world are at the highest risk.

Medium to long term impacts

Breaching 1.5°C radically increases the risk of harm to humans and nature.

The WGII report identifies 127 key climate risks, including the risk of biodiversity loss, health impacts and extinction. It establishes that the impacts for these risk areas are “up to multiple times higher” than currently observed. However, the rate of climate change and its impacts “depend strongly” on what we do to adapt to climate change and mitigate against its worst effects now.


Warming of over 1.5°C will likely cause the release of more greenhouse gases, as Earth’s carbon sinks are compromised. Wildfires, mass loss of trees and the drying of peatlands will all continue and accelerate. Permafrost thawing will increase, releasing large amounts of greenhouse gases that have been trapped underground for centuries. In turn, this will drive global temperatures higher.

Risk of extinction

The risk of extinction of many species will increase with every increment of warming. Depending on the levels of warming, up to nearly 50 per cent of species are at risk of extinction this century. On land, 3 to 14 per cent of species assessed will likely face a high rate of extinction at global warming levels of 1.5°C. This increases to 3 to 18 per cent at 2°C of warming, rising with every fraction of a degree until 3 to 48 per cent of species at 5°C.

Food and water

Water availability will decline, further impacting food security, while water-related hazards will increase. Climate change will put pressure on food production and access to food, especially in vulnerable regions. This will increase the risk of malnutrition in the developing world – a risk that will rise with every bit of warming.


There will be an increase in diseases and premature deaths, including deaths from heatwaves. In fact, climate change is already causing more people to die or get sick from extreme heat, while the number of diseases in animals and humans is increasing. Furthermore, higher temperatures and an increase in rainfall and flooding will mean that more people will get sick from diarrheal diseases, like cholera. Cardiovascular and respiratory diseases will increase as an increasing number of people become exposed to wildfire smoke, atmospheric dust and allergens.

There will be severe mental health costs, and these are already being seen. Trauma from weather and climate extreme events, in addition to the loss of livelihoods and culture due to increasing temperatures, affects peoples’ mental health. Extreme weather has also disrupted health services in some places.

Low-lying and coastal areas

Moreover, there will be significant impacts on cities and settlements, especially in low-lying and coastal areas. Approximately one billion people in low-lying areas are at risk from coastal climate hazards, like sea level rise.

There will be a 20 per cent increase in the population potentially exposed to 100-year coastal flooding if global sea levels rise by 0.15 metres above 2020 levels. This is an existential threat for some Small Islands and low-lying areas.


There will also be significant economic damages, which will increase as warming levels rise. Sectors that are especially exposed to climate change, like agriculture, forestry, fishery, energy and tourism, have already been negatively affected by extreme weather, flooding and fires. Industries relying on outdoor labour productivity are also suffering, as workers grapple with high temperatures.

It is difficult to approximate global estimates for what climate change will cost us economically. However, there are global assets worth at least USD $12.7 trillion in areas at risk of coastal flooding. With every increment of warming, the cost of maintaining and reconstructing damaged urban infrastructure increases.


Cyclones, droughts, flooding and sea level rise will drive displacement as people flee from extreme weather, especially in regions that cannot adapt to climate change. While the WGII report states that this is not likely to be the cause of violent conflict, it will place considerable pressure on urban centres, infrastructure and food and water supplies, as more people move inland or to higher ground.

Some of these impacts will be irreversible – even if warming is reduced – particularly for the polar regions, mountainous regions and coastal ecosystems. At 2°C of warming, it is probable that many ecosystems will not be able to adapt to climate change at all.

What action can we take now?

Many of our efforts to adapt to climate change and cut greenhouse gas emissions have been unsuccessful so far. As a result, the world is not becoming more resilient to climate change, the WGII contribution to the IPCC Sixth Assessment Report indicates. This is especially the case if greenhouse gas emissions do not urgently decline. While every increment of warming matters, we are even less likely to withstand the worst impacts of climate change if the world warms by more than 1.5°C in the near term.

The decisions humans take in the subsequent decades will be crucial to determining whether we can withstand the climate changes to come. Our ability to survive climate change will depend not only on emissions cuts but also on inclusive governance. Furthermore, we must ensure that there are enough human and technological resources for everyone.

Adaptation and mitigation

In order to adapt to climate change and mitigate its worst impacts, we have to find ways to develop in a climate-resilient way. It is still possible for us to do this. However, there is a “rapidly narrowing window of opportunity”, the report states. Moreover, it is not easy for all countries to adapt in the same way, especially areas with gaps in development and limited resources.

This means that governments must make “inclusive development choices” when planning and creating policy – prioritising equality, justice and reducing the risk of climate impacts. This requires inclusive governance, access to technology and rapidly scaled-up finance for all and capacity building of governments. The private sector and civil society can play a key role here.

Safeguarding biodiversity and ecosystems is fundamental to climate-resilient development. We need to conserve between 30 to 50 per cent of Earth’s land, freshwater and ocean areas if we are to ensure the resilience of biodiversity and ecosystem services worldwide, the report states. We must protect and restore ecosystems to ensure that the biosphere is resilient and avoid damaging ecosystems with poorly-designed solutions in the process. However, there is a limit to how much this can do, especially if emissions continue.


The WGII contribution to the Sixth Assessment Report cautions against “maladaptation”. Maladaptation happens when adaptation efforts focus on the short term and exist in isolation. For example, seawalls effectively reduce impacts to people and assets in the short term. However, they can also create lock-ins and increase exposure to climate risks in the long term unless they are integrated into a long-term adaptive plan.

Other examples of maladaptive actions include fire suppression in naturally fire-adapted ecosystems or introducing hard defences against flooding. They only reduce space for natural processes and ecosystems’ resilience to climate change.

As the report notes, the science is now unequivocal. “Climate change is a threat to human well-being and planetary health.” We must move quickly to adapt to climate change and mitigate its worst consequences. Otherwise, we will “miss a brief and rapidly closing window of opportunity to secure a livable and sustainable future for all”.