“Any further delay in global action to slow climate change and adapt to its impacts will miss a brief and rapidly closing window of opportunity to secure a liveable and sustainable future for all”.

So concludes the United Nations’ Intergovernmental Panel on Climate Change (IPCC) sixth assessment report (AR6), the global authority on the Climate Crisis, issuing a call to arms ahead of the COP30 summit to be held in Belém in Brazil in a few months’ time.

Time is running out fast, warns the IPCC, as the Climate Crisis accelerates faster than scientists predicted and is already approaching, or passed, the nine climate tipping points that will lead to irreversible damage. This summer alone Europe has been wracked by an intense heatwave that continues to break temperature records on a daily basis and has already killed an estimated 2,500 people, according to reports.

The AR6 is the direst report the IPCC has ever released: the threat that climate change poses to both human well-being and the planet’s ecosystems is now “unequivocal”.

Among the findings, the IPCC concludes:

• Climate change has already caused major and growing irreversible damage to ecosystems.
• At 1.5C, 9% (up to 14%) of species face very high extinction risk; 10% (18%) at 2C; 12% (29%) at 3C.
• Around 3.3 to 3.6bn people live in highly climate-vulnerable areas.
• Climate change is worsening humanitarian crises and driving displacement, especially in small islands.
• Extreme weather has caused acute food and water insecurity for millions, especially in Africa, Asia, the Americas, small islands and the Arctic.
• By 2100, 50-75% of the global population may face deadly heat and humidity.
• Food production and access will come under growing strain, especially in vulnerable regions.
• Ill health and premature deaths from climate impacts will rise significantly.

Carbon Brief, in an analysis of the report, highlights the unprecedented clarity with which the authors outline current and projected impacts of global warming.

“Climate change has already caused substantial damages and increasingly irreversible losses, in terrestrial, freshwater and coastal and open ocean marine ecosystems,” Carbon Brief says.

The data paint a dire picture. Between 3.3bn and 3.6bn people already live in areas considered highly vulnerable to climate change. If global warming surpasses 1.5C – even temporarily – both human and natural systems will face “additional severe risks”, including those that are “irreversible”. As bne IntelliNews reported in “Countdown to disaster”, the planet already passed a 1.5°C increase last year or this year and will hit 2°C by about 2036. The IPCC itself has already said both these targets are missed and the planet is on course to see a 2.7C-3.1C increase in temperatures, as the best case scenario, which will have cataclysmic consequences.

The likelihood of species extinction also escalates with temperature rises. According to the report, at 1.5°C warming, 9% of terrestrial and freshwater species are at high risk of extinction – a figure that increases to 29% at 3°C.

Carbon Brief notes the particular vulnerability of small island states, where climate change is “increasingly driving displacement” and exacerbating humanitarian crises. Food security is under growing threat and water insecurity has also intensified due to extreme weather events, especially in parts of Africa, Asia, Central and South America, and the Arctic.

Adaptation efforts have been observed globally, the report finds, but they remain “fragmented, small in scale and incremental”. Crucially, “gaps exist between current levels of adaptation and levels needed to respond to impacts and reduce climate risks.” These gaps, Carbon Brief reports, are due in part to a “mismatch between the estimated costs of adaptation and the level of finance allocated to it.”

Government action to deal with the crisis is increasingly misdirected, according to the PICC. Carbon Brief reports the “overwhelming majority” of climate finance continues to be directed at mitigation rather than adaptation.

“Implementing adaptation and mitigation actions together with Sustainable Development Goals helps to exploit synergies, reduce trade-offs and makes all three more effective,” the authors argue.

The report was finalised during an online approval session in February, held under the shadow of Russia’s invasion of Ukraine. Some Ukrainian delegates were forced to withdraw and take shelter during the discussions. One delegate reportedly said, “We will not surrender in Ukraine and we hope the world will not surrender in building a climate-resilient future.”

“Since IPCC AR5, human influence on the Earth’s climate has become unequivocal, increasingly apparent, and widespread,” the report concludes with high confidence.

United Nations Secretary-General António Guterres described the report as “an atlas of human suffering and a damning indictment of failed climate leadership.” He called on G20 nations to “dismantle their coal fleets”, warning that the continued use of fossil fuels “makes the global economy and energy security vulnerable to geopolitical shocks and crises”.

The International Court of Justice (ICJ) ruled in July that a sustainable environment is a human right and that governments have a legal obligation to contain and reduce emissions. However, the world’s top court has no jurisdiction over governments and its rulings are non-binding.

Amongst the rest of Carbon Briefs analysis of the AR6 are the following conclusion:

Land and freshwater ecosystems

• Substantial Damages: Climate change has caused significant and irreversible losses to land ecosystems globally, with impacts larger than previously estimated.
• Species Shifts: Half of studied land species have shifted geographic ranges due to regional climate changes, altering ecosystem composition and potentially increasing invasive species spread.
• Phenology Changes: Climate change has likely affected animal life event timing (e.g., breeding, migration).
• Wildlife Diseases: Increased temperatures and extreme weather have driven new disease emergence, including vector-borne diseases in Arctic regions and forest insect pests in northern regions.
• Extinctions: Climate change likely contributed to the extinction of the white ringtail possum, Bramble Cays Melomys and Golden toad.
• Biome Shifts: Increased frequency of biome shifts (e.g., alpine forests moving upward, trees encroaching into grasslands) since 2014.
• Wildfires: Human-caused climate change doubled wildfire-burned areas in the western US since the 1980s; global fire seasons are 25% longer.
• Tree Die-offs: Climate-driven droughts potentially caused 100 cases of mass tree mortality globally.
• Carbon Storage: Land stores ~3.5 trillion tonnes of carbon, but future warming threatens ecosystem stability.
• Extinction Risks: At 1.5°C warming, 9% of species face high extinction risk, rising to 15% at 5°C; pollinators, amphibians and flowers are most vulnerable at mid-level warming.
• Tipping Points: Frequent extreme events push sensitive species toward irreversible ecological changes.

Marine Ecosystems

• Ocean Changes: Human-driven ocean warming, acidification, and deoxygenation alter marine ecosystems from microbes to mammals, with unprecedented conditions over millennia.
• Species Shifts: Marine species shift poleward at ~60 km/decade since the 1950s; timing of biological events (e.g., fish spawning) altered.
• Marine Heatwaves: High confidence in mass mortality events among foundational species (e.g., kelp, corals) due to heatwaves.
• Coral Reefs: At >1.5°C, coral reefs face erosion outpacing growth, with acidification reducing coral cover and diversity.
• Hypoxia: Low oxygen zones expand, reducing fish habitat (e.g., 15% loss for tuna) and ecosystem function.
• Fisheries Impact: Warming reduces commercial fish yields, exacerbated by overfishing; tropical regions face significant declines.
• Biodiversity Loss: Medium confidence in increased extinction risks at <2°C, particularly for thermally sensitive polar and deep-sea species.
• Adaptation Limits: Ecosystems like mangroves and saltmarshes face high risks from sea-level rise even under low-emission scenarios.

Water Systems

• Water Scarcity: ~50% of the global population faces severe water scarcity at least one month/year.
• Floods and Droughts: Since the 1970s, 44% of disasters were flood-related; droughts caused 34% of disaster deaths, especially in Africa.
• Glacier Loss: Glaciers lost >0.5 m water equivalent/year over the past 20 years, impacting high mountain and polar communities.
• Snow Cover: Northern hemisphere snow cover is decreasing across all months.
• Streamflow Increase: High-latitude rivers show increased streamflow due to warming.
• Groundwater Decline: 21^st century demand (e.g., irrigation) has depleted groundwater in many regions.
• Soil Moisture: Human-caused changes affect agriculture and extreme weather severity.
• Future Risks: At 2°C, 3bn people face water scarcity; at 4°C, 4bn. Flood damages could be 4-5 times higher at 4°C vs. 1.5°C.
• Agriculture Impact: Droughts from 1983-2009 caused yield losses costing ~$166bn globally.

Food and Agriculture

• Food Security: Climate change hinders meeting global nutritional needs, straining agriculture, fisheries and forestry.
• Sudden Losses: Increased frequency of sudden food production losses due to extreme events since the mid-20th century.
• Crop Yields: ~10% yield reduction in major crops (1850–2010); 2°C warming will cause large negative impacts, with one-third of suitable land becoming unsuitable at high emissions.
• Nutrient Loss: Elevated CO2 reduces crop nutrients (e.g., protein, iron) by 5-10%.
• Pest Expansion: Crop pests and pathogens expanded poleward at 2.7 km/year since 1960, increasing future stress.
• Livestock: Heat stress reduces livestock productivity; 2°C warming may cut global livestock numbers by 7-10% by 2050.
• Fisheries: 4% reduction in fish yields (1930-2010); tropical regions face severe declines, impacting nutrition in low-income countries.
• Multi-Breadbasket Failures: Limited evidence of rising synchronized crop failures, with medium confidence in increasing risks.
• Vulnerable Groups: Women and Indigenous groups face higher vulnerability to food insecurity.

Cities

• Urban Growth: By 2050, 2.5bn more people will live in urban areas, 90% in Asia and Africa.
• Heat Islands: Urban areas face doubled heat stress by 2050; low-income communities are more exposed.
• Water Scarcity: One-third of major cities could exhaust water resources by 2050 due to urban expansion and changing rainfall patterns.
• Coastal Flooding: ~896mn people in low-lying cities face increased coastal flood risks by 2050 due to sea-level rise; $7–14 trillion in coastal infrastructure is at risk by 2100.
• Air Pollution: 95% of urban populations exceed WHO PM2.5 guidelines; African cities may become most polluted by 2050.
• Governance Gaps: Inequality and poor governance widen adaptation challenges, exposing more people to climate risks.