IPCC AR6 Assessment Report

• Global surface temperature has increased faster since 1970 than in any other 50-year period over the last 2000 years.
• Historical cumulative net CO₂ emissions from 1850 to 2019 were 2400±240 GtCO2 of which more than half (58%) occurred between 1850 and 1989, and about 42% between 1990 and 2019.
• In 2019, atmospheric CO₂ concentrations (410 parts per million) were higher than at any time in at least 2 million years.
• Concentrations of methane (1866 parts per billion) and nitrous oxide (332 parts per billion) were higher than at any time in the last 800,000 years.
• The largest share and growth in gross greenhouse gasses (GHG) emissions occurred in CO₂ from fossil fuels combustion and industrial processes (CO₂ – fossil fuel investment) followed by methane.
• The highest relative growth occurred in fluorinated gases (F-gases).
• Average annual GHG emissions during 2010-2019 were higher than in any previous decade on record.
• In 2019, approximately 79% of global GHG emissions came from the sectors of energy, industry, transport and buildings together, and 22% from agriculture, forestry and other land use (AFOLU).
• Emissions reductions in CO₂ – FFI (fossil fuel investment) due to improvements in energy intensity of GDP and intensity of energy have been less than emissions increases from rising global activity levels in industry, supply, transport, agriculture and buildings.
• Least developed countries and Small Island Developing States have much lower per capita emissions (1.7 tCO₂-eq and 4.6 tCO₂-eq, respectively) than the global average (6.9 tCO₂-eq), excluding CO₂-LULUCF.
• The 10% of households with the highest per capita emissions contribute 34-35% of global consumption-base household GHG emissions, while the bottom 50% contribute 13-15%.
• Increasing weather and climate extreme events have exposed millions of people to acute food insecurity and reduced water security, with the largest adverse impacts observed in many locations and/or communities in Africa, Asia, Central and South America, least developed countries, Small Islands and the Arctic, and globally for Indigenous Peoples, small-scale food producers and low-income households.
• Between 2010 and 2020, human mortality from floods, droughts and storms was 15 times higher in highly vulnerable regions, compared to regions with very low vulnerability.
• Climate change has caused substantial damages, and increasingly irreversible losses, in terrestrial, freshwater, cryospheric, and coastal and open ocean ecosystems.
• Hundreds of local losses of species have been driven by increases in the magnitude of heat extremes with mass mortality events recorded on land and in the ocean.
• Impacts on some ecosystems are approaching irreversibility such as the impacts of hydrological changes resulting from the retreat of glaciers, or the changes in some mountain and Arctic ecosystems driven by permafrost thaw.
• Climate change has reduced food security and affected water security, hindering efforts to meet Sustainable Development Goals.
• Ocean warming and ocean acidification have adversely affected food production from fisheries and shellfish aquaculture in some oceanic regions.
• Roughly half of the world’s population currently experience severe water scarcity for a t least part of the year to due to a combination of climatic and non-climatic drivers.
• Climate and weather extremes are increasingly driving displacement in Africa, Asia, North America, and Central and South America, with small island states in the Caribbean and South Pacific being disproportionately affected relative to their small population size.
• In urban areas, observed climate change has caused adverse impacts on human health, livelihoods and key infrastructure.
• Urban infrastructure including transportation, water, sanitation and energy systems has been compromised by extreme and slow-onset events.

Observed adverse impacts are concentrated among economically and socially marginalized urban residents.

The International Energy Agency reports that in 2024 energy-related CO₂ emissions hit an all-time high of 37.8 Gt CO₂.