This article documents events, research findings, scientific and technological advances, and human actions to measure, predict, mitigate, and adapt to the effects of global warming and climate change—during the year 2023.
Summaries
6 February: U.N. Secretary-General António Guterres said "I have a special message for fossil fuel producers and their enablers scrambling to expand production and raking in monster profits: If you cannot set a credible course for net-zero, with 2025 and 2030 targets covering all your operations, you should not be in business." 20 March – The final synthesis of the IPCC Sixth Assessment Report is published. It summarises the state of knowledge relating to climate change with assessed levels of confidence. Conclusions in the summary for contemporary policy-makers include that the extent to which both current and future generations will be impacted depends on choices now and in the near-term, with "high confidence" that policies implemented by the end of 2020 are "projected to result in higher global GHG emissions in 2030 than emissions implied by NDCs" and would fail to meet global climate goals. 6 September: U.N. Secretary-General António Guterres said "Our planet has just endured a season of simmering — the hottest summer on record. Climate breakdown has begun." 24 October: BioScience'''s "2023 state of the climate report" stated that "we must shift our perspective on the climate emergency from being just an isolated environmental issue to a systemic, existential threat". 27 December: Inside Climate News summarized the year: "The push and pull of progress and catastrophe made 2023 one of the most discordant—and consequential—years for the world's climate. ... In 2023, clean energy progress and the horrors of a radically warming climate fought almost to a draw."
Measurements and statistics
3 January: the National Snow and Ice Data Center reported that Antarctic sea ice extent stood at the lowest in the 45-year satellite record—more than 500,000 square kilometers (193,000 square miles) below the previous record (2018), with four of the five lowest years for the last half of December having occurred since 2016. 26 January: Bloomberg NEF's "Energy Transition Investment Trends" report estimated that, for the first time, energy transition investment matched global fossil fuel investment—$1.1 trillion in 2022, including China with $546 billion, the US with $141 billion, and the EU if treated as a bloc, $180 billion. 3 April: An unexplained rise of emissions of five chlorofluorocarbons (CFCs), successfully banned by the Montreal Protocol of 1989, is reported in Nature Geoscience. Their climate impact in 2020 is roughly equivalent to that of the CO2e from Denmark in 2018. Reported 10 May: Drax Electric Insights reported that in the first three months of 2023, Britain's wind turbines generated more electricity (32.4%) than gas-fired power stations (31.7%) for the first time. 18 May: a study published in Science reported that more than 50% of freshwater lakes and reservoirs lost volume from 1992 to 2020.
31 May: an international study in Nature, using modelling and literature assessment, codifies, integrates into and quantifies "safe and just Earth system boundaries" (ESBs) with the context of Earth system stability and minimization of human harm. They expand upon earlier boundary frameworks by incorporating concepts such as intra- and intergenerational justice, propose that their framework may better enable a quantitative foundation for safeguarding the global commons, and report many of the ESBs are already exceeded. 15 June: the Copernicus Climate Change Service said that for 11 days, global surface air temperatures had risen to above pre-industrial levels for the first time—the limit aspired to in the 2015 Paris Agreement—the rise occurring near the beginning of an El Niño warming phase. 24 July: the National Data Buoy Center recorded an unprecedented temperature of at a depth of in Florida Bay, Florida, US, raising concerns about catastrophic coral bleaching. 8 August: in coastal Iran, the heat index reached . 29 August: an International Renewable Energy Agency (IRENA) publication stated that ~86% (187 GW) of renewable capacity added in 2022 had lower costs than electricity generated from fossil fuels. 31 August: an article in Geophysical Research Letters reported a March 2022 "unprecedented heatwave" in the Antarctic reaching above average—the largest temperature anomaly ever recorded globally—attributed 2 °C of the increase to global warming, and projected possible heatwaves of an additional warmer by 2100. 29 September: a study published in Nature Communications estimated the global costs of extreme weather attributable to climate change in the last twenty years to be US$143 billion per year, 63% of which is due to human loss of life. 19 October: a study published in Scientific Reports said that the number of North Atlantic tropical cyclones that intensify from a Category 1 into a major hurricane within 36 hours, has more than doubled from 1971–1990 to 2001–2020. 20 November: the Copernicus European Centre for Medium-Range Weather Forecasts reported that 17 November was the first day that the global average surface temperature exceeded pre-industrial levels by more than 2 °C. 29 November: a study published in The BMJ concluded that about 5.13 million excess deaths per year globally are attributable to ambient air pollution from fossil fuel use.
5 December: the annual Global Carbon Budget study finds fossil emissions are still rising when if they stayed the same, the 50% likelihood to limit global warming to 1.5 °C would be exceeded around 2031. 8 May 2024 (reported): Ember reported that for the first time, renewable energy generated a 30% of global electricity in 2023. 28 August 2024: a study published in the journal Nature concluded that the June–September 2023 Canadian wildfires caused carbon emissions that exceeded annual fossil fuel emissions of all nations except India, China and the US. 10 September 2025: a study published in Nature attributed 3,400–7,400 acute deaths in North America and 37,800–90,900 chronic deaths in North America and Europe to PM2.5 (fine particulate matter) exposure from the 2023 Canadian wildfires.
Natural events and phenomena
7 February: a study published in Nature Communications concluded that 15 million people globally are exposed to impacts from potential glacial lake outburst floods (GLOFs), more than half being from India, Pakistan, Peru, and China. Climate change has intensified glacial ice melt and expanded glacial lakes. 13 February: a study published in the Proceedings of the National Academy of Sciences reported that increasing abundance of a thermotolerant symbiotic alga hosted by corals has facilitated maintenance of high coral cover after three mass coral bleaching events, suggesting that future reefs might maintain high cover for several decades, albeit with low diversity and provided that other stressors are minimized. 2 March: a study published in Science said that boreal fires, typically accounting for 10% of global fire emissions, contributed 23% in 2021, by far the highest fraction since 2000. 2021 was an abnormal year because North American and Eurasian boreal forests synchronously experienced their greatest water deficit. 13 March: a study published in Nature Water found that total intensity of extreme events (droughts and pluvials (rainfall events)) is strongly correlated with global mean temperature, and concluded that continued warming of the planet will cause more frequent, more severe, longer and/or larger of such extreme events, and that "distortion of the water cycle... will be among the most conspicuous consequences of climate change". 15 February: Two joint studies by the British Antarctic Survey and the US Antarctic programme finds that glaciers on the icy continent may be more sensitive to changes in sea temperature than previously thought. Researchers used sensors and an underwater robot beneath the Thwaites glacier to study melting. One day earlier, a new record low Antarctic sea ice extent is reported by the National Snow and Ice Data Center in the US, beating the previous record set a year earlier. 29 March: a study published in Nature concluded that under a high-emissions scenario, abyssal warming is set to accelerate over the next 30 years, and that meltwater input around Antarctica drives a contraction of Antarctic Bottom Water (AABW), opening a pathway that allows warm circumpolar deep water greater access to the continental shelf and results in warming and aging of the abyssal ocean. The study described the "critical importance of Antarctic meltwater in setting the abyssal ocean overturning, with implications for global ocean biogeochemistry and climate that could last for centuries". On 25 May, observational evidence for problematic fast slowdown of the Antarctic bottom water current is presented in Nature Climate Change. 7 April: citing reduced air density caused by global warming, a study published in the Bulletin of the American Meteorological Society estimated global warming has enabled more than 500 excess home runs in Major League Baseball since 2010, and projected hundreds more in this century, explaining that "even the elite billion-dollar sports industry is vulnerable to unexpected impacts" of global warming. 5 June: a study published in Current Biology estimated that fungi can fix (remove from the atmosphere) the equivalent of ~36% of global fossil fuel Greenhouse gas emissions. 8 June: NOAA published an "ENSO update" declaring that "El Niño is here", estimating the odds of it becoming a strong event (56%), at least a moderate event (84%), and "fizzling out" (4-7%).
11 June: Fluchthorn, a mountain between Switzerland and Austria, experienced a landslide of and a loss of in height, that has been attributed to melting of permafrost. 20 June (reported): the Panama Canal is experiencing its lowest rainfall since inception, lowering water levels and requiring restrictions for some vessels to limit their cargo by about 25% to maintain a safe draft and avoid running aground. 4 July: the WMO formally declared "onset of El Niño conditions", projecting it to be "at least of moderate strength". 11 July: a study of Chicago structures published in Communications Engineering found that in urban settings, subsurface heat islands caused by global warming cause significant deformations and displacements that may be "incompatible with the operational requirements of civil structures". 28 July: Yale Environment 360 reported that, adding to ongoing climate change's dominant warming influence, additional factors contributing to current temperature increases include: (1) 2022 eruption of an underwater volcano near Tonga, vaporizing large amounts of sea water and contributing an estimated of warming, (2) solar radiance increasing towards its ~2025 11-year peak when it may contribute of warming, and (3) the Pacific Ocean entering its El Niño phase, projected to contribute of warming. 23 August (reported): the Panama Canal experienced an unprecedented dry season causing a decline in water levels and prompting canal administrators to limit daily vessel passages from 36 to 32, and forcing some ships to carry up to 40% less cargo to avoid hitting the bottom. 24 August: a study published in Nature Communications concluded that tropical cyclone rapid intensification (RI) events in offshore areas within of coastlines, tripled in frequency from 1980 to 2020. 8 September (date of report): for the first time in recorded history, all seven tropical ocean basins saw cyclones/hurricanes reach Category 5 strength in the same year.