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    Indicators of Global Climate Change 2025: annual update of key indicators of the state of the climate system and human influence


    Forster, Piers M., Walsh, Tristram, Smith, Chris, Lamb, William F., Lamboll, Robin, Cassou, Christophe, Hauser, Mathias, Hausfather, Zeke, Lee, June-Yi, Palmer, Matthew D., von Schuckmann, Karina, Slangen, Aimée B. A., Szopa, Sophie, Trewin, Blair, Yun, Jeongeun, Gillett, Nathan P., Jenkins, Stuart, Matthews, H. Damon, Raghavan, Krishnan, Ribes, Aurélien, Rogelj, Joeri, Rosen, Debbie, Zhang, Xuebin, Allen, Myles, Andrew, Robbie M., Atkinson, Chris, Betts, Richard A., Bombelli, Antonio, Burgess, Samantha N., Cheng, Lijing, Claxton, Helen E., Friedlingstein, Pierre, Frölicher, Thomas L., Domingues, Catia M., Gasser, Thomas, Gregory, Catherine H., Hoesly, Rachel M., Huppmann, Daniel, Ishii, Masayoshi, Kadow, Christopher, Karwat, Alexia, Kennedy, John, Killick, Rachel E., Kovilakam, Mahesh V. M., Krummel, Paul B., Lan, Xin, Lamarque, Jean-François, Liné, Aurélien, Martín-Míguez, Belén, Monselesan, Didier P., Morice, Colin, Mühle, Jens, Mussak, Pino, Peters, Glen P., Pirani, Anna, Pongratz, Julia, Rigby, Matthew, Rohde, Robert, Savita, Abhishek, Seneviratne, Sonia I., Smith, Steven J., Taha, Ghassan, Tassone, Caterina, Thorne, Peter, Wells, Christopher, Western, Luke M., van der Werf, Guido R., Wijffels, Susan E., Zecchetto, Marco, Zhong, Junting, Zhang, Xiao-Ye, Masson-Delmotte, Valérie and Zhai, Panmao (2026) Indicators of Global Climate Change 2025: annual update of key indicators of the state of the climate system and human influence. Earth System Science Data, 18 (6). pp. 3889-3933. ISSN 1866-3516

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    Abstract

    In a rapidly changing climate, evidence-based decision-making benefits from up-to-date and timely information. We track twelve key sets of indicators of the state of the climate system, closely following Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment report (AR6) methods, to produce our fourth annual publication. One of the indicators, the Earth’s energy imbalance (EEI) provides a crucial integrative measure of the overall heating of the planet and the pace of climate change – this has more than doubled since the 1976–1995 period. A newly added indicator of temperature extremes, the number of days experiencing marine heatwaves, has more than tripled between 1991 and 2025. For the 2016–2025 decade average, observed warming relative to 1850–1900 was 1.26 [1.13 to 1.36] °C, of which 1.24 [1.0 to 1.5] °C was human-induced. Human-induced warming reached 1.37 °C relative to 1850–1900 in the year 2025, increasing at a rate of 0.27 [0.2–0.4] °C per decade over 2016–2025. This high rate of warming, which matches the all-time high seen last year in the instrumental record, was caused by a combination of greenhouse gas emissions being at an all-time high of 54.6 ± 5.5 GtCO2e yr−1 over the last decade (2015–2024), as well as reductions in the strength of aerosol cooling. Despite this, there is evidence that CO2 emission growth is slowing. The continuation of these annual updates could track decreases or increases in the rate of human influence and climatic changes presented here, reflecting the outcomes of societal choices during the critical 2020s decade. The data presented herein can provide a useful reference point for the drafting of the IPCC seventh assessment report. In total, we employ analysis from over 40 global datasets (https://doi.org/10.5281/zenodo.20499280, Smith et al., 2026a). Future monitoring of these indicators, such as ocean and satellite measurements of the Earth’s energy imbalance, are threatened by geopolitical and public funding decisions. Our ability to consistently track many of the indicators requires the continuity of observation programs and coordination mechanisms, including the Global Climate Observing System (GCOS) program, that enable their effective integration and use.
    Item Type: Article
    Additional Information: This research has been supported by the European Union's Horizon Europe research and innovation programme under Grant Agreement Nos. 820829, 101081395, 101081661, 101137656 and 821003, the H2020 European Research Council (grant no. 951542), the Natural Environment Research Council (NE/X00452X/1) and the Engineering and Physical Research Council (EP/V000772/1). Matthew Palmer, Colin Morice, Rachel Killick and Richard Betts were supported by the Met Office Hadley Centre Climate Programme funded by DSIT. Peter Thorne was supported by Co-Centre award number 22/CC/11103. The Co-Centre award is managed by Research Ireland Northern Ireland's Department of Agriculture, Environment and Rural Affairs (DAERA) and UK Research and Innovation (UKRI), and supported via UK's International Science Partnerships Fund (ISPF), and the Irish Government's Shared Island initiative. June-Yi Lee, Jeongeun Yun, and Alexia Karwat were supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. RS-2024-00416848). Aimée Slangen was supported by the research programme ENW-Vidi (DARSea, project number VI.Vidi.2023.058) funded by the Dutch Research Council (NWO).
    Keywords: Indicators; Global Climate Change 2025; annual update; key indicators; climate system; human influence;
    Academic Unit: Faculty of Social Sciences > Geography
    Faculty of Social Sciences > Research Institutes > Irish Climate Analysis and Research Units, ICARUS
    Item ID: 21733
    Identification Number: 10.5194/essd-18-3889-2026
    Depositing User: ICARUS Geography
    Date Deposited: 11 Jun 2026 14:57
    Journal or Publication Title: Earth System Science Data
    Publisher: Copernicus Publications
    Refereed: Yes
    Related URLs:
    Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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