2023 summer warmth unparalleled over the past 2,000 years

ESPER, Jan, Max TORBENSON and Ulf BÜNTGEN. 2023 summer warmth unparalleled over the past 2,000 years. Nature. Nature Research, 2024, vol. 631, No 8019, p. 94-97, 11 pp. ISSN 0028-0836. Available from: https://dx.doi.org/10.1038/s41586-024-07512-y.

Basic information

• Original name: 2023 summer warmth unparalleled over the past 2,000 years
• Authors: ESPER, Jan, Max TORBENSON and Ulf BÜNTGEN (276 Germany, belonging to the institution).
• Edition: Nature, Nature Research, 2024, 0028-0836.

Other information

• Original language: English
• Type of outcome: Article in a journal
• Field of Study: 10500 1.5. Earth and related environmental sciences
• Country of publisher: Germany
• Confidentiality degree: is not subject to a state or trade secret
• WWW: URL
• Impact factor: Impact factor: 64.800 in 2022
• Organization unit: Faculty of Science
• Doi: http://dx.doi.org/10.1038/s41586-024-07512-y
• UT WoS: 001260579300001
• Keywords in English: Climate change; Palaeoclimate
• Tags: rivok
• Tags: International impact, Reviewed

Abstract

Including an exceptionally warm Northern Hemisphere summer1,2, 2023 has been reported as the hottest year on record3,4,5. However, contextualizing recent anthropogenic warming against past natural variability is challenging because the sparse meteorological records from the nineteenth century tend to overestimate temperatures6. Here we combine observed and reconstructed June–August surface air temperatures to show that 2023 was the warmest Northern Hemisphere extra-tropical summer over the past 2,000 years exceeding the 95% confidence range of natural climate variability by more than 0.5 °C. Comparison of the 2023 June–August warming against the coldest reconstructed summer in CE 536 shows a maximum range of pre-Anthropocene-to-2023 temperatures of 3.93 °C. Although 2023 is consistent with a greenhouse-gases-induced warming trend7 that is amplified by an unfolding El Niño event8, this extreme emphasizes the urgency to implement international agreements for carbon emission reduction.