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Title: What caused Earth's record-low reflectivity in 2023?
Plain: In 2023 Earth reflected less sunlight than ever measured, mainly because of fewer low clouds, which added to the record heat. Whether this came from cleaner ship exhaust, natural swings, or a cloud response to warming is unclear.
Precise: Satellite radiation budgets show a record-low planetary albedo in 2023 driven by reduced low cloud cover, contributing roughly 0.2 K to the global temperature anomaly (Goessling and coauthors, 2024). Separate the contributions of reduced sulfate aerosol (including 2020 shipping fuel rules), internal variability and a low-cloud feedback. An answer is a quantitative attribution with uncertainties.
Settled by: Ensemble attribution experiments with observed aerosol emissions and nudged circulation compared against satellite cloud and radiation records.
Kind: phenomenon
Answer type: mechanism
References: (empty)
Literature status: open
Status note: Diagnosed in a 2024 study (arXiv:2405.19986) with the cause left open; a 2025 comment debated the interpretation.
Posed since: (empty)