What caused Earth's record-low reflectivity in 2023?
In plain words
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 statement
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.
What would settle it
Ensemble attribution experiments with observed aerosol emissions and nudged circulation compared against satellite cloud and radiation records.
Status in the literature
Unverified note
Diagnosed in a 2024 study (arXiv:2405.19986) with the cause left open; a 2025 comment debated the interpretation.