“…Such detection and attribution may also be confounded, as pointed out by Boyd [], by shifting baseline conditions due to natural climate variability and the influence of climate change on climate variability [ Boyd et al ., ]. Examples of shifting baselines driven by natural variability include warming [El Niño and La Niña; Sumner , ], cooling (another large‐scale eruption akin to Pinatubo or El Chichón), cryptic shifts in natural carbon sinks [Southern Ocean, Landschützer et al ., ], or oxygen inventories [ Chan et al ., ], which in some cases could negate or exacerbate the signatures from geoengineering [either SRM or CDR, see Boyd and Bressac , ]. Bürger and Cubasch [] have recently employed data sets from CMIP5 [ Taylor et al ., ] and GeoMIP [ Kravitz et al ., ] to reveal difficulties in detecting and attributing (years to decades) the climatic effects of geoengineering against a background of “nonstationary” gradual warming.…”