Poleward shift of Circumpolar Deep Water threatens the East Antarctic Ice SheetHerraiz-Borreguero, Laura; Naveira Garabato, Alberto C.
doi: 10.1038/s41558-022-01424-3pmid: N/A
Future sea-level rise projections carry large uncertainties, mainly driven by the unknown response of the Antarctic Ice Sheet to climate change. During the past four decades, the contribution of the East Antarctic Ice Sheet to sea-level rise has increased. However, unlike for West Antarctica, the causes of East Antarctic ice-mass loss are largely unexplored. Here, using oceanographic observations off East Antarctica (80–160° E) we show that mid-depth Circumpolar Deep Water has warmed by 0.8–2.0 °C along the continental slope between 1930–1990 and 2010–2018. Our results indicate that this warming may be implicated in East Antarctic ice-mass loss and coastal water-mass reorganization. Further, it is associated with an interdecadal, summer-focused poleward shift of the westerlies over the Southern Ocean. Since this shift is predicted to persist into the twenty-first century, the oceanic heat supply to East Antarctica may continue to intensify, threatening the ice sheet’s future stability.
Definitions and implications of climate-neutral aviationBrazzola, Nicoletta; Patt, Anthony; Wohland, Jan
doi: 10.1038/s41558-022-01404-7pmid: N/A
To meet ambitious climate targets, the aviation sector needs to neutralize CO2 emissions and reduce non-CO2 climatic effects. Despite being responsible for approximately two-thirds of aviation’s impacts on the climate, most of aviation non-CO2 species are currently excluded from climate mitigation efforts. Here we identify three plausible definitions of climate-neutral aviation that include non-CO2 forcing and assess their implications considering future demand uncertainty, technological innovation and CO2 removal. We demonstrate that simply neutralizing aviation’s CO2 emissions, if nothing is done to reduce non-CO2 forcing, causes up to 0.4 °C additional warming, thus compromising the 1.5 °C target. We further show that substantial rates of CO2 removal are needed to achieve climate-neutral aviation in scenarios with little mitigation, yet cleaner-flying technologies can drastically reduce them. Our work provides policymakers with consistent definitions of climate-neutral aviation and highlights the beneficial side effects of moving to aircraft types and fuels with lower indirect climate effects.