Reviews and syntheses: Abrupt ocean biogeochemical change under human-made climatic forcing – warming, acidification, and deoxygenation

Published: Oct. 10, 2023

Abstract. Abrupt changes in ocean biogeochemical variables occur as a result of human-induced climate forcing well those which are more gradual and over longer timescales. These abrupt have not yet been identified quantified to the same extent ones. We review synthesise biogeochemistry under climatic forcing. specifically address carbon oxygen cycles because related processes acidification deoxygenation provide important ecosystem hazards. Since depend also on physical environment, we describe relevant warming, circulation, sea ice. include an overview reversibility or irreversibility marine changes. Important implications for ecosystems discussed. conclude that there is evidence increasing occurrence consequence rising greenhouse gas emissions.

Language: Английский

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No Emergency Brake: Slow Ocean Response to Abrupt Stratospheric Aerosol Injection

Authorea (Authorea), Journal Year: 2023, Volume and Issue: unknown

Published: Sept. 11, 2023

Given the possibility of irreversible changes to Earth system, technological interventions such as solar radiation management (SRM) are sometimes framed possible climate emergency brakes. However, little knowledge exists on efficacy disruptive interventions. To fill in this gap, we perform Community System Model 2 (CESM 2) simulations a SSP5-8.5 scenario which impose either gradual early-century SRM stabilise surface temperatures or rapid late-century cooling, both realised via stratospheric aerosol injection (SAI). While scenarios cool Earth’s surface, find that ocean conditions differ drastically. The rapid-cooling fails dissipate sub-surface heat content (OHC), ends up weaker AMOC state and does not restore an ailing North Atlantic deep convection. Furthermore, weakened mediates response SAI, thus inducing interhemispheric temperature asymmetry. Our results advise caution when considering SAI intervention.

Language: Английский

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Modulation of regional carbon uptake by AMOC and alkalinity changes in the subpolar North Atlantic under a warming climate

Frontiers in Marine Science, Journal Year: 2024, Volume and Issue: 11

Published: April 8, 2024

The slowdown of the Atlantic Meridional Overturning Circulation (AMOC) and associated consequences on ocean carbon uptake could have large implications for Earth's climate system its global cycle. This study analyzes ten Earth System Models from Coupled Model Intercomparison Project Phase 6 (CMIP6) reveals that regional in subpolar North under a high CO 2 emission scenario moderately correlates with decline AMOC at 40°N. transports warm salty subtropical waters to regions. stronger generally exhibit weaker surface warming larger salinity alkalinity. We consider two plausible mechanisms linking uptake: reduction alkalinity diminished subduction. reduces ocean's capacity buffer acids leading reduced uptake. important contribution is unique Atlantic. Diminished convective mixing subduction water can further decrease downward transport anthropogenic carbon, as also shown previous research. centennial trends p are decomposed into four components driven by temperature, salinity, dissolved inorganic revealing both significant contributors. alkalinity-driven essentially follows establishing linkage between decline. Our results indicate changes interplay sequestration ability across late 20 th entirety 21 st century

Language: Английский

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Tipping points in ocean and atmosphere circulations

Published: Dec. 11, 2023

Abstract. In this review, we assess scientific evidence for tipping points in ocean and atmosphere circulations. The warming of oceans, modified wind patterns increasing freshwater influx from melting ice hold the potential to disrupt established circulation patterns. literature provides oceanic Atlantic Meridional Overturning Circulation (AMOC), North Subpolar Gyre (SPG), Antarctic Circulation, which may collapse under warmer ‘fresher’ (i.e. less salty) conditions. A slowdown or these circulations would have far-reaching consequences rest climate system could lead strong impacts on human societies biosphere. Among atmospheric systems considered, classify West African monsoon as a system. Its abrupt changes past led vastly different vegetation states Sahara (e.g. “green Sahara” states). Evidence about over South America Asia is limited however, there are multiple sources destabilisation, including large-scale deforestation, air pollution, shifts other (in particular AMOC). Although theoretically possible, currently little indication tropical clouds mid-latitude Similarly, towards more extreme persistent state El Niño-Southern Oscillation (ENSO) not fully supported by models observations. While thresholds many uncertain, severe socio-environmental consequences. Stabilising Earth’s (along with minimising environmental pressures, like aerosol pollution ecosystem degradation) critical reducing likelihood reaching ocean-atmosphere

Language: Английский

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Irreversible loss in marine ecosystem habitability after a temperature overshoot

Research Square (Research Square), Journal Year: 2023, Volume and Issue: unknown

Published: Jan. 9, 2023

Abstract Anthropogenic warming of the oceans and associated deoxygenation are altering marine ecosystems. Current knowledge suggests that these changes might be reversible in centennial timescale ocean surface irreversible at deeper depth if global were to decline. However, on persistence their combined effects ecosystems remains limited. Here we explore what extent will drive alterations habitats by following evolution a metabolic index captures ecophysiological response organisms both temperature oxygen, through an idealised ramp-up ramp-down atmospheric CO 2 concentration experiment. Using multi-model approach, find oxygen drives centuries-long loss ~4% habitable volume upper 1000 m world ocean. These results suggest effect diminish capability hold life far after recovering from overshoot.

Language: Английский

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