An Overview of Ocean Climate Change Indicators: Sea Surface Temperature, Ocean Heat Content, Ocean pH, Dissolved Oxygen Concentration, Arctic Sea Ice Extent, Thickness and Volume, Sea Level and Strength of the AMOC (Atlantic Meridional Overturning Circulation)

• DOI: 10.3389/fmars.2021.642372
• Publication Date: 2021-09-21T05:03:24Z
• Authors: Carlos Garcia-Soto; Lijing Cheng; Levke Caesar; S. Schmidtko; Elizabeth B. Jewett; Alicia Cheripka; Ignatius Rigor; Ainhoa Caballero; Sanae Chiba; Jose Carlos Báez; Tymon Zielinski; John Patrick Abraham
• Keywords: Ocean Acidification

Global ocean physical and chemical trends are reviewed updated using seven key climate change indicators: (i) Sea Surface Temperature, (ii) Ocean Heat Content, (iii) pH, (iv) Dissolved Oxygen concentration (v) Arctic Ice extent, thickness, volume (vi) Level (vii) the strength of Atlantic Meridional Overturning Circulation (AMOC). The globally averaged surface temperature shows a mean warming trend 0.062 ± 0.013°C per decade over last 120 years (1900–2019). During (2010–2019) rate has accelerated to 0.280 0.068°C decade, 4.5 times higher than long term mean. Content in upper 2,000 m linear 0.35 0.08 Wm –2 period 1955–2019 (65 years). during is twice (0.70 0.07 ) record. Each six decades have been warmer previous one. pH declined on average by approximately 0.1 units (from 8.2 8.1) since industrial revolution (1770). By end this century (2100) projected decline additionally 0.1–0.4 depending RCP (Representative Concentration Pathway) SSP (Shared Socioeconomic Pathways) future scenario. time emergence signal varies from 8 15 for open sites, 16–41 coastal sites. dissolved oxygen levels decreased 4.8 petamoles or 2% 5 decades, with profound impacts local basin scale habitats. Regional varying due multiple processes impacting oxygen: solubility change, respiration changes, circulation changes multidecadal variability. sea ice extent declining −13.1% summer (September) −2.6% winter (March) 4 (1979–2020). combined thickness indicate that non-seasonal 75% 1979. level increased 1993–2019 (the altimetry era) at 3.15 0.3 mm year –1 experiencing an acceleration ∼ 0.084 (0.06–0.10) . (1900–2015; 115y) global (GMSL) rised 19 cm, near 40% GMSL rise taken place 1993 (22y). Independent proxies evolution (AMOC) AMOC its weakest several hundreds slowing down century. A final visual summary indicators recent provided.