Time of emergence and large ensemble inter comparison for ocean biogeochemical trends

Schlunegger, Sarah; Rodgers, Keith B.; Sarmiento, Jorge L.; Ilyina, Tatiana; Dunne, John P.; Takano, Yohei; Christian, James R.; Long, Matthew C.; Frölicher, Thomas; Slater, Richard; Lehner, Flavio (2020). Time of emergence and large ensemble inter comparison for ocean biogeochemical trends. Global biogeochemical cycles, 34(8) American Geophysical Union 10.1029/2019GB006453

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Anthropogenically forced changes in ocean biogeochemistry are underway and critical for the ocean carbon sink and marine habitat. Detecting such changes in ocean biogeochemistry will require quantification of the magnitude of the change (anthropogenic signal) and the natural variability inherent to the climate system (noise). Here we use Large Ensemble (LE) experiments from four Earth system models (ESMs) with multiple emissions scenarios to estimate Time of Emergence (ToE) and partition projection uncertainty for anthropogenic signals in five biogeochemically important upper-ocean variables. We find ToEs are robust across ESMs for sea surface temperature and the invasion of anthropogenic carbon; emergence time scales are 20–30 yr. For the biological carbon pump, and sea surface chlorophyll and salinity, emergence time scales are longer (50+ yr), less robust across the ESMs, and more sensitive to the forcing scenario considered. We find internal variability uncertainty, and model differences in the internal variability uncertainty, can be consequential sources of uncertainty for projecting regional changes in ocean biogeochemistry over the coming decades. In combining structural, scenario, and internal variability uncertainty, this study represents the most comprehensive characterization of biogeochemical emergence time scales and uncertainty to date. Our findings delineate critical spatial and duration requirements for marine observing systems to robustly detect anthropogenic change.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)

UniBE Contributor:

Frölicher, Thomas

Subjects:

500 Science > 530 Physics

ISSN:

0886-6236

Publisher:

American Geophysical Union

Language:

English

Submitter:

BORIS Import 2

Date Deposited:

13 Sep 2021 15:35

Last Modified:

13 Sep 2021 15:38

Publisher DOI:

10.1029/2019GB006453

BORIS DOI:

10.48350/158643

URI:

https://boris.unibe.ch/id/eprint/158643

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