Identification

Title

Climatic changes in North Atlantic O2 amplified by temperature sensitivity of phytoplankton growth

Abstract

Ocean warming is associated with a decline in the global oxygen (O-2) inventory, but the ratio of O-2 loss to heat gain is poorly understood. We analyzed historical variability in temperature (T), O-2, and nitrate (NO3- ) in hydrographic observations and model simulations of the North Atlantic, a relatively well-sampled region that is important for deep ocean ventilation. Multidecadal fluctuations of O-2 concentrations in subpolar thermocline waters (100-700 m) are correlated with changes in their heat content, with a slope 35% steeper than that expected from thermal solubility. Variations of O-2 in excess of the solubility effect are correlated with observed decadal changes in NO3- in the surface layer (0-50 m), which declines by similar to 1 mmol N m(-3) per degree of temperature anomaly. Enhanced biologically mediated drawdown of nutrients from the photic zone and associated respiration in deeper water account for the additional depletion of thermocline O-2 during warm years. In model simulations, increased nutrient consumption in warm periods is driven by an early start of the phytoplankton growing season and faster phytoplankton growth rates at higher temperatures. Our results highlight a role for phytoplankton T-dependent growth rates in amplifying ocean O-2 loss.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7zc870j

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2023-12-01T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact