Global constraints on net primary production and inorganic carbon supply during glacial and interglacial cycles

Abstract

.[1] Relaxation-type models have good skill at reproducing glacial-interglacial transitions in climatic variables. Here we propose a simple two-box and two-state relaxation-type model for the upper ocean (surface and permanent thermocline layers) where dissolved inorganic carbon/nutrients are supplied by the deep ocean and through remineralization within the upper ocean. The model is tuned using genetic algorithms to simulate the atmospheric CO 2 time series for the last four glacial-interglacial cycles. The fit to the data is very good, with correlations above 0.8, as the upper ocean responds to shifts in (1) the intensity of the meridional overturning circulation, from off to on during the glacial-interglacial transition, and (2) the size and sign of net primary production, with respiration greatly exceeding primary production during interglacial periods and production larger than respiration during the glacial phase. The glacial-interglacial transitions are interpreted as shifts between two distinct metabolic states of the Earth system, with high/low supply of dissolved inorganic carbon and nutrients to the productive upper ocean during interglacial/glacial periods.Citation: Pelegrı´, J. L., P. De La Fuente, R. Olivella, and A. Garcı´a-Olivares (2013), Global constraints on net primary production and inorganic carbon supply during glacial and interglacial cycles, Paleoceanography, 28, 713-725,

Analysis of the planetary thermal distribution with a simple three-zone maximum-flux model

“…Our study has two principal underlying ideas. The first one is that the Earth, as any living being, is a complex system that optimizes the distribution of resources, very particularly the heat arriving from the Sun [14,15]. How this is accomplished, i.e.…”

“…The living Earth is a good example of this behavior, with its thermodynamics and energy balance revolving at any time near one attractor but experiencing transitions from one state to another. This behavior resembles the shifts between periods of rest and exercise that characterize all living beings: during the resting interval the system makes up reserves that are used during the exercise period [14][15].…”

The Brazil-Malvinas Confluence : from local to global scales

“…Part I Time-independent box-type models, time-dependent heuristic models and deterministic boxtype models have been used to identify and parameterize the factors controlling the way the Earth changes between different thermodynamic states (Sarmiento and Toogweiller, 1984;Siegenthaler and Wenk, 1984;Paillar, 1998;Paillard and Parrenin, 2004;Garcia-Olivares and Herrero, 2012;2013;Pelegrí et al, 2013). Despite their relative simplicity, these models are able to satisfactorily reproduce the glacial-interglacial periods as well as the maximum and minimum CO 2 concentration or δ 18 O (used as a proxy of temperature).…”

“…(blue line) adjusted to the Vostok's CO2 time series (Petit et al, 1999) (green line). The corresponding MOC water mass transport is also shown (red line) (Pelegrí et al, 2013).…”

“…where A= 20.5 W m -2 and C 0 =280 ppm. For the carbon dioxide time series, we use the simulation values for the last 450 kyr by Pelegrí et al (2013). The resulting time series for the greenhouse radiation is shown in Figure 1.3.…”