Climate Change Impacts on Natural Sulfur Production: Ocean Acidification and Community Shifts

Abstract

Utilizing the reduced-complexity model Hector, a regional scale analysis was conducted quantifying the possible effects climate change may have on dimethyl sulfide (DMS) emissions within the oceans. The investigation began with a review of the sulfur cycle in modern Earth system models. We then expanded the biogeochemical representation within Hector to include a natural ocean component while accounting for acidification and planktonic community shifts. The report presents results from both a latitudinal and a global perspective. This new approach highlights disparate outcomes which have been inadequately characterized via planetary averages in past publications. Our findings suggest that natural sulfur emissions (ESN) may exert a forcing up to 4 times that of the CO 2 marine feedback, 0.62 and 0.15 Wm −2 , respectively, and reverse the radiative forcing sign in low latitudes. Additionally, sensitivity tests were conducted to demonstrate the need for further examination of the DMS loop. Ultimately, the present work attempts to include dynamic ESN within reduced-complexity simulations of the sulfur cycle, illustrating its impact on the global radiative budget.

The FuGas 2.3 Framework for Atmosphere–Ocean Coupling: Comparing Algorithms for the Estimation of Solubilities and Gas Fluxes

“…In general, both formulations estimated similar solubilities despite their distinct chemistry backgrounds, as demonstrated by their ratio k H [20] /k H [2] close to 1 (Figure 1a-c). Nevertheless, differences from 10% to −5% for CO 2 , 11% to 5% for CH 4 , and 7% to −5% for N 2 O were observed in freshwaters. Determining which formulation provides more accurate estimates of greenhouse gas (GHG) solubilities in freshwater is fundamental for Earth System Modelling, because rivers and freshwater reservoirs are important sources of GHG to the atmosphere, even if only seasonably [7][8][9][10][11][12][13][14]16].…”

“…Then, Equation (6) converted the k H cp to k H at a given temperature and 0 ppt salinity. The term −∆ soln H/R reflected the temperature dependence of solubility, having a value of 2400 for CO 2 , 1700 for CH 4 and 2600 for N 2 O. The correction to a given salinity (Equation (7)) relied on the empirical Setschenow constants (K S = θ·logV b ) reporting the effect of electrolytes salting-out gases proportionally to their liquid molar volume at boiling point (V b ).…”

“…The transfer velocities of CO 2 , CH 4 and N 2 O were estimated from atmospheric and oceanographic re-analysed (Level 4) data retrieved for the European shores (Mediterranean and North Atlantic to the tip of Scotland) from the 24 May 2014 at 06 h to the 27 May 2014 at 00 h. All variables were interpolated to the same 0.09 • grid (roughly 11 km at Europe's latitudes) and 1 h time steps. This resulted in a data set with 17 variables × 41,776 locations × 66 time instances.…”

“…The ∆C w was converted to mass units using the molar weights of the specific gas (M gas ), respectively 44.01 for CO 2 , 16.043 for CH 4 and 44.013 for N 2 O. The C a was estimated from the atmospheric pressure (P in atm) and the partial pressure (ρ gas ) of CO 2 , CH 4 or N 2 O, 390 ppm, 1.75 ppm and 0.325 ppm respectively [80], assuming that they were approximately uniform all over the atmospheric surface boundary layer (SBL). The ρ gas was divided by 10 6 to re-scale from ppm to dimensionless.…”

“…In the sub-polar regions, for instance, the solubility pump retrieves large amounts of greenhouse gases from the atmosphere, which are then advected to the deep ocean [1,2]. On the other hand, at the surface of coastal waters the balances and fluxes of CO 2 , CH 4 , N 2 O and DMS are very heterogenic, mostly due to factors like upwelling, plankton productivity, and land-originated loads of both natural and anthropogenic cause. Consequently, besides DMS [3,4] the coastal ocean can be, at least seasonally, also a source of CO 2 [1,2,[5][6][7][8][9][10][11], CH 4 [2,10,12], and N 2 O [2,10,[13][14][15] to the atmosphere.…”