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Monterey Bay and contiguous waters of the California Current System have been observed repeatedly since 1929, most intensively since 1989 with ships, moorings, and autonomous vehicles. Here, seasonal, interannual, and multidecadal variations are linked to regional weather and large-scale climate ocean-atmosphere dynamics. In the springtime, the Northeast Pacific subtropical high-pressure system strengthens, intensifying northwesterly alongshore winds. These winds drive coastal upwelling that fertilizes nearshore surface water with phytoplankton nutrients, resulting in a dramatic increase in biological productivity. Upwelling weakens over summer into fall, allowing nutrient-depleted offshore water to move toward the coast. Southerly winter storm winds deepen the mixed layer and further enhance onshore flow. El Niño interrupts these seasonal cycles with varying intensity every three to eight years, but typically peaks during the low-productivity winter season, lessening its biological impact. Over the 1989–2016 period of observation, a negative phase of the multidecadal Pacific Decadal Oscillation is observed as a 15-year cool period following the strong 1997–1998 El Niño. Two recently identified basin-scale phenomena, the central Pacific El Niño Modoki and the North Pacific Gyre Oscillation, increased in strength during this period. In Monterey Bay, primary productivity increased substantially during the cool period, at about 3% per year. This shift also marked the beginning of a monotonic decline in subsurface oxygen, which decreased by 3% annually in the 300–400 m depth horizon, above the oxygen minimum zone. Anthropogenically driven increases in surfacepCO₂ and acidity (pH) are notable in Monterey Bay in spite of high near-surface variability. Recently, over 2014–2016, Monterey Bay has warmed, interrupting the 1988–2012 cooling trend. Even with the warm years included, however, there is no overall increasing trend in temperature at any depth from 1988 to the present. A recompilation of historical temperature data back to 1929 indicates that over this longer period, average and cool years have not been significantly different, but warm episodes have been hotter over the last few decades, leading to a trend of increasing temperature over the past 89 years. The 2014–2016 warm period included “the Blob” and an El Niño, and is reminiscent of similar conditions in the early 1940s. It is not known if the warm conditions will continue, or we will return to a cooler and drier than average period. Our observations highlight the value of long-term data. Such data collections will need to be automated to increase their value and sustainability.

The availability of iron is known to exert a controlling influence on biological productivity in surface waters over large areas of the ocean and may have been an important factor in the variation of the concentration of atmospheric carbon dioxide over glacial cycles. The effect of iron in the Southern Ocean is particularly important because of its large area and abundant nitrate, yet iron-enhanced growth of phytoplankton may be differentially expressed between waters with high silicic acid in the south and low silicic acid in the north, where diatom growth may be limited by both silicic acid and iron. Two mesoscale experiments, designed to investigate the effects of iron enrichment in regions with high and low concentrations of silicic acid, were performed in the Southern Ocean. These experiments demonstrate iron's pivotal role in controlling carbon uptake and regulating atmospheric partial pressure of carbon dioxide.

The availability of iron, an essential nutrient, controls rates of phytoplankton primary productivity in the open-ocean, upwelling ecosystems of the equatorial Pacific 1 , 2 . Upwelling injects large amounts of macronutrients into the euphotic zone of eastern boundary currents, such as the California Current System (CCS), where iron can become the limiting factor on productivity 3 , 4 . Iron addition to samples from some areas of the CCS has been shown to increase rates of biomass production 5 , 6 , but the processes that control iron availability in these systems remain poorly understood. Here we report measurements of dissolvable iron (that is, dissolved plus leachable iron at pH 3) in transects across the CCS in March of 1997 and 1998. We foundhigh concentrations of iron in 1997 during strong upwelling conditions. During the 1998 El Niño, the concentration of dissolvable iron in surface waters was low, even though that yearwas marked by high river flow and low offshore salinity. These results indicate that the primary source of iron in the CCS isresuspension of particles in the benthic boundary layer, followed by upwelling of this iron-rich water, rather than direct riverine input. This source of iron must be an essential but variable component of the high productivity found in upwelling ecosystems.

Field experiments were conducted to test ideas for fossil fuel carbon dioxide ocean disposal as a solid hydrate at depths ranging from 349 to 3627 meters and from 8 degrees to 1.6 degrees C. Hydrate formed instantly from the gas phase at 349 meters but then decomposed rapidly in ambient seawater. At 3627 meters, the seawater-carbon dioxide interface rose rapidly because of massive hydrate formation, forcing spillover of the liquid carbon dioxide from the container. A strong barrier between the liquid carbon dioxide and interaction with the sediments was observed. A pool of liquid carbon dioxide on the sea floor would expand in volume more than four times, forming hydrate, which will dissolve.

Oceanic iron (Fe) fertilization experiments have advanced the understanding of how Fe regulates biological productivity and air-sea carbon dioxide ( CO2) exchange. However, little is known about the production and consumption of halocarbons and other gases as a result of Fe addition. Besides metabolizing inorganic carbon, marine microorganisms produce and consume many other trace gases. Several of these gases, which individually impact global climate, stratospheric ozone concentration, or local photochemistry, have not been previously quantified during an Feenrichment experiment. We describe results for selected dissolved trace gases including methane ( CH4), isoprene ( C5H8), methyl bromide ( CH3Br), dimethyl sulfide, and oxygen ( O2), which increased subsequent to Fe fertilization, and the associated decreases in concentrations of carbon monoxide (CO), methyl iodide ( CH3I), and CO2observed during the Southern Ocean Iron Enrichment Experiments.

Saline and warm Mediterranean water flowing through the Bosporus Strait maintains a permanent pycnocline with vertical separation of oxic (O2), suboxic (absence of O2 and H2S), and anoxic ($\\text{S}_{2}\\text{S}$) zones in the Black Sea. The stable suboxic zone implies restricted vertical mixing of the upper oxic and lower anoxic layers and limited vertical flux of oxygen that cannot balance the upward flux of sulfide. We report data that directly confirm massive lateral injections (>200 km from the Bosporus) of oxygen-enriched waters of the Bosporus plume, created by the mixing of shallow, cold, intermediate-layer Black Sea water with Mediterranean water. These plume waters are laterally injected into the oxic layer and, more importantly, into the suboxic and anoxic layers over several small vertical scales (\"fingers\" of ∼5 m) at water densities ($\\sigma _{\\text{t}}$) from 15.0 to 16.4. O2 injection oxidizes Mn(II) to Mn(III,IV), which then oxidizes H2S. The onset of H2S detection occurs in deeper waters in the southwest (>170 m; $\\sigma _{\\text{t}}\\approx 16.4$) relative to the west central Black Sea (110 m; $\\sigma _{\\text{t}}\\approx 16.2$) and coincides with increased $\\text{MnO}_{2}$ and $\\text{S}_{8}$ formation in the southwest.

Silica cycling was examined during a major upwelling event in Monterey Bay, California. Strong upwelling-favorable winds blew for 6 d with speeds up to 15 m s-1 just prior to the study. A survey of the region near the end of the wind event showed newly upwelled water at the north end of the bay, with silicic acid concentrations up to 29.8μ M. Silicic acid concentrations decreased to a minimum of 15μ M along the upwelling plume. Biogenic silica concentrations in the upwelling plume were generally between 2 and 5μ mol Si liter-1. Specific rates of biogenic silica production were$<0.2 d^-1$in the frshly upwelled waters and increased to$>1.0 d^-1$downplume. Kinetic experiments indicated that silicic acid concentrations throughout the upwelling plume supported maximal rates of silica production. Silica production rates were ∼ 1μ mol Si liter-1 d-1 at the upwelling source, increasing to 7μ mol liter-1 d-1 downplume. The upwelling event was followed by several days of calm winds, creating ideal conditions for a phytoplankton bloom. Integrated biogenic silica concentrations between the surface and the 0.1% light depth during the calm period ranged from 56 to 566 mmol Si m-2, with 8 of 11 stations exhibiting concentrations$>100 mmol Si m^-2$. Specific production rates of biogenic silica were generally$>1 d^-1$, with production rates between 10 and 30μ mol Si liter-1 d-1. Integrated silica production rates averaged 205 mmol Si m-2 d-1 (range 13-1,140 mmol m-2 d-1), which is four times greater than the average rate observed for other coastal upwelling systems. The maximum value observed (1,140 mmol m-2 d-1) is nearly four times greater than levels ever observed before in the sea. The ligh silica production rates seemed to result from an inefficient silicate pump. On average, 72% of the biogenic silica produced in the upwelling plume was retained in the surface waters, resulting in biogenic silica concentrations of 6.7-13.7mu mol Si liter-1 at stations where integrated production rates were$>200 mmol Si m^-2 d^-1$. Ambient silicic acid concentrations in these same waters were generally$>8\\mu M$. Kinetic studies showed that these silicic acid concentrations supported nearly maximal rates of silica production. Substrate limitation of silica production became readily detectable at 5μ M Si(OH)4. By that time, 80 to$>90%$of the silicic acid and ∼ 90% of the nitrate in the upwelled waters had been consumed, indicating that substrate limitation of silica production played only a minor role in controlling the magnitude of both net silica production and new production by diatoms.

We show, from recent data obtained at specimen North Pacific stations, that the fossil fuel CO 2 signal is strongly present in the upper 400 m, and that we may consider areal extrapolations from geochemical surveys to determine the magnitude of ocean fossil fuel CO 2 uptake. The debate surrounding this topic is illustrated by contrasting reports which suggest, based upon atmospheric observations and models, that the oceanic CO 2 sink is small at these latitudes; or that the oceanic CO 2 sink, based upon oceanic data and models, is large. The difference between these two estimates is at least a factor of two. There are contradictions arising from estimates based on surface partial pressures of CO 2 alone, where the signal sought is small compared with regional and seasonal variability; and estimates of the accumulated subsurface burden, which correlates well other oceanic tracers. Ocean surface waters today contain about 45 μmol⋅kg −1 excess CO 2 compared with those of the preindustrial era, and the signal is rising rapidly. What limits should we place on such calculations? The answer lies in the scientific questions to be asked. Recovery of the fossil fuel CO 2 contamination signal from analysis of ocean water masses is robust enough to permit reasonable budget estimates. However, because we do not have sufficient data from the preindustrial ocean, the estimation of the required Redfield oxidation ratio in the upper several hundred meters is already blurred by the very fossil fuel CO 2 signal we seek to resolve.

Oceanic iron (Fe) fertilization experiments have advanced the understanding of how Fe regulates biological productivity and air-sea carbon dioxide (CO(2)) exchange. However, little is known about the production and consumption of halocarbons and other gases as a result of Fe addition. Besides metabolizing inorganic carbon, marine microorganisms produce and consume many other trace gases. Several of these gases, which individually impact global climate, stratospheric ozone concentration, or local photochemistry, have not been previously quantified during an Fe-enrichment experiment. We describe results for selected dissolved trace gases including methane (CH(4)), isoprene (C(5)H(8)), methyl bromide (CH(3)Br), dimethyl sulfide, and oxygen (O(2)), which increased subsequent to Fe fertilization, and the associated decreases in concentrations of carbon monoxide (CO), methyl iodide (CH(3)I), and CO(2) observed during the Southern Ocean Iron Enrichment Experiments.

Oceanic iron (Fe) fertilization experiments have advanced the understanding of how Fe regulates biological productivity and air–sea carbon dioxide (CO 2 ) exchange. However, little is known about the production and consumption of halocarbons and other gases as a result of Fe addition. Besides metabolizing inorganic carbon, marine microorganisms produce and consume many other trace gases. Several of these gases, which individually impact global climate, stratospheric ozone concentration, or local photochemistry, have not been previously quantified during an Fe-enrichment experiment. We describe results for selected dissolved trace gases including methane (CH 4 ), isoprene (C 5 H 8 ), methyl bromide (CH 3 Br), dimethyl sulfide, and oxygen (O 2 ), which increased subsequent to Fe fertilization, and the associated decreases in concentrations of carbon monoxide (CO), methyl iodide (CH 3 I), and CO 2 observed during the Southern Ocean Iron Enrichment Experiments.