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MCCIP Rolling Evidence Updates

MCCIP Rolling Evidence Updates

Russian gas exports to Europe have traditionally meant one thing: pipeline supplies from Gazprom. But since December 2017, Russian LNG cargoes from the Yamal LNG project led by the private Russian company, Novatek, have increasingly made their mark, especially in North-Western Europe. Despite the original intention that Yamal LNG cargoes would be predominantly shipped to Asia – via the Northern Sea Route in the summer and via transshipment in Europe in the winter – Yamal LNG cargoes have increasingly remained in Europe, prompting debates over possible competition between the two sources of Russian gas. In our analysis, we find although Yamal LNG cargoes may indeed compete with Gazprom’s pipeline supplies in Europe, once the cargoes have left Yamal not only does the Russian government not have the ability to ‘manage’ competition between Gazprom and Yamal LNG, but those Yamal LNG cargoes become (to all intents and purposes) no different to any other LNG cargoes with which Gazprom’s pipeline supplies compete. We conclude that the Russian government has implicitly recognised this, and has chosen to support the expansion of Russia’s LNG export capacity even at the potential expense of competition with Gazprom’s pipeline supplies, as this is preferable to simply ceding market share to other non-Russian LNG suppliers.

The decline in dissolved oxygen and onset of oxygen deficiency and hypoxia are naturally occurring phenomenon in aquatic environments, typically occurring on seasonal timescales. Over decadal timescales, there has been a measurable decline in dissolved oxygen concentrations in the global ocean due to warming caused by anthropogenic activity. Approximately 15% of the global decline in oxygen has been attributed to reduced solubility in response to ocean warming, with the remaining 85% due to intensified stratification. The relative contribution of these factors in coastal and shelf-sea waters is currently unknown. In UK waters, sustained observations in the North Sea reveal the recent onset of oxygen deficiency in late summer, partially due to ocean warming. Models designed to represent coastal and shelf sea processes suggest there are large parts of the Celtic Sea, English Channel and Irish Sea that are prone to oxygen deficiency, but data is too sparse in time and space to support these findings. In addition, the ability of models to accurately represent oxygen dynamics is still under debate due to correct representation of physical and biological processes within models. Physical processes play a key role in the development of oxygen deficient regions and thus understanding how oxygen concentrations will respond to climate change requires a coupled physical and biogeochemical approach.

© 2019 This work examines the seasonal cycle of vertical density structure and its influence on primary production in a temperate shelf sea, with a particular focus on the breakdown of stratification in autumn. We do this by combining new, high resolution observations of water column structure, meteorological forcing, nitrate and chlorophyll fluorescence collected between March 2014 and July 2015 on the North West European Shelf. Our results challenge the generally accepted assumption that convection dominates over wind driven mixing resulting in seasonal breakdown of stratification. Furthermore we found, that vertical mixing in autumn not only transformed the vertical density structure but also the vertical structure of chlorophyll biomass and surface nutrients. The subsurface chlorophyll maximum was eroded and a vertically homogeneous profile of chlorophyll biomass established itself above the pycnocline. This increased mixing also led to replenishment of surface nitrate concentrations, which supported an autumn phytoplankton bloom. While the significance of phytoplankton blooms in autumn has previously not been well quantified, we argue that these can act as a significant contributor to the seasonal drawdown of carbon.

We report a new synthesis of best estimates of the inputs of fixed nitrogen to the world ocean via atmospheric deposition and compare this to fluvial inputs and dinitrogen fixation. We evaluate the scale of human perturbation of these fluxes. Fluvial inputs dominate inputs to the continental shelf, and we estimate that about 75% of this fluvial nitrogen escapes from the shelf to the open ocean. Biological dinitrogen fixation is the main external source of nitrogen to the open ocean, i.e., beyond the continental shelf. Atmospheric deposition is the primary mechanism by which land-based nitrogen inputs, and hence human perturbations of the nitrogen cycle, reach the open ocean. We estimate that anthropogenic inputs are currently leading to an increase in overall ocean carbon sequestration of ~0.4% (equivalent to an uptake of 0.15 Pg C yr−1 and less than the Duce et al. (2008) estimate). The resulting reduction in climate change forcing from this ocean CO2 uptake is offset to a small extent by an increase in ocean N2O emissions. We identify four important feedbacks in the ocean atmosphere nitrogen system that need to be better quantified to improve our understanding of the perturbation of ocean biogeochemistry by atmospheric nitrogen inputs. These feedbacks are recycling of (1) ammonia and (2) organic nitrogen from the ocean to the atmosphere and back, (3) the suppression of nitrogen fixation by increased nitrogen concentrations in surface waters from atmospheric deposition, and (4) increased loss of nitrogen from the ocean by denitrification due to increased productivity stimulated by atmospheric inputs.