To provide an observational basis for the Intergovernmental Panel on Climate Change projections of a slowing Atlantic meridional overturning circulation (MOC) in the 21st century, the Overturning in the Subpolar North Atlantic Program (OSNAP) observing system was launched in the summer of 2014. The first 21-month record reveals a highly variable overturning circulation responsible for the majority of the heat and freshwater transport across the OSNAP line. In a departure from the prevailing view that changes in deep water formation in the Labrador Sea dominate MOC variability, these results suggest that the conversion of warm, salty, shallow Atlantic waters into colder, fresher, deep waters that move southward in the Irminger and Iceland basins is largely responsible for overturning and its variability in the subpolar basin.

This paper examines the challenges facing English flood risk management (FRM) policy and practice when considering fair decision‐making processes and outcomes at a range of spatial scales. It is recognised that flooding is not fair per se: the inherent natural spatial inequality of flood frequency and extent, plus the legacy of differential system interventions, being the cause. But, drawing on the three social justice models – procedural equality, Rawls’ maximin rule and maximum utility – the authors examine the fairness principles currently employed in FRM decision‐making. This is achieved, firstly, in relation to the distribution of taxpayer's money for FRM at the national, regional and local levels and, secondly, for non‐structural strategies – most notably those of insurance, flood warnings and awareness raising, land use control, home owner adaptation and emergency management. A case study of the Lower Thames catchment illustrates the challenges facing decision‐makers in ‘real life’: how those strategies which appear to be most technically and economically effective fall far short of being fair from either a vulnerability or equality perspective. The paper concludes that if we are to manage flood risk somewhat more fairly then a move in the direction of government funding of nationally consistent non‐structural strategies, in conjunction with lower investment decision thresholds for other local‐level FRM options, appears to offer a greater contribution to equality and vulnerability‐based social justice principles than the status quo.

Flood risk management (FRM) in England is undergoing a major paradigm shift as it moves from an ideology dominated by flood defence to one in which the management of all floods, their probabilities and consequences is now of central concern. This change has led to searching questions both within government, and more widely, concerning the appropriate division of responsibility between the state and its citizens, the appropriate balance between structural and nonstructural risk management options, and the 'fitness for purpose' of the current appraisal, prioritization and decision-making processes. In this paper, the authors examine how a desire to 'make space for water' in England has the potential to alter the division of responsibility between the public and private domain, presenting new opportunities, potential barriers and possible solutions.

The tied relationship between flood disasters and the demand for a policy response is well known. What is not well known is how and why particular policy ideas emerge as policy change options. Drawing on the public policy theoretical literature, the paper evaluates the policy impact of four of the most significant flood disasters in England and Wales in the past 50 years. In so doing, it seeks to highlight which of the environmental, contextual and behavioural drivers have, in the past, been critical factors in the elevation of policy options to policy agendas. By monitoring changes in such drivers we can offer an understanding of the potential policy changes that may occur in response to flood disasters in the future.

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Changes in the Atlantic Meridional Overturning Circulation, which have the potential to drive societally-important climate impacts, have traditionally been linked to the strength of deep water formation in the subpolar North Atlantic. Yet there is neither clear observational evidence nor agreement among models about how changes in deep water formation influence overturning. Here, we use data from a trans-basin mooring array (OSNAP—Overturning in the Subpolar North Atlantic Program) to show that winter convection during 2014–2018 in the interior basin had minimal impact on density changes in the deep western boundary currents in the subpolar basins. Contrary to previous modeling studies, we find no discernable relationship between western boundary changes and subpolar overturning variability over the observational time scales. Our results require a reconsideration of the notion of deep western boundary changes representing overturning characteristics, with implications for constraining the source of overturning variability within and downstream of the subpolar region.

The North Atlantic is characterized by diatom-dominated spring blooms that results in significant transfer of carbon to higher trophic levels and the deep ocean. These blooms are terminated by limiting silicate concentrations in summer. Numerous regional studies have demonstrated phytoplankton community shifts to lightly-silicified diatoms and non-silicifying plankton at the onset of silicate limitation. However, to understand basin-scale patterns in ecosystem and climate dynamics, nutrient inventories must be examined over sufficient temporal and spatial scales. Here we show, from a new comprehensive compilation of data from the subpolar Atlantic Ocean, clear evidence of a marked pre-bloom silicate decline of 1.5–2 µM throughout the winter mixed layer during the last 25 years. This silicate decrease is primarily attributed to natural multi-decadal variability through decreased winter convection depths since the mid-1990s, a weakening and retraction of the subpolar gyre and an associated increased influence of nutrient-poor water of subtropical origin. Reduced Arctic silicate import and the projected hemispheric-scale climate change-induced weakening of vertical mixing may have acted to amplify the recent decline. These marked fluctuations in pre-bloom silicate inventories will likely have important consequences for the spatial and temporal extent of diatom blooms, thus impacting ecosystem productivity and ocean-atmosphere climate dynamics.

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