Benjamin James Harrison

We show that the winter North Atlantic Oscillation (NAO) forecast provides useful season-ahead information on the severity of the UK storm surge winter season. We use both observations and numerical simulations. Using Aberdeen as a case study—where NAO-surge coupling is particularly strong—we show that a high winter-mean NAO index is a necessary, though not sufficient, condition for multiple exceedances of the one-year surge return level. Next, applying a log-linear Poisson regression to the NAO-exceedance count relationship, we find that conditioning exceedance counts on the NAO improves predictive skill relative to climatology at Aberdeen. Observed NAO produces a strong likelihood-ratio signal, and forecast NAO, evaluated through leave-one-out cross-validation, also assigns higher probability to realised outcomes, notably in high-exceedance years. NAO-conditioned models outperform unconditioned alternatives in NAO-positive years, indicating predictive value despite forecast noise. We then examine the storm-track characteristics that distinguish winters with and without clustering and extend the analysis to three additional UK coastal sites—Sheerness, Millport and Weymouth—to illustrate contrasting regions of storm-track sensitivity around the coastline. Finally, we build on previously-identified patterns of correlation between the winter mean NAO index and annual storm surge extremes, showing that similar spatial patterns of correlation remain when the observations are replaced by a forecasted NAO.

We present a framework for developing storylines of UK sea level rise to aid risk communication and coastal adaptation planning. Our approach builds on the UK national climate projections (UKCP18) and maintains the same physically consistent methods that preserve component correlations and traceability between global mean sea level (GMSL) and local relative sea level (RSL). Five example storylines are presented that represent singular trajectories of future sea level rise drawn from the underlying large Monte Carlo simulations. The first three storylines span the total range of the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6) likely range GMSL projections across the SSP1-2.6 and SSP5-8.5 scenarios. The final two storylines are based upon recent high-end storylines of GMSL presented in AR6 and the recent literature. Our results suggest that even the most optimistic sea level rise outcomes for the UK will require adaptation of up to 1 m of sea level rise for large sections of coastline by 2300. For the storyline most consistent with current international greenhouse gas emissions pledges and a moderate sea level rise response, UK capital cities will experience between about 1 and 2 m of sea level rise by 2300, with continued rise beyond 2300. The storyline based on the upper end of the AR6 likely range sea level projections yields much larger values for UK capital cities that range between about 3 and 4 m at 2300. The two high-end scenarios, which are based on a recent study that showed accelerated sea level rise associated with ice sheet instability feedbacks, lead to sea level rise for UK capital cities at 2300 that range between about 8 m and 17 m. These magnitudes of rise would pose enormous challenges for UK coastal communities and are likely to be beyond the limits of adaptation at some locations.

The northwest European shelf (NWS) seas are environmentally and economically important, and an understanding of how their climate may change helps with their management. However, as the NWS seas are poorly represented in global climate models, a common approach is to dynamically downscale with an appropriate shelf sea model. We develop a set of physical marine climate projections for the NWS. We dynamically downscale 12 members of the HadGEM3-GC3.05 perturbed parameter ensemble (approximately 70 km horizontal resolution over Europe), developed for UKCP18, using the shelf sea model NEMO CO9 (7 km horizontal resolution). These are run under the RCP8.5 high-greenhouse-gas-emission scenario as continuous simulations over the period 1990–2098. We evaluate the simulations against observations in terms of tides, sea surface temperature (SST), surface and near-bed temperature and salinity, and sea surface height. These simulations represent the state of the art for NWS marine projections. We project an SST rise of 3.11 °C (± 2σ = 0.98 °C) and a sea surface salinity (SSS) freshening of −1.01 (± 2σ = 0.93; on the (unitless) practical salinity scale) for 2079–2098 relative to 2000–2019, averaged over the NWS (approximately bounded by the 200 m isobar and excluding the Norwegian Trench, the Skagerrak and Kattegat), a substantial seasonal stratification increase (23 d over the NWS seas), and a general weakening of the NWS residual circulation. While the patterns of NWS changes are similar to our previous projections, there is a greater warming and freshening that could reflect the change from the A1B emissions scenario to the RCP8.5 concentrations pathway or the higher climate sensitivity exhibited by HadGEM3-GC3.05. Off the shelf, south of Iceland, there is limited warming, consistent with a reduction in the Atlantic Meridional Overturning Circulation and associated northward heat transport. These projections have been publicly released, along with a consistent 200-year present-day control simulation, to provide an evidence base for climate change assessments and to facilitate climate impact studies. For example, we illustrate how the two products can be used to estimate climate trends, unforced variability and the time of emergence (ToE) of the climate signals. We calculate the average NWS SST ToE to be 2034 (with an 8-year range) and 2046 (with a 33-year range) for SSS. We also discuss how these projections can be used to describe NWS conditions under 2 and 4 °C global mean warming (compared with 1850–1900), as a policy-relevant exemplar use case.

The North West European Shelf Seas (NWS) are environmentally and economically important, and an understanding of how their climate may change helps with their management. However, as the NWS are poorly represented in Global Climate Models, a common approach is to dynamically downscale with an appropriate shelf seas model. We develop a set of physical marine climate projections for the NWS. We dynamically downscale 12 members of the HadGEM3-GC3.05 Perturbed Parameter Ensemble (approximately 70 km horizontal resolution over Europe), developed for UKCP18, using the shelf-seas model NEMO CO9 (7 km horizontal resolution). These are run under the high greenhouse gas emissions RCP8.5 scenario as continuous simulations over the period 1990–2098. We evaluate the simulations against observations in terms of tides, sea surface temperature, surface and near-bed temperature and salinity, and sea surface-height. These simulations represent the state-of-the-art for marine UK projections. We project a Sea-Surface Temperature (SST) rise of 3.11 °C (±2σ = 0.98 °C), and a Sea-Surface Salinity (SSS) freshening of −1.01 psu (±2σ = 0.93 psu) for 2079–2098 relative to 2000–2019, averaged over the NWS (approximately bounded by the 200 m isobar and excluding the Norwegian Trench, Skagerrak, and Kattegat). While the patterns of NWS changes are similar to our previous projections, there is a greater warming and freshening, that could reflect the change from the A1B emissions scenario to the RCP8.5 concentrations pathway or the higher climate sensitivity exhibited by HadGEM3-GC3.05. Off the shelf, south of Iceland, there is limited warming, consistent with a reduction in the Atlantic Meridional Overturning Circulations and associated northward heat transport. These projections have been publicly released, along with a consistent 200-year present day control simulation, to provide an evidence-base for climate change assessments and to facilitate climate impact studies. For example, we illustrate how the two products can be used to estimate of climate trends, unforced variability, and the Time of Emergence (ToE) of the climate signals. We calculate the average NWS SST ToE to be 2034 (with an 8-year range) and 2046 (with a 33-year range) for SSS. We also discuss how these projections can be used to describe NWS conditions under 2 °C and 4 °C global mean warming (compared to 1850–1900), as a policy relevant exemplar use-case.

The North West European Shelf Seas (NWS) are environmentally and economically important, and an understanding of how their climate may change helps with their management. However, as the NWS are poorly represented in Global Climate Models, a common approach is to dynamically downscale with an appropriate shelf seas model. We develop a set of physical marine climate projections for the NWS. We dynamically downscale 12 members of the HadGEM3-GC3.05 Perturbed Parameter Ensemble (approximately 70 km horizontal resolution over Europe), developed for UKCP18, using the shelf-seas model NEMO CO9 (7 km horizontal resolution). These are run under the high greenhouse gas emissions RCP8.5 scenario as continuous simulations over the period 1990–2098. We evaluate the simulations against observations in terms of tides, sea surface temperature, surface and near-bed temperature and salinity, and sea surface-height. These simulations represent the state-of-the-art for marine UK projections. We project a Sea-Surface Temperature (SST) rise of 3.11 °C (±2σ = 0.98 °C), and a Sea-Surface Salinity (SSS) freshening of −1.01 psu (±2σ = 0.93 psu) for 2079–2098 relative to 2000–2019, averaged over the NWS (approximately bounded by the 200 m isobar and excluding the Norwegian Trench, Skagerrak, and Kattegat). While the patterns of NWS changes are similar to our previous projections, there is a greater warming and freshening, that could reflect the change from the A1B emissions scenario to the RCP8.5 concentrations pathway or the higher climate sensitivity exhibited by HadGEM3-GC3.05. Off the shelf, south of Iceland, there is limited warming, consistent with a reduction in the Atlantic Meridional Overturning Circulations and associated northward heat transport. These projections have been publicly released, along with a consistent 200-year present day control simulation, to provide an evidence-base for climate change assessments and to facilitate climate impact studies. For example, we illustrate how the two products can be used to estimate of climate trends, unforced variability, and the Time of Emergence (ToE) of the climate signals. We calculate the average NWS SST ToE to be 2034 (with an 8-year range) and 2046 (with a 33-year range) for SSS. We also discuss how these projections can be used to describe NWS conditions under 2 °C and 4 °C global mean warming (compared to 1850–1900), as a policy relevant exemplar use-case.

The North West European Shelf Seas (NWS) are environmentally and economically important, and an understanding of how their climate may change helps with their management. However, as the NWS are poorly represented in Global Climate Models, a common approach is to dynamically downscale with an appropriate shelf seas model. We develop a set of physical marine climate projections for the NWS. We dynamically downscale 12 members of the HadGEM3-GC3.05 Perturbed Parameter Ensemble (approximately 70 km horizontal resolution over Europe), developed for UKCP18, using the shelf-seas model NEMO CO9 (7 km horizontal resolution). These are run under the high greenhouse gas emissions RCP8.5 scenario as continuous simulations over the period 1990–2098. We evaluate the simulations against observations in terms of tides, sea surface temperature, surface and near-bed temperature and salinity, and sea surface-height. These simulations represent the state-of-the-art for marine UK projections. We project a Sea-Surface Temperature (SST) rise of 3.11 °C (±2σ = 0.98 °C), and a Sea-Surface Salinity (SSS) freshening of −1.01 psu (±2σ = 0.93 psu) for 2079–2098 relative to 2000–2019, averaged over the NWS (approximately bounded by the 200 m isobar and excluding the Norwegian Trench, Skagerrak, and Kattegat). While the patterns of NWS changes are similar to our previous projections, there is a greater warming and freshening, that could reflect the change from the A1B emissions scenario to the RCP8.5 concentrations pathway or the higher climate sensitivity exhibited by HadGEM3-GC3.05. Off the shelf, south of Iceland, there is limited warming, consistent with a reduction in the Atlantic Meridional Overturning Circulations and associated northward heat transport. These projections have been publicly released, along with a consistent 200-year present day control simulation, to provide an evidence-base for climate change assessments and to facilitate climate impact studies. For example, we illustrate how the two products can be used to estimate of climate trends, unforced variability, and the Time of Emergence (ToE) of the climate signals. We calculate the average NWS SST ToE to be 2034 (with an 8-year range) and 2046 (with a 33-year range) for SSS. We also discuss how these projections can be used to describe NWS conditions under 2 °C and 4 °C global mean warming (compared to 1850–1900), as a policy relevant exemplar use-case.

Pakistan is vulnerable to a range of climate hazards, including sea-level rise. The Indus Delta region, situated in the coastal Sindh province, is particularly at risk of sea-level rise due to low-lying land and fragile ecosystems. In this article, expertise is drawn together from the newly established Pakistan Sea-Level Working Group, consisting of policy experts, scientists, and practitioners, to provide recommendations for future research, investment, and coastal risk management. An assessment of the current scientific understanding of sea-level change and coastal climate risks in Pakistan highlights an urgent need to improve the availability and access to sea-level data and other coastal measurements. In addition, reflecting on the policy environment and the enablers needed to facilitate effective responses to future sea-level change, recommendations are made to integrate coastal climate services into the National Adaptation Plan and develop a National Framework for Climate Services. Such a framework, alongside collaboration, co-production, and capacity development, could help support required improvements in coastal observations and monitoring and continuously deliver useful, usable, and accessible sea-level information for use by practitioners and decision-makers.

The North West European Shelf Seas (NWS) are environmentally and economically important, and an understanding of how their climate may change helps with their management. However, as the NWS are poorly represented in Global Climate Models, a common approach is to dynamically downscale with an appropriate shelf seas model. We develop a set of physical marine climate projections for the NWS. We dynamically downscale 12 members of the HadGEM3-GC3.05 Perturbed Parameter Ensemble (approximately 70 km horizontal resolution over Europe), developed for UKCP18, using the shelf-seas model NEMO CO9 (7 km horizontal resolution). These are run under the high greenhouse gas emissions RCP8.5 scenario as continuous simulations over the period 1990–2098. We evaluate the simulations against observations in terms of tides, sea surface temperature, surface and near-bed temperature and salinity, and sea surface-height. These simulations represent the state-of-the-art for marine UK projections. We project a Sea-Surface Temperature (SST) rise of 3.11 °C (±2σ = 0.98 °C), and a Sea-Surface Salinity (SSS) freshening of −1.01 psu (±2σ = 0.93 psu) for 2079–2098 relative to 2000–2019, averaged over the NWS (approximately bounded by the 200 m isobar and excluding the Norwegian Trench, Skagerrak, and Kattegat). While the patterns of NWS changes are similar to our previous projections, there is a greater warming and freshening, that could reflect the change from the A1B emissions scenario to the RCP8.5 concentrations pathway or the higher climate sensitivity exhibited by HadGEM3-GC3.05. Off the shelf, south of Iceland, there is limited warming, consistent with a reduction in the Atlantic Meridional Overturning Circulations and associated northward heat transport. These projections have been publicly released, along with a consistent 200-year present day control simulation, to provide an evidence-base for climate change assessments and to facilitate climate impact studies. For example, we illustrate how the two products can be used to estimate of climate trends, unforced variability, and the Time of Emergence (ToE) of the climate signals. We calculate the average NWS SST ToE to be 2034 (with an 8-year range) and 2046 (with a 33-year range) for SSS. We also discuss how these projections can be used to describe NWS conditions under 2 °C and 4 °C global mean warming (compared to 1850–1900), as a policy relevant exemplar use-case.

The North West European Shelf Seas (NWS) are environmentally and economically important, and an understanding of how their climate may change helps with their management. However, as the NWS are poorly represented in Global Climate Models, a common approach is to dynamically downscale with an appropriate shelf seas model. We develop a set of physical marine climate projections for the NWS. We dynamically downscale 12 members of the HadGEM3-GC3.05 Perturbed Parameter Ensemble (approximately 70 km horizontal resolution over Europe), developed for UKCP18, using the shelf-seas model NEMO CO9 (7 km horizontal resolution). These are run under the high greenhouse gas emissions RCP8.5 scenario as continuous simulations over the period 1990–2098. We evaluate the simulations against observations in terms of tides, sea surface temperature, surface and near-bed temperature and salinity, and sea surface-height. These simulations represent the state-of-the-art for marine UK projections. We project a Sea-Surface Temperature (SST) rise of 3.11 °C (±2σ = 0.98 °C), and a Sea-Surface Salinity (SSS) freshening of −1.01 psu (±2σ = 0.93 psu) for 2079–2098 relative to 2000–2019, averaged over the NWS (approximately bounded by the 200 m isobar and excluding the Norwegian Trench, Skagerrak, and Kattegat). While the patterns of NWS changes are similar to our previous projections, there is a greater warming and freshening, that could reflect the change from the A1B emissions scenario to the RCP8.5 concentrations pathway or the higher climate sensitivity exhibited by HadGEM3-GC3.05. Off the shelf, south of Iceland, there is limited warming, consistent with a reduction in the Atlantic Meridional Overturning Circulations and associated northward heat transport. These projections have been publicly released, along with a consistent 200-year present day control simulation, to provide an evidence-base for climate change assessments and to facilitate climate impact studies. For example, we illustrate how the two products can be used to estimate of climate trends, unforced variability, and the Time of Emergence (ToE) of the climate signals. We calculate the average NWS SST ToE to be 2034 (with an 8-year range) and 2046 (with a 33-year range) for SSS. We also discuss how these projections can be used to describe NWS conditions under 2 °C and 4 °C global mean warming (compared to 1850–1900), as a policy relevant exemplar use-case.

The North West European Shelf Seas (NWS) are environmentally and economically important, and an understanding of how their climate may change helps with their management. However, as the NWS are poorly represented in Global Climate Models, a common approach is to dynamically downscale with an appropriate shelf seas model. We develop a set of physical marine climate projections for the NWS. We dynamically downscale 12 members of the HadGEM3-GC3.05 Perturbed Parameter Ensemble (approximately 70 km horizontal resolution over Europe), developed for UKCP18, using the shelf-seas model NEMO CO9 (7 km horizontal resolution). These are run under the high greenhouse gas emissions RCP8.5 scenario as continuous simulations over the period 1990–2098. We evaluate the simulations against observations in terms of tides, sea surface temperature, surface and near-bed temperature and salinity, and sea surface-height. These simulations represent the state-of-the-art for marine UK projections. We project a Sea-Surface Temperature (SST) rise of 3.11 °C (±2σ = 0.98 °C), and a Sea-Surface Salinity (SSS) freshening of −1.01 psu (±2σ = 0.93 psu) for 2079–2098 relative to 2000–2019, averaged over the NWS (approximately bounded by the 200 m isobar and excluding the Norwegian Trench, Skagerrak, and Kattegat). While the patterns of NWS changes are similar to our previous projections, there is a greater warming and freshening, that could reflect the change from the A1B emissions scenario to the RCP8.5 concentrations pathway or the higher climate sensitivity exhibited by HadGEM3-GC3.05. Off the shelf, south of Iceland, there is limited warming, consistent with a reduction in the Atlantic Meridional Overturning Circulations and associated northward heat transport. These projections have been publicly released, along with a consistent 200-year present day control simulation, to provide an evidence-base for climate change assessments and to facilitate climate impact studies. For example, we illustrate how the two products can be used to estimate of climate trends, unforced variability, and the Time of Emergence (ToE) of the climate signals. We calculate the average NWS SST ToE to be 2034 (with an 8-year range) and 2046 (with a 33-year range) for SSS. We also discuss how these projections can be used to describe NWS conditions under 2 °C and 4 °C global mean warming (compared to 1850–1900), as a policy relevant exemplar use-case.