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The City of Venice and the surrounding lagoonal ecosystem are highly vulnerable to variations in relative sea level. In the past ~150 years, this was characterized by a secular linear trend of about 2.5 mm/year resulting from the combined contributions of vertical land movement and sea-level rise. This literature review reassesses and synthesizes the progress achieved in understanding, estimating and predicting the individual contributions to local relative sea level, with focus on the most recent publications. The current best estimate of historical sea-level rise in Venice, based on tide-gauge data after removal of subsidence effects, is 1.23 ± 0.13 mm/year (period from 1872 to 2019). Subsidence thus contributed to about half of the observed relative sea-level rise over the same period. A higher – yet more uncertain – rate of sea-level rise is observed during recent decades, estimated from tide-gauge data to be about 2.76 ± 1.75 mm/year in the period 1993–2019 for the climatic component alone. An unresolved issue is the contrast between the observational capacity of tide gauges and satellite altimetry, with the latter tool not covering the Venice Lagoon. Water mass exchanges through the Gibraltar Strait currently constitute a source of substantial uncertainty for estimating future deviations of the Mediterranean mean sea-level trend from the global-mean value. Subsidence and regional atmospheric and oceanic circulation mechanisms can deviate Venetian relative sea-level trends from the global mean values for several decades. Regional processes will likely continue to determine significant interannual and interdecadal variability of Venetian sea level with magnitude comparable to that observed in the past, as well as non-negligible differential trends. Our estimate of the likely range of mean sea-level rise in Venice by 2100 due to climate change is presently estimated between 11 and 110 centimetres. An improbable yet possible high-end scenario linked to strong ice

The city of Venice and the surrounding lagoonal ecosystem are highly vulnerable to variations in relative sea level. In the past ∼150 years, this was characterized by an average rate of relative sea-level rise of about 2.5 mm/year resulting from the combined contributions of vertical land movement and sea-level rise. This literature review reassesses and synthesizes the progress achieved in quantification, understanding and prediction of the individual contributions to local relative sea level, with a focus on the most recent studies. Subsidence contributed to about half of the historical relative sea-level rise in Venice. The current best estimate of the average rate of sea-level rise during the observational period from 1872 to 2019 based on tide-gauge data after removal of subsidence effects is 1.23 ± 0.13 mm/year. A higher – but more uncertain – rate of sea-level rise is observed for more recent years. Between 1993 and 2019, an average change of about +2.76 ± 1.75 mm/year is estimated from tide-gauge data after removal of subsidence. Unfortunately, satellite altimetry does not provide reliable sea-level data within the Venice Lagoon. Local sea-level changes in Venice closely depend on sea-level variations in the Adriatic Sea, which in turn are linked to sea-level variations in the Mediterranean Sea. Water mass exchange through the Strait of Gibraltar and its drivers currently constitute a source of substantial uncertainty for estimating future deviations of the Mediterranean mean sea-level trend from the global-mean value. Regional atmospheric and oceanic processes will likely contribute significant interannual and interdecadal future variability in Venetian sea level with a magnitude comparable to that observed in the past. On the basis of regional projections of sea-level rise and an understanding of the local and regional processes affecting relative sea-level trends in Venice, the likely range of atmospherically corrected relative sea-level rise in Venice by

Springtime stratospheric final warming (SFW) variability has been suggested to be linked to the tropospheric circulation, particularly over the North Atlantic sector. These findings, however, are based on reanalysis data that cover a rather short period of time (1979 to present). The present work aims to improve the understanding of drivers, trends and surface impact of dynamical variability of boreal SFWs using chemistry‐climate models. We use multidecadal integrations of the fully coupled chemistry‐climate models Community Earth System Model version 1 (Whole Atmosphere Community Climate Model) and ECHAM/Modular Earth Submodel System Atmospheric Chemistry‐O. Four sensitivity experiments are analyzed to assess the impact of external factors; namely, the quasi‐biennial oscillation, sea surface temperature (SST) variability, and anthropogenic emissions. SFWs are classified into two types with respect to their vertical development; that is, events which occur first in the midstratosphere (10‐hPa first SFWs) or first in the upper stratosphere (1‐hPa first SFWs). Our results confirm previous reanalysis results regarding the differences in the time evolution of stratospheric conditions and near‐surface circulation between 10 and 1‐hPa first SFWs. Additionally, a tripolar SST pattern is, for the first time, identified over the North Atlantic in spring months related to the SFW variability. Our analysis of the influence of remote modulators on SFWs revealed that the occurrence of major warmings in the previous winter favors the occurrence of 10‐hPa first SFWs later on. We further found that quasi‐biennial oscillation and SST variability significantly affect the ratio between 1‐hPa first and 10‐hPa first SFWs. Finally, our results suggest that ozone recovery may impact the timing of the occurrence of 1‐hPa first SFWs.

The surface response to the 11-yr solar cycle is assessed in ensemble simulations of the 20th century climate performed in the framework of the 5th phase of the Coupled Model Inter-Comparison Project (CMIP5). A lead/lag multiple linear regression analysis identifies a multi-model mean (MMM) global mean surface warming of about 0.07 K lagging the solar cycle by one to two years on average. The anomalous warming penetrates to approximately the first 80–100 m depth in the ocean. Solar signals in the troposphere show a similar time lag of one to two years and the strongest MMM warming is simulated in the tropics above 300 hPa. At the surface, the MMM response in a subset of models that show statistically significant global mean warming (CMIP5-SIG95) is characterized by an anomalous warming in the west equatorial Pacific Ocean and the Arctic, at one to two years after solar maximum. The Arctic warming is twice as strong as the global mean response and appears in winter months only. The surface warming in the equatorial Pacific Ocean is related to dynamical/thermodynamical processes. Different increase rates of global mean precipitation and atmospheric water vapor in response to a warmer surface lead to a weaker Walker circulation and anomalous westerly winds over the equatorial Pacific in years following solar maximum. Owing to atmosphere–ocean coupling, the anomalous westerly winds cool the subsurface and warm the surface in the western equatorial Pacific by ∼ 0.14 K. The CMIP5-SIG95 MMM surface warming in the equatorial Pacific and Arctic is weak but qualitatively similar compared to solar signals in the HadCRUT4 dataset.