Shipping is the most cost-effective option for the global transport of goods, and over 90 % of world trade is carried by sea. The shipping sector, however, contributes to emissions of pollutants into the air and water. Estimates of deposition and near-surface concentrations of sulfur, nitrogen, and particulate matter originating from shipping in the Baltic Sea region have been developed for present conditions concerning traffic intensity and fuel as well as for future scenarios until 2050.

A dimensionally consistent governing equation of transient, saturated groundwater flow in fractional time in a multi-fractional confined aquifer is developed. First a continuity equation for groundwater flow in fractional time and in a multi-fractional, multidimensional confined aquifer is developed. An equation of water flux is also developed. The governing equation of transient groundwater flow in a multi-fractional, multidimensional confined aquifer in fractional time is then obtained.

Groundwater level fluctuations in confined aquifer wells with long observations exhibit site-specific fractal scaling behavior, and the underlying distribution exhibits either non-Gaussian characteristics, which may be fitted by the Lévy stable distribution, or Gaussian characteristics. The estimated Hurst exponent is highly dependent on the length and the specific time interval of the time series. The MF-DFA and MMA analyses showed that different levels of multifractality exist.

We define three new climate indices based on monthly mean temperature and total precipitation values that describe the main features of the climate in the Baltic states. Higher values in each index correspond to (1) less distinct seasonality and (2) warmer and (3) wetter climate. It was calculated that in the future all three indices will increase. Such indices summarize and illustrate the spatial features of the Baltic climate, and they can be used in further analysis of climate change impact.

Trends and regime shifts in climatic and hydrological parameters are analysed in Estonia during 1951–2015. The most important finding was the regime shift in the majority of parameters since the winter 1988/1989. The intensity of westerly circulation described by the NAO and AO indices increased, winter mean air temperature and precipitation also increased, and snow cover duration decreased. Consequently, specific runoff of rivers increased in January, February and March but decreased in April.

Today, human interactions with the Earth system lead to complex feedbacks between social and ecological dynamics. Modeling such feedbacks explicitly in Earth system models (ESMs) requires making assumptions about individual decision making and behavior, social interaction, and their aggregation. In this overview paper, we compare different modeling approaches and techniques and highlight important consequences of modeling assumptions. We illustrate them with examples from land-use modeling.

We explain how the extreme 2015–2016 El Niño event lengthened the day by 0.8 ms. The 2015–2016 event was an El Niño event of a different type compared to previous extreme events; thus, we expected different mechanisms of coupling with the solid Earth. We showed that the atmospheric torque on the American topography, usually acting alone during classical El Niños, was, in 2015–2016, augmented by a friction torque over the Pacific Ocean and inherent to the different nature of this particular event.

Relationships between meteorological parameters between Arctic and the Baltic Sea regions were investigated using NCEP-CFSR reanalysis for 1979–2015. The Greenland and Baffin Bay regions climate have the most significant teleconnections with the Baltic Sea region temperature, specific humidity and wind speed. These relationships can be explained by the AO/NAO index variability only in winter. The results are valuable for selecting Arctic regions with the largest effect on the Baltic Sea region.

We statistically analysed the mechanisms of the variability in decadal sea-level trends for the whole Baltic Sea basin over the last century. We used two different sea-level data sets and several climatic data sets. The results of this study showed that precipitation has a lagged effect on decadal sea-level trend variations from which the signature of atmospheric effect is removed. This detected underlying factor is not connected to oceanic forcing driven from the North Atlantic region.

Solar and wind energy generation are weather dependent and can not be switched on when needed. Despite this, stable electricity supply can be obtained by aggregation over large areas, for example Europe. However, we show that strong climate change impedes spatial balancing of electricity because countries are more likely to suffer from simultaneous generation shortfall. As a consequence, local scarcity can less often be balanced by imports.

Floods are the main natural disaster in Brazil, causing substantial economic damage and loss of life. Here we seek to better understand the flood-generating mechanisms in the flood-prone Paraná River basin, including large-scale patterns of the ocean and atmospheric circulation. This study provides new insights for understanding causes of floods in the region and around the world and is a step forward to improve flood risk management, statistical assessments, and short-term flood forecasts.

Coastal environments and shelf sea represent 7.6 % of the total oceanic surface area. They are, however, biogeochemically more dynamic and probably more vulnerable to climate change than the open ocean. Whatever the responses of the open ocean to climate change, they will propagate to the coastal ocean. We used the self-organizing multiple linear output (SOMLO) method to estimate the ocean surface pCO₂ in the Baltic Sea from remotely sensed measurements and we estimated the air–sea CO₂ flux.

This review describes the general knowledge of the marine acid–base system as well as the peculiarities identified and reported for the Baltic Sea specifically. We discuss issues such as dissociation constants in the brackish water, the structure of the total alkalinity in the Baltic Sea, long-term changes in total alkalinity, and the acid–base effects of biomass production and mineralization. We identify research gaps and specify bottlenecks concerning the Baltic Sea acid–base system.

Nitrogen input in natural ecosystems usually has a positive effect on plant growth. However, too much N causes N leaching, which contributes to water pollution. Using a global model we estimated that N leaching from natural lands has increased by 73 % during the 20th century, mainly due to rising N deposition from the atmosphere caused by emissions from fossil fuels and agriculture. Climate change and increasing CO₂ concentration had positive and negative effects (respectively) on N leaching.

Sahel greening and browning are discussed based on the relevance of edaphic factors, the importance of the observation period, and modifications in the vegetation pattern. The key findings are that (i) vegetation recovery predominantly depends on soil types, (ii) botanical investigations and EO-based time series show a substantial decline in the diversity and cover density of woody species compared to pre-drought conditions, (iii) and pattern formation is a key indicator for ecosystem changes.

We use a Bayesian approach for inferring inverse, stochastic–dynamic models from northern Greenland (NGRIP) oxygen and dust records of subdecadal resolution for the interval 59 to 22 ka b2k. Our model reproduces the statistical and dynamical characteristics of the records, including the Dansgaard–Oeschger variability, with no need for external forcing. The crucial ingredients are cubic drift terms, nonlinear coupling terms between the oxygen and dust time series, and non-Markovian contributions.

The UN sustainable development goals for eradicating hunger are at high risk for failure in the Sahel. We show that the demand for food and feed biomass will begin to outstrip its supply in the 2040s if current trends continue. Though supply continues to increase it is outpaced by a greater increase in demand due to a combination of population growth and a shift to diets rich in animal proteins. This underscores the importance of policy interventions that would act to mitigate such developments.

Local mean sea level often varies strongly from year to year (on the order of a few decimeters). This is mainly due to interannual variability in wind climate and atmospheric pressure. In this paper, regional differences in the sensitivity of mean sea level to atmospheric forcing are studied in an inter-tidal basin. Correcting for the atmospheric effects removes most of the interannual variability in mean sea level.

Fires damage large areas of eastern Amazon forests when ignitions from human activity coincide with droughts, while more humid central and western regions are less affected. Here, we use a fire model to estimate that fire activity could increase by an order of magnitude without climate mitigation. Our results show that avoiding further agricultural expansion can limit fire ignitions but that tackling climate change is essential to insulate the interior Amazon through the 21st century.

This paper analyzes the origin of the moisture in two extremely important atmospheric river (and extreme precipitation) events. The distribution of the moisture with regard to the low-level jet is analyzed as well, and the classic association of the atmospheric river to the former is discussed.

The southern part of Pakistan (Sindh province) has been exposed to frequent and intense temperature extremes recently and is highly vulnerable to their impacts due to lack of information on recurrence of extremes. In this paper for the first time we estimated the return levels of daily maximum temperatures and daily maximum wet-bulb temperatures over the different return periods in Sindh, which would help the local administrations to prioritize the regions in terms of adaptations.