According to climate model estimates, the land stored 2 % of the system's heat excess in the last decades, while observational studies show it was around 6 %. This difference stems from these models using land components that are too shallow to constrain land heat uptake. Deepening the land component does not affect the surface temperature. This result can be used to derive land heat uptake estimates from different sources, which are much closer to previous observational reports.

Ocean acidification is likely to impact all stages of the ocean carbonate pump. We show divergent responses of CaCO₃ export throughout this century in earth system models, with anomalies by 2100 ranging from −74 % to +23 % under a high-emission scenario. While we confirm the limited impact of carbonate pump anomalies on 21st century ocean carbon uptake and acidification, we highlight a potentially abrupt shift in CaCO₃ dissolution from deep to subsurface waters beyond 2100.

Using a special suite of climate simulations, we determine if and when climate change is detectable and translate this to the global warming prevalent in the corresponding year. Our results show that, at 1.5°C warming, >85 % of the global population (>95 % at 2.0° warming) is already exposed to nighttime temperatures altered by climate change beyond natural variability. Furthermore, even incremental changes in global warming levels result in increased human exposure to emerged climate signals.

We develop a new classification method for synoptic circulation patterns. Its unique novelty is the use of the modified structural similarity index metric (SSIM). We demonstrate an exemplary application of the synoptic circulation classes obtained with the new classification method for evaluating historical climate simulations. We introduce a distance metric to measure the match in frequency and duration of synoptic classes between a climate simulation and the reference.

We qualitatively study the long-term stability of the Greenland Ice Sheet and AMOC as tipping elements in the Earth system, which is largely unknown given their interaction in a positive–negative feedback loop. Depending on the timescales of ice loss and the position of the AMOC’s state relative to its critical threshold, we find distinct dynamic regimes of cascading tipping. These suggest that respecting safe rates of environmental change is necessary to mitigate potential domino effects.

Lakes worldwide are changing and under threat due to stressors such as overload of nutrients, increased input of organic carbon (“browning”), and climate change, which may cause reduced water volume, salinization, or even loss of waterbodies. Some of these changes are abrupt to the extent that they can be characterized as tipping points for that particular system. Such changes may also cause increased release of greenhouse gases, and lakes are major players in the global climate in this context.

Ocean acidification will cause profound shifts in many marine ecosystems by impairing the ability of calcareous taxa to grow and by influencing the photophysiology of many others. Physiological tipping points will likely be reached in the next 20 years. Small changes in organism physiology result in larger ecological tipping points being crossed. Ecosystems will shift from having higher abundances of calcifying taxa and towards increased abundances of non-calcareous species under elevated CO₂.

This study explores Atlantic–Pacific interactions and their response to external factors. Causal analysis of 1950–2014 data reveals a shift from a Pacific- to an Atlantic-driven regime. Contrasting impacts between El Niño and tropical Atlantic temperatures are highlighted, along with different pathways connecting the two oceans. The findings also suggest increasing remote contributions of forced Atlantic responses in modulating local Pacific responses during the most recent analyzed decades.

Heat extremes have severe implications for human health and ecosystems. Heat extremes are mostly introduced by large-scale atmospheric circulation but can be modulated by vegetation. Vegetation with access to water uses solar energy to evaporate water into the atmosphere. Under dry conditions, water may not be available, suppressing evaporation and heating the atmosphere. Using climate projections, we show that regionally less water is available for vegetation, intensifying future heat extremes.

We aim to combine multiple global climate models (GCMs) to enhance the robustness of future projections. We introduce a novel approach, called "α pooling", aggregating the cumulative distribution functions (CDFs) of the models into a CDF more aligned with historical data. The new CDFs allow us to perform bias adjustment of all the raw climate simulations at once. Experiments with European temperature and precipitation demonstrate the superiority of this approach over conventional techniques.

Elevated CO₂ concentration (eCO₂) is critical for shaping the future path of forest carbon uptake, while uncertainties remain about concurrent carbon loss. Here, we found that eCO₂ might amplify competition-induced carbon loss, while the extent of drought-induced carbon loss hinges on the balance between heightened biomass density and water-saving benefits. This is the first time that such carbon loss responses to ongoing climate change have been quantified separately over the Amazon rainforest.

Global warming has triggered profound transformations in the Earth's climate system. Our study reveals a reduction in the connectivity of highly isolated nodes located along the Equator, particularly regarding their interactions with neighboring regions within the same oceanic basin. Conversely, these nodes display strengthened connections with specific continents, highlighting the intricate interplay between global warming and the evolving structure of climate networks.

Cascading effects through cross-system interactions are one of the biggest promises of positive tipping points to create rapid climate and sustainability action. Here, we review these in terms of their interactions with sociotechnical systems such as energy, transport, agriculture, society, and policy.

Oceanic bromoform, produced by algae, is an important precursor of atmospheric bromine, highlighting the importance of implementing these emissions in climate models. The simulated mean oceanic concentrations align well with observations, while the mean atmospheric values are lower than the observed ones. Modelled annual mean emissions mostly occur from the sea to the air and are driven by oceanic concentrations, sea surface temperature, and wind speed, which depend on season and location.