Abstract. With progressing global warming, there is an increased risk that one or several tipping elements in the climate system might cross a critical threshold, resulting in severe consequences for the global climate, ecosystems and human societies. While the underlying processes are fairly well-understood, it is unclear how their interactions might impact the overall stability of the Earth's climate system. As of yet, this cannot be fully analysed with state-of-the-art Earth system models due to computational constraints as well as some missing and uncertain process representations of certain tipping elements. Here, we explicitly study the effects of known physical interactions among the Greenland and West Antarctic ice sheets, the Atlantic Meridional Overturning Circulation (AMOC) and the Amazon rainforest using a conceptual network approach. We analyse the risk of domino effects being triggered by each of the individual tipping elements under global warming in equilibrium experiments. In these experiments, we propagate the uncertainties in critical temperature thresholds, interaction strengths and interaction structure via large ensembles of simulations in a Monte Carlo approach. Overall, we find that the interactions tend to destabilise the network of tipping elements. Furthermore, our analysis reveals the qualitative role of each of the four tipping elements within the network, showing that the polar ice sheets on Greenland and West Antarctica are oftentimes the initiators of tipping cascades, while the AMOC acts as a mediator transmitting cascades. This indicates that the ice sheets, which are already at risk of transgressing their temperature thresholds within the Paris range of 1.5 to 2 ∘C, are of particular importance for the stability of the climate system as a whole.

Anthropogenic climate change profoundly alters the ocean’s environmental conditions, which, in turn, impact marine ecosystems. Some of these changes are happening fast and may be difficult to reverse. The identification and monitoring of such changes, which also includes tipping points, is an ongoing and emerging research effort. Prevention of negative impacts requires mitigation efforts based on feasible research-based pathways. Climate-induced tipping points are traditionally associated with singular catastrophic events (relative to natural variations) of dramatic negative impact. High-probability high-impact ocean tipping points due to warming, ocean acidification, and deoxygenation may be more fragmented both regionally and in time but add up to global dimensions. These tipping points in combination with gradual changes need to be addressed as seriously as singular catastrophic events in order to prevent the cumulative and often compounding negative societal and Earth system impacts.

Abstract. The retreat of sea ice is very significant in the Arctic under global warming. It is projected to continue and have great impacts on navigation. In this investigation, decadal changes in sea ice parameters were evaluated by multimodel from the Coupled Model Intercomparison Project Phase 6, and Arctic navigability was assessed under two shared socioeconomic pathways (SSPs) and two vessel classes within the Arctic transportation accessibility model. The sea ice extent is expected to decrease along the SSP5-8.5 scenario with a high possibility under current emissions and climate change. The decadal decreasing rate will increase in March but decrease in September until 2060 when the oldest ice completely disappears and sea ice changes reach an irreversible tipping point. The sea ice thickness will decrease and transit in parts of the Arctic and will decline overall by −0.22 m per decade after September 2060. Both the sea ice concentration and volume will thoroughly decline with decreasing decadal rates, while the decrease in volume will be higher in March than in September. Open water ships will be able to cross the Northeast Passage and Northwest Passage in August–October 2045–2055, with a maximum navigable area in September. The opportunistic crossing time for polar class 6 (PC6) ships will advance to October–December in 2021–2030, while the maximum navigable area will be seen in October. In addition, the Central Passage will also open for PC6 ships during September–October in 2021–2030.

The loss of ecosystem carbon (the sum of vegetation, litter, and soil carbon) may occur in a permafrost region under mitigation pathways, which could reduce the efficiency of carbon dioxide removal. Here, we investigate changes in permafrost under net-zero and negative emissions, based on idealized emission-driven simulations using a state-of-the-art Earth system model. While acting as a net ecosystem carbon sink during most of the positive emission phase, permafrost becomes a net ecosystem carbon source just before reaching net-zero and negative emissions. Permafrost slowly recovers, especially in regions with high organic carbon content, and net ecosystem carbon loss persists until the end of simulations, resulting in a cumulative net ecosystem carbon loss of approximately 14 petagrams of carbon (PgC) in both scenarios. In addition, methane emissions increase under net-zero and negative emissions, due to the irreversibility of the inundated areas. We conclude that the permafrost ecosystem carbon loss may continue under net-zero and negative emissions, which could hinder climate change mitigation efforts.

There is mounting evidence that some parts of the Earth system may be at risk of abrupt and potentially irreversible changes, driven by the cumulative impact of incremental global warming. Such a non-linear transition could be triggered if a critical threshold in global temperature – a “tipping point” – is crossed, when a small change could push a system into a completely new state, with potentially catastrophic impacts. In this technical briefing, we will first define tipping points and tipping elements, then explore several tipping elements in more detail and discuss the questions of abruptness, irreversibility, timescales and uncertainties for each of them. We also investigate the possibility of developing early warning systems for tipping points, and the risk of cascades of interacting tipping points, where one tipping point could trigger another.

The retreat of sea ice has been found to be very significant in the Arctic under global warming. It is projected to continue and will have great impacts on navigation. Perspectives on the changes in sea ice and navigability are crucial to the circulation pattern and future of the Arctic. In this investigation, the decadal changes in sea ice parameters were evaluated by the multi-model from the Coupled Model Inter-comparison Project Phase 6, and Arctic navigability was assessed under two shared socioeconomic pathways (SSPs) and two vessel classes with the Arctic transportation accessibility model. The sea ice extent shows a high possibility of decreasing along SSP5-8.5 under current emissions and climate change. The decadal rate of decreasing sea ice extent will increase in March but decrease in September until 2060, when the oldest ice will have completely disappeared and the sea ice will reach an irreversible tipping point. Sea ice thickness is expected to decrease and transit in certain parts, declining by −0.22 m per decade after September 2060. Both the sea ice concentration and volume will thoroughly decline at decreasing decadal rates, with a greater decrease in volume in March than in September. Open water ships will be able to cross the Northern Sea Route and Northwest Passage between August and October during the period from 2045 to 2055, with a maximum navigable percentage in September. The time for Polar Class 6 (PC6) ships will shift to October–December during the

have severe impacts on human society and may accelerate global warming. Tipping behavior is found across the climate system, for example in ice sheets In climate science, a tipping point is a critical threshold that, when crossed, leads to large, accelerating and often irreversible changes in the climate system. If tipping points are crossed, they are likely to have severe impacts on human society and may accelerate global warming. Tipping behavior is found across the climate system, for example in ice sheets, mountain glaciers, circulation patt Th… Mountain glaciers are the largest repository of land-bound ice after the Greenland and the Antarctica ice sheets, and they are also undergoing melting as the result of climate change. A glacier tipping point is when it enters a disequilibrium state with the climate and will melt away unless the temperatures go down. Examples include glaciers of the North Cascade Range, where even in 2005 67% of the glaciers observed were in disequilibrium and will not survive the continuation of the present climate, or the French Alps, where The Argentière and Mer de Glace glaciers are expected to disappear completely by end of the 21st century if current climate trends persist. Altogether, it was estimated in 2023 that 49% of the world's glaciers would be lost by 2100 at 1.5 °C (2.7 °F) of global warming, and 83% of glaciers would be lost at 4 °C (7.2 °F). This would amount to one quarter and nearly half of mountain glacier *mass* loss, respectively, as only the largest, most resilient glaciers would survive the century. This ice loss would also contribute ~9 cm (3+1⁄2 in) and ~15 cm (6 in) to sea level rise, while the current likely trajectory of 2.7 °C (4.9 °F) would result in the SLR contribution of ~11 cm (4+1⁄2 in) by 2100. The absolute largest amount of glacier ice is located in the Hindu Kush Himalaya region, which is colloquially known as the Earth's Third Pole as the result. It is believed that one third of that ice will be lost by 2100 even if the warming is limited to 1.5 °C (2.7 °F), while the intermediate and severe climate change scenarios (Representative Concentration Pathways (RCP) 4.5 and 8.5) are likely to lead to the losses of 50% and >67% of the region's glaciers over the same timeframe. Glacier melt is projected to accelerate regional river flows until the amount of meltwater peaks around 2060, going into an irreversible decline afterwards. Since regional precipitation will continue to increase even as the glacier meltwater contribution declines, annual river flows are only expected to diminish in the western basins where contribution from the monsoon is low: however, irrigation and hydropower generation would still have to adjust to greater interannual…

The speed of West Antarctic melting is a very important factor in determining the degree of future global sea level rise. Loss of the Thwaites glacier due to global warming will have various regime changes in line with changes in the Earth system. The basal melting as a result of ocean warming can cause loss at an inhomogeneous rate across the underlying topography and overlying ice volume, while the change in precipitation from snow to rain as atmospheric warming can accelerate surface melting and trigger the irreversible loss.  In this study, the ISSM model was driven with the ocean and atmospheric forcings obtained from the CMIP6 earth system model results, and future prediction experiments were performed until 2300. As a result, the accelerated period of melting of the Thwaites glacier related with forcings and the period of irreversible loss according to the structural characteristics and degree of warming are investigated. The mechanisms and timing that cause rapid ice loss are analyzed and the tipping point at which irreversible losses are triggered has been proposed as a function of warming.

We are just beginning to grasp the meaning of this loss in terms of opportunity costs to human society and the less quantifiable losses associated with simplification of natural ecosystems. In the case of both global warming and reduction of biological diversity, man is affecting nature in an unprecedented fashion, on a global scale, and with unpredictable and frequently irreversible results. Published in Environmental health perspectives (1991)

regions. Some climate scientists think that global warming is permanently expanding the Sahara Desert southward … could have global consequences. Ozone depletion in the upper atmosphere is clearly a global problem, but … about global warming and related aspects of human-induced climate change. The Environment and Global Change

The marine-based West Antarctic Ice Sheet (WAIS) is considered vulnerable to irreversible collapse under future climate trajectories, and its tipping point may lie within the mitigated warming scenarios of 1.5° to 2°C of the United Nations Paris Agreement. Knowledge of ice loss during similarly warm past climates could resolve this uncertainty, including the Last Interglacial when global sea levels were 5 to 10 meters higher than today and global average temperatures were 0.5° to 1.5°C warmer than preindustrial levels. Using a panel of genome-wide, single-nucleotide polymorphisms of a circum-Antarctic octopus, we show persistent, historic signals of gene flow only possible with complete WAIS collapse. Our results provide the first empirical evidence that the tipping point of WAIS loss could be reached even under stringent climate mitigation scenarios.