scholarly journals Interacting tipping elements increase risk of climate domino effects under global warming

2021 ◽  
Vol 12 (2) ◽  
pp. 601-619
Author(s):  
Nico Wunderling ◽  
Jonathan F. Donges ◽  
Jürgen Kurths ◽  
Ricarda Winkelmann
Keyword(s):  
Global Warming ◽  
Global Climate ◽  
Ice Sheets ◽  
Meridional Overturning Circulation ◽  
Climate System ◽  
Critical Threshold ◽  
West Antarctic ◽  
Increased Risk ◽  
Temperature Thresholds ◽  
The Individual

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.

scholarly journals Interacting tipping elements increase risk of climate domino effects under global warming

2020 ◽  
Author(s):  
Nico Wunderling ◽  
Jonathan F. Donges ◽  
Jürgen Kurths ◽  
Ricarda Winkelmann
Keyword(s):  
Global Warming ◽  
Southern Oscillation ◽  
Ice Sheets ◽  
Meridional Overturning Circulation ◽  
Climate System ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Temperature Thresholds ◽  
Earth’S Climate ◽  
The Individual

Abstract. There exists a range of subsystems in the climate system exhibiting threshold behaviour which could be triggered under global warming within this century resulting in severe consequences for biosphere and human societies. While their individual tipping thresholds are fairly well understood, it is of yet unclear how their interactions might impact the overall stability of the Earth's climate system. This cannot be studied yet with state-of-the-art Earth system models due to computational constraints as well as missing and uncertain process representations of some tipping elements. Here, we explicitly study the effects of known physical interactions between the Greenland and West Antarctic Ice Sheet, the Atlantic Meridional Overturning Circulation, the El-Nino Southern Oscillation 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, propagating uncertainties in critical temperature thresholds and interaction strengths via a Monte-Carlo approach. Overall, we find that the interactions tend to destabilise the network. Furthermore, our analysis reveals the qualitative role of each of the five tipping elements 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 implies 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.

scholarly journals Earth’s radiative imbalance from the Last Glacial Maximum to the present

2019 ◽  
Vol 116 (30) ◽  
pp. 14881-14886 ◽  
Author(s):  
Daniel Baggenstos ◽  
Marcel Häberli ◽  
Jochen Schmitt ◽  
Sarah A. Shackleton ◽  
Benjamin Birner ◽  
...  
Keyword(s):  
Energy Content ◽  
Heat Budget ◽  
Global Climate ◽  
Noble Gas ◽  
Ice Core ◽  
Meridional Overturning Circulation ◽  
Climate System ◽  
Ocean Heat Uptake ◽  
Radiative Balance ◽  
West Antarctic

The energy imbalance at the top of the atmosphere determines the temporal evolution of the global climate, and vice versa changes in the climate system can alter the planetary energy fluxes. This interplay is fundamental to our understanding of Earth’s heat budget and the climate system. However, even today, the direct measurement of global radiative fluxes is difficult, such that most assessments are based on changes in the total energy content of the climate system. We apply the same approach to estimate the long-term evolution of Earth’s radiative imbalance in the past. New measurements of noble gas-derived mean ocean temperature from the European Project for Ice Coring in Antarctica Dome C ice core covering the last 40,000 y, combined with recent results from the West Antarctic Ice Sheet Divide ice core and the sea-level record, allow us to quantitatively reconstruct the history of the climate system energy budget. The temporal derivative of this quantity must be equal to the planetary radiative imbalance. During the deglaciation, a positive imbalance of typically +0.2 W⋅m−2 is maintained for ∼10,000 y, however, with two distinct peaks that reach up to 0.4 W⋅m−2 during times of substantially reduced Atlantic Meridional Overturning Circulation. We conclude that these peaks are related to net changes in ocean heat uptake, likely due to rapid changes in North Atlantic deep-water formation and their impact on the global radiative balance, while changes in cloud coverage, albeit uncertain, may also factor into the picture.

Interacting tipping elements increase risk of climate domino effects

2020 ◽  
Author(s):  
Nico Wunderling ◽  
Jonathan Donges ◽  
Jürgen Kurths ◽  
Ricarda Winkelmann
Keyword(s):  
Ice Sheets ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Meridional Overturning Circulation ◽  
Climate System ◽  
Amazon Rainforest ◽  
Freshwater Flux ◽  
West Antarctica ◽  
The Earth ◽  
Temperature Thresholds

<p>The Greenland Ice Sheet, West Antarctic Ice Sheet, Atlantic Meridional Overturning Circulation (AMOC), El-Nino Southern Oscillation (ENSO) and the Amazon rainforest have been identified as potential tipping elements in the Earth system, exhibiting threshold behavior. While their individual tipping thresholds are fairly well understood, it is of yet unclear how their interactions might impact the overall stability of the Earth’s climate system. Here, we explicitly study the effects of known physical interactions using a paradigmatic network approach which is not yet possible with more complex global circulation models or process-based models in a comprehensive way.</p><p>We analyze the risk of domino effects being triggered by each of the individual tipping elements under global warming in equilibrium experiments, propagating uncertainties in critical temperature thresholds and interaction strengths via a Monte-Carlo approach.</p><p>Overall, we find that the interactions tend to destabilize the network, with cascading failures occurring in 41% of cases in warming scenarios up to 2°C. More specifically, we uncover that:</p><p>(i) With increasing coupling strength, the temperature thresholds for inducing critical transitions are lowered significantly for West Antarctica, AMOC, ENSO and the Amazon rainforest. The dampening feedback loop between the Greenland Ice Sheet and the AMOC due to increased freshwater flux on the one hand and relative cooling around Greenland on the other, leads to an enhanced ambivalency whether the Greenland Ice Sheet tips or not.</p><p>(ii) Furthermore, our analysis reveals the role of each of the five tipping elements showing that the polar ice sheets on Greenland and West Antarctica are oftentimes the initiators of tipping cascades (in up to 40% of ensemble members for Greenland), while the AMOC acts as a mediator, transmitting cascades.</p><p>This implies 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.</p>

scholarly journals Synergistic impacts of global warming and thermohaline circulation collapse on amphibians

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Julián A. Velasco ◽  
Francisco Estrada ◽  
Oscar Calderón-Bustamante ◽  
Didier Swingedouw ◽  
Carolina Ureta ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Thermohaline Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Extinction Risk ◽  
Meridional Overturning Circulation ◽  
Mitigation Strategies ◽  
Amphibian Species ◽  
Climate Conditions

AbstractImpacts on ecosystems and biodiversity are a prominent area of research in climate change. However, little is known about the effects of abrupt climate change and climate catastrophes on them. The probability of occurrence of such events is largely unknown but the associated risks could be large enough to influence global climate policy. Amphibians are indicators of ecosystems’ health and particularly sensitive to novel climate conditions. Using state-of-the-art climate model simulations, we present a global assessment of the effects of unabated global warming and a collapse of the Atlantic meridional overturning circulation (AMOC) on the distribution of 2509 amphibian species across six biogeographical realms and extinction risk categories. Global warming impacts are severe and strongly enhanced by additional and substantial AMOC weakening, showing tipping point behavior for many amphibian species. Further declines in climatically suitable areas are projected across multiple clades, and biogeographical regions. Species loss in regional assemblages is extensive across regions, with Neotropical, Nearctic and Palearctic regions being most affected. Results underline the need to expand existing knowledge about the consequences of climate catastrophes on human and natural systems to properly assess the risks of unabated warming and the benefits of active mitigation strategies.

scholarly journals Impact of mid-glacial ice sheets on deep ocean circulation and global climate: Role of surface cooling on the AMOC

2020 ◽  
Author(s):  
Sam Sherriff-Tadano ◽  
Ayako Abe-Ouchi ◽  
Akira Oka
Keyword(s):  
North Atlantic ◽  
General Circulation ◽  
Global Climate ◽  
Surface Wind ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Meridional Overturning Circulation ◽  
Strengthening Effect ◽  
Surface Cooling ◽  
Glacial Ice

Abstract. This study explores the effect of southward expansion of mid-glacial ice sheets on the global climate and the Atlantic meridional overturning circulation (AMOC), as well as the processes by which the ice sheets modify the AMOC. For this purpose, simulations of Marine Isotope Stage (MIS) 3 and 5a are performed with an atmosphere-ocean general circulation model. In the MIS3 and MIS5a simulations, the global average temperature decreases by 5.0 °C and 2.2 °C, respectively, compared with the preindustrial climate simulation. The AMOC weakens by 3 % in MIS3, whereas it is enhanced by 16 % in MIS5a, both of which are consistent with a reconstruction. Sensitivity experiments extracting the effect of the expansion of glacial ice sheets from MIS5a to MIS3 show a global cooling of 1.1 °C, contributing to about 40 % of the total surface cooling from MIS5a to MIS3. These experiments also demonstrate that the ice sheet expansion leads to a surface cooling of 2 °C over the Southern Ocean as a result of colder North Atlantic deep water. We find that the southward expansion of the mid-glacial ice sheet exerts a small impact on the AMOC. Partially coupled experiments reveal that the global surface cooling by the glacial ice sheet tends to reduce the AMOC by increasing the sea ice at both poles, and hence compensates for the strengthening effect of the enhanced surface wind over the North Atlantic. Our results show that the total effect of glacial ice sheets on the AMOC is determined by the two competing effects, surface wind and surface cooling. The relative strength of surface wind and surface cooling depends on the ice sheet configuration, and the strength of the surface cooling can be comparable to that of surface wind when changes in the extent of ice sheet are prominent.

scholarly journals Increased risk of near term global warming due to a recent AMOC weakening

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Rémy Bonnet ◽  
Didier Swingedouw ◽  
Guillaume Gastineau ◽  
Olivier Boucher ◽  
Julie Deshayes ◽  
...  
Keyword(s):  
Global Warming ◽  
Low Frequency ◽  
Internal Variability ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
The Past ◽  
Increased Risk ◽  
Meridional Overturning ◽  
Near Term ◽  
New Generation

AbstractSome of the new generation CMIP6 models are characterised by a strong temperature increase in response to increasing greenhouse gases concentration1. At first glance, these models seem less consistent with the temperature warming observed over the last decades. Here, we investigate this issue through the prism of low-frequency internal variability by comparing with observations an ensemble of 32 historical simulations performed with the IPSL-CM6A-LR model, characterized by a rather large climate sensitivity. We show that members with the smallest rates of global warming over the past 6-7 decades are also those with a large internally-driven weakening of the Atlantic Meridional Overturning Circulation (AMOC). This subset of members also matches several AMOC observational fingerprints, which are in line with such a weakening. This suggests that internal variability from the Atlantic Ocean may have dampened the magnitude of global warming over the historical era. Taking into account this AMOC weakening over the past decades means that it will be harder to avoid crossing the 2 °C warming threshold.

Cascading tipping behavior of the interacting Greenland Ice Sheet and Atlantic Meridional Overturning Circulation in a model of low complexity 

2021 ◽  
Author(s):  
Ann Kristin Klose ◽  
Jonathan F. Donges ◽  
Ulrike Feudel ◽  
Ricarda Winkelmann
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Coupled System ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
Climate System ◽  
Critical Threshold ◽  
Overturning Circulation ◽  
Meridional Overturning ◽  
Tipping Behavior

<p>The Greenland Ice Sheet (GIS) and the Atlantic Meridional Overturning Circulation (AMOC) have been identified as possible tipping elements of the climate system, transitioning into a qualitatively different state with the crossing of a critical driver threshold. They interact via freshwater fluxes into the North Atlantic originating from a melting GIS on the one hand, and via a relative cooling around Greenland with a slowdown of the AMOC on the other. This positive-negative feedback loop raises the question how these effects will influence the overall stability of the coupled system. Here, we qualitatively explore the dynamics and in particular the emergence of cascading tipping behavior of the interacting GIS and AMOC by using process-based but still conceptual models of the individual tipping elements with a simple coupling under idealized forcing scenarios.</p><p>We identify patterns of multiple tipping such as (i) <strong>overshoot cascades</strong>, developing with a temporary threshold overshoot, and (ii) <strong>rate-induced cascades</strong>, arising under very rapid changes of tipping element drivers. Their occurrence within distinct corridors of dangerous tipping pathways is affected by the melting patterns of the GIS and thus eventually by the imposed external forcing and its time scales.</p><p>The conceptual nature of the proposed model does not allow for quantitative statements or projections on the emergence of tipping cascades in the climate system. Rather, our results stress that it is not only necessary to stay below a certain critical threshold to hinder tipping cascades but also to respect safe rates of environmental change to mitigate domino effects and in turn to maintain the resilience of the Earth system.</p>

Impact of mid-glacial ice sheets on deep ocean circulation and global climate

2021 ◽  
Author(s):  
Sam Sherriff-Tadano ◽  
Ayako Abe-Ouchi ◽  
Akira Oka
Keyword(s):  
North Atlantic ◽  
Global Climate ◽  
Surface Wind ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Meridional Overturning Circulation ◽  
Strengthening Effect ◽  
Surface Cooling ◽  
Glacial Ice ◽  
Cooling Effects

<p>This study explores the effect of southward expansion of Northern Hemisphere (American) mid-glacial ice sheets on the global climate and the Atlantic Meridional Overturning Circulation (AMOC), as well as the processes by which the ice sheets modify the AMOC. For this purpose, simulations of Marine Isotope Stage (MIS) 3 (36ka) and 5a (80ka) are performed with an atmosphere-ocean general circulation model. In the MIS3 and MIS5a simulations, the global average temperature decreases by 5.0 °C and 2.2 °C, respectively, compared with the preindustrial climate simulation. The AMOC weakens by 3% in MIS3, whereas it strengthens by 16% in MIS5a, both of which are consistent with an estimate based on <sup>231</sup>Pa/<sup>230</sup>Th. Sensitivity experiments extracting the effect of the southward expansion of glacial ice sheets from MIS5a to MIS3 show a global cooling of 1.1 °C, contributing to about 40% of the total surface cooling from MIS5a to MIS3. These experiments also demonstrate that the ice sheet expansion leads to a surface cooling of 2 °C over the Southern Ocean as a result of colder North Atlantic deep water. We find that the southward expansion of the mid-glacial ice sheet exerts a small impact on the AMOC. Partially coupled experiments reveal that the global surface cooling by the glacial ice sheet tends to reduce the AMOC by increasing the sea ice at both poles, and hence compensates for the strengthening effect of the enhanced surface wind over the North Atlantic. Our results show that the total effect of glacial ice sheets on the AMOC is determined by the two competing effects, surface wind and surface cooling. The relative strength of surface wind and surface cooling effects depends on the ice sheet configuration, and the strength of the surface cooling can be comparable to that of surface wind when changes in the extent of ice sheet are prominent.</p>

scholarly journals Evolution of the Asian–African Monsoonal Precipitation over the last 21 kyr and the Associated Dynamic Mechanisms

2019 ◽  
Vol 32 (19) ◽  
pp. 6551-6569 ◽  
Author(s):  
Jian Shi ◽  
Qing Yan
Keyword(s):  
Ice Sheets ◽  
Greenland Ice Sheet ◽  
Meridional Overturning Circulation ◽  
Precipitation Pattern ◽  
External Forcings ◽  
Climate Simulations ◽  
Monsoonal Precipitation ◽  
Meridional Overturning ◽  
The Individual ◽  
Long Term Behavior

Abstract The Asian–African monsoonal precipitation (AAMP) has a significant impact on the water availability, biodiversity, and livelihoods of billions of people. A comprehensive understanding of the AAMP behavior over Earth’s history will help to make better future projections. Using a set of transient climate simulations over the last 21 000 years (21 ka), the variation of the AAMP and its responses to various external forcings, including orbital insolation, greenhouse gases (GHGs), and ice sheets, are explored. The precipitation evolutions in the individual monsoon domains have the characteristic of hemispheric synchrony over the last 21 ka. Specifically, the AAMP increased from the Last Glacial Maximum to the early Holocene with several abrupt events and then decreased subsequently. The raised orbital insolation and GHGs lead to an overall AAMP increase, but the enhanced insolation tends to induce a systematic northward shift of the Asian–African monsoon domain. Decreased meltwater discharge could promote the African and Indian monsoonal precipitation through strengthening the Atlantic Ocean meridional overturning circulation. However, the lowering of ice sheets (i.e., orographic effect) results in an anomalous dipole precipitation pattern between North China and India. An analysis of the moisture budget suggests that, although different external forcings may lead to the same sign of precipitation change (e.g., both increased insolation and GHGs can cause the enhanced AAMP), the thermodynamic and dynamic contributions to precipitation could vary greatly by region and forcing. This study provides a reference for the long-term behavior of the AAMP with rising GHGs, higher insolation, and potential melting of the Greenland Ice Sheet.

A review of recent developments in climate change science. Part I: Understanding of future change in the large-scale climate system

2011 ◽  
Vol 35 (3) ◽  
pp. 281-296 ◽  
Author(s):  
Peter Good ◽  
John Caesar ◽  
Dan Bernie ◽  
Jason A. Lowe ◽  
Paul van der Linden ◽  
...  
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Global Climate ◽  
Scientific Progress ◽  
Meridional Overturning Circulation ◽  
Climate System ◽  
Intergovernmental Panel ◽  
Recent Developments ◽  
Substantial Progress ◽  
Multiple Experts

This article reviews some of the major lines of recent scientific progress relevant to the choice of global climate policy targets, focusing on changes in understanding since publication of the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4). Developments are highlighted in the following major climate system components: ice sheets; sea ice; the Atlantic Meridional Overturning Circulation; tropical forests; and accelerated carbon release from permafrost and ocean hydrates. The most significant developments in each component are identified by synthesizing input from multiple experts from each field. Overall, while large uncertainties remain in all fields, some substantial progress in understanding is revealed.

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