Our Common Future Under Climate Change

International Scientific Conference 7-10 JULY 2015 Paris, France

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Wednesday 8 July - 11:30-13:00 UNESCO Fontenoy - ROOM IV

L2.4 - Early Warning for Thresholds and Tipping Points in the Earth System

Large Parallel Session

Chair(s): M. Bustamante (Universidade de Brasília, Brasilia, Brazil)

Lead Convener(s): T. Lenton (university of exeter, exeter, United Kingdom)

11:30

Early warning of climate tipping points

T. Lenton (university of exeter, exeter, United Kingdom)

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Early warning of climate tipping points

T. Lenton (1)
(1) university of exeter, exeter, United Kingdom

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A ‘tipping point’ occurs when a small change in forcing triggers a strongly non-linear response in the internal dynamics of a system, qualitatively changing its future state.  Large-scale ‘tipping elements’ have been identified in the Earth’s climate system that may pass a tipping point under human-induced global change this century.  At the smaller scale of ecosystems, some tipping points have already been observed, and more are anticipated in future.  Our capacity to forecast such abrupt, non-linear changes has historically been poor.  However, much excitement has recently been generated by the theory that some approaching tipping points carry generic early warning signals.  I will critically examine the prospects for gaining early warning of approaching tipping points.  Promising methods are based on detecting ‘critical slowing down’ in the rate a system recovers from small perturbations, and on accompanying changes in the statistical distribution of its behaviour.  I will show examples of early warning signals in paleo-data approaching past abrupt climate changes, and in models being gradually forced past physical climate tipping points.  I will also discuss the conditions under which the methods fail.  Finally, I will show an example of pronounced slowing down in observational climate data, for North Pacific sea surface temperatures, and explore the implications for well-known marine ecosystem ‘regime shifts’. 

11:50

Are there tipping points in terrestrial ecosystems?

M. Hirota (Federal University of Santa Catarina , Santa Catarina, Brazil)

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Are there tipping points in terrestrial ecosystems?

M. Hirota (1)
(1) Federal University of Santa Catarina, Santa Catarina, Brazil

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Terrestrial ecosystems have been undergoing unprecedented climate and human-induced disturbances, which are likely to push these systems towards changes in their physiognomies, structure, and functioning. It has been hypothesized that these new configurations may be alternative regimes of systems comprising vegetation-climate-disturbance interactions. Thus, one way of explaining the dynamics of ecosystems in transition may be the theory of multi-stability and concepts such as resilience, hysteresis and tipping points. However, whether such multiple regimes indeed exist in climate-vegetation-disturbance systems and whether we can identify and quantify tipping points of such systems still remain largely unclear due to various reasons such as the role of heterogeneity and multi-scale processes in amplifying or dampening hysteresis and environmental change. This highlights the need to inter- multidisciplinary teams, which investigate such questions and help addressing management practices and preserving ecosystem services for future adaptation policies.

 

Acknowledgements:

This work is a contribution from the Brazilian National Institute of Science and Technology (INCT) for Climate Change funded by CNPq Grant Number 573797/2008-0 and FAPESP Grant Number 2008/57719-9, and from a proposal funded by Microsoft-FAPESP grant number 13/50169-1.

12:00

Approaching Tipping Points: context, anticipation and community-based monitoring

M. Nuttall (University of Alberta, Alberta, Canada)

Abstract details
Approaching Tipping Points: context, anticipation and community-based monitoring

M. Nuttall (1)
(1) University of Alberta, Department of anthropology, Alberta, Canada

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From the Arctic to the topics, Prairie and steppeland environments to high mountain areas, deltaic regions and low-lying ecosystems, people are observing and experiencing significant environmental shifts. However, it does not necessarily follow that they think about climate change as the most pressing issue affecting their lives. In this presentation, I discuss some aspects of how to understand the consequences of climate change, as well as identifying tipping points and thresholds, in a broader context. Rapid social, economic and demographic change, resource management and resource development, quota systems, trade barriers and conservation policies, among many things, have significant implications for human security and livelihoods. In many cases, climate change merely magnifies existing societal, political, economic, legal, institutional and other challenges that people experience in their everyday lives. In the far north of Greenland, for example, while the thinning sea ice and melting glaciers are perceived as troubling and worrying, local people see economic opportunities for their communities in the form of emerging halibut fisheries. Yet, although dramatic changes in climate require people to respond in particular ways, transformations in global markets that affect small-scale fisheries often have greater consequences. And while the disappearance of sea ice and glacial retreat may indicate approaching tipping points, irreversible social, cultural and economic change was precipitated in the 1980s by environmentalist opposition to seal hunting, while the prospect of oil development and mining mean different kinds of tipping points in the near future. As they reflect on a changing climate, local people do so from the position of living through considerable social and economic transformation that may have nothing to do with environmental change.     

In this presentation, I consider the above and then focus on two things. First, building on earlier work on tipping points and anticipatory knowledge, I consider anticipation; how people think about the world around them, how they orient themselves and live toward the future, and how they create and enact change within a world that is also undergoing a constant process of becoming and being remade. I discuss how a focus on anticipation in local settings would give us a greater understanding of a diversity of approaches to precaution, pre-emption and preparedness. Given the challenges (as well as opportunities) that climate change brings to environment and society, understanding how anticipation is inherent in everyday life and implicit in social relations and cultural practices, and how aspects of those relations and practices can emerge from anticipation, is a way to understand successful local strategies of adaptation, the nature of resilience and how people prepare themselves for uncertain futures. Second, I discuss some anthropological methods and prospects for identifying and gaining early warning of tipping points through reflection on collaborative and participatory-based community research. By way of example, I draw on an interdisciplinary project in the High Arctic environment of northern Greenland (the EU-funded ICE-ARC project) which is working with communities to help them prepare for and negotiate change in the future. Central to this project is community-based monitoring, a process that not only seeks to identify early warnings of tipping points, but something that builds local research capacity and puts in place a local observing system. This will help improve climate predictions for understanding the impacts of climate change on marine ecosystems and Arctic societies and enable communities to build capacity towards ensuring sustainable livelihoods.  

12:10

Can we avoid the next tipping in Antarctica?

R. Winkelmann (PIK Potsdam, -, Germany)

Abstract details
Can we avoid the next tipping in Antarctica?

R. Winkelmann (1)
(1) PIK Potsdam, -, Germany

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Sea-level rise is a given consequence of anthropogenic climate change. How much and how fast it is going to rise will depend critically on the future evolution of the Antarctic Ice Sheet which stores water equivalent to more than 50 meters of global sea-level rise. Most of West Antarctica’s marine ice sheet lies on an inland-sloping bed and is thereby prone to an instability mechanism, the so-called marine ice sheet instability. Recent observations suggest that the grounding line has probably already transgressed into the unstable regime in part of the West Antarctic Ice Sheet due to warm water intrusion into the shelf cavities. Similar topographic configurations are found in large parts of the East Antarctic Ice Sheet which holds marine ice equivalent to 19 meters of global sea-level rise, more than five times as much as West Antarctica. For Wilkes basin in East Antarctica, it has been shown that removing a specific coastal ice volume, a so-called ice plug, can destabilize the entire basin, leading to self-sustained ice discharge and long-term sea-level rise of several meters. Here, we will explore the regions which might be subject to the marine ice-sheet instability, the processes potentially triggering it, and the consequences and implications for future sea-level rise. 

12:20

Effects of climate change and other driver of global changes on biodiversity

C. Bellard (Université Paris Sud, Paris, France)

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Effects of climate change and other driver of global changes on biodiversity

C. Bellard (1)
(1) Université Paris Sud, Paris, France

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Current threats have greatly accelerated the rate at which extinctions occur. Climate change is expected to become one of the most important threat in the future (Bellard et al. 2012). In general, multiple threats, such as habitat destruction, invasive species, overexploitation, and climate change lead to an increase in species extinction risk. The combined impacts of multiple threats are also diminishing the capacity of natural systems to cope with the effects of these changes. Yet, over the past decade most studies have assessed the future spatial distribution of these threats individually. This approach can be ineffective and ecologically misleading, because cumulative effect of different threats are not considered. Most of the conservation measures that are based on such studies consider a subset of threats, which may be of little benefit if other threats remain unaddressed. In addition, the combined impacts of different threats might be larger than the cumulative effect of each threat on biodiversity. Because little is known about the possible existence of interacting effects, quantifying the magnitude of potential synergies should become a priority.

Here, we propose to use two case studies at a global scale: biodiversity hotspot (Bellard et al. 2014), and USA to illustrate the need to consider multiple interactions between climate change and other threats. For instance, we will examine the effect of climate change including sea level rise and land use changes on biodiversity hotspot. We will discuss congruence between threats, species vulnerability and protected areas through the biodiversity hotspot. We will also discuss the potential impact of future interaction of climate change, land use changes, and invasive species for 196 endemic species across USA (Bellard et al., submitted). To this aim, we took into account the spatial distribution of biodiversity vulnerable to these threats. In particular, we found high cumulative threat values (>2 threats) aggregated over the eastern part of the USA, with lower values in the central and western parts.  Cumulative impact analyses also suggested that the return on investments for conservation purposes may be low when high cumulative threat areas with low species diversity require protection from many threats (e.g., Minnesota, Wisconsin, Michigan, Iowa states). These analyses provide a useful means of identifying where conservation measures and monitoring programs that should consider multiple threats should be implemented in the future. Ultimately, we will further discuss why manager should consider multiple threats to mitigate the future effect of climate change.

 

Bellard, C., Bertelsmeier, C., Leadley, P., Thuiller, W., & Courchamp, F. (2012). Impacts of climate change on the future of biodiversity. Ecology Letters, 15(4), 365–377. doi:10.1111/j.1461-0248.2011.01736.x

Bellard, C., Leclerc, C., Leroy, B., Bakkenes, M., Veloz, S., Thuiller, W., & Courchamp, F. (2014). Vulnerability of biodiversity hotspots to global change. Global Ecology and Biogeography, 23(12), 1376–1386. doi:10.1111/geb.12228

Bellard, C., Leclerc, & Courchamp, F. Combined impacts of global changes on biodiversity across the USA submitted

12:30

Q&A session

M. Bustamante (Universidade de Brasília, Brasilia, Brazil)

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Q&A session
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