Thresholds and Points of No Return: Managing Arctic Ecosystems under Rapid Change

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1 Thresholds and Points of No Return: Managing Arctic Ecosystems under Rapid Change Carlos M. Duarte IMEDEA (CSIC-UIB), Mallorca, Spain Arvid Sveen Arctic Frontiers, Tromsø, 24 January 2011

2 What are ecological Thresholds? Sea Ice Extent Changes in nature are often assumed to be smooth and reversible in scientific and managerial frameworks Global Warming

3 smooth Sea Ice Extent abrupt But... Responses of natural systems and their components to climate change may be smooth or abrupt depending on the functional relationships involved and the interactions between components Global Warming

4 Changes resulting from global human impacts are often abrupt and/or irreversible (at least at opperational time scales) Ozone Layer: Two decades after the Montreal Protocol, there is no sign of ozone recovery and predictions of when this may happen get delayed by a decade every year (i.e. no recovery now expected along the 21 st Century). Collapsed Fisheries: No recovery of some collapsed fisheries despite efforts (e.g. no recovery of Canadian cod fisheries 20 years following moratorium). Ice loss: No possible recovery of lost ice shelves and platforms and glaciars (ice age of thousands of years). Global Warming: No ambition to cool the planet, but struggles are directed at preventing excessive warming. Ocean acidification: No ambition to titrate the oceans back, but struggles are directed at preventing further ph decline. Species Extinctions: Extinctions are clearly terminal, irreversible events.

5 Understanding and Managing Abrupt Change Complex systems, such as most components of the Earth System, are inherently non-linear, displaying complex behavior. Non linear behavior is characterised by shifts in status (i.e. alternative end-points that differ in profund QUALITATIVE elements) across thresholds or tipping points that represent the breaking points of the system. Once tresspassed, recovery may be slow or unlikely.

6 What are ecological Thresholds? Sea Ice Extent Mode A Mode B Global Warming

7 What are ecological Thresholds? Sea Ice Extent Threshold or Tipping Point Mode A Mode B Global Warming

8 What are Points of no Return? Sea Ice Extent Threshold or Tipping Point Mode A Mode B Global Warming

9 ICE is clearly the QUALITATIVE element separating two alternativee states of the Arctic: A White, Frozen and B Blue, Open Arctic

10 December 2010 had the lowest ice extent for the month since the beginning of satellite records (by 270,000 Km 2 ). The linear rate of decline for the month is 3.5% per decade. (NSIDC, US) Trend through ice extent in December

11 Abrupt Changes in the Arctic: ice is a strongly non-linear element of the Earth System Did we cross a Tipping Point in 2007?

12 Ho do we know we are approaching a Tipping Point without crossing it? Increased Variance as a Leading Indicator Increased Variance (Scheffer et al 2009)

13 Increased Variance is a Leading Indicator of Abrupt Change Time series observations warn of an adjacent tipping point in Arctic ice extent Increased Variance

14 Warm Cold Snow Ball - Hot House Earth The Earth has oscillated between two climatic modes along its history: A warm mode, named the Hot House, and a cold mode, named the Snow Ball Earth, with an average temperature difference between these two models of about 15 º C One of these Hot House periods was the Jurasic, with dinosaurs on Earth, when there was no ice on Earth. Millions of years before present Hoffman and Scharg (1999)

15 Transition from Hot House to Cold House 1 What triggers this? Built up of CO2 (weathering consumption of CO2 is alted) Green House Gases (Methane) Hofman and Schrag Transition requires ~ 1 million years

16 Methane in the Arctic Methane Hydrates

17 Gas Hydrates are stable during galciar periods and are movilised during warm periods

18 The Reserves of Methane Hydrates in the shelves of the Arctic Ocean are huge and, if released, would cause abrupt climate change There is evidence that they are starting to bubble to the atmosphere

19 Permafrost melting, Thermokarst formation and Increased Runoff and freshwater discharge to the ocean

20 Increased Puede el deshielo Freshwater Ártico runoff acelerar may el cambio affect global climático? ocean circulation and regional climate

21 Impacts on biodiversity that depends on ice as critical habitat Profound changes in the Arctic ecosystem

22 A sharp threshold in habitat availability exists below which a species rapidly becomes extinct. A similar threshold exists for the rate of climate change beyond which species extinction becomes likely. The interaction between climate change and habitat loss might be disastrous. During climate change, the habitat threshold occurs sooner. Similarly, species suffer more from climate change in a fragmented habitat.

23 Ice melting sets a cascade of abrupt, chainned changes in motion Non-linear Tipping elements in the Arctic a region prone to rapid change Sea ice and albedo (acting, decades) Greenland ice sheet (acting, centuries) Sea level rise (acting, centuries to milenia) Thermokarst and Permaforst Melting (acting, decades) Increased Freshwater Runoff (acting, decades) Methane Hydrate release (acting?, decades?) Pollutant release (acting, decades) Ocean reversal to CO2 source (decades) Subarctic Boreal Forest dieback (acting?, decades) Peat Fire (acting?, decades) An Arctic Domino Effect

24 Tipping Elements of the Earth System Six out of 14 Tipping Elements in the Earth System are located in the Arctic PNAS 2008

25 Facing Change (open access)

26 The Problem with Our Times is that the Future is no Longer what it Used to Be Paul Valery

27 The Problem with Our Times is that the Future is no Longer what it Used to Be Paul Valery The Arctic Paradox: Arctic nations are responsible for 26% of global CO2 emissions (2009) and include three (USA, Rusia and Canada) of the top 10 nations by CO2 emissions, as well as some of the nations with highest per capita emissions. Global Warming, largely due to human use of fosil fuels, is triggering Arctic ice loss and associated abrupt, potentially dangerous, changes with global consequences. Arctic nations claim to be concerned, but decline taking potential unilateral steps (how to break through that loop?), while jumping on opportunities (profitable navigation routes, minerals, gas oil and fisheries in the changing Arctic), which partially involve movilising more fosil fuels. How do the risks associated with these changes balance with benefits from the perceived opportunities?. Are there incentives to mitigate these changes?

28 Managing Arctic Ecosystems Near Tipping Points Increase Observation Efforts to Detect the proximity to Tipping Points and Improve understanding of the system to identify chainned tipping elements triggering Domino Effects. Address the paradox by evaluating the economic costs of abrupt changes, compared to the income from emerging opportunities. Manage Arctic ecosystems to build resistance and resilience to thresholds and tipping points (i.e.minimise local pressures). Allocate funds derived from new opportunities to this goal. This Conference! Develop dialogues between scientists examining tipping points, and Arctic managers and policy makers. Promote international cooperation toward these ends.

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