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ATP Report Summary

Project ID: 226248
Funded under: FP7-ENVIRONMENT
Country: Norway

Periodic Report Summary 2 - ATP (Arctic tipping points)

The ATP project investigated the existence of climate driven tipping points for key species and ecosystem processes in the Arctic Ocean, in particular in its European sector. This was carried out through an analysis of available time series data and coordinated experimental studies. The experimental evaluations were used to validate the thresholds identified from time series analysis and to postulate new climate driven tipping points. Ecosystem models helped to formulate future trajectories of Arctic marine ecosystems under climate change scenarios that considered the possibilities of tipping points.

The first work package (WP1) of ATP ensured the efficient and effective coordination and management of the project to meet all its objectives within time and budget allocation.

WP2 provided the most complete set of data available on the variability of sea ice extent, concentration and thickness in the European Arctic, and of oceanographic parameters such as temperature and salinity profiles and heat and freshwater fluxes. It identified trends and possible abrupt changes in oceanographic parameters, sea ice edge location, ice covered area and sea ice thickness. It also predicted changes in the structure of the upper ocean and in the sea ice cover of the European Arctic in the forthcoming decades.

WP3 used new statistical and analytical tools to extract regime shifts and tipping points from historical time series of ecological properties of the Arctic marine ecosystem. The results were transferred to WP5 to investigate the stability of regimes for the present and projected future climatic conditions.

WP4 supplied WP5 with climatic thresholds and tipping points for key Arctic ecosystem components and processes and also aimed to validate those thresholds and points identified in WP3. Ecological modelling and experimentation worked best in an iterative manner, where each informed subsequent activities by the other. Therefore, experiments conducted under WP4 were used to test climatic thresholds and tipping points hypothesised from the WP5 model outputs.

More specifically, WP5 aimed at projecting the likely future trajectories of Arctic marine ecosystems. It ran the well established coupled hydrodynamic ecosystem model (SINMOD) with projected climatic forcing and implemented the mechanisms leading to abrupt changes derived from the time series and experimental analyses from WP3 and WP4 that were incorporated into the model. For the climatic forcing, high resolved regional climate simulations were carried out using a regional climate model. A control period of present and past climate as well as two future climate scenarios for the period from 2010 to 2100 were available. The incorporation of results from WP2, WP3 and WP4 into SINMOD allowed the development of future trajectories for Arctic marine ecosystems and formulated projections on when, under different scenarios, Arctic tipping points would be exceeded.


1. tested the performance of different harvest control rules in fisheries under varying environmental conditions
2. modelled optimal oil and gas exploitation strategies under uncertain prices and weather conditions and
3. examined how institutions and policies for the management of living marine resources, tourism and petroleum development could cope with very rapid changes in ecosystems driven by climate change.

WP7 provided policy makers, managers, stakeholders and the general public with an understanding of the ecological thresholds and regime shifts that might develop in the Arctic in response to climate change and how the ecosystems responded to the European Union's targets for emissions. This information could then be used as a basis to refine policy targets, mitigate these impacts, take advantage of natural resilience already within the ecosystem and identify ways of promoting recovery. Furthermore, WP7 informed the general public of the possible consequences of climate change on the Arctic ecosystem to help build support for policy frameworks reacting to these predictions.

Since the beginning of the project the following activities were undertaken:

1. compilation of data sets and analysis of historical time series (WP2 and WP3)
2. execution of all planned experimental designs (WP4)
3. amendments to the SINMOD model, which was a physical and biological coupled model for the European Arctic, based on sensitivity analysis of the ecological one-dimensional model to various future climate scenarios and regional climate scenario model runs (WP5)
4. development of a two-dimensional cellular automata (CA) model to be used as a scenario model for testing the properties of different fisheries' management regimes (WP6)
5. development of ideas and concepts on how the institutions for the management of the Arctic marine environment and economic activities there could cope with climate driven, rapid change in the marine ecosystems (WP6)
6. dissemination and outreach activities at various levels, including scientific talks and publications, project web page, newspaper articles, television documentaries, organisation of events for the public, etc. (WP7)

Roughly 50 % of the Arctic sea ice has melted since the mid-1970s. A tipping point would be met for ice cover, in that it would change to a purely seasonal cover of first-year ice. Analyses of time series showed that the accelerated melting of sea ice in 1996 was preceded by a period with increased fluctuations in sea ice cover as an early warning indicator of an approaching tipping point. The response of the zooplankton community to temperature was not abrupt, except for the Arctic species calanus glacialis whose abundance was significantly reduced with temperatures above 6 °C. A tipping point in the bottom fauna community was observed in two Svalbard fjords, consistent with increasing temperature.

Tipping points were detected in the growth and activity of microbial communities within the expected range of warming for the Arctic. Net community production decreased abruptly at about 5 °C, while community respiration increased. Evidence suggested that enhanced heterotrophic combined with decreasing autotrophic processes would result in a shift towards more heterotrophic microbial communities in a warmer Arctic. Above a threshold of 6 °C the respiratory demands of c. glacialis exceeded that of ingested carbon. Overall, the boreal species calanus finmarchicus did better than its Arctic congener, c. glacialis, at temperatures above 6 °C. A tipping point between c. finmarchicus and c. glacialis could be expected between temperatures of 5 to 6 °C, with major ramifications for the food webs supporting higher trophic levels such as fish. Arctic rocky-bottom communities showed tipping points in terms of abrupt increases in macroalgal cover associated with longer ice-free periods and higher water temperature. Annual production, abundance and depth extension of kelps along Arctic shorelines increased in response to longer open-water periods and higher water temperatures. A threshold in response to acidification was found for calcification in an Arctic bivalve at a similar level that has been found in a number of other species, implying potential community-wide effects in case this level was reached.

The reduction of sea ice overall led to significant increase in modelled production, the most dramatic changes taking place for mesozooplankton. Transition to ice-free areas was abrupt and accompanied with large inter-annual variability. The model predicted that annual primary production decreased in areas dominated by Atlantic Water. A tipping point was predicted for c. glacialis, which would disappear from northern Barents Sea.

The aquaculture industry would adapt to increased water temperature by reallocating farms. Future fisheries' management would be based on limited knowledge on system dynamics and conflicting objectives. Uncertainty regarding system dynamics would include both ecosystem and market dynamics. It would be increasingly important to develop robust and resilient harvest control rules, develop system knowledge and clear management objectives. Climate driven changes would reduce oil and gas exploration costs and increased activity would be likely in some regions. A robust framework for policy and management should be put in place to address the risk of tipping points and associated regime shifts. Ecosystem-based oceans management would be a useful strategy for confronting the challenges posed by rapid climate change. Existing management regimes in the Arctic would be flexible and have a proven capacity to adapt to change.

We identified climate thresholds and tipping points for key Arctic marine ecosystem components and processes. For sea ice a tipping point was reached when the multiyear ice and its specific ice biota disappeared in about more than 20 years. For microbial, phytoplankton and key zooplankton species a tipping point was identified at around 5 to 6 °C.

We modelled future trajectories, tipping points and regime shifts through a coupled physical and biological model. They showed a general increase in primary production, but a decrease in today's most productive regions. Tipping points of key zooplankton species were expected in the northern Barents Sea while productivity along the Siberian shelf increased. Sea ice disappearance and tipping points for key species opened the possibility for regime shifts.

We developed a method of early warning indicators of climatic thresholds time series variables in general and key taxa in particular. Increased standard deviations were the best available bell weather for future tipping points, underlining the significance of time series. Whole ecosystem experiments and studies of selected key animals suggested tipping points at around 5 to 6 °C, generally speaking.

We evaluated the expected changes in the relationships between:

1. climate forcing and biological responses and
2. ecosystem components and their inter-relationship during regime shifts.

The model studies indicated in detail what response could be expected for key biological processes in the various regions of the Arctic Ocean during the 21st century. We had no good understanding as yet for the interrelationship between ecosystems' components and their relationship during regime shifts. Fortunately, we had no opportunity to experience tipping points closely, let alone regime shifts.

We assessed the implications of changes in the Arctic for socioeconomic activities and governance of Arctic resources. We carried out investigations about the effects of climate change on aquaculture, oil and gas exploration and fisheries' management. Advice on sustainable resource management and climate effects on different climate scenarios, based upon socioeconomic assumptions, was provided to the Intergovernmental Panel on Climate Change (IPCC).

We formulated a White Paper evaluating policy options in avoiding exceeding tipping points for the Arctic ecosystem. It showed that the effects of the climate change that had already taken place were dominant and that the differences between the two examined scenarios were small. Further information could be provided at: ''.

Related information


Elisabeth HALVORSEN, (Consultant, Project Secretary)
Tel.: +47-776-20856
Fax: +47-776-46020
Record Number: 53714 / Last updated on: 2012-09-20
Information source: SESAM
Collaboration sought: N/A
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