The ADSIMNOR project
The Rossby Centre led project ADSIMNOR (ADvanced Simulation of Arctic Climate Change and IMpact on NOrthern Regions) will come to an end during 2014. It is a collaborative project of Stockholm university (SU), Lund university (LU), the Royal Science Academy (KVA) and SMHI Rossby Centre and oceanography research groups, funded by the Swedish research council FORMAS. ADSIMNOR connected process understanding, and model development together with new climate scenarios and user studies.
Making advances in knowledge of climate change in the Arctic
The Arctic warms faster than other areas. This Arctic amplification is considered as an inherent characteristic of the global climate system. ADSIMNOR partners (SU) provided results concerning the relative importance of different feedback components. In addition to the role of sea ice-albedo-feedback, understanding of the Arctic amplification became more multifaceted by involving contributions of cloud and water vapour feedback, lapse-rate feedback, atmospheric circulation feedbacks, and reduced mixing in the Arctic atmospheric boundary layer, which all modify the direct effects of Arctic climate warming. In addition, transport of heat into the Arctic by both ocean and atmosphere plays a role.
The decline of Arctic sea ice cover during recent years is connected to rapid events leading to new record low summer ice extents. Simulation results, in agreement with observations, can largely explain rapid reduction events by changing atmospheric circulation patterns (SMHI Rossby Centre). Additional influence is exerted by clouds and water vapour changes in spring (SU). In years where the end-of-summer sea-ice extent is well below normal, an enhanced inflow of humid air into the event region is evident during the spring before. As a result, downward long-wave radiation at the surface is larger than usual in spring, which enhances the ice melt.
The influence of ocean processes on the sea ice cover is largely blocked by a top layer of cold and fresh water situated directly underneath the ice. Freshwater dynamics are important to understand the stability of the isolation. Regional ocean simulations allow for estimating components of the Arctic ocean fresh water budget (SMHI oceanography). Input from Eurasian rivers and extraction by sea-ice formation dominate the composition of the Arctic freshwater content whilst Pacific water increases in importance in the Canadian Basin.
Uncertainties in simulating the reduction rate of sea ice cover on seasonal to annual time scales are partly due to difficulties in correctly simulating sea level pressure in many models (Rossby Centre). ADSIMNOR research shows the potential improvement that can be obtained by simulating correct summer sea ice extents when prescribing observed sea level pressure (Rossby Centre). On decadal time scales, and based on retrospective global climate simulations, a generally good predictability for integrated Arctic sea ice conditions is found (Rossby Centre).
During the project, new global climate projections for possible future climates have also been generated. Regional downscaling for the Arctic gives information at 25 km resolution. Results point to a clear influence of ocean heat transport from the Atlantic ocean into the Barents Sea, on the position of the sea ice edge. A fully coupled (atmosphere-ocean-sea ice) regional interpretation of global climate projection gives larger multi-annual and decadal variability, compared to global projections.
Assessing the impact of Arctic climate change
ADSIMNOR partners (KVA) have been able to apply ADSIMNOR regional climate scenarios for assessing the impact of local climate change in the Swedish Torneträsk area on permafrost changes. This was possible by using empirical regional relations from long-term monitoring by the Abisko research station. The methods is seen as a prototype for other well observed areas.
On a pan-Arctic scale, Rossby Centre projections have been used to estimate associated vegetation changes (LU). Thereby, it is important to understand land surface feedbacks associated with vegetation shifts and ecosystem biogeochemical cycling. The simulated vegetation distribution for recent climate agrees well with observed conditions. For the future, a poleward advance of the forest–tundra boundary, an expansion of tall shrub tundra, and a dominance shift from deciduous to evergreen boreal conifer forest over northern Eurasia is projected. Ecosystems continue to be a sink of carbon for the next few decades.
The expected climate change in the Arctic is impacting on living conditions and a number economic and societal sectors in this region. ADSIMNOR is involved in a two-way stakeholder dialogue, communicating possible usage of climate projections for additional impact assessment and local decision making. Users provide requests and questions to be addressed by the climate researchers. Sectors considered within ADSIMNOR have included reindeer herding, traffic and tourism. Other sectors have also been included in the discussion by connecting to another FORMAS-funded project on stakeholder interaction, lead by KVA. Frequent topics of exchange are the perception of ongoing climate change and the need for a long term perspective on the consequences of change on a local scale. A final stakeholder dialogue will be organised during spring 2014 under the leadership of the ADSIMNOR partner KVA.