Global warming is causing dramatic changes in the cryosphere, including Arctic Sea and Eurasian snow cover. These are expected to accelerate over the next decades. However, there is large uncertainty associated with anticipated future changes, in particular with regard to the extent, timing, and impacts of such changes. These uncertainties compromise the ability to plan adaptation strategies with northern communities and to develop strategies for sustained GREEN GROWTH in an era of rapid climatic and social change.
GREENICE will tackle one of the biggest uncertainties in the interaction between climate change and the cryosphere: how will climate respond to the future changes in sea-ice and snow cover?
The spate of recent extreme weather events over the extra-tropical Northern Hemisphere, including winter cold snaps and summer heat waves, were linked to the dramatic loss of sea ice and warming occurring in the Arctic, and to increases in Eurasian autumn and winter snow cover. Most of these changes in the cryosphere are likely to be a result of global warming, and thus may accelerate. Although observational, theoretical, and modelling studies indicate that the sea-ice and snow-cover changes have a significant impact on the large-scale atmospheric circulation and weather extremes, controversy exists regarding the magnitude of these impacts and their underlying mechanisms. In particular, natural unforced climate variability may partly explain the observed pronounced decadal climate fluctuations in the Northern Hemisphere, including the recent changes in the cryosphere. Thus, the extent to which the observed extreme events were caused by cryosphere changes due to climate change or natural variability remains an open question.
By means of a thorough analysis of observations and coordinated experiments with global and regional atmospheric models, GREENICE will improve our understanding of the atmospheric response to sea-ice and snow-cover changes and our ability to predict both anthropogenic and naturally-driven changes on 10-30 year timescales.
Future changes in the cryosphere, and in the large-scale atmospheric circulation and weather extremes over the extra-tropical Northern Hemisphere will, with stressors of globalization, have major socio-economic impacts, particularly in high latitudes. GREENICE will consider uncertainties due to unforced natural climate variability, and will use model formulation and global-warming scenarios to enhance forecast reliability. A more comprehensive and sophisticated interdisciplinary understanding of future changes will facilitate the ability of Arctic societies to adapt to climate change, and address problems of green-growth development.
By using case studies, GREENICE will assess vulnerability and resilience factors for specific communities, and evaluate culturally and contextually appropriate measures for effective adaptation to predicted future climate changes associated with sea-ice and snow-cover changes. GREENICE results will benefit private and public industry in the areas of renewable energy, e.g., hydropower and wind, but also non-renewable energy and shipping sectors that are moving to exploit an ice-free arctic.
A key sector is hydropower, the main source of energy for Norway. GREENICE will work with two hydropower companies in western Norway to incorporate GREENICE prediction results into their future planning on issues related to climate change. We will actively seek other potential stakeholders in Nordic countries from these various sectors with the aim of mobilizing our increased knowledge of future climate change to help plan sustainable, responsible and environmentally-friendly development.
Importantly, stakeholders will provide key input to experimental design, so that their needs are best served by the project.
- Assess and reduce uncertainties in the quantitative description of the interaction between climate change and the cryosphere, focusing on the impact of sea-ice and snow-cover changes on large-scale atmospheric circulation and weather extremes.
- Provide better constrained predictions of near-term (10-30 year) changes in Northern Hemisphere climate and associated weather extremes, by using improved knowledge and atmospheric models driven by projected Arctic sea-ice and Northern Hemisphere snow-cover changes.
- Share research results concerning the uncertainties of Northern Hemisphere climate change with stakeholders and northern communities, and integrate and relate knowledge of potential impacts in terms of key economic and social factors relevant to the welfare and sustainable development of these communities and the Nordic region.
- Better understand the present and historical adaptation of Arctic communities to rapid weather, sea-ice and resource-governance events, and to include local experience-based knowledge-holders in dialogue with researchers and stakeholders.
And now TRACE?
Society will feel the impacts of global warming most through regional changes in climate and weather extremes. Unfortunately uncertainties in future projections at these scales are large. They are dominated by both internal climate dynamics and model systematic errors. Initiating climate predictions from concurrent observations can reduce uncertainties due to internal climate dynamics on time scales shorter than a decade. Better simulating the atmosphere’s interaction with other parts of the climate system is a promising strategy to achieve more reliable long-term climate projections. For example, reducing uncertainties in the atmospheric response to arctic sea ice loss could help constrain regional climate change projections. This was GREENICE’s main objective, but our climate model experiments show that arctic sea ice has a rather limited impact on the northern hemisphere mid-latitudes.
TRACE aims to enhance Nordic-Russian cooperation in Higher Education and Research in GREENICE and the Nordic Centre of Excellence ARCPATH. It will achieve this through a joint study addressing an important scientific question that is not considered by either of these NordForsk projects: Can better resolving the sharp Gulf Stream sea surface temperature front help constrain future projections of climate and weather extremes over Eurasia? Addressing this requires the key expertise of the Nordic and Russian research teams, the mobility of junior and senior researchers, joint use of infrastructure, and the joint development of methods.
North Atlantic sea surface temperature (SST) may have a more direct influence on Eurasian climate than arctic sea ice loss. Here a slowing of the ocean circulation is expected to mediate the impact of global warming. This rather robust effect among models may already be occurring, and may also influence Eurasian climate and weather extremes. Thus, representing better ocean-atmosphere interaction in this region could enhance short and long term climate prediction.
The North Atlantic Ocean may influence climate and weather in two key ways. Firstly, basin-wide SST changes can influence the north-south temperature gradient in the lower atmosphere, and thus the large-scale atmospheric circulation. However, relatively coarse resolution models provide little evidence that global-warming induced changes in the North Atlantic will impact climate in this way. Secondly, the sharp SST gradients in the Gulf Stream and its extension influence deep atmospheric heating and anchor the North Atlantic storm track. These features can be reproduced by atmospheric models when the underlying SST gradients are properly resolved and the horizontal model resolution is 50km or finer; importantly, atmospheric blocking and weather extremes over Europe are also better reproduced.
The horizontal resolution of current models used to predict climate change is 1 degree or coarser. Thus, these models cannot resolve the fine structure of the North Atlantic SST front and they also poorly simulate its position, both deficiencies adversely impact the simulation of atmospheric circulation and blocking. How these model deficiencies affect projected changes in Eurasian climate and weather extremes remains unknown.
The main OBJECTIVE of TRACE is to assess the role of the Gulf Stream – North Atlantic SST front in future climate change over Eurasia.