Rapid change of the Arctic climate system and its global influences

Dr Takashi Yamanouchi from the National Institute of Polar Research highlights the Green Network of Excellence (GRENE) Arctic Climate Change Research project and its impact

The Arctic has become a hot topic not only in the scientific sector, but also in society, due to the abrupt retreat in summer sea ice area associated with global warming, rapid warming in surface air temperature, reduction of glaciers, melting permafrost and many other changes, recently. We started a Japanese initiative – “Arctic Climate Change Research Project” – within the framework of the Green Network of Excellence (GRENE) Program, funded by the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT), in 2011. This Project targeted understanding and forecasting “Rapid Change of the Arctic Climate System and its Global Influences.” Four strategic research targets are set by the Ministry:

1. Understanding the mechanism of warming amplification in the Arctic;

2. Understanding the Arctic climate system for global climate and future change;

3. Evaluation of the impacts of Arctic change on the weather and climate in Japan, marine ecosystems and fisheries;

4. Projection of sea ice distribution and Arctic sea Routes.

Through a network of universities and institutions in Japan, this 5-year Project involves more than 300 scientists from 39 institutions and universities. The National Institute of Polar Research (NIPR) works as the core institute and The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) joins as the supporting institute. There are 7 bottoms up research themes approved: the atmosphere, terrestrial ecosystems, cryosphere, greenhouse gases, marine ecology and fisheries, sea ice and Arctic sea routes and climate modelling, among 22 applications. The Project will realise the multi-disciplinal study of the Arctic region and connect to the projection of the future Arctic and global climatic change by modelling.

The project has been running since the beginning of 2011 and in those 5 years, pan-Arctic observations have been carried out in many locations, such as Svalbard, Russian Siberia, Alaska, Canada, Greenland and the Arctic Ocean. In particular, 95 GHz cloud-profiling radar in high precision was established at Ny-Ålesund, Svalbard, and intensive atmospheric observations were carried out in 2014 and 2015. In addition, the Arctic Ocean cruises by R/V “Mirai” (belonging to JAMSTEC) and other icebreakers belonging to other countries were conducted and mooring buoy observations were also carried out. The data retrieved during these observations was accumulated in the Arctic Data archive System (ADS) and served with interfaces for analysis. In addition, modelling studies have been promoted from a fundamental process model to a general circulation model.

Through these observations and analyses, new research results have come to light. For example, the recent surface temperature rise in the Arctic is about twice as much as the global average. There is no doubt that ice-albedo feedback can accelerate warming of the ocean and atmosphere and melt of sea ice. However, beyond that, the Arctic change is likely to result from a complex combination of different factors. We will provide a joint perspective from modelling, land processes, the atmosphere, cryosphere and carbon cycle groups, and discuss our integrated strategy for investigating underlying mechanisms and relative contributions from different factors relevant to Arctic change and global impacts. This Arctic amplification was predicted decades ago by numerical simulations and verified by observations more recently. While albedo feedback is the most cited, many other processes operate simultaneously and were also suggested as important in previous studies. It is challenging to quantify systematically the relative importance of such processes in Arctic warming, yet necessary in order to understand the mechanism.

The diagnosis from the experiments in the MIROC3 GCM quantified the relative importance of individual feedback and provided insight into what processes contribute to enhanced Arctic warming above the global average and what processes contribute to the enhanced Arctic surface warming. We apply the CFRAM (Climate Feedback-Response Analysis Method) to model output by including additional terms omitted in the previous study, in order to investigate the seasonality of processes contributing to Arctic warming. The smallest warming occurs in June-July, the largest reduction of sea ice concentration occurs in September, and the largest warming occurs in October- November-December (Yoshimori 2015).

In addition to scientific outcomes, results also contribute to the stakeholders. Understanding of mid-latitude weather links will help to forecast extreme weather (cold winter and heavy snow storm) in our societies, sea level rise, impact on marine ecosystems including fisheries, and possibilities for Arctic sea routes. The successor of the project, ArCS (Arctic Challenge for Sustainability), which lays delivering emphasis on robust scientific information to stakeholders for decision making and solving problems, was started in FY2015.

Dr Takashi Yamanouchi

Project Professor and Professor Emeritus

National Institute of Polar Research and SOKENDAI

(The Graduate University for Advanced Studies)

yamanou@nipr.ac.jp

www.nipr.ac.jp