Warming ampli cation in the Arctic and its global impact The key to Arctic climate change is Arctic warming ampli cation (AA). AA leads to the change in sea ice extent and then to the realization of the Arctic sea routes. It also a ects the global climate, such as atmospheric circulation, cryosphere, and the carbon cycle. Moreover, AA will alter marine chemical components and the living environment for plankton, and hence have impacts on the major  sh species and  sheries. AA will also Earth! in uence the mid-latitude weather and climate, and bring cold and heavy snow to Japan in winter. Arctic Climate Change The Arctic, the fastest-warming place on

1 Mechanism of warming ampli cation in the Arctic trial biological activity will alter the amount of atmospheric carbon led all aspects of the Arctic climate system. Comprehensive Arctic What is happening now in the Arctic, under global warming? and the warming of the ocean are expected to lead to changes not dioxide absorption by vegetation, and will a ect global warming research incorporating multidisciplinary work and collaborations Warming ampli cation in the Arctic Research Project In warming due to anthropogenic increases in carbon dioxide only in the physical and chemical ocean environment, but also to as feedback. Although it is far away from Japan, we cannot turn a between observation and modeling have been realized. concentration, the surface temperature in the Arctic is increasing changes of marine ecosystems. blind eye to Arctic climate change, since we are a ected by it, too. Here we will report the scienti c results achieved. In the proj- with a speed that is more than double the global average. We call Looking at the land area, many glaciers distributed around the In order to grasp these abrupt changes in the Arctic, to under- ect, four strategic research targets were presented and the outcomes Surface albedo Rapid Change of the Arctic Climate this “Arctic warming ampli cation,” and an understanding of its Arctic are retreating.  e Greenland ice sheet, the largest ice mass stand the mechanism, and to contribute to future climate change for each target are described on the following pages. Finally, the Heat Cloud Black mechanism is urgently needed. in the northern hemisphere, is also melting markedly, and the  ow- 2 Arctic system for transport carbon 4 Projection of sea ice projection, we conducted the Green Network of Excellence Program mutual relationships between each target and a synthesis of “Rapid Reduction of sea ice extent in the Arctic Ocean is continuing, out or collapse from its terminal glacier is serious.  is will be a global climate and Glacier Snow Sea ice distribution and Arctic microorganisms System and its Global In uences (GRENE) Arctic Climate Change Research Project “Rapid Change Change of the Arctic Climate System and its Global In uences” are future change sea routes and an abrupt decrease since the 2000s is especially noticeable. concern in terms of the world sea level rise. Moreover, the duration of the Arctic Climate System and its Global In uences” for ve shown in the  ow diagram on the back page. Owing to this change, potential for regular ship navigation through of the snow season is decreasing. In such ways, snow and ice have years between 2011 and 2016. 39 institutes all over Japan have par- • Intensi cation of • Change of sea ice the Arctic Ocean have increased, and they have become broadly been showing great changes, and thus great impacts on atmospheric atmospheric circulation distribution and known as “Arctic sea routes.”  e reduction of the sea ice extent circulation and terrestrial biology are foreseen. Changes in terres- ticipated in the project, and more than 360 Japanese scientists tack- rafting eect GRENE Arctic Climate Change Research Project • Change of heat transport Increase of extreme events • Change of thermohaline Summary of outcomes, 2011–2016 • Reduction of circulation and Stratospheric circulation ocean circulation heat budget Stratospheric circulation 2.0 Surface air temperature change • Change of snow area • Inuence on mid-latitude • Ocean acidi cation (from the data of UK Met. O ce) • Stratosphere-troposphere • Change of primary • Projection of sea ice interaction 1.5 production Average in the Arctic • Change of atmos. circulation extent and Arctic sea • Sea level rise by glacier routes (north of 60°N) and ice-sheet melting 1.0

Tropospheric circulation • Cold wave and heavy • Change of primary Tropospheric circulation snow in Japan species of sh • Change of carbon cycle 0.5

Stratosphere– • Change of CO2 sink 3 a Impacts on weather 3 b Impacts on marine Stratosphere– Troposphere interaction Troposphere interaction in Japan ecosystem and sheries change Surface air temperature 0.9°C 2.0°C 0.0

since the beginning of the 20th century the beginning since (°C) Global average

Map of GRENE-Arctic observation activities -0.5 Retreating Suntar-Khayata 0° 15°W 30°W 45°W 60°W 75°W 90°W 1850 1900 1950 2000 2050 2100 Mountain Glacier in Siberia 10 Terrestrial ecosystem Observation region Atmospheric heating Simulation Atmospheric heating

(Photo by Hiroyuki Enomoto, National Atmosphere ) 8 2 (AR4, SRES A1B) Impact of the Institute of Polar Research) Simulation Impact of the Cryosphere km Arctic warming 15°E 105°W 6 (AR5, RCP4.5) Arctic warming Warming ampli cation Cloud 6 Warming ampli cation Cloud on the mid latitude Ice-albedo Greenhouse gas on the mid latitude Ice-albedo CO2 feedback CH4 in the Arctic CO2 feedback CH4 in the Arctic Marine ecosystem 4 Churchill Sea Ice and ocean environment Sea ice area (10 Sea area ice 2 Snow survey lines Ice-albedo Ice-albedo Hiiumaa LSSL Permafrost survey lines Change of sea ice area in September (from the IPCC reports) feedback 30°E Saaremaa 120°W 0 feedback Helsinki Qaanaaq Fort Smith Snow Hyyti ä l ä Airliner Snow Ice-sheet Ny-Ålesund (Upper) The mean surface Ice-sheet Kaarina Fort Providence Snow Cloud-sea ice Sodankyla Solid-lines (yellow, orange, pink, blue): Ship air temperature in the Snow Cloud-sea ice Glacier interaction Nurmes Kevo Glacier interaction Vario Arctic has clearly increased Sea ice Norman Wells twice as rapidly as that of Sea ice About the project 45°E Inuvik 135°W the global mean, both in Prudhoe Bay Arctic Climate Change Research Project: the last 100 years and in the Rapid Change of the Arctic Climate System Black carbon Icebreakers’ Poker Flat last 40 years. Black carbon Degrading underground and its Global In uences observation area (Lower) The Arctic sea ice ice (yedoma) in the per- Barrow Anchorage “Green Network of Excellence” (GRENE) extent in September has mafrost zone of the North Fairbanks Program by Ministry of Education, Culture, decreased faster than what Slope, Alaska Sports, Science & Technology, Japan (MEXT) 60°E 150°W has been simulated by cli- (Courtesy of Masao Uchida, National Core Institute: National Institute of Polar Tundra Ship mate models. Moreover, Tundra Ship Institute for Environmental Studies; Go Research Boreal forest Iwahana, International Arctic Research MIRAI MR15-03 the decrease is projected to Boreal forest Center) Associated Institute: Japan Agency for MIRAI MR14-05 continue through the 21st (Permafrost) Marine-Earth Science and Technology (Permafrost) Tura MIRAI MR13-06 century. Period: July 2011—March 2016 Ocean-sea ice Impact on Mirny S.W.L http://www.nipr.ac.jp/grene/ Ocean-sea ice Impact on MIRAI interaction marine ecosystem 75°E HAKUHO MARU 165°W interaction marine ecosystem Oymyakon MR12-E03 For further details: Final Report of GRENE Glaciers in Suntar-Khayata region Arctic Climate Change Research Project (Japanese edition only) OSHORO MARU Editing/Publication Inter-university Research Institute Corporation Marine ecosystem Research Organization of Information and Systems Marine ecosystem National Institute of Polar Research 10-3 Midori-cho, Tachikawa-shi, Tokyo 190-8518, Japan Ocean circulation 90°E 180° Telephone: +81-42-512-0922 Ocean circulation http://www.nipr.ac.jp Japan Issued Japan August 31, 2016 Front cover: Meltwater stream over a glacier surface darkened by glacier microorganisms in Greenland 105°E 120°E 135°E 150°E 165°E (Photo by Shin Sugiyama, Hokkaido Univ.) Pre-warming On-warming Greenhouse Inhibition of Strategic Research Targets 2 Understanding the Arctic system for global climate and future change Strategic Research Targets 1 Understanding the mechanism of warming ampli cation in the Arctic e ect convention Strategic Research Targets 4 Projection of sea ice distribution and Arctic sea routes Sunlight High sensitivity Warming at surface Sea ice Cloud Sea ice to the temperature and snow and snow increase Arctic change is advancing with Quanti cation of relative contribution to Arctic Ocean  e Arctic sea routes: Sea ice melt and temperature rise Warming Relaxation of warming potential global in uence. warming ampli cation factors and their seasonality. Summer JUN-JUL Increase in absorbed AUG-SEP Increase in ocean heat NOV-JAN Heat release from the Feasible for sustainable use. sunlight due to retreat of storage ocean to the atmosphere. sea ice and exposure of Trapping of heat near the  e land and ocean in the Arctic have an by ecosystem model simulations, which tent may lead to extreme events such as By analyzing future climate change projection datasets simu- mer. Its additional heat warms the land surface, though part of sea surface surface, increase in cloud, etc. We have proposed empirical method to ice from satellite-derived high-accuracy good forecast of the timing of summer important role in the uptake of CO2 from suggests that CO2 uptake by the Arctic heavy snowfall in mid-latitude regions lated by a number of climate models from the Coupled Model this enhances surface evaporation and reduces surface warming. estimate timing of disappearance of sea sea ice motion data. We also conducted a ice retreat and the spatial pattern of the 15 the atmosphere, which has been demon- may not continue in the future. due to changes in the atmospheric circu- Intercomparison Project Phase 5 (CMIP5), we quantify the role In winter, on the other hand, the land has no heat storage to re- ice, and proposed a simple model using study using a high-resolution numerical minimum ice cover. Our activity regard- strated by observations of atmospheric  e GRENE-Arctic project has also lation pattern.  ese may also a ect the of various factors contributing to the Arctic warming ampli ca- lease into the atmosphere.  erefore, the amplitude of seasonal just sea ice motion to evaluate volume Arctic Ocean model to reveal the struc- ing the Arctic sea route included many CO2 concentration. An increase in terres- revealed that snow duration is getting Arctic and sub-Arctic ecosystems, result- tion and clarify their seasonality. variation for surface warming is smaller over the Arctic land than transportation of upper ocean circulation, ture of the heat transport system from the other themes, such as the optimal routing trial uptake for the most recent 10 years shorter and that reduction of sea ice ex- ing in changes in the CO2 budget. Increases in surface air temperature over the Arctic regions over the Arctic Ocean. 10 so called “Beaufort Gyre”, that delivers the Atlantic to the Arctic, and the impact of of ships, engineering studies on ship/ice was also suggested by the observed data. are smallest in summer but largest in winter. Over the Arctic  is study clari es the seasonality and the relative contribu- Seasonal cycle of surface warming heat into the central Arctic Ocean and af- meso-scale eddies on the advance/retreat interaction, ship icing, economic evalua- Net uptake (or release) of CO2 by the Ocean in summer, ice-albedo feedback due to sea ice retreat has tions of various factors that were separately investigated, and also fects fate of sea ice. Analyses using in-situ of sea ice cover. tions, and a proposal of scenarios for the land is a balance between net primary the largest tendency to warm the surface. However, the surface provides a comprehensive understanding of the mechanism of Others and satellite observation data have clari ed Another important theme of ours is use of Arctic sea routes. With these mul- 5 (trapping of heat, increase in cloud, etc.) production of vegetation and soil respira- Atmospheric CO2 warming is smallest because of the large heat uptake by the open Arctic warming ampli cation. that volume transportation of the oceanic seasonal-scale sea ice prediction, which tidisciplinary e orts, studies for realizing Ocean heat uptake and release tion. It had been generally believed that ocean. In autumn and winter, the heat stored in the Arctic Ocean Beaufort Gyre is determined by past sea is necessary for a decision of whether the sustainable use of Arctic sea routes the productivity of vegetation in cold re- Land Ocean in summer is released into the atmosphere. Moreover, there are a ice motion from about four years previ- or not to take the Arctic route. We have have advanced greatly during the GRENE CO2 emission CO2 uptake gions such as the Arctic and sub-Arctic number of other factors that contribute to warming the surface: Ice-albedo feedback: 0 Heating by ice-albedo feedback due ously. We have also constructed methods improved the statistical method of the Arctic Research Project. from the soil by vegetation CO2 CO2 to sea ice reduction increased with warming. However, tree strong vertical stability in the atmosphere traps warming close to As the temperature rises over the Arctic, snow and ice with high re ectance re- to derive the timing of the disappearance prediction using satellite remote-sensing treat, and the land and the ocean surfaces with low re ectance are exposed. The ring analyses for circum-arctic forest eco- the surface; increased low-level clouds enhance the greenhouse absorption of sunlight then increases, leading to a further increase in tempera- of sea ice associated with ra ing of sea data. In 2015, our prediction provided a systems revealed that not all regions in the e ect by trapping more longwave radiation; surface warming ture and hence to a further increase in snow and ice retreat. -5 Arctic and sub-Arctic show increases in sensitivity is larger in colder regions than in warmer regions due JAN FEB MAR APR May JUN JUL AUG SEP OCT NOV DEC Temperature change from the end of 20th century the end of 21st century change from to (°C) Temperature tree growth. Tree growth is decreasing in to the e ect of the Stefan-Boltzmann law; and so on. As a conse- 2015/09/11 0° -30° some regions such as eastern Siberia, the quence, the largest surface warming occurs in winter. Over the The seasonal cycle of warming ampli cation over the Arctic Ocean and its contributing factors. The black line shows the seasonal cycle of temperature increases from the end 30° Alaska Interior, and Canada. Moreover, Arctic land, the ice-albedo feedback has a peak in the early sum- of the 20th century to the end of the 21st century averaged over the Arctic Ocean under the moderate warming scenario of RCP4.5. The contributions from the major factors contributing to the Arctic ampli cation are shown by the colored lines (red, blue and green). soil respiration is expected to increase -60° End of 21st century Present with temperature, which has been shown 60°

Strategic Research Targets 3 a Evaluation of the impacts of Arctic change on weather and climate in Japan Strategic Research Targets 3 b Evaluation of the impacts of Arctic change on marine ecosystems and fisheries 90° -90°

Image of CO exchange 2 Laptev Sea in the Arctic Climate change in the Arctic brings Changes and shi s in the Arctic marine 120° Canada -120° Snow sampling site near Denali National Park, Alaska Production increased cold spells and snowstorms over Japan. ecosystem have been evident. (Photo by Yoshimi Tsukagawa, National Institute of Polar Research) Decreased East Siberian Sea Arctic–mid-latitude climate linkage refers to possible impacts at a stratospheric involvement in the Arctic–mid-latitude climate  e Arctic Ocean has experienced signi cant warming, freshen- Currently, a bloom of phytoplankton at the ice edge in spring to 150° -150° of Arctic climate change on mid-latitude climate and weather, linkage. By arti cially suppressing the stratospheric wave–mean ing, and ocean acidi cation mainly caused by rapid reduction summer sinks down to the sea oor and becomes food for the -180° Alaska which have recently been intensively studied. Severe weather in  ow interactions in numerical experiments, tropospheric signals of sea ice. In the project Ecosystem Studies on the Arctic Ocean benthos (Pelagic-Benthic scheme, Figure below le ). However, Sea Ice Thickness [m] the northern mid-latitudes is o en associated with meandering of the Arctic–mid-latitude climate linkage can be signi cantly with Declining Sea Ice (ECOARCS), we investigated the impact warming due to faster sea ice retreat may increase the population 0 0.25 0.5 0.75 1 jet stream and the negative phase of the Arctic Oscillation (AO). reduced, and thus we con rm that the stratosphere plays a cru- of sea ice decreases on marine ecosystems. Our results show sev- of zooplankton and sh, which feed on phytoplankton at the ice Both observations and model simulations provide evidence that cial role in the Arctic–mid-latitude linkage.  e results also im- eral forms of scienti c evidence for changes in the marine eco- edge (Pelagic-Pelagic scheme, Figure below right). Predicted (green line, forecasted at the end of May) and observed (white area) ice area An example of optimal routing based on the predicted sea ice thick- reductions in Arctic sea ice, or an increase in the Eurasian snow ply that realistic representations of both Arctic surface boundary system: the dominance of larger phytoplankton due to faster sea  e Arctic region will warm more rapidly than the global on September 11, 2015 ness on 24 October, 2011 with the prediction system for Arctic sea routes cover, tend to cause a negative AO phase, which is o en preceded conditions and stratospheric processes are critical for improving ice retreat in spring in the shelf region of the Arctic Ocean and mean, and the resultant changes in Arctic environments could by weakening of the stratospheric polar vortex.  is evidence hints predictions of weather and climate in the mid-latitudes. Bering Sea; and a northward shi in the geographic distribution serve as an indication of global climate change, and should ring of the zooplankton community, benthos, sh, and marine mam- alarm bells not only for scientists, but also for the public.  at mals. On the other hand, we found that the North Paci c species is why we need to continue to monitor Arctic environmental of zooplankton transported into the Chukchi Sea (Arctic Ocean) changes and responses of marine ecosystems to assess how they Decelerated is unlikely to establish stable Arctic populations in the near fu- can or cannot adapt to these changes. polar vortex ture due to large di erences in geographic and life conditions. Polar vortex Trends of tree production Stratosphere in the second half of the Pelagic-Benthic scheme Pelagic-Pelagic scheme 20th century inferred from Jet stream Cold in Euro-Atlantic tree ring analyses region Phytoplankton

Zooplankton Stronger Siberian High Negative AO Troposphere Shortening Lengthening Changes in snow cover duration during Plankton & Fish Eaters the past 30 years. The red area indicates Cold in Siberia Icebreaker navigating the -58.4 -38.9 -19.5 0.0 19.5 38.9 58.4 77.9 97.3 shortening of the snow-covered period, and Far East Meandering jet stream Benthos Benthos Feeders thin ice area Trend of Snow Cover Duration [Day/30 years] while the blue area indicates lengthen- ing. There has been a signi cant reduc- (Photo by Kazutaka Tateyama, Kitami (Period: 1982-2013, excl. 1994, 1995) Institute of Technology) tion of snow cover duration in Europe. Mechanism of the impacts of Arctic change on weather and climate in Japan Fallen tree by a snowstorm (Photo by Shuhei Takahashi, Okhotsk Sea Ice Museum of Hokkaido)