Evolutionary characteristics of export trade network in the Arctic region

The economic potential induced by environmental changes in the Arctic region garnered substantial interest,which positions Arctic trade as a crucial indicator in forecasting the impacts of climate change on the global economy.Nevertheless,attention devoted to the evolving dynamics of trade in the Arctic region remains scarce.In this study,we constructed export trade network in the Arctic region(including Denmark,Finland,Sweden,Norway,Iceland,the Canadian Arctic,the Russian Arctic,Alaska State of the USA,and Greenland)from 1990 to 2019 and analyzed its topology and evolutionary characteristics through complex network theory.We used a structural entropy index based on the distribution of the number of trading partners and the degree of trade concentration to assess export diversity,while we also utilized a revealed comparative advantage index to evaluate product export competitiveness using the share of trade volume of each type of product.The results indicate that the total export trade in the Arctic region increased by 53.4%during 1990-2019,with the most significant growth observed in the exports of chemical products and mineral fuels.The increasing complexity of trade network in the Arctic region resulted in the region’s export destinations no longer being concentrated on a few major countries and regions.The proportion of exports from the Arctic region to Europe decreased by 13.5%,while the proportion of exports from the Arctic region to Asia and North America increased by 6.8%and 3.1%,respectively.The Arctic region exhibited clear distinctions in the range of flows of different products,and its export trade was becoming increasingly diversified.Although differences in comparative advantages between products within individual countries or regions have narrowed,substantial gaps persist.The findings of this study can enhance the comprehensive understanding of the significance and function of Arctic trade activities within the global economy,providing a scientific basis for addressing the associated challenges and opportunities in the context of climate change.

Experiments on the Resistance of a Large Transport Vessel Navigating in the Arctic Region in Pack Ice Conditions

In this study, we carried out model tests to investigate the ice failure process and the resistance experienced by a transport vessel navigating in the Arctic region in pack ice conditions. We tested different navigation velocities, ice plate sizes, and ice concentrations. During the tests, we closely observed several phenomena, including the modes of interaction of the ice ship and the moving and failure modes of ice. We also measured the vessel resistances under different conditions. The test results indicate that the navigation velocity is a significant determinant of the moving and failure modes of ice. Moreover, vessel resistance is remarkably dependent on the ice concentration and navigation velocity. The variances of the mean and maximum resistance are also compared and discussed in detail.

Seismicity,structure and tectonics in the Arctic region

The "Arctic" region,where the North Pole occupies the center of the Arctic Ocean,has been affecting the environmental variation of the Earth from geological time to the present.However,the seismic activities in the area are not adequately monitored.Therefore,by conducting long term monitoring of seismic phenomenon as sustainable parameters,our understanding of both the tectonic evolution of the Earth and the dynamic interaction between the cryosphere and geosphere in surface layers of the Earth will increase.In this paper,the association of the seismicity and structure of the Arctic region,particularly focused on Eurasian continent and surrounding oceans,and its relationship with regional evolution during the Earth’s history is studied.The target areas cover representative tectonic provinces in the Eurasian Arctic,such as the wide area of Siberia,Baikal Rift Zone.Far East Russia,Arctic Ocean together with Greenland and Northern Canada.Based on discussion including characteristics of seismicity,heterogeneous structure of the crust and upper mantle,tectonic history and recent dynamic features of the Earth’s surface in the Arctic are summarized.

Advances in Chinese Arctic and subarctic research in marine biology and ecology with emphasis on the Pacific Arctic sector

The Arctic is one of the most sensitive regions that respond through feedback to global climate changes. Climatic, hydrological and ecological changes in the Arctic are clear evidence of global warming. In 2012 and 2014, the 5th and 6th Chinese National Arctic Research Expeditions undertook studies in the Bering Sea, the Arctic Ocean （including the Chukchi Sea）, and the Norwegian Sea. These studies provided us with a better understanding of the marine biology and ecology in the Arctic and subarctic regions, particularly in the Pacific Arctic sector. Rapid changes observed in the Arctic environment include the shrinking of cold-water masses in the Bering Sea in the summer, and elevated water temperatures promoting phytoplankton blooms, leading to an increase in phytoplankton transferred to higher trophic levels. As a result, the transfer efficiency of organic matter toward the bottom weakened, leading to a reduction in benthic biomass. This is consistent with expectations that the overall carbon and energy flux will ultimately switch from the dominant mode of sea ice-algae-benthos to one of phytoplankton-zooplankton. Influenced by Pacific water inflow, fluvial runoff and melting sea ice, the Chukchi Sea exhibited different responses to various environmental changes. Interactions between water masses led to other interannual ecological shifts. With the increase in sea ice melt and sunlight in the central region of the Arctic Ocean, the relative abundance of heterotrophic bacteria is expected to increase, and play a vital role in the Arctic microbial loop.

Summertime CO_2 fluxes from tundra of Ny-?lesund in the High Arctic

The Arctic ecosystem, especially High Arctic tundra, plays a unique role in the global carbon cycle because of amplified warming in the region. However, relatively little research has been conducted in High Arctic tundra compared with other global ecosystems. In the present work, summertime net ecosystem exchange （NEE）, ecosystem respiration （ER）, and photosynthesis were investigated at six tundra sites （DM1-DM6） on Ny-A.lesund in the High Arctic. NEE at the tundra sites varied between a weak sink and strong source （-3.3 to 19.0 mg CO2·m-2.h-1）. ER and gross photosynthesis were 42.8 to 92.9 mg CO2·m-2·h-1 and 54.7 to 108.7 mg CO2·m-2·h-1, respectively. The NEE variations showed a significant correlation with photosynthesis rates, whereas no significant correlation was found with ecosystem respiration, indicating that NEE variations across the region were controlled by differences in net uptake of CO2 owing to photosynthesis, rather than by variations in ER. A Qm value of 1.80 indicated weak temperature sensitivity of tundra ER and its response to future global warming. NEE and gross photosynthesis also showed relatively strong correlations with C/N ratio. The tundra ER, NEE, and gross photosynthesis showed variations over slightly waterlogged wetland tundra, mesic and dry tundra. Overall, soil temperature, nutrients and moisture can be key effects on CO2 fluxes, ecosystem respiration, and NEE in the High Arctic.

Lessons and prospects of Sino-Russian Arctic cooperation

The strategic partnership between China and Russia is creating solid ground for the cooperative development of the Arctic. These two states＇ joint development of the Northern Sea Route will not only provide additional impulse to the export- oriented economy of China and allow further diversification of supply routes to China, but will also promote investment into the infrastructure and economic growth of Russian northern territories. Climate change in the Arctic has forced China and Russia to acknowledge the sustainable use of the Arctic. On the one hand, exploration of the region should not harm indigenous people＇s rights and should help this population improve their standard of living by providing qualified healthcare and opportunities for commercial fulfillment of traditional crafts. On the other hand, this exploration should also include elimination of harmful anthropogenic impact and provide support for environment self-restoration. Sino-Russian Arctic cooperation will help humans discover eco-friendly approaches to use Arctic resources, promote rational use of the Arctic and inspire sustainable development of the region.

On the Governance of the Arctic Region under the Tragedy of the Commons

Because of global climate change,the natural environment is rapidly changing in the Arctic.The large amount of sea ice melting in the Arctic can lead to a great increase in the use of the world’s natural resources.This thesis focuses on the exploration and utilization of public waters in the Arctic region based on the economic theory of the Tragedy of the Commons,analyzes the current situation of Arctic governance,and predicts potential problems in the Arctic region,mainly including overfishing and environmental problems caused by coal and natural gas exploitation.Additionally,it makes an in-depth analysis on the current Arctic governance model based on the Arctic Council,and finally proposes some countermeasures and suggestions for Arctic governance.

Mechanism and effects of the increase in winter temperatures in the Arctic region on cold winters in Heilongjiang Province,Northeast China for the period 1961-2018

With the advent of climate change,winter temperatures have been steadily increasing in the middle-to-high latitudes of the world.However,we have not found a corresponding decrease in the number of extremely cold winters.This paper,based on Climatic Research Unit(CRU)re-analysis data,and methods of trend analysis,mutation analysis,correlation analysis,reports on the effects of Arctic warming on winter temperatures in Heilongjiang Province,Northeast China.The results show that:(1)during the period 1961-2018,winter temperatures in the Arctic increased considerably,that is,3.5 times those of the Equator,which has led to an increasing temperature gradient between the Arctic and the Equator.An abrupt change in winter temperatures in the Arctic was observed in 2000.(2)Due to the global warming,an extremely significant warming occurred in Heilongjiang in winter,in particular,after the Arctic mutation in 2000,although there were two warm winters,more cold winters were observed and the interannual variability of winter temperature also increased.(3)Affected by the warming trend in the Arctic,the Siberian High has intensified,and both the Arctic Vortex and the Eurasian Zonal Circulation Index has weakened.This explains the decrease in winter temperatures in Heilongjiang,and why cold winters still dominate.Moreover,the increase in temperature difference between the Arctic and the Equator is another reason for the decrease in winter temperatures in Heilongjiang.

Advances in Climate Change Research 12(2021)48-65 Review

In boreal and arctic regions,forest fires exert great influences on biogeochemical processes,hydrothermal dynamics of the active layer and near-surface permafrost,and subsequent nutrient cycles.In this article,the studies on impacts of forest fires on the permafrost environment are reviewed.These studies indicate that forest fires could result in an irreversible degradation of permafrost,successions of boreal forests,rapid losses of soil carbon stock,and increased hazardous periglacial landforms.After forest fires,soil temperatures rise;active layer thickens;the release of soil carbon and nitrogen enhances,and;vegetation changes from coniferous forests to broad-leaved forests,shrublands or grasslands.It may take decades or even centuries for the fire-disturbed ecosystems and permafrost environment to return to pre-fire conditions,if ever possible.In boreal forest,the thickness of organic layer has a key influence on changes in permafrost and vegetation.In addition,climate warming,change of vegetation,shortening of fire return intervals,and extent of fire range and increasing of fire severity may all modify the change trajectory of the fire-impacted permafrost environment.However,the observations and research on the relationships and interactive mechanisms among the forest fires,vegetation,carbon cycle and permafrost under a changing climate are still inadequate for a systematic impact evaluation.Using the chronosequence approach of evaluating the temporal changes by measuring changes in the permafrost environment at different stages at various sites(possibly representing varied stages of permafrost degradation and modes),multi-source data assimilation and model predictions and simulations should be integrated with the results from long-and short-term field investigations,geophysical investigations and airborne surveys,laboratory testing and remote sensing.Future studies may enable quantitatively assess and predict the feed-back relationship and influence mechanism among organic layer,permafrost and active layer processes,vegetation and soil carbon under a warming climate at desired spatial and temporal scales.The irreversible changes in the boreal and artic forest ecosystem and their ecological and hydrothermal thresholds,such as those induced by forest fires,should be better and systematically studied.