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The combined effect of the Pacific-Japan (PJ) pattern and Mediterranean-northern Eurasia (MnE) pattern on East Asian surface air temperature (SAT) during summer is investigated using the Japanese 55-year reanalysis and Climatic Research Unit SAT data over the period of 1958-2016. The results show that the combination of the two patterns in different phases can result in different SAT anomalies. During the in-phase PJ-MnE years, the overlapping of opposite signs of the atmospheric circulations associated with the PJ and MnE patterns results in weak atmospheric circulation and SAT anomalies in central East Asia; during these years, the significant SAT anomalies are over northern East Asia. In contrast, during the out-of-phase PJ-MnE years, the overlapping of the same signs of the atmospheric circulations associated with the PJ and MnE patterns leads to significant atmospheric circulation and SAT anomalies in central East Asia and northern Asia. The analysis in this study indicates that to better understand and predict the variability of East Asian summer SATs, the combined effect of the PJ and MnE patterns should be taken into account.

The study presents a simulation of climate change across Northern Eurasia during the 20th and 21st centuries using two different versions of the Earth system model developed by the Marchuk Institute of Numerical Mathematics at the Russian Academy of Sciences (INMCM). Model version INMCM5 participates in Coupled Model Intercomparison Project Phase 6 (CMIP6) and has the lowest equilibrium climate sensitivity (ECS) among the CMIP6 models. In the next model version, INMCM6, changes in the physical parameterisations lead to an increase in ECS by a factor of 2. Changes in near-surface temperature, precipitation, snow cover area and sea ice extent simulated by both model versions are compared with available observational and reanalysis data. Climate change predictions for the middle and end of the twenty-first century are provided by two model versions. Both model versions simulate similar climate changes for the upcoming two decades. After the middle of twenty-first century, the model version with high equilibrium climate sensitivity simulates stronger climate changes over Northern Eurasia than the model version with low sensitivity. But, in general, the ratio of predicted warming is much less than the ratio of ECS.

The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. Floating ice shelves preserve few direct traces after their disappearance, making reconstructions difficult. Seafloor imprints of ice shelves should, however, exist where ice grounded along their flow paths. Here we present new evidence of ice-shelf groundings on bathymetric highs in the central Arctic Ocean, resurrecting the concept of an ice shelf extending over the entire central Arctic Ocean during at least one previous ice age. New and previously mapped glacial landforms together reveal flow of a spatially coherent, in some regions >1-km thick, central Arctic Ocean ice shelf dated to marine isotope stage 6 (∼140 ka). Bathymetric highs were likely critical in the ice-shelf development by acting as pinning points where stabilizing ice rises formed, thereby providing sufficient back stress to allow ice shelf thickening. The development of pan-Arctic Ocean ice shelves during peak glacials was proposed in the 1970s, an idea that has been disputed due to lack of evidence. Here, the authors present geophysical mapping data supporting the presence of such an ice shelf during the peak of the penultimate glaciation ∼140–160 ka.

Assessing the performance of climate models in surface air temperature (SAT) simulation and projection have received increasing attention during the recent decades. This paper assesses the performance of the Coupled Model Intercomparison Project phase 5 (CMIP5) in simulating intra-annual, annual and decadal temperature over Northern Eurasia from 1901 to 2005. We evaluate the skill of different multi-model ensemble techniques and use the best technique to project the future SAT changes under different emission scenarios. The results show that most of the general circulation models (GCMs) overestimate the annual mean SAT in Northern Eurasia and the difference between the observation and the simulations primarily comes from the winter season. Most of the GCMs can approximately capture the decadal SAT trend; however, the accuracy of annual SAT simulation is relatively low. The correlation coefficient R between each GCM simulation and the annual observation is in the range of 0.20 to 0.56. The Taylor diagram shows that the ensemble results generated by the simple model averaging (SMA), reliability ensemble averaging (REA) and Bayesian model averaging (BMA) methods are superior to any single GCM output; and the decadal SAT change generated by SMA, REA and BMA are almost identical during 1901-2005. Heuristically, the uncertainty of BMA simulation is the smallest among the three multi-model ensemble simulations. The future SAT projection generated by the BMA shows that the SAT in Northern Eurasia will increase in the 21st century by around 1.03 °C 100 yr, 3.11 °C 100 yr and 7.14 °C 100 yr under the RCP 2.6, RCP 4.5 and RCP 8.5 scenarios, respectively; and the warming accelerates with the increasing latitude. In addition, the spring season contributes most to the decadal warming occurring under the RCP 2.6 and RCP 4.5 scenarios, while the winter season contributes most to the decadal warming occurring under the RCP 8.5 scenario. Generally, the uncertainty of the SAT projections increases with time in the 21st century.

Wildfires heighten the risks of ecosystem degradation and increase carbon emissions, significantly impacting ecological stability and climate change. However, changes in extreme wildfire regimes and their consequential impact on carbon emissions and burned area (BA) remain unclear. Our results indicate that extreme wildfires in northern Eurasia exhibit a latitudinal shift in intensity and frequency during 2003–2023. Within the historically fire-prone latitude band of approximately 50° N–60° N, a declining trend is observed in both intensity and frequency of extreme wildfires. Conversely, a northward shift of high-intensity extreme wildfires brings unprecedented carbon emissions and BAs to high-latitude regions that are rich in forest carbon storage and permafrost. Although extreme wildfires account for only 10% of all fire events, they contribute to over 30% of total wildfire carbon emissions and BAs across most regions of northern Eurasia.

The Northern Annular Mode (NAM) represents the primary form of atmospheric variability in the northern extratropics, significantly influencing the climate in the northern mid-high latitudes. In this study, the linkages between the previous wintertime (December-January-February-March) NAM (WNAM) and springtime vegetation growth across North Eurasia (NEUA), as measured by the normalized difference vegetation index (NDVI), were investigated. Results indicate vegetation cover tends be higher than normal over Europe (western Siberia) in March (May) during or after WNAM’s positive phase, and the opposite for WNAM’s negative phase. However, reduced April vegetation growth across central NEUA is apparent after both the positive and negative phases of the WNAM. In March, the WNAM anomaly excites a Rossby wave from the North Atlantic to western NEUA, generating anomalous high pressure and an anticyclone across western NEUA during WNAM’s positive phase. Consequently, there is a notable increase in 2-m air temperature in the region, which favors vegetation growth. In April, a North Atlantic tripole pattern of sea surface temperature (SST) anomalies preserves the previous WNAM signal and triggers atmospheric wave trains from the North Atlantic to central NEUA after WNAM’s positive phase. This in turn leads to anomalous low pressure and increased cloudiness in central NEUA, which results in a reduction in temperature and solar radiation, thereby inhibiting vegetation growth in the region. However, in April after WNAM’s negative phase, positive snow cover anomalies reduce the turbulent heat flux to the south of Lake Baikal, altering the temperature gradient and triggering an anomalous cyclone, which also leads to reduced temperatures and solar radiation, thereby suppressing vegetation growth in central NEUA in April. WNAM’s impact on vegetation in May mirrors the physical processes after its positive phase in April, particularly in connection with the North Atlantic tripole SST. The findings offer new insights into WNAM’s impact on climate and vegetation in the northern mid-high latitudes, suggesting that WNAM could serve as a reliable predictor for spring vegetation growth anomalies in NEUA.

Previous studies have emphasized the significant influence of the atmospheric heat source of the Tibetan Plateau (TPHS) on the weather and climate in East Asia, but the causes and mechanisms of the TPHS variations remain unclear. In this study, the physical linkage between the winter northern Eurasian snow depth and early summer (May and June) TPHS during 1950–2019 is investigated. Our results indicate that excessive winter northern Eurasian snow can decrease the early summer TPHS through a delayed hydrological effect. In winter, excessive northern Eurasian snow depths lead to more snowmelt and wetter local soil in early summer. The wetter soil not only reduces the surface temperatures in northern Eurasia but also cools the atmosphere in the middle and upper troposphere. This cooling enhances the meridional temperature gradient between northern and southern Eurasia, which reinforces the westerly jet stream at mid-latitudes. The strong westerly jet stream enhances the sensible heat flux over the Tibetan Plateau (TP) by increasing the near-surface wind speed. Moreover, the enhanced meridional temperature gradient generates an anticyclonic and high-pressure anomaly over the southwestern side of the TP, thus decreasing the latent heat release over the TP. Because early summer marks the beginning of the rainy season on the TP, the TPHS in early summer is dominated by latent heat released by precipitation, which means that the wetter soil caused by the excessive winter snow depth in northern Eurasia eventually weakens the TPHS in early summer.

The dryland belt (DLB) in Northern Eurasia is the largest contiguous dryland on Earth. During the last century, changes here have included land use change (e.g. expansion of croplands and cities), resource extraction (e.g. coal, ores, oil, and gas), rapid institutional shifts (e.g. collapse of the Soviet Union), climatic changes, and natural disturbances (e.g. wildfires, floods, and dust storms). These factors intertwine, overlap, and sometimes mitigate, but can sometimes feedback upon each other to exacerbate their synergistic and cumulative effects. Thus, it is important to properly document each of these external and internal factors and to characterize the structural relationships among them in order to develop better approaches to alleviating negative consequences of these regional environmental changes. This paper addresses the climatic changes observed over the DLB in recent decades and outlines possible links of these changes (both impacts and feedback) with other external and internal factors of contemporary regional environmental changes and human activities within the DLB.

This article describes the first release version of a new lexicostatistical database of Northern Eurasia, which includes Europe as the most well-researched linguistic area. Unlike in other areas of the world, where databases are restricted to covering a small number of concepts as far as possible based on often sparse documentation, good lexical resources providing wide coverage of the lexicon are available even for many smaller languages in our target area. This makes it possible to attain near-completeness for a substantial number of concepts. The resulting database provides a basis for rich benchmarks that can be used to test automated methods which aim to derive new knowledge about language history in underresearched areas.

Wildfires play a critical role in re-shaping boreal ecosystems and climate. It was projected that, owing to the Arctic amplification, boreal wildfires would become more frequent and severe in the coming decades. Although provoking concern, the spatiotemporal changes in boreal wildfires remain unclear, and there are substantial inconsistencies among previous findings. In this study, we performed a comprehensive analysis to determine the spatiotemporal changes in wildfires over Northern Eurasia (NEA) from 2003 to 2020 using a reconstructed Moderate Resolution Imaging Spectroradiometer (MODIS) active fire product. We found that wildfires in NEA exhibited contrasting changes in different latitudinal zones, land cover types, and seasons from 2003 to 2020. Cropland wildfires, mainly distributed at low latitudes (50–60°N), considerably decreased by 81% during the study period. Whereas forest wildfires ignited at high latitudes (north of 60°N) have nearly tripled (increasing at rate of 11~13% per year) during the past two decades. The southwestern and northeastern NEA regions exhibited contrasting patterns of wildfire changes. The active fire counts in the southwestern NEA decreased by 90% at a rate of 0.29(±0.12) × 105 per year, with cropland fires contributing to ~66% of the decrease. However, the fire counts in the northeastern NEA increased by 292% at a rate of 0.23(±0.12) × 105 per year, with boreal forests contributing to ~97% of the increase. It is worth noting that the contrasting changes in wildfires during the past two decades have led to significant structural alternation in the NEA wildfire composition. Forest fires, contributing over 60% of the total fire counts in NEA nowadays, have become the predominant component of the NEA wildfires. The contrasting changes in NEA wildfires imply that more forest fires may emerge in far northern regions of the North Hemisphere as the Arctic becomes progressively warmer in the coming decades. As wildfires continue to increase, more gases and aerosols would be released to the atmosphere and cause considerable feedback to the Arctic climate. The increased wildfire-related climate feedbacks should, therefore, be seriously considered in climate models and projections.