Arctic Temperature Research Articles

Polar bear's range dynamics and survival in the Holocene

Polar bear (Ursus maritimus) is the apex predator of the Arctic, largely dependent on sea-ice. The expected disappearance of the ice cover of the Arctic seas by the mid 21st century is predicted to cause a dramatic decrease in the global range and population size of the species. To place this scenario against the backdrop of past distribution changes and their causes, we use a fossil dataset to investigate the polar bear's past distribution dynamics during the Late Glacial and the Holocene. Fossil results indicate that during the last deglaciation, polar bears were present at the southwestern margin of the Scandinavian Ice Sheet, surviving until the earliest Holocene. There are no Arctic polar bear findings from 8000–6000 years ago (8–6 ka), the Holocene's warmest period. However, fossils that date from 8-9 ka and 5–6 ka suggest that the species likely survived this period in cold refugia located near the East Siberian Sea, northern Greenland and the Canadian Archipelago. Polar bear range expansion is documented by an increase in fossils during the last 4000 years in tandem with cooling climate and expanding Arctic sea ice. The results document changes in polar bear's distribution in response to Late Glacial and Holocene Arctic temperature and sea ice trends.

Super Climate Events

New environmental extremes are currently underway and are much greater than those in previous records. These are mostly regional, singular events that are caused by global change/local weather combinations and are larger than the impact of linear temperature increases projected using climate models. These new states cannot easily be assigned probabilities because they often have no historical analogs. Thus, the term super climate extremes is used. Examples are the loss of sea ice and ecosystem reorganization in northern marine Alaska, heatwave extreme in western Canada, and the loss of snow in Greenland. New combined extreme occurrences, which are reported almost daily, lead to a new, higher level of climate change urgency. The loss of sea ice in 2018–2019 was a result of warmer Arctic temperatures and changes in the jet stream. They resulted in a chain of impacts from southerly winds, the northward movement of predatory fish, and the reduction of food security for coastal communities. Record temperatures were measured in southwestern British Columbia following previous drought conditions, a confluence of two storm tracks, and warming through atmospheric subsidence. Greenland’s losses had clear skies and jet stream events. Such new extremes are present indicators of climate change. Their impacts result from the interaction between physical and ecological processes, and they justify the creation of a new climate change category based on super climate extremes.

An interdecadal change in the relationship between summer Arctic Oscillation and surface air temperature over the eastern Tibetan Plateau around the late 1990s

An interdecadal change in the relationship between summer Arctic Oscillation and surface air temperature over the eastern Tibetan Plateau around the late 1990s

A fjord with a land-terminating glacier: Meltwater, bio-optics, particulate matter, nutrients, phytoplankton species, and primary production in west Greenland

Land-terminating glaciers and submarine melting of marine-terminating glaciers are significant features in Arctic regions and are foreseen to become more frequent as marine-terminating glaciers ultimately develop into a land-terminated state. A transition driven by the continuous rise in Arctic air temperatures, and emphasizes the importance of studies of land-terminating glaciers their bio-optical properties and biogeochemistry. Kangerlussuaq in west Greenland with a land-terminating glaciers and was selected for this study. During a research cruise we measured spectral and PAR attenuation, particulate matter concentrations, salinity, nutrient concentrations, Chla, and phytoplankton species composition, along a transect from river outlet to open marine waters. Results showed that surface waters in Kangerlussuaq were strongly influenced by meltwater with low salinities, high particulate matter concentrations, high PAR and spectral light attenuation coefficients, and low nutrient concentrations. Spectral composition was also affected by the particulate matter. PAR photic depths varied between 4 and 9 m dependent on particulate matter concentrations. There was a decrease with distance from outlet in silicate concentrations, and opposite for phosphate, which increased significantly from river outlet to the marine. Phytoplankton species number (42) and diversity were high at the marine station but low (3) in turbid waters dominated by the diatom Skeletonema costatum in high numbers. A meltwater plume covered about 50 % of the Kangerlussuaq at average discharges in early August. Primary production was quantified with a simple model based on light attenuation coefficients, and showed a near exponential decrease in production with increase in attenuation.

Decadal changes in the relationship between Arctic stratospheric ozone and sea surface temperatures in the North Pacific

Using multi-source observations and ERA-Interim reanalysis data, this study found that the relationship between Arctic stratospheric ozone in March and North Pacific sea surface temperature (SST) in April shows dramatic decadal changes, and it significantly weakens since the 2000s. By enhancing the stratospheric circulations, a decreased Arctic stratospheric ozone favors tropospheric positive Arctic Oscillation (+AO)-like anomaly during PRE eras (1979–1999), with positive geopotential height (GH) anomalies over high-latitude Asia. The stratospheric ozone anomaly also favors the Asian positive GH anomalies via modulating high cloud and its related longwave radiation. According to geostrophic wind relationships, the Asian positive GH anomalies are accompanied by easterly anomalies over midlatitude Asia in late March, which further extend eastward and thereby induce easterly anomalies over the midlatitude North Pacific. The North Pacific easterly anomalies result in negative North Pacific Oscillation (–NPO)-like anomaly via vorticity forcing of zonal wind and the interactions between synoptic-scale eddies and mean flow, forcing significant SST anomalies. However, during POST eras (2000–2019), firstly, the +AO-related positive GH anomalies over high-latitude Asia are relatively weak, accompanied by weak easterly anomalies over midlatitude Asia according to geostrophic wind relations, which induce weak easterly anomalies over the North Pacific. Secondly, a westerly anomaly occurs over the midlatitude North Pacific, which partly offsets the easterly anomalies from Asia, weakening the North Pacific easterly anomalies. The weak easterly anomalies further induce weak –NPO and SST anomalies during the POST eras. Our analysis further indicates that the North Pacific westerly anomalies and weakening of the positive GH anomalies over high-latitude Asia associated with ozone are related to the interference of the westerly phase of quasi-biennial oscillation and the weakened stratospheric ozone anomaly over high-latitude Asia, respectively.

Ice Freeze‐Up and Break‐Up in Arctic Rivers Observed With Satellite L‐Band Passive Microwave Data From 2010 to 2020

AbstractThe timing of ice freeze‐up and break‐up in the Arctic may be responding to climate change. Passive microwave remote sensing is a powerful technique for monitoring this timing. We processed low‐frequency microwave time series from the European Space Agency Soil Moisture and Ocean Salinity (SMOS) mission for a set of 31 satellite gauging reaches (SGRs) above 65°N between 2010 and 2020 to determine timing of freeze‐up and break‐up and annual river ice durations. We found indication of progressive ice cover reduction over more than half of the monitored river reaches, with possibly the fastest rate occurring over northeast Russia. Some rivers in high‐latitude North America experienced a slight increase in ice cover. Across the data set, we observed an average 2.2 days shift toward later ice freeze‐up in autumn and an average 0.6 days shift toward earlier ice break‐up in spring, resulting in an average decrease of 3.4 days in ice duration between 2010 and 2020. River reaches with the longest duration of ice cover appeared to have experienced the fastest rate of decrease. A possible reduction of the time lag between air temperature rise or fall and corresponding river ice break‐up and freeze‐up was also observed. Yet results on variability are carefuly interpreted given the short length of the time series (2010–2020) and the low statistical confidence rates calculated for the decadal tendency. Still outcomes are consistent with increases in global and Arctic surface air temperature. Following these time series over the next decade using passive microwave satellite sensors can monitor ice cover duration in the Arctic and will further determine temporal and regional trends.

The Problem with the Anthropocene: Kainos, Not Anthropos

The Problem with the Anthropocene: <i>Kainos</i>, Not <i>Anthropos</i>

A 600‐year marine record associated with the dynamics of the eastern Penny Ice Cap (Baffin Island, Nunavut, Canada)

ABSTRACTTwo composite sedimentary sequences sampled in the ice‐proximal (12CS) and ice‐distal (02CS) areas of Coronation Fjord (Baffin Island, Nunavut, Canada) were investigated in order to reconstruct the effect of climate variability on 600 years of changes in sediment transfer from the eastern Penny Ice Cap (PIC). Detrital proxies, and physical and sedimentological analyses revealed that glacial meltwater discharges led to frequent rapidly deposited layers (RDLs) in ice‐proximal settings. RDLs in ice‐distal settings involved the sudden release of a large quantity of sediment‐laden water during floods probably originating from adjacent fjords with large sandur deltas. Laminated sediments with ice‐rafted debris throughout the Little Ice Age interval in the ice‐proximal environment suggest that colder conditions promoted glacier growth, leading to successive episodes of turbid hyperpycnal meltwater plumes and iceberg calving in Coronation Fjord. Since 1850 ce, the accelerated Coronation retreat in response to modern warming has led to increased sedimentation rates, abrupt mineralogical and grain size proxy variations and more frequent RDLs. Similar trends between the detrital proxies of the ice‐proximal core and Atlantic Multidecadal Oscillation record and Arctic surface air temperature suggest high connectivity between atmospheric and sea surface temperature variations and PIC dynamics over the last 600 years.

Static compressive stress–strain behaviours of normal weight concrete at Arctic low temperatures

This study experimentally investigated the compressive stress–strain (σ-ε) response of normal weight concrete (NWC) at low temperatures. 72 NWC cubes and 35 NWC prisms in three grades (C25, C45, and C55) were tested under axial compression at four temperature levels (T) of −80, −60, −30, and 20 °C. The failure modes, cubic and prism compressive strength (fcuT and fcT), modulus of elasticity (EcT), and peak strain (ε0T) were studied in detail. In addition, the low-temperature effects of specimen shapes on the compressive strength of NWC were studied. These experimental results reflected that dropping T from ambient temperature to −80 °C did not influence the peak strain of NWC, but significantly increased the fcuT, fcT, and EcT of C55 NWC by 47.3 %, 69.0 %, and 45.3 %, respectively. Finally, prediction equations were established to describe the low-temperature σ-ε constitutive model of NWC. The validations confirmed that the proposed low-temperature compressive constitutive models provided reasonable predictions on the σ-ε behaviours of NWC at a T range of −80 ∼ 20 °C.

Arctic Seasonal Variability and Extremes, and the Role of Weather Systems in a Changing Climate

AbstractThe effects of global warming are strongly amplified in the Arctic, causing rapidly rising temperatures and ongoing dramatic loss of sea ice, which itself is subject to large interannual variability. We investigate changes in seasonal‐mean temperature and precipitation, its variability and extremes, using large‐ensemble climate model data with a representative concentration pathway 8.5 forcing scenario for historical (S2000) and end‐of‐century projections (S2100). Our results reveal regionally and seasonally dependent changes in Arctic interannual temperature and precipitation variability that are strongly linked to sea‐ice loss. We show a doubling in precipitation variability over the Arctic Ocean and a significant reduction in temperature variability in the Barents Sea. Extremely warm seasons in S2000 rank among the coldest seasons or become unrealistic in S2100. We further show the key role of large‐scale weather systems for shaping seasonal temperature and precipitation extremes in the Arctic which persists under climate warming.

Clouds Increasingly Influence Arctic Sea Surface Temperatures as CO2 Rises

AbstractAs Arctic sea ice retreats during the melt season, the upper ocean warms in response to atmospheric heat fluxes. Overall, clouds reduce these fluxes in summer, but how the radiative impacts of clouds on ocean warming could change as sea ice declines has not been documented. In global climate model simulations with variable CO2, the timing of sea ice retreat strongly influences the amplitude of cloud‐induced summer cooling at the ocean surface. Under pre‐industrial CO2 concentrations, summer clouds have little direct effect on maximum annual sea surface temperatures (SST). When CO2 concentrations increase, sea ice retreats earlier, allowing more solar radiation to warm the ocean. Clouds can counteract this summer warming by reflecting solar radiation back to space. Consequently, clouds explain up to 13% more variability in maximum annual SST under modern‐day CO2 concentrations. Maximum annual SST are three times more sensitive to summer clouds when CO2 concentrations are four times pre‐industrial levels.

Seasonal and regional contrasts of future trends in interannual arctic climate variability

Future changes in interannual variability (IAV) of Arctic climate indicators such as sea ice and precipitation are still fairly uncertain. Alongside global warming-induced changes in means, a thorough understanding of IAV is needed to more accurately predict sea ice variability, distinguish trends and natural variability, as well as to reduce uncertainty around the likelihood of extreme events. In this study we rank and select CMIP6 models based on their ability to replicate observations, and quantify simulated IAV trends (1981–2100) of Arctic surface air temperature, evaporation, precipitation, and sea ice concentration under continued global warming. We argue that calculating IAV on grid points before area-averaging allows for a more realistic picture of Arctic-wide changes. Large model ensembles suggest that on shorter time scales (30 years), IAV of all variables is strongly dominated by natural variability (e.g. 93% for sea ice area in March). Long-term trends of IAV are more robust, and reveal strong seasonal and regional differences in their magnitude or even sign. For example, IAV of surface temperature increases in the Central Arctic, but decreases in lower latitudes. Arctic precipitation variability increases more in summer than in winter; especially over land, where in the future it will dominantly fall as rain. Our results emphasize the need to address such seasonal and regional differences when portraying future trends of Arctic climate variability.

Asymmetric changes in temperature in the Arctic during the Holocene based on a transient run with the Community Earth System Model (CESM)

Abstract. The Arctic temperature changes are closely linked to midlatitude weather variability and extreme events, which has attracted much attention in recent decades. Syntheses of proxy data from poleward of 60∘ N indicate that there was asymmetric cooling of −1.54 and −0.61 ∘C for the Atlantic Arctic and the Pacific Arctic during the Holocene, respectively. We also present a similar consistent cooling pattern from an accelerated transient Holocene climate simulation based on the Community Earth System Model. Our results indicate that the asymmetric Holocene Arctic cooling trend is dominated by the winter temperature variability, with −0.67 ∘C cooling for the Atlantic Arctic and 0.09 ∘C warming for the Pacific Arctic, which is particularly pronounced at the proxy sites. Our findings indicate that sea ice in the North Atlantic expanded significantly during the late Holocene, while a sea ice retreat is seen in the North Pacific, amplifying the cooling in the Atlantic Arctic by the sea ice feedback. The positive Arctic dipole pattern, which promotes warm southerly winds to the North Pacific, offsets parts of the cooling trend in the Pacific Arctic. The Arctic dipole pattern also causes sea ice expansion in the North Atlantic, further amplifying the cooling asymmetry. We found that the temperature asymmetry is more pronounced in a simulation driven only by orbital forcing. The accelerated simulations lead to a partial delay in the feedback of climate processes. Therefore, we confirm the occurrence of the asymmetry of the Arctic temperature changes in un-accelerated simulations using ECBilt-CLIO, IPSL, and in TraCE-21k.

Cyclic compressive stress-strain behaviours of normal weight concrete at Arctic low temperatures

To propose more accurate constitutive models for low-temperature concrete structures subjected to cyclic loading, this paper experimentally studied the cyclic compressive behaviours of normal weight concrete (NWC) at low temperatures. Firstly, cyclic compression tests on 36 NWC prisms of C25, C45, and C55 grades were performed at four low-temperature levels, i.e., 20, −30, −60, and − 80 °C. By comparing with monotonic results, it was confirmed that the low-temperature cyclic envelope curves of NWC can be predicted by the corresponding monotonic constitutive models. Furthermore, the effects of low temperatures and grades of NWC on key indexes in constitutive models of NWC under cyclic compression were discussed and analyzed in detail, e.g., plastic strain, stress deterioration ratio, endpoint strain, and damage variable. Through the regression analysis of test data, the cyclic constitutive models composed of the envelope, unloading, and reloading curves were established to describe cyclic stress-strain behaviours of NWC at 20 ∼ −80 °C. Finally, the validations proved that the developed models provided reasonable predictions on low-temperature cyclic response of NWC.

Newly reconstructed Arctic surface air temperatures for 1979–2021 with deep learning method

A precise Arctic surface air temperature (SAT) dataset, that is regularly updated, has more complete spatial and temporal coverage, and is based on instrumental observations, is critically important for timely monitoring and improving understanding of the rapid change in the Arctic climate. In this study, a new monthly gridded Arctic SAT dataset dated back to 1979 was reconstructed with a deep learning method by combining surface air temperatures from multiple data sources. The source data include the observations from land station of GHCN (Global Historical Climatology Network), ICOADS (International Comprehensive Ocean-Atmosphere Data Set) over the oceans, drifting ice station of Russian NP (North Pole), and buoys of IABP (International Arctic Buoy Programme). The last two are crucial for improving the representation of the in-situ observed temperatures within the Arctic. The newly reconstructed dataset includes monthly Arctic SAT beginning in 1979 and daily Arctic SAT beginning in 2011. This dataset would represent a new improvement in developing observational temperature datasets and can be used for a variety of applications.

Reduction in the Arctic Surface Warm Bias in the NCAR CAM6 by Reducing Excessive Low-Level Clouds in the Arctic

High-latitude low clouds in the Northern winter have been known to be closely related to the Arctic surface air temperature by controlling downward longwave radiation, but Earth system models often fail to accurately simulate this relationship. In this study, we conducted a series of model experiments to examine the role of winter high-latitude low-level clouds in determining the Arctic surface temperature. Our findings show that low-level clouds play a significant role in regulating the Arctic surface temperature. We used the NCAR CAM6 model and compared the results of an unforced simulation run with those of an experiment using an empirical low-level cloud scheme to alleviate the typical overestimation of the low cloud fraction of state-of-the-art general circulation models at high latitudes. The unforced simulation exhibited excessive downward longwave radiation in the Arctic, resulting in a significant warm bias compared to reanalysis data. On the other hand, the experiment using a modified scheme more closely resembled the reanalysis data in terms of low-level cloud simulation. Overall, our study underscores the importance of accurately representing low-level clouds in high-latitude regions to reduce surface temperature bias in the model.

Photoinduced CO2 Conversion under Arctic Conditions─The High Potential of Plasmon Chemistry under Low Temperature

The conversion of CO2 to fine chemicals is an efficient tool for reducing the negative impact of human activities on the environment. In this work, we show that CO2 capture and its sunlight-based activation can proceed efficiently even at low, practically arctic temperatures with the implementation of so-called plasmon-assisted chemistry. We propose the specific photocatalyst consisting of two parts: (i) an organic shell responsible for CO2 capture and (ii) a plasmon-active metal nanoparticle core for activation of entrapped CO2 and involving it in the cycloaddition reaction. The effect of temperature on the plasmon-assisted CO2 cycloaddition was studied, and a reaction with only slight temperature sensitivity was observed. Theoretical calculations indicated a significant decrease in the “apparent” activation barrier of the reaction under the plasmon-assisted mechanism. Our results open an opportunity for the world economy to exploit the vast Arctic and Antarctic (or close to them) territories where the powerful solar potential is practically not used yet.

Distinct impacts of two types of El Niño events on northern winter high-latitude temperatures simulated by CMIP6 climate models

The interannual variability of the Northern Hemisphere winter climate is strongly linked to the El Niño-southern oscillation (ENSO). While North Pacific and North America often exhibit a robust response to ENSO, so-called the Pacific–North America pattern, the Arctic and Eurasian climate responses to ENSO remain elusive. This study examines 40 different climate models from the coupled model intercomparison project phase 6 (CMIP6) to find the distinct Arctic and Eurasian temperature response to two types of El Niño events. Specifically, Central Pacific El Niño events are accompanied by significant pan-Arctic warming, whereas Eastern Pacific (EP) El Niño events are accompanied by cooling over the Barents-Kara Seas and Eurasian continent. During the EP El Niño events, pan-Arctic sea-level pressure (SLP) effectively strengthens, leading to weaker westerlies and surface air cooling over the northern Eurasian continent. These distinct Arctic and Eurasian winter temperature responses to two types of El Niño do not appear clearly in reanalysis data, spanning 1979–2021, probably because of the small sample size of El Niño events since the satellite era.

Flexural behavior and microstructural material properties of sandwich foam core under arctic temperature conditions

This study investigates three types of foam core materials used in composite sandwich structures at various densities: H60, H100, F50, F90, PN115, PN200 and PN250. Three-point bending test is conducted to determine relationships between material and flexural properties at both room and low temperature Arctic conditions. X-ray micro-computed tomography is utilized to observe the microstructural relationships between foam density and mechanical properties of the core. This study evaluates Arctic temperature effects on mechanical properties for various types of foam core at varying densities with the intention for future Arctic applications. Although foam core materials become more brittle at a lower temperature, their flexural stiffness and flexural strength are further increased. However, due to the enhanced brittleness, the energy required for fracture is significantly reduced at low temperature conditions. This study utilizes statistical analysis to create contour plots and linear regression equations to predict flexural properties as a function of temperature and foam density. Molecular dynamics simulation is employed to verify experimental results to elucidate the effect of temperature on material behavior. This work provides a deeper understanding of how flexural strength relates to foam density, adding to existing data on foam strength properties under compressive, shear and tensile loads.

Mechanical properties of high strength steels and weld metals at arctic low temperatures

This paper attempts to acquire fundamental knowledge on the mechanical properties of high strength steels and the corresponding high strength weld metals at arctic low temperatures. Two types of high strength steels (Q890, Q960) and three types of high strength weld metals (made of ER100S-G, ER110S-G, ER120S-G feedstock wires) were tested at arctic low and ambient temperatures ranging from −75 °C to 25 °C. Tensile coupon specimens for steel materials were directly extracted from high strength steel plates, whilst robotic gas metal arc welding was employed to fabricate the tensile specimens of weld metals. The tensile coupon specimens were designed as per ASTM E8M and wire-cut into shapes. Twenty-three tensile coupon tests on high strength steels and eighteen tensile coupon tests on high strength weld metals were carried out. Coupon specimens were tested in liquid nitrogen cooling chamber to mimic the arctic low temperature environment. The stress–strain responses and key mechanical properties of high strength steels and weld metals at both ambient and arctic low temperatures are presented and discussed. Prediction equations for key mechanical properties, including the Young’s modulus, yield stress and ultimate tensile strength, of high strength steels and weld metals at arctic low temperatures were proposed.