Search

Key observational indicators of climate change in the Arctic, most spanning a 47 year period (1971–2017) demonstrate fundamental changes among nine key elements of the Arctic system. We find that, coherent with increasing air temperature, there is an intensification of the hydrological cycle, evident from increases in humidity, precipitation, river discharge, glacier equilibrium line altitude and land ice wastage. Downward trends continue in sea ice thickness (and extent) and spring snow cover extent and duration, while near-surface permafrost continues to warm. Several of the climate indicators exhibit a significant statistical correlation with air temperature or precipitation, reinforcing the notion that increasing air temperatures and precipitation are drivers of major changes in various components of the Arctic system. To progress beyond a presentation of the Arctic physical climate changes, we find a correspondence between air temperature and biophysical indicators such as tundra biomass and identify numerous biophysical disruptions with cascading effects throughout the trophic levels. These include: increased delivery of organic matter and nutrients to Arctic near‐coastal zones; condensed flowering and pollination plant species periods; timing mismatch between plant flowering and pollinators; increased plant vulnerability to insect disturbance; increased shrub biomass; increased ignition of wildfires; increased growing season CO2 uptake, with counterbalancing increases in shoulder season and winter CO2 emissions; increased carbon cycling, regulated by local hydrology and permafrost thaw; conversion between terrestrial and aquatic ecosystems; and shifting animal distribution and demographics. The Arctic biophysical system is now clearly trending away from its 20th Century state and into an unprecedented state, with implications not only within but beyond the Arctic. The indicator time series of this study are freely downloadable at AMAP.no.

Polychlorinated biphenyls (PCBs) can be used as chemical sentinels for the assessment of anthropogenic influences on Arctic environmental change. We present an overview of studies on PCBs in the Arctic and combine these with the findings from ArcRisk—a major European Union-funded project aimed at examining the effects of climate change on the transport of contaminants to and their behaviour of in the Arctic—to provide a case study on the behaviour and impact of PCBs over time in the Arctic. PCBs in the Arctic have shown declining trends in the environment over the last few decades. Atmospheric long-range transport from secondary and primary sources is the major input of PCBs to the Arctic region. Modelling of the atmospheric PCB composition and behaviour showed some increases in environmental concentrations in a warmer Arctic, but the general decline in PCB levels is still the most prominent feature. ‘Within-Arctic’ processing of PCBs will be affected by climate change-related processes such as changing wet deposition. These in turn will influence biological exposure and uptake of PCBs. The pan-Arctic rivers draining large Arctic/sub-Arctic catchments provide a significant source of PCBs to the Arctic Ocean, although changes in hydrology/sediment transport combined with a changing marine environment remain areas of uncertainty with regard to PCB fate. Indirect effects of climate change on human exposure, such as a changing diet will influence and possibly reduce PCB exposure for indigenous peoples. Body burdens of PCBs have declined since the 1980s and are predicted to decline further.

Results of the EU ArcRisk project on human health impacts in the Arctic owing to climate-induced changes in contaminant cycling are summarized in the context of their policy application. The question on how will climate change affect the transport of selected persistent organic pollutants (POPs) and mercury, both to and within the Arctic has been addressed, as well as the issue of human health impacts of these pollutants in the Arctic in relation to exposed local populations. It was concluded that better characterization of primary and secondary sources of POPs and more accurate quantification of current and future releases of POPs from these sources are needed for better prediction of environmental exposure to these contaminants and interpretation of monitoring data. Further improvement of fate and transport modeling in the physical environment is necessary in order to consider in the models not only the relatively well studied direct effects of climate change (e.g., changes in temperature, ice and snow cover, precipitation, wind speed and ocean currents) on contaminants fate and behavior but also indirect effects, e.g., alterations in carbon cycling, catchment hydrology, land use, vegetation cover, etc. Long-term environmental monitoring of POPs (at multiple sampling stations within and outside the Arctic and at regular sampling intervals facilitates temporal trend analysis) and measurements of concentrations in human milk and blood plasma are needed. Finally, more information should be gathered on the human health effects of newly identified POPs, such as perfluorooctanesulfonic acid (PFOS), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), and other substances with POP-like characteristics, particularly the effects on very young (including fetus) and elderly subgroups of the human population. The ArcRisk developed methodologies and tools that can be used in further studies to resolve various uncertainties already defined in the analysis of

A team of specialist market researchers and Value of Time experts comprising members from SYSTRA, Imperial College London and the Technical University of Denmark has conducted a formal audit and peer review of research undertaken by Arup/ITS Leeds/Accent to derive Value of Travel Time Savings on behalf of the UK Department for Transport (DfT). The research team has completed their analysis and modelling of the collected data, and has delivered their Final Report to the DfT. The research team has provided the peer reviewers with access to data collection processes for on-site auditing, and some interim reports and technical notes covering interim modelling activities; and provided clarification on some points when requested by the reviewers. The review team has taken the opportunity to audit and review all aspects of the survey data collected; and the methods of analysis and modelling of the data, as reported by the research team. The review team has also been provided with some meta-code for some key model estimations but were not provided with the actual code used in the final choice model estimation, such as the syntax used to develop the final Stated Preference (SP) and Revealed Preference (RP) models that were used to derive final Values of Travel Time (VTT). This report contains the findings of our audit and peer review of the procedures adopted by the research team during data collection of the three surveys (SP, RP and Employers Surveys); a peer review of the reported approach and implementation to data modelling; and an audit of the research team’s Implementation Tool that weighted the modelled parameters to give overall national VTT estimates for use in transport scheme appraisals.