Search

Climate change in the circumpolar region is causing dramatic environmental change that is increasing the vulnerability of infrastructure. We quantified the economic impacts of climate change on Alaska public infrastructure under relatively high and low climate forcing scenarios [representative concentration pathway 8.5 (RCP8.5) and RCP4.5] using an infrastructure model modified to account for unique climate impacts at northern latitudes, including near-surface permafrost thaw. Additionally, we evaluated how proactive adaptation influenced economic impacts on select infrastructure types and developed first-order estimates of potential land losses associated with coastal erosion and lengthening of the coastal ice-free season for 12 communities. Cumulative estimated expenses from climate-related damage to infrastructure without adaptation measures (hereafter damages) from 2015 to 2099 totaled $5.5 billion (2015 dollars, 3% discount) for RCP8.5 and $4.2 billion for RCP4.5, suggesting that reducing greenhouse gas emissions could lessen damages by $1.3 billion this century. The distribution of damages varied across the state, with the largest damages projected for the interior and southcentral Alaska. The largest source of damages was road flooding caused by increased precipitation followed by damages to buildings associated with near-surface permafrost thaw. Smaller damages were observed for airports, railroads, and pipelines. Proactive adaptation reduced total projected cumulative expenditures to $2.9 billion for RCP8.5 and $2.3 billion for RCP4.5. For road flooding, adaptation provided an annual savings of 80–100% across four study eras. For nearly all infrastructure types and time periods evaluated, damages and adaptation costs were larger for RCP8.5 than RCP4.5. Estimated coastal erosion losses were also larger for RCP8.5., United States. Environmental Protection Agency. Climate Change Division (Contract EP-D-14-031)

The ocean margins of high-latitude seas, such as the eastern Bering Sea, are recognized as important areas for the enhanced scavenging removal of particle reactive chemicals and for the potential to sequester atmospheric carbon dioxide via photosynthetic conversion to biogenic particles and subsequent downward particle transport to deeper waters. This region is expected to warm in the future, and with the warming will come a reduction in the extent and duration of seasonal sea-ice. This physical process exerts an important control on the timing, location, and magnitude of the spring primary production bloom. Within the context that 2008-2010 are characterized as cold years in the eastern Bering Sea, establishing the mechanistic link between primary production and the seasonal progression in particle export represents a significant challenge because these processes exert a control on organic matter transport from the surface ocean and on the success of economically and culturally important animals. During spring and summer cruises in 2009 and 2010, distributions of 234Th (t1/2 = 24.1 days) in the water column and sediments were measured at ∼60 stations over the middle and outer regions of the shelf and at the shelf break. The inventory of excess 234Th (234Th which is not produced in the sediments) in shelf sediments was ∼1/3 of the total deficit of 234Th (234Th scavenged by sinking particles) in the overlying water column leading to an average focusing factor of 0.34 ± 0.23. Further, 234Th export from the shelf was determined to ∼30% of the total production of this radionuclide by 238U decay based on a 234Th budget. These results, taken together with elevated focusing factors in the off-shelf region, suggest that the shelf sediments and lateral transport of particles from the shelf represent significant sinks for biogenic particles produced over the shelf in the spring and summer. The elevated focusing factors at the shelf break are attributed to enhanced particle fl