New insights into projected Arctic sea road: operational risks, economic values, and policy implications.

As Arctic sea ice continues to retreat, the seasonally navigable Arctic expected by mid-century or earlier is likely to facilitate the growth of polar maritime and coastal development. Here, we systematically explore the potentials for opening of trans-Arctic sea routes across a range of emissions futures and multi-model ensembles on daily timescales. We find a new Transpolar Sea Route in the western Arctic for open water vessels starting in 2045 in addition to the central Arctic corridor over the North Pole, with its frequency comparable to the latter during the 2070s under the worst-case scenario. The emergence of this new western route could be decisive for operational and strategic outcomes. Specifically, the route redistributes transits away from the Russian-administered Northern Sea Route, lowering the navigational and financial risks and the regulatory friction. Navigational risks arise from narrow straits that are often icy choke points. Financial risks arise from the substantial interannual sea ice variability and associated uncertainty. Regulatory friction arises from Russian requirements imposed under the Polar Code and Article 234 of the UN Convention on the Law of the Sea. These imposts are significantly reduced with shipping route regimes that enable open water transits wholly outside Russian territorial waters, and these regimes are revealed most accurately using daily ice information. The near-term navigability transition period (2025-2045) may offer an opportunity for maritime policy evaluation, revision, and action. Our user-inspired evaluation contributes towards achieving operational, economic and geopolitical objectives and serves the goal of planning a resilient, sustainable, and adaptive Arctic future. Supplementary Information: The online version contains supplementary material available at 10.1007/s10584-023-03505-4.

The interaction of ice and law in Arctic marine accessibility.

Sea ice levies an impost on maritime navigability in the Arctic, but ice cover diminution due to anthropogenic climate change is generating expectations for improved accessibility in coming decades. Projections of sea ice cover retreating preferentially from the eastern Arctic suggest key provisions of international law of the sea will require revision. Specifically, protections against marine pollution in ice-covered seas enshrined in Article 234 of the United Nations Convention on the Law of the Sea have been used in recent decades to extend jurisdictional competence over the Northern Sea Route only loosely associated with environmental outcomes. Projections show that plausible open water routes through international waters may be accessible by midcentury under all but the most aggressive of emissions control scenarios. While inter- and intraannual variability places the economic viability of these routes in question for some time, the inevitability of a seasonally ice-free Arctic will be attended by a reduction of regulatory friction and a recalibration of associated legal frameworks.

The step-like evolution of Arctic open water.

September open water fraction in the Arctic is analyzed using the satellite era record of ice concentration (1979-2017). Evidence is presented that three breakpoints (shifts in the mean) occurred in the Pacific sector, with higher amounts of open water starting in 1989, 2002, and 2007. Breakpoints in the Atlantic sector record of open water are evident in 1971 in longer records, and around 2000 and 2011. Multiple breakpoints are also evident in the Canadian and Russian halves. Statistical models that use detected breakpoints of the Pacific and Atlantic sectors, as well as models with breakpoints in the Canadian and Russian halves and the Arctic as a whole, outperform linear trend models in fitting the data. From a physical standpoint, the results support the thesis that Arctic sea ice may have critical points beyond which a return to the previous state is less likely. From an analysis standpoint, the findings imply that de-meaning the data using the breakpoint means is less likely to cause spurious signals than employing a linear detrend.

Integrative Governance of Environmental Water in Australia's Murray-Darling Basin: Evolving Challenges and Emerging Pathways.

Integration, a widely promoted response to the multi-scale complexities of social-environmental sustainability, is diversely and sometimes poorly conceptualized. In this paper we explore integrative governance, which we define as an iterative and contextual process for negotiating and advancing the common interest. We ground this definition in a discussion of institutional factors conditioning integrative governance of environmental water in Australia's Murray-Darling Basin. The Murray-Darling Basin is an iconic system of social-ecological complexity, evocative of large-scale conservation challenges in other developed arid river basins. Our critical assessment of integrative governance practices in that context emerges through analysis of interviews with policy participants and documents pertaining to environmental water management in the tri-state area of southwestern New South Wales, northwestern Victoria, and the South Australian Riverland. We identify four linked challenges: (i) decision support for developing socially robust environmental water management goals, (ii) resource constraints on adaptive practice, (iii) inter-state differences in participatory decision-making and devolution of authority, and (iv) representative inclusion in decision-making. Our appraisal demonstrates these as pivotal challenges for integrative governance in the common interest. We conclude by offering a perspective on the potential for supporting integrative governance through the bridging capacity of Australia's Commonwealth Environmental Water Holder.