Peat plateaus are widespread at high northern latitudes and are important soil organic carbon reservoirs. A warming climate can cause either increased ground subsidence (thermokarst) resulting in lake formation or increased drainage as the permafrost thaws. A better understanding of spatiotemporal variations in these landforms in relation to climate change is important for predicting the future thawing permafrost carbon feedback. In this study, dynamics in thermokarst lake extent during the last 35-50 years has been quantified through time series analysis of aerial photographs and high-resolution satellite images (IKONOS/QuickBird) in three peat plateau complexes, spread out across the northern circumpolar region along a climatic and permafrost gradient. From the mid-1970s until the mid-2000s there has been an increase in mean annual air temperature, winter precipitation, and ground temperature in all three study areas. The two peat plateaus located in the continuous and discontinuous permafrost zones, respectively, where mean annual air temperatures are below -5°C and ground temperatures are -2°C or colder, have experienced small changes in thermokarst lake extent. In the peat plateau located in the sporadic permafrost zone where the mean annual air temperature is around -3°C, and the ground temperature is close to 0°C, lake drainage and infilling with fen vegetation has been extensive and many new thermokarst lakes have formed. In a future progressively warmer and wetter climate permafrost degradation can cause significant impacts on landscape composition and greenhouse gas exchange also in areas with extensive peat plateaus, which presently still experience stable permafrost conditions.

The G7 is a forum designed for frank and open discussion between leaders, ministers and policy-makers. As a member of the G7, Canada plays a leading role on the international stage and is able to advance domestic and international priorities. The G7 provides global leadership and serves as a powerful catalyst on issues that are later taken up by other fora with broader global and regional membership. The G7 brings together the world’s advanced economies to influence global trends and tackle pervasive and crosscutting issues, as well as emergent global crises. The G7 has strengthened international economic and security policies, advanced discussion of global issues including climate change and gender equality, brought donors together and supported disarmament programs. Most recently, the G7 has worked to tackle the COVID-19 pandemic and respond to Russia’s illegal invasion of Ukraine. At the G7, Canada has advanced its domestic and international priorities, including gender equality, peace and security, climate change and building a sustainable global economy. Transparent and inclusive engagement with Canadian and international stakeholders has helped Canada to deliver on priorities that are important to Canadians.

We describe the contemporary hydrography of the pan-Arctic land area draining into the Arctic Ocean, northern Bering Sea, and Hudson Bay on the basis of observational records of river discharge and computed runoff. The Regional Arctic Hydrographic Network data set, R-ArcticNET, is presented, which is based on 3754 recording stations drawn from Russian, Canadian, European, and U.S. archives. R-ArcticNET represents the single largest data compendium of observed discharge in the Arctic. Approximately 73% of the nonglaciated area of the pan-Arctic is monitored by at least one river discharge gage giving a mean gage density of 168 gages per 106 km2. Average annual runoff is 212 mm yr−1 with approximately 60% of the river discharge occurring from April to July. Gridded runoff surfaces are generated for the gaged portion of the pan-Arctic region to investigate global change signals. Siberia and Alaska showed increases in winter runoff during the 1980s relative to the 1960s and 1970s during annual and seasonal periods. These changes are consistent with observations of change in the climatology of the region. Western Canada experienced decreased spring and summer runoff. The CD-ROM contains a comprehensive river discharge database for the entire pan-Arctic drainage system using data from 3713 gauges. The pan-Arctic drainage region covers a land area of approximately 21 million km2 that drains into the Arctic Ocean as well as Hudson Bay, James Bay and the Northern Bering Strait, including the Yukon and Anadyr Rivers.The data set contains monthly river discharge data extending from the 1890s (for four Canadian and five Russian gauges) until the early 1990s. The length of record for individual gauges is extremely variable, but the majority of data was collected between 1960 and 1990.The project concentrates on the hydrological cycle of the northern latitudes, especially the development of a river discharge database for the entire Pan-Arctic region. A coarse grid cell resolution of 30 minutes latitude by 30 minutes longitude allows for modeling of the data. Most of the drainage basins used were greater than 15,000 km2; however, for Canada and Russia we collected all available river gauges. The gauges for large drainage areas are of the greatest interest in the regional, continental and global-scale scientific community for modeling purposes.With the potential sensitivity of arctic sea ice formation to inputs from the terrestrial land surface there is a need to provide the Arctic scientific community with time series of river discharge data. This data set provides a baseline against which Arctic system scientists can compare simulation results and which can provide a boundary condition for Ocean circulation models.The data on this CD-ROM addresses the need to inventory and make available data for water resources assessments in the context of deteriorating monitoring networks. The Global River Discharge Database (RivDIS 1.0) published recently by UNESCO as part of the Technical Documents in Hydrology series and this arctic river discharge database developed at the University of New Hampshire and released on CD-ROM by the National Snow and Ice Data Center, Boulder, CO are part of ongoing efforts to consolidate and electronically archive hydrometeorological data.

Predicting future thaw slump activity requires a sound understanding of the atmospheric drivers and geomorphic controls on mass wasting across a range of time scales. On sub-seasonal time scales, sparse measurements indicate that mass wasting at active slumps is often limited by the energy available for melting ground ice, but other drivers such as rainfall or the formation of an insulating veneer are also thought important. To study the sub-seasonal drivers, we derive topographic changes from single-pass radar interferometric data acquired by the TanDEM-X satellite (12 m resolution). The high vertical precision (around 30 cm), frequent observations (11 days) and large coverage (5000 km²) allow us to track volume losses as drivers such as the available energy change during summer in two study regions. We find that thaw slumps in the Tuktoyaktuk coastlands, Canada, are not energy limited in June, as they undergo limited mass wasting (height loss of around 0 cm/day) despite the ample available energy, indicating the widespread presence of an insulating snow or debris veneer. Later in summer, height losses generally increase (around 3 cm/day), but they do so in distinct ways. For many slumps, mass wasting tracks the available energy, a temporal pattern that is also observed at coastal yedoma cliffs on the Bykovsky Peninsula, Russia. However, the other two common temporal trajectories are asynchronous with the available energy, as they track strong precipitation events or show a sudden speed-up in late August, respectively. The observed temporal patterns are poorly related to slump characteristics like the slump area. The contrasting temporal behaviour of nearby thaw slumps highlights the importance of complex local and temporally varying controls on mass wasting.