GCOS Implementation Plan - WMO

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Implementation Plan for the Global Observing System for Climate in Support of the UNFCCC (2010 Update) The TOPC, in consultation with the AOPC, WCRP CliC and WMO Technical Commissions, will consolidate and, where necessary, recommend standards and protocols for measuring snow cover and SWE, design an optimum network, and recommend International Data Centre and analysis centre responsibilities. TOPC’s current cryosphere activities can provide a starting point, but the required activity would need dedicated funding for meetings and workshops in which to agree on standards and protocols (cf. T1), funding for report preparation, and funding for filling gaps in networks. The development of guidelines and standards is one of the tasks of the evolving Global Cryosphere Watch. Action T16 [IP-04 T11] Action: Obtain integrated analyses of snow cover over both hemispheres. Who: Space agencies and research agencies in cooperation with WMO GCW and CliC, with advice from TOPC, AOPC and IACS. Time-Frame: Continuous. Performance Indicator: Availability of snow-cover products for both hemispheres. Annual Cost Implications: 1-10M US$ (Mainly by Annex-I Parties). ECV – Glaciers and Ice Caps Changes in mountain glaciers and ice caps provide some of the clearest evidence of climate change, constitute key variables for early-detection strategies in global climate-related observations, and cause serious impacts on the terrestrial water cycle and on societies dependent on glacial melt water. The Global Terrestrial Network for Glaciers (GTN-G), based on century-long world-wide observations, has developed an integrated, multi-level strategy for global observations. The strategy combines detailed process-oriented in situ studies (annual mass balance) with satellite-based coverage of large glacier ensembles in entire mountain systems (glacier inventories, digital elevation models). GTN-G is a collaboration among the World Glacier Monitoring Service (WGMS) which is sponsored by the ICSU (FAGS), the IACS of the International Union of Geodesy and Geophysics (IUGG), UNEP, UNESCO, and WMO; the Global Land Ice Measurement from Space (GLIMS) initiative, and the NSIDC at Boulder Colorado, USA. The WGMS is in charge of collecting and disseminating standardised data from in situ measurements world-wide through a network of national correspondents and principal investigators. The GLIMS initiative – now also supported by the ESAfunded GlobGlacier project – aims at creating a globally complete glacier inventory, hosted by the NSIDC and based on outlines of glaciers combined with digital terrain information. National and international efforts have assured the continuation of these fundamentally important activities. These initiatives plan to reach coverage of a significant fraction of the most important glacier-covered regions globally over the next 3-5 years. Field measurements of the change in length and mass balance of glaciers and ice caps are made by national services and research groups to determine regional changes. Overall volume changes can be calculated using cost-saving methodologies (e.g., index stakes with repeated mapping and Digital Elevation Model (DEM) differencing) in order to interpolate and extrapolate detailed local measurements at higher temporal resolution (winter/summer, year) in time and space. This activity can be further supported by application of numerical models (reconstructions, future scenarios). Mass balance measurements are now being (re-)initiated at selected glaciers in equatorial Africa, Patagonia, New Zealand, and the Himalayas so that global patterns of glacier changes can be monitored better. A quality rating must be assigned to long-term mass balance observations. Glacier inventories derived from satellite remote sensing and digital terrain information should be repeated at time intervals of about a decade (GTN-G, Tier 5). Current efforts for this activity mainly depend on processing of Landsat Thematic Mapper (TM)/ETM+ and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) data following the guidelines provided by GLIMS. An important incentive for the completion of a detailed global glacier inventory comes from the recent opening of the USGS Landsat archive and the free availability of global DEMs from the Shuttle Radar Topography Mission (SRTM) and ASTER. Further activities in this direction from space agencies and data holders are strongly encouraged (see also Actions T20 and T28). 116
Implementation Plan for the Global Observing System for Climate in Support of the UNFCCC (2010 Update) Continental-scale transects of observations exist in the American Cordilleras (N-S), in the Africa- Pyrenees-Alps-Scandinavia-Svalbard system (N-S), and through central Eurasia (E-W). GTN-G, through contact with institutions making measurements in the Southern Hemisphere (especially Patagonia and New Zealand), implements a web-based data management and data dissemination system of existing historical records and selected archived satellite data. Action T17 [IP-04 T13] Action: Maintain current glacier observing sites and add additional sites and infrastructure in data-sparse regions, including South America, Africa, the Himalayas, and New Zealand; attribute quality levels to long-term mass balance measurements; complete satellite-based glacier inventories in key areas. Who: Parties’ national services and agencies coordinated by GTN-G partners, WGMS, GLIMS, and NSIDC. Time-Frame: Continuing, new sites by 2015. Performance Indicator: Completeness of database held at NSIDC from WGMS and GLIMS. Annual Cost Implications: 10-30M US$ (80% in non-Annex-I Parties). ECV – Ice Sheets Our understanding of the time scale of ice sheet response to climate change has changed dramatically over the last decade. Rapid changes in ice-sheet mass have surely contributed to abrupt changes in climate and sea level in the past. The mass balance loss of the Greenland Ice Sheet increased in the late 1990s to 100 gigatonnes per year (Gt a -1 ) or to even more than 200 Gt a -1 for the most recent observations in 2006. It is extremely likely that the Greenland Ice Sheet has been losing mass, and very likely on an accelerated path, since the mid-1990s. The mass balance for Antarctica as a whole is close to equilibrium, but with a likely net loss since 2000 at rates of a few tens of gigatonnes per year. The largest losses are concentrated along the Amundsen and Bellinghausen sectors of West Antarctica and the northern tip of the Antarctic Peninsula. The potentially sensitive regions for rapid changes in ice volume are those with ice masses grounded below sea level, such as the West Antarctic Ice Sheet which, if it melted, would raise sea level by 7 m, or large glaciers in Greenland like the Jakobshavn, also known as Jakobshavn Isbræ and Sermeq Kujalleq (in Greenlandic), with an over-deepened channel reaching far inland. There are large mass-budget uncertainties from errors in both snow accumulation and calculated ice losses for Antarctica (~±160 Gt a -1 ) and for Greenland (~±35 Gt a -1 ). Most climate models suggest that climate warming would cause increased melting from coastal regions in Greenland and an overall increase in snowfall. However, they do not predict the substantial acceleration of some outlet glaciers that we are now observing. This results from a fundamental weakness in the existing models, which are incapable of realistically simulating the outlet glaciers that discharge ice into the ocean. Observations show that Greenland is thickening at high elevations due to the increase in snowfall, which has been predicted, but that this gain is more than offset by an accelerating mass loss, with a large component from rapidly thinning and accelerating outlet glaciers. Although there is no evidence for increasing snowfall over Antarctica, observations show that some higher elevation regions are also thickening, likely as a result of high interannual variability in snowfall. There is little surface melting in Antarctica, and the substantial ice losses from West Antarctica and the Antarctic Peninsula are very likely caused by increased ice discharge as the velocities of some glaciers increase. This is of particular concern in West Antarctica, where bedrock beneath the ice sheet is deep below sea level, and outlet glaciers are to some extent “contained” by the ice shelves into which they flow. Some of these ice shelves are thinning, and some have totally broken up. These are the regions where the glaciers are accelerating and thinning most rapidly. Recent observations show a high correlation between periods of heavy surface melting and increase in glacier velocity. A possible cause is rapid meltwater drainage to the base of the glacier, where it enhances basal sliding. An increase in meltwater production in a warmer climate will likely have major consequences on ice-flow rate and mass loss. Recent rapid changes in marginal regions of the Greenland and West Antarctic ice sheets show mainly acceleration and thinning, with some glacier velocities increasing more than twofold. Many of these glacier accelerations have closely followed reduction or loss of their floating extensions known as ice shelves. 117
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WORLD METEOROLOGICAL ORGANIZATION I
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FOREWORD This 2010 Update of the Im
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Implementation Plan for the Global
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GCOS Implementation Plan - WMO

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