Toward a definition of Essential Mountain Climate Variables

The numerous processes implicated in the rapid and profound climate-driven changes that are underway across world's mountains must be well monitored, understood, and—as far as possible—accurately projected. However, not only available environmental data upon which such activities hinge often severely limited, but interdisciplinary consensus regarding variables should considered observation priorities also remains elusive. Here, concept of Essential Mountain Climate Variables (EMCVs) is introduced a potential means ameliorating situation. After review change mountains, preliminary set corresponding EMCVs proposed. pertaining to several disciplines naturally feature prominently. In addition, currently hold broader global relevance, justifies our mountain-specific approach. Established emerging possibilities measure, generate, apply then summarized. Finally, future toward concept’s formalization recommended. Ultimately, approach hopes increase utility mountainous both fundamental science decision making related management, risk mitigation, adaptation. Mountainous regions provide ecosystem goods services human populations within downstream their boundaries including water, hydropower, timber, settings for leisure tourism-related activities.1Grêt-Regamey A. Brunner S.H. Kienast F. services: who cares?.Mt. Res. Dev. 2012; 32: S23-S34Crossref Scopus (172) Google Scholar result ongoing general climatic warming trends, many system components from these derive evolving rapidly, with adverse consequences. Some changes, widespread retreat mountain glaciers2Huss M. Hock R. Global-scale hydrological response glacier mass loss.Nat. Clim. Chang. 2018; 8: 135-140Crossref (293) Scholar,3Zemp Huss Thibert E. Eckert N. McNabb Huber J. Barandun Machguth H. Nussbaumer S.U. 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Although significant advances remote-sensing technologies have been made late, they panacea terrain; shall explained fully shortly, situ observations retain crucial role regards. As such, pragmatic decisions prioritized measurement conversely (i.e., where limited resources best invested) routinely required, this situation persist years come. At present, tend established fairly ad hoc fashion according needs individual projects programs, leaving landscape rather fragmented heterogeneous exhibits little commonality. Specifically, better monitoring, understanding, ultimately predicting globally—and how can obtained systematic, intercomparable way—remains lacking. If standardized generally recognized informative regard dominant change, plus associated minimum requirements strong open data-sharing policies, could identified agreed researchers, practitioners, policymakers, possible compile globally database diverse consistent useable evidence. Many applications database—spanning range spatial scales—could envisaged, impactful. This perspective brings together experience an group researchers propose help address broad challenge, communicate steps already undertaken objective. briefly providing specific examples benefit initiative, we outline background proposed solution. main operating environments—including projected changes—are reviewed major systems; serves basis identification list candidate priority variables, ranked perceived importance. Thereafter, overview approaches techniques measuring otherwise deriving provided. closing, certain additional contribute eventual uptake before conclusions drawn. stated above, consistent, paramount, inter alia, developing systems and—by extension—generating reliable useful predictions them. To illustrate point, elevation-dependent (EDW)12Pepin Bradley R.S. Diaz H.F. Baraer Caceres E.B. Forsythe Fowler Greenwood Hashmi M.Z. 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Are treelines advancing? meta-analysis warming.Ecol. 12: 1040-1049Crossref (736) again influence albedo, energy flux partitioning, fashion.27Tao Dong Yu Jiang Zhang Zhu effects greenness southwest China during 1982–2013.Int. 38: 2029-2038Crossref (20) Considered together, evidently act multiple different (or “spheres”) Earth specifically, atmosphere (processes 2–5), cryosphere (1 3), biosphere (6), hydrosphere (1, 2, 4). improved will require analysis integration, example, into sophisticated numerical models) large quantity reliable, long-term, observational traditionally distinct disciplines. Note context, “improved understanding” mean able attribute underlying causal thereby assessing relative importance each, any geographical temporal thereof. represents however. host mountain-related require, least would from, diverse, timely “direct.” For instance, needed inform policy-oriented assessment exercises, those conduced level under auspices organizations Science-Policy Platform Biodiversity Ecosystem Services. They likewise reporting regularly confidently respect targets prescribed policy agendas, UN 2030 Agenda Sustainable Development Sendai Framework Disaster Risk Reduction. Observations furthermore iterative refinement instruments, local level, feasibility, effectiveness maintained. Clearly, draw uniformity informativeness support tasks extremely beneficial. Looking ahead, empirical greatly regional- local-scale policy, mitigation measures founded. statistical downscaling information evaluation. so-called impact models, seek translate scenarios plausible cryosphere, biosphere, hydrosphere. sense, historical constraining so subsequently applied confidence mode. attention paid avoid overfitting, employing reliant, terms coverage, resolution, accuracy minimize inconsistency “data characteristics” uncertainty maximize robustness interventions basis. It follows deficiencies existence, discoverability, accessibility, quality, length, consistency, representativeness, usability impinge completed science-policy-practice continuum relation state change. terrain, existing deeply embedded challenging overcome, there course differences regions. principal issues limit quantity, representativeness summarized, worth reiterating slightly expanding here. first comparative inaccessibility inhospitality terrain. second number, complexity, diversity, physical encountered; much encounters driven complex, rugged topography. Thirdly, funds technical capacities represent constraints reasons practicality cost, meteorological stations (for example) situated valley bottoms opposed slopes summits. Their distribution biased, affects capacity characterize pronounced fields variables—perhaps precipitation above all—often exhibit elevated, Furthermore, if dense coverage attained, affect quality accuracy. gauge undercatch, heavily accentuated snowy windy totals underestimated.28Kochendorfer Rasmussen Wolff Baker Hall M.E. Meyers Landolt Jachcik Isaksen Brækkan al.The quantification correction wind-induced errors.Hydrol. Syst. Sci. 2017; 21: 1973-1989Crossref (60) Technological advancements undoubtedly helping traditional challenges. advent new cosmic ray sensors, soil theoretically measured reasonably integrated merely point locations.29Evans J.G. Ward H.C. Blake Hewitt E.J. Morrison Fry Ball L.A. Doughty L.C. Libre J.W. Hitt O.E. al.Soil southern England derived cosmic-ray observing – COSMOS-UK.Hydrol. Process. 30: 4987-4999Crossref (44) Perhaps importantly, satellite remote sensing has vastly variables. extents retrieved moderate resolutions free provided NASA Copernicus. Indeed, progress retrieval methods provides argument need converge standards generate interoperable products future. remotely situ, contrasting characteristics sources, versus make them complementary. impossible all, else requisite and/or applications, sensing. Given monitoring activities, focus required Establishing that, enable invested optimally. Over time, long-term datasets hopefully emerge. because amount realized, “priority” form foci attempts intelligently extract maximal value datasets, retrospectively generating datasets. summary, defining climate-related attributes “observation requirements” met ensure usefulness) fairer comparisons regions, answering increasingly urgent questions, meet various needs. Below, framework Four questions considered:1.What drivers, processes, change?2.Which involved impacts, predictions, reporting?3.What exist obtaining variables?4.What formalized? challenge(s) outlined, (EMCVs). builds (ECVs), gained traction.30Bojinski Verstraete Peterson Richter Simmons Zemp essential research, policy.Bull. Am. Soc. 95: 1431-1443Crossref (335) Essentially, ECVs intends irrespective sector, all users access basic addressing level. definitive curated Observing System (GCOS; https://gcos.wmo.int/), defines “physical, chemical biological critically contributes characterization Earth's climate” “provide evidence understand predict evolution climate, guide adaptation measures, assess risks attribution events causes, underpin services.”31Global SystemAbout variables.https://gcos.wmo.int/en/essential-climate-variables/aboutDate: 2020Google “Climate” here encompassing components, hydrosphere, biosphere. inclusive definition maintained modified regards rendered applicable contexts (cf. Miloslavich al.32Miloslavich Bax N.J. S.E. Klein Appeltans W. Aburto-Oropeza O. Andersen Garcia Batten S.D. Benedetti-Cecchi Checkley D.M. al.Essential ocean sustained biodiversity changes.Glob. 24: 2416-2433Crossref (109) Scholar). Certain ECVs—such oceans—are largely irrelevant areas. Other insufficient reasons, constrained readily added removed). might share name ECV, measurements endowed (henceforth, requirements”) differ substantially. resolution capture elevated specification careful dedicated discussion. variable included relevant insight Earth’s changes), technically economically feasible standard technologies. strongly rooted empiricism. regard, proposing framework, advocate divergences framework. First, technological economic feasibility relaxed. independent sensor capabilities practical considerations, arrived aspirational. ways, prioritizing, highlighting, problems focusing routine Second, unique posed conc