Relevance of Hydro-Climatic Change Projection and Monitoring for Assessment of Water Cycle Changes in the Arctic

Abstract

Rapid changes to the Arctic hydrological cycle challenge both our process understanding and our ability to find appropriate adaptation strategies. We have investigated the relevance and accuracy development of climate change projections for assessment of water cycle changes in major Arctic drainage basins. Results show relatively good agreement of climate model projections with observed temperature changes, but high model inaccuracy relative to available observation data for precipitation changes. Direct observations further show systematically larger (smaller) runoff than precipitation increases (decreases). This result is partly attributable to uncertainties and systematic bias in precipitation observations, but still indicates that some of the observed increase in Arctic river runoff is due to water storage changes, for example melting permafrost and/or groundwater storage changes, within the drainage basins. Such causes of runoff change affect sea level, in addition to ocean salinity, and inland water resources, ecosystems, and infrastructure. Process-based hydrological modeling and observations, which can resolve changes in evapotranspiration, and groundwater and permafrost storage at and below river basin scales, are needed in order to accurately interpret and translate climate-driven precipitation changes to changes in freshwater cycling and runoff. In contrast to this need, our results show that the density of Arctic runoff monitoring has become increasingly biased and less relevant by decreasing most and being lowest in river basins with the largest expected climatic changes.

Arctic Climate and Water Change: Model and Observation Relevance for Assessment and Adaptation

“…1; adapted from Bring and Destouni 2011). Temperature projections are compatible with observed deviations during the late twentieth and early twenty-first century, both for the TAR and AR4, while precipitation projections indicate an increase that is hitherto not evident in observations.…”

Resilience of river flow regimes

“…Flow regimes not only constrain anthropogenic uses, such as energy production and irrigation, but shape form and functions of riverine ecosystems owing to the dynamic control of flow magnitude on stream habitats (1,4,(6)(7)(8). In the past decades, natural and anthropogenic modifications of climate drivers (9), jointly with landscape changes, have led to increasingly nonstationary flow regimes (10)(11)(12)(13)(14). These ubiquitous and accelerating alterations of river flows challenge the sustainability of water uses (5,15) and the ecosystem services provided by river biomes (6,16,17).…”

Interacting effects of change in climate, human population, land use, and water use on biodiversity and ecosystem services

“…In NDB, present climate models also underestimate current regional temperatures, although model projections might capture the relative degree of future change. Furthermore, because temperature and precipitation can change along different trajectories (Bring and Destouni 2011), it might be valuable to take several climate variables into account. In NDB, long-term data on temperature as well as on precipitation and water flow are available , but in many other areas the temporal extent of such data is considerably shorter (Koutsouris et al 2010, Bring andDestouni 2011).…”

“…Scale mismatches in data also affect assessments of water-use change. Across regions, Ecology and Society 20(1): 23 http://www.ecologyandsociety.org/vol20/iss1/art23/ there are disparities between areas covered by hydrological monitoring and areas with substantial pressure from eutrophication and pollution (Hannerz and Destouni 2006) or climate change (Bring and Destouni 2011). Substantial variation in land cover and water conditions makes it both essential and difficult to assess hydro-climatic changes at the scales relevant for water governance (Koutsouris et al 2010).…”