Our Common Future Under Climate Change

International Scientific Conference 7-10 JULY 2015 Paris, France

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Tuesday 7 July - 17:00-18:30 UPMC Jussieu - ROOM 107 - Block 24/34

1109 - Understanding the Earth’s changing water cycle

Parallel Session

Lead Convener(s): C. Stubenrauch (Laboratoire de Météorologie Dynamique, Paris, France)

Convener(s): P. Groisman (UCAR at NOAA National Climatic Data Center, Asheville, North Carolina, United States of America), D. Schimel (JPL, Pasadena, United States of America)

17:00

Connections between water and energy: Clouds, water vapour, radiation and precipitation

G. Stephens (JPL, California Institute of Technology, Pasadena, United States of America)

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Connections between water and energy: Clouds, water vapour, radiation and precipitation

G. Stephens (1)
(1) JPL, California Institute of Technology, Pasadena, United States of America

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Water and energy are intimately coupled together in the Earth’s climate system. Each controls the other. This talk will concentrate on atmospheric feedbacks that develop between water and energy that influence the global hydrological cycle response in a warming and moistening climate.  As the planet warms, the amount the global precipitation increases is determined by the increased emission from the atmosphere that is mostly controlled by the increases to water vapor. The increases to water vapor, especially that transported to the upper atmosphere by convection, fundamentally affects the radiation balance both directly through the influence the clear-sky emission and by enhancing the absorption of radiation by the upper tropospheric clouds that develop as a consequence of the moistened upper troposphere. Thus feedbacks develop between radiation, clouds and precipitation develop that influence how the global hydrological cycle responds to a warmed climate.  These feedbacks, and others will be discussed in the context of both global and regional changes to the hydrological cycle. 

17:22

Land processes and the global water cycle: Past results and upcoming CMIP6 plans

S. Seneviratne (ETH, Zurich, Zurich, Switzerland), B. Van Den Hurk (KNMI, De Bilt, Netherlands), G. Krinner (LGGE, Grenoble, France), H. Kim (University of Tokyo, Tokyo, Japan), C. Derksen (Environment Canada, Toronto, Canada), T. Oki (University of Tokyo, Tokyo, Japan)

Abstract details
Land processes and the global water cycle: Past results and upcoming CMIP6 plans

S. Seneviratne (1) ; B. Van Den Hurk (2) ; G. Krinner (3) ; H. Kim (4) ; C. Derksen (5) ; T. Oki (4)
(1) ETH, Zurich, Institute for atmospheric and climate science, Zurich, Switzerland; (2) KNMI, Model Development, De Bilt, Netherlands; (3) LGGE, Grenoble, France; (4) University of Tokyo, Global hydrology and water resources engineering, Tokyo, Japan; (5) Environment Canada, Climate research division, Toronto, Canada

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Terrestrial processes play an essential role in the global water cycle, through a range of mechanisms. Soil moisture-climate interactions affect both extreme temperatures and precipitation on land (e.g. Seneviratne et al. 2010, Hurk et al. 2011, Seneviratne et al. 2013, Guillod et al. 2015) and also explain discrepancies between global-scale patterns in wetting and drying and respective trends over land (Greve et al. 2014). But recent analyses suggest that models may share common biases in their representation. Snow-climate feedbacks are also of strong relevance, but associated with substantial uncertainties (Derksen and Brown 2012, Brutel-Vuilmet et al. 2013). This presentation will provide an overview on the role of land surface exchanges in the global water cycle and on current perspectives for future research in this field. In particular, it will highlight plans for the Land Surface, Snow, and Soil moisture Multimodel Intercomparison Project (LS3MIP) under the 6th phase of the Coupled Model Intercomparison Project (CMIP6), which will allow a better validation, assessment, and quantification of the underlying processes and feedbacks in current climate models.

References

Brutel-Vuilmet, C., M. Ménégoz, and G. Krinner, 2013: An analysis of present and future seasonal Northern Hemisphere land snow cover simulated by CMIP5 coupled climate models. The Cryosphere, 7, 67–80, doi:10.5194/tc‐ 7‐ 67‐2013.

Derksen, C., and R. Brown, 2012: Spring snow cover extent reductions in the 2008–2012 period exceeding climate model projections. Geophys. Res. Lett., 39, L19504, doi:10.1029/2012GL053387.

Guillod, B.P., B. Orlowsky, D.G. Miralles, A.J. Teuling, and S.I. Seneviratne, 2015: Reconciling spatial and temporal soil moisture effects on afternoon rainfall. Nature Communications, 6, 6443.

Greve, P., B. Orlowsky, B. Mueller, J. Sheffield, M. Reichstein, and S.I. Seneviratne, 2014: Global assessment of trends in wetting and drying over land. Nature Geoscience, 7, 716-721, doi: 10.1038/NGEO2247.

Seneviratne, S.I., T. Corti, E.L. Davin, M. Hirschi, E.B. Jaeger, I. Lehner, B. Orlowsky, and A.J. Teuling, 2010: Investigating soil moisture-climate interactions in a changing climate: A review. Earth-Science Reviews, 99, 3-4, 125-161, doi:10.1016/j.earscirev.2010.02.004.

Seneviratne, S.I., M. Wilhelm, T. Stanelle, B.J.J.M. van den Hurk, S. Hagemann, A. Berg, F. Cheruy, M.E. Higgins, A. Meier, V. Brovkin, M. Claussen, A. Ducharne, J.-L. Dufresne, K.L. Findell, J. Ghattas, D.M. Lawrence, S. Malyshev, M. Rummukainen, and B. Smith, 2013: Impact of soil moisture-climate feedbacks on CMIP5 projections: First results from the GLACE-CMIP5 experiment. Geophys. Res. Lett., 40 (19), 5212-5217.

van den Hurk, B., M. Best, P. Dirmeyer, A. Pitman, J. Polcher, and J. Santanello, 2011: Acceleration of Land Surface Model Development over a Decade of Glass. Bull. Am. Meteorol. Soc., 92, 1593–1600, doi:10.1175/BAMS‐D‐11‐00007.1

17:44

Changes in continental water cycle and extreme events

O. Zolina (Joseph Fourier University, Grenoble, France)

Abstract details
Changes in continental water cycle and extreme events

O. Zolina (1)
(1) Joseph Fourier University, Le laboratoire de glaciologie et géophysique de l'environnement, Grenoble, France

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Ongoing and projected changes in continental water cycle are closely connected with extreme events which provide specific mechanisms of water cycle changes. We are going to address observed variability and change in continental water cycle in the context of climate extremes. Although hydroclimate extremes result from many factors that sometimes act together, water is a central component of these extremes via either its excess or scarcity. The major factor underlying hydroclimate extremes is precipitation, closely associated with flooding and droughts resulting from long dry periods and substantial water deficits over large regions. Among the major problems of changes in water cycle associated with extremes we will consider changes in temporal structure of precipitation or precipitation timing. Over last several decades both wet and dry periods have become longer in several large European regions, specifically in Central and Eastern Europe. This effect is not associated with changes in the number of wet days but, rather, with the grouping of wet days into prolonged wet and dry periods, increasing the likelihood of floods and droughts, respectively. Another critical problem for accurate quantification of the impact of extremes on water cycle is scaling of precipitation. Representation of the impact of precipitation extremes on the water cycle strongly depends on spatial and temporal scales resolved by observational networks and models. With given resolutions we only partly capture the effect of extreme events in changes of hydrological cycle. We will demonstrate potential of very dense observational networks for accurate estimation of the role of hydroclimate extremes in continental scale water cycle. We will also consider the role of atmospheric moisture transport in forming extreme precipitation in different midlatitudinal regions, analyzing mechanisms associated with cyclone activity and transports by the mean flow. Finally, we will discuss the requirements for data characteristics and model resolution for accurate estimation of the strongly localized nature of hydroclimate extremes and their impact on continental water cycle.

18:06

Poster presentations

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Poster presentations
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