Seneviratne s 20150707_1700_upmc_jussieu_-_room_107

Sonia Seneviratne / IAC ETH Zurich 7.7.2015 Our common future under climate change

Land processes and the global water cycle: Past

results and upcoming CMIP6 plans

Sonia I. Seneviratne1, Bart van den Hurk2, Gerhard Krinner3,

Hyungjun Kim4, Chris Derksen5, and Taikan Oki4

1Institute for Atmospheric and Climate Science, ETH Zurich, Switzerland

[email protected] 2KNMI, De Bilt, Netherlands 3LGGE, Grenoble, France 4University of Tokyo, Tokyo, Japan 5Environment Canada

Our common future under climate change, Paris, 7.7.2015


Global water cycle

Terrestrial

Precipitation

(100%)

(Flux estimates: Oki and Kanae 2008, Science)

Terrestrial

Evapotranspiration

(60%)

Oceanic

Precipitation

(350%)

Oceanic

Evaporation

(390%) Streamflow

(40%)

Atmospheric

transport

(40%)


Land water and energy balances

P E Rn lE

Water Energy

H

E=60%P lE=50-60%Rn


Land water and energy balances

P E Rn lE

Water Energy

H

E=60%P lE=50-60%Rn

SWin a SWin

a variations due to

snow: ~0.4-0.5


Soil moisture-evapotranspiration coupling

(Seneviratne et al. 2010, Earth Science Reviews)


Land-climate interactions

Climate

Land processes

IMPACTS FEEDBACKS


Outline

Land-temperature feedbacks

Land-precipitation feedbacks

Land controls on droughts

CMIP6 land modeling plans: LS3MIP experiment

Conclusions


(Mueller and Seneviratne 2012, PNAS)

NHD: # hot days

SPI: Standardized Precipitation Index

Land-temperature feedbacks: Observations


Soil moisture (point in Central Europe)

Impact of decadal

changes in soil

moisture (and

evapotranspiration)

on climate

First stage: 5 CMIP5

models (CESM, EC-

EARTH, GFDL, IPSL,

MPI-ESM)

GLACE-CMIP5 (“Global Land-

Atmosphere Coupled Experiment”)

(Seneviratne et al. 2013, GRL)

Effects of land evapotranspiration on climate change


Linear increase of

temperature (up to 2ºC

additional warming) as a

function of change in

evapotranspiration

Substantial component of

warming in projections

(e.g. Mediterranean region:

20% of summer warming,

25% of warming of hot

extremes)

Effects of land evapotranspiration on climate change

(Seneviratne et al. 2013, GRL)


Role of land vs oceans?

Variance difference (in %) when prescribing soil moisture (left)

or SST (right)

Interannual time scale, local warm season (warmest 3 months),

CESM simulations (ocean-land-atmosphere)

(Orth and Seneviratne, in preparation)


Role of land vs oceans?

Variance difference (in %) when prescribing soil moisture (left)

or SST (right)

Interannual time scale, local warm season (warmest 3 months),

CESM simulations (ocean-land-atmosphere)

(Orth and Seneviratne, in preparation)

Similar effect of soil moisture and SSTs! Additive effects (not

feedbacks)


Snow-climate feedbacks

Spread in snow albedo feedback

accounts for much of the CMIP5

spread in the 21st century

warming of Northern Hemisphere

land masses

(Qu and Hall 2014, Climate Dynamics)


Outline





Conclusions


Soil moisture-precipitation feedbacks

Soil moisture - precipitation coupling strength (JJA) averaged across AGCMs

(Koster et al. 2004, Science)


Sign of soil moisture-precipitation feedbacks

Some inconsistent results?

(Findell et al. 2011, Nature Geoscience)

(Taylor et al. 2012, Nature)



(Guillod et al. 2015, Nature Communications)



Using consistent data:

GLEAM evaporative

stress

CMORPH precipitation

(data gaps filled with

GPCP and ERA-

interim)

(Guillod et al. 2015, Nature Communications)

Implications for

climate change

projections?


Soil moisture-precipitation feedbacks

(Martius et al. 2013, Quart. J. Roy. Met. Soc)

Model simulations of Pakistan 2010 floods with (left) and without (right)

evapotranspiration from land surface

Air masses spent 72 hours over land before raining out: Model suggests that 90%

and 60% of rainfall over Pakistan was originating from land (reevaporation)


Outline





Conclusions


Trends in salinity in the oceans

(1950-2000): “dry” regions

become “drier”, “wet” regions

become “wetter” (DDWW)

(Durack et al. 2012, Science)

Validity of “dry gets drier, wet gets wetter” paradigm?


(Greve et al. 2014, Nature Geoscience)

Robust dryness trends on

land (1948-68 vs 1985-

2005)

the DDWW paradigm

does not apply on land!!

Trends in salinity in the oceans

(1950-2000): “dry” regions

become “drier”, “wet” regions

become “wetter” (DDWW)

(Durack et al. 2012, Science)



(Greve et al. 2014, Nature Geoscience;

Greve and Seneviratne 2015, GRL)

Different response

over land compared

to global and ocean

behaviour: Because

of soil moisture

limitation!



Uncertainties of land datasets

(Greve et al. 2014, Nature Geoscience)

4 P datasets,

11 Ep datasets,

7 ET datasets

ET

P

Ep

Weighted errors

based on all

possible

combinations within

Budyko framework

Largest uncertainty

in ET! (related to

soil moisture

limitation and other

plant physiological

effects)


Impact of human water use

Human impact

simulations

compared to

naturalized runoff

(1971-2000)

Climate impact

simulations for 2ºC

increase compared to

naturalized runoff

(Haddeland et al. 2013, PNAS)


Outline





Conclusions


LS3MIP: Overview and scientific goal

• Multi-model based reanalysis of land surface (from early 20th century)

• Explore land-atmosphere coupling and its impacts (for historical

climate trends and projections, water resources, predictability)

• Link patterns and trends of essential climate variables to model

properties and biases

Land Surface, Snow, and Soil moisture MIP (CMIP6)

Co-chairs: B. van den Hurk, G. Krinner, S. Seneviratne, H. Kim, C. Derksen, and T. Oki


“LandMIPs”


Outline





Conclusions


Conclusions

• Land hydrology (soil moisture, snow) substantially

affects the water cycle on land, as well as temperatures

• Large remaining uncertainties, necessity to better

quantify underlying causes for model spread

• The Land Surface, Snow and Soil Moisture MIP

(LS3MIP) will provide for the first time a systematic

evaluation of land water cycle processes and feedbacks

in the CMIP context

Seneviratne s 20150707_1700_upmc_jussieu_-_room_107

Science

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