Abrupt climate change superimposed to RCP 8.5 IPCC scenario : potential consequences for

population migration

Gilles Ramstein1, Dimitri Defrance1, Christophe Dumas1, Sylvie Charbit1, Nada Caud1, François Gemenne2,3, Jean-Paul Vanderlinden2,4, Sandra Bouneau5, Sylvain David5 and

Karlis Krumins6

(1)LSCE CEA/CNRS, Gif Sur Yvette, France, (2)Université de Versailles Saint-Quentin-en-Yvelines, CEARC, Guyancourt, France, (3)Université de Liège, CEDEM, Liège, Belgium, (4)Observatoire de Versailles Saint-Quentin-en-Yvelines, Guyancourt, France, (5)CNRS/IN2P3/ Université Paris Sud 11, Institut de Physique

Nucléaire, Orsay, France (6) Vidzeme University of Applied Sciences, Valmiera (Latvia) Gilles.ramstein@lsce.ipsl.fr www.lsce.ipsl.fr/Pisp/gilles.ramstein/

CFCC15, amphi Durand, 7 July 2015 G. Ramstein et al., Devonian Paradox,

CFCC15, July 7 2015 1

Estimation of average increase of sea level rise following

selon 6 scenarios (AR4 IPCC 2007)

State of the art 1

Age (kyr BP)

d1

8O

(‰

) -41

-39

-37

-35

-33 H4 H5 H1 H2 H3

GRIP

10 15 20 25 30 35 40 45 50 5 0

D 20°C D T ° up to 10°C

D Masses d’air

D Téléconnexions

Fennoscandia and

Laurentide ice sheets

instabilities

Weak amplitude oscillations Abrupt climate changes

Stability of ice sheets

(Western Antarctic

+ Greenland)

?

Possible melting of the

Remaining ice sheets

(Western Antarctic + Greenland)

Stability of Earth System at Millennium Scale

2 X CO2 D 5°C 4 X CO2 D 8°C (IPCC, 2001)

?

Interglaciaire Glaciaire Future

Observations • During summer 2002,

complete melting of the Larsen B Ice shelf.

no consequence on sea level rise major consequences on the ice sheet dynamics. • Buttressing effect of the ice

shelves on the ice sheet large acceleration of ice streams and icebergs which, in contrast, increase the sea level.

Alvarez-Solas et al. “Can recent ice discharges following the Larsen-B ice-shelf collapse be used to infer the driving mechanisms of millennial-scale variations of the Laurentide ice sheet?” The Cryosphere, 6, 687–693, 2012

Instability I: ice shelf

Heinrich Events -from 60ky to 15ky very unstable glacial climate. -instability of the North America, produced huge quantities of icebergs (Heinrich events) breakdown of the

thermohaline circulation. Global climate impact

Instability II: Heinrich events

Exploring future instabilities annual sea level rise (aslt) -During the last deglaciation: maximum 37mm/year (melt water) with an annual average rate of 10 mm/year. -present day : 3.3 mm/year -21st century in RCP 8.5 scenario: around 10 mm/year.

Instability III: melt water during deglaciation

G. Ramstein et al., Devonian Paradox, CFCC15, July 7 2015

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scenarios :

Superimposed to the most realistic scenario of IPCC : RCP 8.5, we add a perturbation of either Greenland or West Antarctica corresponding to 3 meters of sea level rise. 3 simulations using IPSL AOGCM version 5A corresponding to : -a drastic reduction of the Greenland ice sheet - a destabilization of west Antarctica - a mix between Greenland and west Antarctica melting The fresh water corresponds to 0.68 Sv during 50 years, the perturbation is applied from 2020 to 2070.

Methodology

Geometry of the ice sheets after the perturbation

T2C : Greenland/RCP 8.5 anomaly in 2045-2049 T2C : Greenland/RCP 8.5 anomaly in 2145-2149

Two Meters temperature anomaly between perturbed (fresh water) and unperturbed (RCP 8.5) Simulations for the maximum effect 2045-2049 for the Greenland contribution scenario.

Impact on temperature: scenario 1

JJAS precipitation in West Africa

Monsoon changes and shift in Inter Tropical Convergence Zone Because of the large density of population in Monsoon areas, these changes will led to majoror migrations.

Impact on West African precipitation for summer

Nicholls R J et al. Phil. Trans. R. Soc. A 2011;369:161-181

Migration due to sea-level rise

Impacted populations for a sea level rise of 0.5 and 2.0 m

- In this project, we developed a consistent approach for different scenarios of sea level rise. Our aim is to infer the migration due to climate change which is superimposed to sea level rise. -Direct effect of sea level rise causes large damage in costal areas while climate change due to ice sheet melting has drastic effect on monsoon areas. Anyway, both forcing factors act in regions of highly densified population. The last step would be to explore the changes in energy supply when such huge migration of population occur.

Conclusions and ongoing work :

THANK YOU for staying so long

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