Determining allowable CO2 emissions from regional- and ... · 14.6.2016 Sonia Seneviratne / IAC ETH...
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Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Determining allowable CO2 emissions from regional- and impact-related climate targets Sonia I. Seneviratne
Institute for Atmospheric and Climate Science, ETH Zurich, Switzerland [email protected]
Acknowledgements: M. Donat, A.J. Pitman, R. Knutti, R. Wilby, E. Davin, A. Hirsch, Q. Lejeune, R. Orth, M. Vogel, and M. Wilhelm Ecole Polytechnique, France, 14.06.2016
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
2015 Paris agreement
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
COP21: 1.5° vs 2°
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Climate projections
(IPCC 2013)
Agreement at COP21 to hold the increase in global temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit increases to 1.5°
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
3 questions using climate simulations: • Identify optimal target between 1.5°-2°: Including the impact
perspective
• How do we reduce uncertainties: • Example: Land surface feedbacks for temperature extremes
• How do we reduce regional impacts?
Towards a 1.5°-2° world…
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Allowable CO2 emissions based on regional targets?
(Seneviratne et al. 2016, Nature)
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Link between cumulative CO2 emissions and global T°
Direct link between cumulative CO2 emissions and climate response A global T° target can be linked to cumulative emissions target
(IPCC 2013)
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
What are implications of global temperature changes?
“People are not killed by the global temperature”… …what matters are regional changes in extremes and impacts
How do these relate to the projected global temperature changes?
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
1.5°C and 2°C targets: “reasons for concern”
(IPCC 2014, WG2)
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
1.5°C and 2°C targets: “reasons for concern”
(IPCC 2014, WG2)
Can we be more quantitative?
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Scaling relationships for extremes
Can these scaling relationships be used to relate regional changes with global T° changes and thus with cumulative CO2 emissions targets?
(Seneviratne et al. 2016, Nature)
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Relating regional climate targets with CO2 emissions
(Seneviratne et al. 2016, Nature)
RCP8.5 RCP4.5
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Relating regional climate targets with CO2 emissions
Interesting results: • Almost linear scaling for
multi-model mean (see also Fischer et al. 2014, GRL)
(Seneviratne et al. 2016, Nature)
RCP8.5 RCP4.5
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Relating regional climate targets with CO2 emissions
Interesting results: • Almost linear scaling for
multi-model mean (see also Fischer et al. 2014, GRL)
• Pattern independent of
emissions scenario!
(Seneviratne et al. 2016, Nature)
RCP8.5 RCP4.5
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Relating regional climate targets with CO2 emissions
Interesting results: • Almost linear scaling for
multi-model mean (see also Fischer et al. 2014, GRL)
• Pattern independent of
emissions scenario!
• Tool to define impact-based targets?
(Seneviratne et al. 2016, Nature)
RCP8.5 RCP4.5
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Relating regional climate targets with CO2 emissions
Rx5day Southern Asia
(Seneviratne et al. 2016, Nature)
Also scaling found for warming of minimum temperatures
RCP8.5
RCP4.5
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Relating regional climate targets with CO2 emissions
Rx5day Southern Asia
(Seneviratne et al. 2016, Nature)
Also scaling found for warming of minimum temperatures and changes in heavy precipitation
RCP8.5
RCP4.5
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Relating regional climate targets with CO2 emissions
Advantages:
1. Provides a better quantitative understanding of relation between emissions and impacts for stakeholders
2. Independent of emissions scenario, direct link between political decisions and impacts
3. Help linkage between costs of emissions reduction and avoided costs of impacts
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Relating regional climate targets with CO2 emissions
Advantages:
1. Provides a better quantitative understanding of relation between emissions and impacts for stakeholders
2. Independent of emissions scenario, direct link between political decisions and impacts
3. Help linkage between costs of emissions reduction and avoided costs of impacts
Caveats:
• Large uncertainty ranges in some cases (e.g. droughts) • Shared model biases • Does not consider the impact of local forcing (land use, aerosols) • Does not include uncertainty of scaling of CO2 emissions with global T°
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
3 questions using climate simulations: • Identify optimal target between 1.5°-2°: Including the impact
perspective
• How do we reduce uncertainties: • Example: Land surface feedbacks for temperature extremes
• How do we reduce regional impacts?
Towards a 1.5°-2° world…
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Uncertainties in scaling: Example from 2 regions
Contiguous US
Central Europe
IPCC SREX regions
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Uncertainties in scaling: Example from 2 regions
Txx, CEU
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Role of soil moisture – temperature feedbacks
T+
GHG
T++
GHG
è evidence in projections: Seneviratne et al. 2006, Nature; Diffenbaugh et al. 2007, GRL; Seneviratne et al. 2013, GRL è observational evidence: Hirschi et al. 2011, Nature Geoscience; Quesada et al. 2012, Nature Climate Change; Mueller and Seneviratne 2012, PNAS; Miralles et al. 2014, Nature Geoscience
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Analysis for Southeastern Europe Quantile regression of %HD with 6-month SPI
(Hirschi et al. 2011, Nature Geoscience)
Soil moisture – temperature feedbacks: Observations
Impact of soil moisture on hot extremes
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Analysis for Southeastern Europe Quantile regression of %HD with 6-month SPI
(Hirschi et al. 2011, Nature Geoscience)
Impact of soil moisture on hot extremes
Conditional probability: Higher probability of occurrence with drier springs
Soil moisture – temperature feedbacks: Observations
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
(Mueller and Seneviratne 2012, PNAS)
NHD: # hot days SPI: Standardized Precipitation Index
Soil moisture – temperature feedbacks: Observations
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
(Mueller and Seneviratne 2012, PNAS)
NHD: # hot days SPI: Standardized Precipitation Index
Soil moisture – temperature feedbacks: Observations
Generally strong lag relationship between precipitation deficits and temperature extremes in transitional regions between dry and wet climates
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Soil moisture-temperature feedbacks in global climate models
Soil moisture (point in Central Europe)
GLACE-CMIP5 investigates the impact of decadal changes in soil moisture on climate 5 CMIP5 models (CESM, EC-EARTH, GFDL, IPSL, MPI-ESM)
(Seneviratne et al. 2013, GRL)
GLACE-CMIP5 experiment
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
(GLACE-CMIP5 experiments, Seneviratne et al. 2013, GRL)
Mean drying of the soil is explaining added warming in extremes in several land regions
Role of soil moisture feedbacks
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
(GLACE-CMIP5 experiments, Seneviratne et al. 2013, GRL)
Mean drying of the soil is explaining added warming in extremes in several land regions
Role of soil moisture feedbacks
Regions with strong soil moisture effects in projections correspond well to those showing a stronger warming of extremes
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Txx, CEU
By how much can we reduce the uncertainty in projections (e.g. using ground and remote sensing observations of land variables)?
ERC DROUGHT-HEAT project
Uncertainties in scaling: Example from 2 regions
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Txx, CEU
By how much can we reduce the uncertainty in projections (e.g. using ground and remote sensing observations of land variables)?
ERC DROUGHT-HEAT project
Uncertainties in scaling: Example from 2 regions
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
(Mueller and Seneviratne 2014, GRL)
Evidence of systematic biases in current climate models
Systematic biases in climate models
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
3 questions using multi-model climate simulations: • Identify optimal target between 1.5°-2°: Including the impact
perspective
• How do we reduce uncertainties: • Example: Land surface feedbacks for temperature extremes
• How do we reduce regional impacts?
Towards a 1.5°-2° world…
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Reducing impacts
RCP8.5 RCP4.5
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
RCP2.6 scenario
(VanVuuren et al. 2011, Clim. Change)
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
RCP2.6 scenario
(VanVuuren et al. 2011, Clim. Change)
Present simulations do not include biophysical impacts of land use (will be investigated in CMIP6 LUMIP experiment)
e.g. reforestation leading to warming in high-latitudes!
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Impact of land use and land cover changes on climate
Impact of land cover type on surface fluxes during heatwaves Forests lead to a warming compared to grasslands!
(Teuling et al. 2010, Nature Geoscience)
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Impact of land use and land cover changes on climate
Impact of land cover type on surface fluxes during heatwaves Forests lead to a warming compared to grasslands!
(Teuling et al. 2010, Nature Geoscience)
NB: Behaviour may reverse under long droughts
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Impact of land use and land cover changes on climate
(Teuling et al. 2010, Nature Geoscience)
NB: Behaviour may reverse under long droughts
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Changes in albedo induced by agricultural management
Differences in surface albedo from no-till farming
Photograph by Jim Richardson (National Geographic) (Davin et al. 2014, PNAS)
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Crop distribution (%)
(Davin et al. 2014, PNAS)
Summer mean temperature changes
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Changes in albedo induced by agricultural management
(Davin et al. 2014, PNAS)
Preferential cooling of hot extremes when considering combined albedo and evaporation effects!
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Reducing impacts
Regional scale increases in temperature could also be reduced through regional measures (e.g. irrigation, changes in surface reflectivity): Regional “land climate engineering”
RCP8.5 RCP4.5
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Reducing impacts
Regional scale increases in temperature could also be reduced through regional measures (e.g. irrigation, changes in surface reflectivity): Regional “land climate engineering” But no/little effects on ocean acidification, sea level rise
RCP8.5 RCP4.5
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
ERC DROUGHT-HEAT project
ERC consolidator grant (2014-2019)
Sonia Seneviratne / IAC ETH Zurich 14.6.2016 Ecole Polytechnique
Conclusions and outlook • Scaling of regional changes in extremes with changes in global
temperature (and cumulative global CO2 emissions) • Relationship can be used to:
• Inform choice of global temperature targets • Reduce uncertainties in projections • Link costs of adaptation and mitigation • Design strategies for regional adaptation
• Soil moisture and land albedo effects are important for land climate and in particular for temperature extremes èrelevant for projections, mitigation and adaptation
Contact: [email protected]