SUMMIT 2017GLOBAL RISK INSTITUTE

PRESENTATION BY:

Gernot WagnerCo-Director, Harvard’s Solar Geoengineering Research Program and Research Associate, Harvard University

Climate Shock

Gernot Wagnergwagner@fas.harvard.edugwagner.com

Pricing climate risk

$40

>>$40

1.5 – 4.5°C

* Charney et al (1979)

1.5 – 4.5°C

* IPCC (1990)

1.5 – 4.5°C

* IPCC (1990, 1992)

1.5 – 4.5°C

* IPCC (1990, 1992, 1995)

1.5 – 4.5°C

* IPCC (1990, 1992, 1995, 2001)

1.5 – 4.5°C

* IPCC (2007)

2.0 – 4.5°C

* IPCC (2013)

1.5 – 4.5°C

Source: Meinshausen et al (2009)

Source: Meinshausen et al (2009)

IPCC’s “likely” range 1.5-4.5°C ‘Heavy-tailed’ climate sensitivity calibration using log-normal, mirroring effects of Roe-Baker

Source: Wagner & Weitzman’s Climate Shock (2015)

Equal mass below and above “likely” range likely conservative assumption

Final temperatures resulting in large probability of ‘tail event’IEA’s “New Policies Scenario” reaches 700 ppm by 2100

Source: Wagner & Weitzman’s Climate Shock (2015)

>10% probability of final temperatures exceeding 6°C

It’s not over ‘til the fat tail zingsRapidly increasing probability of extreme final temperatures

Source: Wagner & Weitzman’s Climate Shock (2015)

CO2e (ppm) 400 450 500 550 600 650 700 750 800

Median Δ°C 1.3°C 1.8°C 2.2°C 2.5°C 2.7°C 3.2°C 3.4°C 3.7°C 3.9°C

Prob >6°C 0.04% 0.3% 1.2% 3% 5% 8% 11% 14% 17%

Analysis beyond standard benefit-cost analysis (and, thus, Social Cost)?

By 2100, per IEA’s

“New Policies Scenario”

10x10x

10x<1.5x

>>$40

Gernot Wagnergwagner@fas.harvard.edugwagner.com

CO2

CO2

SO2

CO2

SO2

CO2

SO2

Complement, not substitute

Complement, not substitute

Complement, not substitute

Gernot Wagnergwagner@fas.harvard.edugwagner.com