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How do climate-related uncertainties influence 2 and 1.5 °C pathways?

Authors :: Su X
Shiogama H
Tanaka K
Fujimori S
Hasegawa T
Hijioka Y
Takahashi K
Liu J
Source :: Sustainability science [Sustain Sci] 2018; Vol. 13 (2), pp. 291-299. Date of Electronic Publication: 2018 Jan 09.
Publication Year :: 2018
Abstract: We investigate how uncertainties in key parameters in the carbon cycle and climate system propagate to the costs of climate change mitigation and adaptation needed to achieve the 2 and 1.5 °C targets by 2100 using a stochastic version of the simple climate model for optimization (SCM4OPT), an integrated assessment model. For the 2 °C target, we find a difference in 2100 CO <subscript>2</subscript> emission levels of 20.5 GtCO <subscript>2</subscript> (- 1.2 GtCO <subscript>2</subscript> to 19.4 GtCO <subscript>2</subscript> ), whereas this difference is 12.0 GtCO <subscript>2</subscript> (- 6.9 GtCO <subscript>2</subscript> to 5.1 GtCO <subscript>2</subscript> ) for the 1.5 °C target (17-83% range). Total radiative forcing in 2100 is estimated to be 3.3 (2.7-3.9) Wm <superscript>-2</superscript> for the 2 °C case and 2.5 (2.0-3.0) Wm <superscript>-2</superscript> for the 1.5 °C case. Carbon prices in 2100 are 482 (181-732) USD(2005)/tCO <subscript>2</subscript> and 713 (498-1014) USD(2005)/tCO <subscript>2</subscript> for the 2 and 1.5 °C targets, respectively. We estimate GDP losses in 2100 that correspond to 1.9 (1.2-2.5)% of total gross output for the 2 °C target and 2.0 (1.5-2.7)% for the 1.5 °C target.