25
emission mitigation pathways; (2) carbon budget calculations; (3) attribution of
GHG emissions to specific entities. Relevant, such findings are mostly contained in
IPCC’s official documents, being the same IPCC “the global clearing house of climate research” (Ghaleigh 2016).
2.1 GHG Emission Pathways
Ever since its foundation in 1987, IPCC has extensively established through computer models (with a level of confidence of 9 chances out of 10) that a direct, linear
link exists between anthropogenic GHG emission and average temperature rise
(Mastrandrea and Schneider 2014). In this regard, since the drafting of the 1997
UNFCCC Kyoto Protocol targets, country-based elaborations on GHG mitigation
pathways have been increasingly refined, up to the very specific long-term scenarios
in the 2018 IPCC 1.5° Report. The 1.5° Report sets down the emission reductions
necessary to ensure a 66% likelihood of achieving the temperature target agreed
upon in the 2015 Paris Agreement. Accordingly, in model pathways with no or limited overshoot of 1.5 °C, global net anthropogenic CO 2 emissions must decline by
about 45% from 2010 levels by 2030, reaching net zero around 2050 (Rogelj et al.
2018, p. 95). To limit global warming to below 2 °C, CO 2 emissions are projected to
decline by about 20% by 2030 in most pathways, and eventually reach net zero
around 2075 (Victor et al. 2014, p. 124). Non-CO 2 GHG emissions (CH4, sulphur
dioxide, etc.) should follow similar emission reduction pathways (Rogelj et al.
2018, p. 96). Moreover, and perhaps more importantly, each IPCC global warming
scenario is linked to specific implications in terms of climate-related risks to health,
livelihoods, human security, and growth (Hoegh-Guldberg et al. 2018). Further calculations are annually conducted by UNEP to keep track of the progress made in
achieving the above emission reduction pathways, thus highlighting the existing gap
between the ideal trajectories and the actual collective efforts being made by countries (UNEP 2018).
Relevant from a legal standpoint, scientific findings on climate mitigation targets
and pathways as factored into climate change scenarios are now capable of adequately appraising the short and long-term risks climate change will pose in terms
of livelihood losses, damages to specific areas, impact on food production, and
therefore in terms of disruption of property, family life, etc., thus pitching the proposed emission mitigation targets accordingly.
2.2 Carbon Budget
Explicit GHG emission reduction targets as set out in national (or supranational)
legislation and policies may well be of assistance to courts seeking a defensible
basis for ‘scaling down’ an assessment of the significance of a given project’s
Climate Science Before the Courts: Turning the Tide in Climate Change Litigation
emission mitigation pathways; (2) carbon budget calculations; (3) attribution of
GHG emissions to specific entities. Relevant, such findings are mostly contained in
IPCC’s official documents, being the same IPCC “the global clearing house of climate research” (Ghaleigh 2016).
2.1 GHG Emission Pathways
Ever since its foundation in 1987, IPCC has extensively established through computer models (with a level of confidence of 9 chances out of 10) that a direct, linear
link exists between anthropogenic GHG emission and average temperature rise
(Mastrandrea and Schneider 2014). In this regard, since the drafting of the 1997
UNFCCC Kyoto Protocol targets, country-based elaborations on GHG mitigation
pathways have been increasingly refined, up to the very specific long-term scenarios
in the 2018 IPCC 1.5° Report. The 1.5° Report sets down the emission reductions
necessary to ensure a 66% likelihood of achieving the temperature target agreed
upon in the 2015 Paris Agreement. Accordingly, in model pathways with no or limited overshoot of 1.5 °C, global net anthropogenic CO 2 emissions must decline by
about 45% from 2010 levels by 2030, reaching net zero around 2050 (Rogelj et al.
2018, p. 95). To limit global warming to below 2 °C, CO 2 emissions are projected to
decline by about 20% by 2030 in most pathways, and eventually reach net zero
around 2075 (Victor et al. 2014, p. 124). Non-CO 2 GHG emissions (CH4, sulphur
dioxide, etc.) should follow similar emission reduction pathways (Rogelj et al.
2018, p. 96). Moreover, and perhaps more importantly, each IPCC global warming
scenario is linked to specific implications in terms of climate-related risks to health,
livelihoods, human security, and growth (Hoegh-Guldberg et al. 2018). Further calculations are annually conducted by UNEP to keep track of the progress made in
achieving the above emission reduction pathways, thus highlighting the existing gap
between the ideal trajectories and the actual collective efforts being made by countries (UNEP 2018).
Relevant from a legal standpoint, scientific findings on climate mitigation targets
and pathways as factored into climate change scenarios are now capable of adequately appraising the short and long-term risks climate change will pose in terms
of livelihood losses, damages to specific areas, impact on food production, and
therefore in terms of disruption of property, family life, etc., thus pitching the proposed emission mitigation targets accordingly.
2.2 Carbon Budget
Explicit GHG emission reduction targets as set out in national (or supranational)
legislation and policies may well be of assistance to courts seeking a defensible
basis for ‘scaling down’ an assessment of the significance of a given project’s
Climate Science Before the Courts: Turning the Tide in Climate Change Litigation