Assessing “Dangerous Climate Change”: Required reduction of carbon emissions to protect young people, future generations and ngature
Résumé
We assess climate impacts of global warming
using ongoing observations and paleoclimate data. We
use Earth’s measured energy imbalance, paleoclimate
data, and simple representations of the global carbon
cycle and temperature to define emission reductions
needed to stabilize climate and avoid potentially disastrous impacts on today’s young people, future generations, and nature. A cumulative industrial-era limit of
,500 GtC fossil fuel emissions and 100 GtC storage in the
biosphere and soil would keep climate close to the
Holocene range to which humanity and other species are
adapted. Cumulative emissions of ,1000 GtC, sometimes
associated with 2°C global warming, would spur ‘‘slow’’
feedbacks and eventual warming of 3–4°C with disastrous
consequences. Rapid emissions reduction is required to
restore Earth’s energy balance and avoid ocean heat
uptake that would practically guarantee irreversible
effects. Continuation of high fossil fuel emissions, given
current knowledge of the consequences, would be an act
of extraordinary witting intergenerational injustice. Responsible policymaking requires a rising price on carbon
emissions that would preclude emissions from most
remaining coal and unconventional fossil fuels and phase
down emissions from conventional fossil fuels
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