Assessing "dangerous climate change": required reduction of carbon emissions to protect young people, future generations and nature

James Hansen*, Pushker Kharecha, Makiko Sato, Valerie Masson-Delmotte, Frank Ackerman, David J Beerling, Paul J Hearty, Ove Hoegh-Guldberg, Shi-Ling Hsu, Camille Parmesan, Johan Rockstrom, Eelco J Rohling, Jeffrey Sachs, Pete Smith, Konrad Steffen, Lise Van Susteren, Karina von Schuckmann, James C Zachos

*Corresponding author for this work

Research output: Contribution to journalLiterature reviewpeer-review

442 Citations (Scopus)
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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 similar to 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 similar to 1000 GtC, sometimes associated with 2 degrees C global warming, would spur "slow" feedbacks and eventual warming of 3-4 degrees 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.

Original languageEnglish
Article numbere81648
Number of pages26
JournalPloS ONE
Issue number12
Publication statusPublished - 3 Dec 2013


  • sea-level rise
  • Antarctic Ice-Sheet
  • last interglacial highstand
  • greenhouse-gas emissions
  • land-use change
  • global temperature
  • oil sands
  • probabilistic assessment
  • intense preciptation
  • anthropogenic carbon


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