Historical and future learning about climate sensitivity

Nathan M. Urban, Philip B. Holden, Neil R. Edwards, Ryan L. Sriver, Klaus Keller

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Equilibrium climate sensitivity measures the long-term response of surface temperature to changes in atmospheric CO2 the range of climate sensitivities in the Intergovernmental Panel on Climate Change Fifth Assessment Report is unchanged from that published almost 30-years earlier in the Charney Report. We conduct perfect model experiments using an energy balance model to study the rate at which uncertainties might be reduced by observation of global temperature and ocean heat uptake. We find that a climate sensitivity of 1.5°C can be statistically distinguished from 3°C by 2030, 3°C from 4.5°C by 2040, and 4.5°C from 6°C by 2065. Learning rates are slowest in the scenarios of greatest concern (high sensitivities), due to a longer ocean response time, which may have bearing on wait-and-see versus precautionary mitigation policies. Learning rates are optimistic in presuming the availability of whole ocean heat data but pessimistic by using simple aggregated metrics and model physics. Key Points Climate sensitivity uncertainty not greatly reduced over decades of research Continued observations may substantially reduce uncertainty over the next decades Rate of learning may affect wait-and-see versus precautionary mitigation policies

Original languageEnglish (US)
Pages (from-to)2543-2552
Number of pages10
JournalGeophysical Research Letters
Issue number7
StatePublished - Apr 16 2014

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences


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