Australia: The Land Where Time Began

A biography of the Australian continent 

Climate Sensitivity to Cumulative Carbon Emissions Due to Ocean Heat and Carbon Uptake

It has been shown by climate model experiments that transient global warming is nearly proportional to cumulative carbon emissions on timescales that are multi-decadal to millennial (Matthews et al., 2009; Allen et al., 2009; Zickfield et al., 2009; Zickfield et al., 2013; Gillet, Arora, Matthews & Allen, 2013). It is, however, not quantitatively understood how this near-linear dependence between warming and carbon emissions arises in transient climate simulations (IPCC, Climate Change 2013; Collins et al., 2013). In this paper Goodwin, Williams & Ridgwell present an equation that is theoretically derived of the dependence of global warming on cumulative carbon emissions over time. Their analysis, for an atmosphere-ocean system, has identified a surface warming response to cumulative carbon emissions of 1.5 ± 0.7 K per 1,000 Pg of carbon that is emitted. By the end of the century and beyond this surface warming response is reduced by typically by 10-20 %. As a result of partially opposing effects of the uptake by the ocean of heat and carbon, the climate response remains nearly constant on multi-decadal to millennial timescales (Solomon et al., 2009), the warming that results then becoming proportional to cumulative carbon emissions after many centuries, as pointed out earlier (Williams et al., 2012). When estimates of the uptake of terrestrial carbon are incorporated (Friedlingstein et al., 2006), the surface warming response is reduced to 1.1 ± 0.5 K per 1,000 Pg of carbon that is emitted, though Goodwin, Williams & Ridgwell suggest it is not likely this modification will significantly affect the way in which the climate response changes over time. Goodwin, Williams & Ridgwell suggest their theoretical framework may be used in climate models to diagnose and mechanistically understand the differences between their projections.

Sources & Further reading

1. Goodwin, P., R. G. Williams and A. Ridgwell (2015). "Sensitivity of climate to cumulative carbon emissions due to compensation of ocean heat and carbon uptake." Nature Geosci 8(1): 29-34.