Caldeira Lab

Maximum warming occurs about one decade after carbon dioxide emission

Katharine Ricke & Ken Caldeira

Ricke, K. L., and K. Caldeira, 2014: Maximum warming occurs about one decade after a carbon dioxide emission. Environ. Res. Lett., 9, 124002, doi:10.1088/1748-9326/9/12/124002.


Katharine Ricke - click to read the video transcript



It is known that carbon dioxide emissions cause the Earth to warm, but
no previous study has focused on examining how long it takes to reach maximum
warming following a particular CO2 emission. Using conjoined results of carboncycle
and physical-climate model intercomparison projects (Joos et al 2013,
Taylor et al 2012), we find the median time between an emission and maximum
warming is 10.1 years, with a 90% probability range of 6.6 to 30.7 years. We
evaluate uncertainties in timing and amount of warming, partitioning them into
three contributing factors: carbon cycle, climate sensitivity and ocean thermal
inertia. If uncertainty in any one factor is reduced to zero without reducing
uncertainty in the other factors, the majority of overall uncertainty remains. Thus,
narrowing uncertainty in century-scale warming depends on narrowing
uncertainty in all contributing factors. Our results indicate that benefit from
avoided climate damage from avoided CO2 emissions will be manifested within
the lifetimes of people who acted to avoid that emission. While such avoidance
could be expected to benefit future generations, there is potential for emissions
avoidance to provide substantial benefit to current generations.


Figure 1. Temperature increase from an individual emission of carbon dioxide (CO2). Time series of the marginal warming in mK (=milliKelvin = 0.001 K) per GtC (=1015 g carbon) as projected by 6000 convolution-function simulations for the first 100 years after the emission. Maximum warming occurs a median of 10.1 years after the CO2 emission event and has a median value of 2.2 mK GtC−1. The colors represent the relative density of simulations in a given region of the plot.
Figure 2. Frequency distributions of time to ΔTmax, magnitude of ΔTmax, and ΔT at year 100 relative to ΔTmax. The frequency distribution functions, based on all 6000 simulations, for: (a) the time until the maximum temperature increase achieved in the first 100 years after a CO2 emission (ΔTmax) is reached (in years), (b) the magnitude of ΔTmax (in milliKelvins per gigatonne carbon), and (c) the fraction of that warming remaining 100 years after the emission. Vertical axis units are the multiplicative inverse of the horizontal axis units.
Figure 3. Partitioned uncertainty over time. The fraction of 90% (very likely) uncertainty range remaining if different contributors to overall uncertainty were reduced to zero: (a) uncertainty of two factors is reduced to zero, with no reduction in uncertainty in the third (labeled) factor, (b) uncertainty of one factor is reduced to zero, with no reduction in uncertainty in the other two factors.


Ken Caldeira