This topic has already had a thread or two but the Science article on which it is based it available to the public. It may be downloaded in its 2-page entirety at http://science.sciencemag.org/content/sci/363/6423/128.full.pdf.
The article makes use of published studies by Lijing Cheng, John Abraham, Zeke Hausfather, Kevin E. Trenberth. All the studies made use of improved error correction algorithms to improve XBT and ARGO observations.
The IPCC's AR5 contained five different datasets of ocean heat content (OHC) trends for 0-700m produced by five different data processing methods. The variance between the different sets was high, complicating interpretation. As well, the observational trends showed lower OHC increases than did the CMIP5 GCMs.
The data processing used in the OHC data shown in AR5 had been corrected for expendable bathythermograph (XBT) data used in AR4. It was differences in these correction methods that led to most of the differences in their results. In the intervening time, researchers had developed greatly improved methods for correcting XBT biases.
Other studies had developed improved methods for handling data suffering from spatial or temporal gaps. It had been found that prior methods introduced a conservative bias into results. Domingues et al introduced an improved gap-filling method using satellite altimetry data. Cheng et al used a multi-model approach to improve the accuracy of extrapolating from data-rich regions to fill nearby gaps.
The result is a much-reduced variance between datasets and between datasets and CMIP5 projections. The conclusion also displays greater warming over the 1997-2010 time span than shown in AR5. For the 2005-2017 period, where ARGO data are available, the CMIP5 ensemble results show 0.68 ± 0.02 Wm^-2. The observational results are 0.54 ± 0.02, 0.64 ± 0.02 and 0.68 ± 0.60 W m^−2, showing close agreement.
For the RCP 8.5, Business-as-Usual emissions scenario, the projected OHC warming by 2100 is 2,020 ZetaJoules. This would produce 30 cm of sea level rise purely from ocean warming (ie, ignoring concurrent ice melt)
The article makes use of published studies by Lijing Cheng, John Abraham, Zeke Hausfather, Kevin E. Trenberth. All the studies made use of improved error correction algorithms to improve XBT and ARGO observations.
The IPCC's AR5 contained five different datasets of ocean heat content (OHC) trends for 0-700m produced by five different data processing methods. The variance between the different sets was high, complicating interpretation. As well, the observational trends showed lower OHC increases than did the CMIP5 GCMs.
The data processing used in the OHC data shown in AR5 had been corrected for expendable bathythermograph (XBT) data used in AR4. It was differences in these correction methods that led to most of the differences in their results. In the intervening time, researchers had developed greatly improved methods for correcting XBT biases.
Other studies had developed improved methods for handling data suffering from spatial or temporal gaps. It had been found that prior methods introduced a conservative bias into results. Domingues et al introduced an improved gap-filling method using satellite altimetry data. Cheng et al used a multi-model approach to improve the accuracy of extrapolating from data-rich regions to fill nearby gaps.
The result is a much-reduced variance between datasets and between datasets and CMIP5 projections. The conclusion also displays greater warming over the 1997-2010 time span than shown in AR5. For the 2005-2017 period, where ARGO data are available, the CMIP5 ensemble results show 0.68 ± 0.02 Wm^-2. The observational results are 0.54 ± 0.02, 0.64 ± 0.02 and 0.68 ± 0.60 W m^−2, showing close agreement.
For the RCP 8.5, Business-as-Usual emissions scenario, the projected OHC warming by 2100 is 2,020 ZetaJoules. This would produce 30 cm of sea level rise purely from ocean warming (ie, ignoring concurrent ice melt)
