Observed and simulated full-depth ocean heat-content changes for 1970–2005

Abstract. Greenhouse-gas emissions have created a planetary energy imbalance that is primarily manifested by increasing ocean heat content (OHC). Updated observational estimates of full-depth OHC change since 1970 are presented that account for recent advancements in reducing observation errors and biases. The full-depth OHC has increased by 0.74 [0.68, 0.80]  ×  1022 J yr−1 (0.46 Wm−2) and 1.22 [1.16–1.29]  ×  1022 J yr−1 (0.75 Wm−2) for 1970–2005 and 1992–2005, respectively, with a 5 to 95 % confidence interval of the median. The CMIP5 models show large spread in OHC changes, suggesting that some models are not state-of-the-art and require further improvements. However, the ensemble median has excellent agreement with our observational estimate: 0.68 [0.54–0.82]  ×  1022 J yr−1 (0.42 Wm−2) from 1970 to 2005 and 1.25 [1.10–1.41]  ×  1022 J yr−1 (0.77 Wm−2) from 1992 to 2005. These results increase confidence in both the observational and model estimates to quantify and study changes in Earth's energy imbalance over the historical period. We suggest that OHC be a fundamental metric for climate model validation and evaluation, especially for forced changes (decadal timescales).

[1]  K. Trenberth,et al.  Tracking Earth’s Energy: From El Niño to Global Warming , 2012, Surveys in Geophysics.

[2]  Veronika Eyring,et al.  Evaluation of Climate Models. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change , 2013 .

[3]  James Hansen,et al.  An imperative to monitor Earth's energy imbalance , 2016 .

[4]  W. Hobbs,et al.  An Energy Conservation Analysis of Ocean Drift in the CMIP5 Global Coupled Models , 2016 .

[5]  M. Kimoto,et al.  Historical ocean subsurface temperature analysis with error estimates , 2003 .

[6]  Karl E. Taylor,et al.  An overview of CMIP5 and the experiment design , 2012 .

[7]  Matthew D. Palmer,et al.  Internal variability of Earth’s energy budget simulated by CMIP5 climate models , 2014 .

[8]  Timothy P. Boyer,et al.  World Ocean Database 2013. , 2013 .

[9]  John Abraham,et al.  XBT Science: Assessment of Instrumental Biases and Errors , 2016 .

[10]  David R. Doelling,et al.  Observed changes in top-of-the-atmosphere radiation and upper-ocean heating consistent within uncertainty , 2012 .

[11]  Gregory C. Johnson,et al.  Warming of Global Abyssal and Deep Southern Ocean Waters between the 1990s and 2000s: Contributions to Global Heat and Sea Level Rise Budgets* , 2010 .

[12]  J. Willis,et al.  Future observations for monitoring global ocean heat content , 2010 .

[13]  Jiang Zhu,et al.  Influences of the Choice of Climatology on Ocean Heat Content Estimation , 2015 .

[14]  Kevin E. Trenberth,et al.  Distinctive climate signals in reanalysis of global ocean heat content , 2013 .

[15]  Arun Kumar,et al.  A Comparative Analysis of Upper-Ocean Heat Content Variability from an Ensemble of Operational Ocean Reanalyses , 2012 .

[16]  J. Gregory,et al.  Ocean heat uptake and its consequences for the magnitude of sea level rise and climate change , 2012 .

[17]  J. Abraham,et al.  Global Upper Ocean Heat Content Estimation: Recent Progress and the Remaining Challenges , 2015 .

[18]  Lijing Cheng,et al.  Time, Probe Type, and Temperature Variable Bias Corrections to Historical Expendable Bathythermograph Observations , 2014 .

[19]  K. Taylor,et al.  Quantifying underestimates of long-term upper-ocean warming , 2014 .

[20]  Doug M. Smith,et al.  An objective ocean temperature and salinity analysis using covariances from a global climate model , 2007 .

[21]  Andrei P. Sokolov,et al.  Constraining climate model parameters from observed 20th century changes , 2008 .

[22]  D. Roemmich,et al.  The global ocean imprint of ENSO , 2011 .

[23]  K. Haines,et al.  Estimating Oceanic Heat Content Change Using Isotherms , 2009 .

[24]  Timothy P. Boyer,et al.  Warming of the world ocean, 1955–2003 , 2005 .

[25]  Gregory C. Johnson,et al.  Robust warming of the global upper ocean , 2010, Nature.

[26]  K. Koltermann,et al.  How much is the ocean really warming? , 2007 .

[27]  Mark A. Cane,et al.  Volcanic and Solar Forcing of the Tropical Pacific over the Past 1000 Years , 2005 .

[28]  Jiang Zhu,et al.  Artifacts in variations of ocean heat content induced by the observation system changes , 2014 .

[29]  S. Wijffels,et al.  Fifty-Year Trends in Global Ocean Salinities and Their Relationship to Broad-Scale Warming , 2010 .

[30]  Peter J. Gleckler,et al.  Improved estimates of upper-ocean warming and multi-decadal sea-level rise , 2008, Nature.

[31]  K. Trenberth,et al.  The Response of Tropical Atmospheric Energy Budgets to ENSO , 2013 .

[32]  Jaclyn N. Brown,et al.  Climate Drift in the CMIP5 Models , 2013 .

[33]  Eric Rignot,et al.  Revisiting the Earth's sea-level and energy budgets from 1961 to 2008 , 2011 .

[34]  Tong Lee,et al.  Ocean heat content variability and change in an ensemble of ocean reanalyses , 2017, Climate Dynamics.

[35]  D. Chambers,et al.  Consistency of the current global ocean observing systems from an Argo perspective , 2014 .

[36]  Kevin E. Trenberth,et al.  Earth’s Energy Imbalance , 2014 .

[37]  Dean Roemmich,et al.  Unabated planetary warming and its ocean structure since 2006 , 2015 .

[38]  B. Santer,et al.  Human-induced global ocean warming on multidecadal timescales , 2012 .

[39]  D. Shindell,et al.  Anthropogenic and Natural Radiative Forcing , 2014 .

[40]  K. Trenberth,et al.  Has there been a hiatus? , 2015, Science.

[41]  S. Levitus,et al.  World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010 , 2012 .

[42]  John Abraham,et al.  A review of global ocean temperature observations: Implications for ocean heat content estimates and climate change , 2013, Reviews of Geophysics.

[43]  Chris E. Forest,et al.  Industrial-era global ocean heat uptake doubles in recent decades , 2016 .

[44]  John F. B. Mitchell,et al.  THE WCRP CMIP3 Multimodel Dataset: A New Era in Climate Change Research , 2007 .

[45]  G. Johnson,et al.  Estimating Global Ocean Heat Content Changes in the Upper 1800 m since 1950 and the Influence of Climatology Choice , 2014 .

[46]  M. Kimoto,et al.  Reevaluation of historical ocean heat content variations with time-varying XBT and MBT depth bias corrections , 2009 .

[47]  John P. Krasting,et al.  Dominance of the Southern Ocean in Anthropogenic Carbon and Heat Uptake in CMIP5 Models , 2015 .

[48]  J. Arblaster,et al.  Significant decadal-scale impact of volcanic eruptions on sea level and ocean heat content , 2005, Nature.

[49]  K. Haines,et al.  A new perspective on warming of the global oceans , 2009 .