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Attribution of the 2001-2010 global temperature plateau

Attribution of the 2001-2010 global temperature plateau. Virginie Guemas, Francisco J. Doblas-Reyes, Isabel Andreu-Burillo and Muhammad Asif. Issue. A steady increase in greenhouse gas concentration. N. N. N. N = Niño N = Niña V = Volcano. V. V. N. V. N. Issue.

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Attribution of the 2001-2010 global temperature plateau

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  1. Attribution of the 2001-2010 global temperature plateau Virginie Guemas, Francisco J. Doblas-Reyes, Isabel Andreu-Burillo and Muhammad Asif

  2. Issue A steady increase in greenhouse gas concentration

  3. N N N N = Niño N = Niña V = Volcano V V N V N Issue Ed Hawkins, Climate Lab Book, NCAS

  4. Issue Is there an inconsistency between projected global mean temperature and observed one ? Why do we observed such temperature plateau instead of a temperature increase ? Not within observational and model uncertainty The issue we focus on here

  5. Issue What are the mechanisms behind the temperature plateau ?

  6. Hypotheses A - a decrease in the stratospheric water vapour concentration (Solomon, 2010) B - an increase in the background stratospheric aerosol concentration (Solomon, 2013; Fyfe et al, 2013) C - the deep and long solar minimum (Kaufmann et al., 2011; Hansen et al., 2011) D - an increase in the tropospheric aerosol concentration (Kaufmann et al., 2011; Murphy, 2013) E - an increase in the subsurface ocean heat uptake (Meehl et al, 2011; Katsman and Van Oldenborgh, 2011; Balmaseda et al, 2013)

  7. A : Stratospheric water vapour decrease From observations and reanalyses Water vapour changes 1996-2000 -> 2001-2005 explains about -0.1W.m-2 (net forcing : ~0.5W.m-2) Solomon et al., 2010

  8. B : Stratospheric aerosol increase Amman et al, 2003 Sato et al, 1993 Vernier et al, 2011 Background stratospheric aerosol explains  -0.1W.m-2, which was not accounted for in CMIP5 Solomon et al., 2013

  9. C : Long solar minimum From observations and reconstructions Linear trend Sum 1 +2 1. Net anthropogenic forcing Temperature 2. Solar Anthropogenic sulfur Solar cycle minimum explains about -0.2W.m-2, to be compared with ~0.5W.m-2 total forcing Kaufmann et al., 2011

  10. D : Tropospheric aerosol increase From observations and reconstructions Linear trend Sum 1 +2 1. Net anthropogenic forcing Temperature 2. Solar Anthropogenic sulfur Tropospheric aerosol forcing explains about -0.06W.m-2 since 2002 (net forcing : ~0.5W.m-2) Kaufmann et al., 2011

  11. Observed Top-Of-Atmosphere net input energy Stratospheric water vapour Aerosols Solar minimum CERES TOA input energy still positiveduring the last decade, why does not it warm the surface ? Loeb et al., 2009

  12. E : Increased ocean heat uptake Composites of meridional overturning streamfunction anomalies during decades of surface temperature cooling in CCSM4 Pacific Atlantic Strengthening of the subtropical cells Weakening of the deep convection Increased subsurface ocean heat uptake might compensate for TOA absorption during hiatus periods Meehl et al, 2011

  13. Hypotheses A - a decrease in the stratospheric water vapour concentration (Solomon, 2010) B - an increase in the background stratospheric aerosol concentration (Solomon, 2013; Fyfe et al, 2013) C - the deep and long solar minimum (Kaufmann et al., 2011; Hansen et al., 2011) D - an increase in the tropospheric aerosol concentration (Kaufmann et al., 2011; Murphy, 2013) E - an increase in the subsurface ocean heat uptake (Meehl et al, 2011; Katsman and Van Oldenborgh, 2011; Balmaseda et al, 2013)

  14. Can we use climate predictions to assess the contributions of those various factors? Guemas V. , Doblas-Reyes F. J., Andreu-Burillo I., Asif M., 2013, Retrospective prediction of the global warming slowdown in the past decade. Nature Climate Change, doi : 10.1038/nclimate1863.

  15. Methodology Experimental setup 5-member prediction started 1 Nov 1960 Observations 1990 2012 1960

  16. Methodology Experimental setup 5-member prediction started 1 Nov 1961 5-member prediction started 1 Nov 1960 1961 Observations 1990 2012 1960

  17. Methodology Experimental setup 5-member prediction started 1 Nov 1961 5-member prediction started 1 Nov 1962 5-member prediction started 1 Nov 1960 1961 Observations 1990 2012 1960 1962

  18. Methodology … until 2012 Experimental setup 5-member prediction started 1 Nov 1990 5-member prediction started 1 Nov 1961 …. every year … 5-member prediction started 1 Nov 1962 5-member prediction started 1 Nov 1960 1961 Observations 1990 2012 1960 1962

  19. Methodology … until 2012 Experimental setup 5-member prediction started 1 Nov 1990 5-member prediction started 1 Nov 1961 …. every year … 5-member prediction started 1 Nov 1962 5-member prediction started 1 Nov 1960 Greenhouse Gases + Aerosols + Solar Cycle CMIP5 historical / 2005 / RCP4.5 1961 Observations 1990 2012 1960 1962

  20. Methodology Model

  21. Methodology Full field Initialisation ERA40/ERAinterim ORAS4 GLORYS2V1 + NEMO-LIM run forced by DFS4.3

  22. Methodology Analyses: Example : Focus on 3rd forecast year 1961 Observations 1990 2012 1960 1962

  23. Methodology Analyses: Example : Focus on 3rd forecast year 1961 Observations 1990 2012 1960 1962

  24. Methodology Analyses: Example : Focus on 3rd forecast year 1961 Observations 1990 2012 1960 1962

  25. Methodology Analyses: Example : Focus on 3rd forecast year 51 forecasts : anomalies relative to 1971-2000 1961 Observations 1990 2012 1960 1962

  26. Successful climate prediction of the 2000-2010 global temperature plateau Global mean Sea Surface Temperature (60°S-60°N) Forecast years 1 to 3 ERSST The climate predictions capture the warming slowdown

  27. Successful climate prediction of the 2000-2010 global temperature plateau Global mean Sea Surface Temperature (60°S-60°N) EC-Earth historical simulations starting from 1850 preindustrial control simulations Init NoInit Initializing from observations is crucial to capture the plateau

  28. Successful climate prediction of the 2000-2010 global temperature plateau Global mean Sea Surface Temperature (60°S-60°N) Smoothing with 1-year running mean ERSST Init NoInit Initializing allows to the SST evolution along the predictions

  29. Successful climate prediction of the 2000-2010 global temperature plateau Global mean Sea Surface Temperature (60°S-60°N) Smoothing with 1-year running mean ERSST Init NoInit Initializing allows to the SST evolution along the predictions

  30. Methodology Analyses: 3-year mean changes along the forecast 5-member prediction started 1 Nov 1960 Years 3 to 5 Years 1 to 3 Observations 1990 2012

  31. Methodology Analyses: 3-year mean changes along the forecast Observations 1990 2012

  32. Successful climate prediction of the 2000-2010 global temperature plateau 3-year mean change in global SST (60°S-60°N) Init ERSST NoInit Initialization improves the SST trend along the forecast

  33. Heat budget on those climate predictions to attribute the 2000-2010 global temperature plateau Global Top-of Atmosphere Excess Energy Forecast years 2 to 4 Init CERES NoInit TOA input energy around 0.4 x 1023 Joules captured

  34. Heat budget on those climate predictions to attribute the 2000-2010 global temperature plateau Global Ocean Heat Uptake Global TOA Excess Energy Init ORAS4 NoInit Increased Ocean Heat Uptake compensates for TOA inflow

  35. Heat budget on those climate predictions to attribute the 2000-2010 global temperature plateau Global Ocean Heat Uptake Init ORAS4 NoInit Largest ever recorded peak in ocean heat uptake

  36. Analysis of these predictions to attribute the 2000-2010 global temperature plateau ORAS4 Ocean heat uptake (0-800m excluding the mixed layer) at the onset of the plateau The plateau seems due to increased ocean heat absorption

  37. Analysis of these predictions to attribute the 2000-2010 global temperature plateau ORAS4 Init Increased ocean heat uptake in the Pacific captured by Init

  38. Analysis of these predictions to attribute the 2000-2010 global temperature plateau ORAS4 NoInit Weak signals after ensemble-mean operator on NoInit

  39. Summary of the results • Ec-Earth climate predictions capture the temperature plateau until 5 years ahead. The realism of the SST trend along the forecast is improved with initialization. • The Earth’s heat budget shows that the TOA excess energy has been mainly absorbed in the ocean below the mixed layer at the onset of the plateau. Guemas V. , Doblas-Reyes F. J., Andreu-Burillo I., Asif M., 2013, Retrospective prediction of the global warming slowdown in the past decade. Nature Climate Change, doi : 10.1038/nclimate1863.

  40. Discussion : Back to the hypotheses A - Our simulations show negligible contribution from stratospheric water vapour feedbacks B - Our simulations underestimate the background stratospheric aerosol concentration C - Additional sensitivity experiments show negligible sensitivity from the solar minimum D - Our simulations most probably underestimate the tropospheric anthropogenic aerosol concentration E - The increased ocean heat uptake stands as a possible explanation for only the first half of the decade according to our simulations.

  41. Thank you very much for your attention virginie.guemas@ic3.cat This work was supported by the EU- funded SPECS project, under grant agreement 308378

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