Consistency between planetary heat balance and ocean heat storage Clivar research focus team:

1. Consistencybetweenplanetaryheat balance and oceanheatstorage Clivarresearch focus team: Karina vonSchuckmann, Bernard Barnier, Carol Anne Clayson, Catia Domingues, SergeyGulev, Keith Haines, Simon Josey, Norman Loeb, Pierre-Philippe Mathieu, Mathew Palmer, Anne-Marie Treguier, Kevin Trenberth, Maria Valdivieso, Martin Visbeck, Martin Wild

2. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage: General Context • Climate is the result of energy transfer between the different components of the Earth's system. • Energy flows alter clouds, and weather and internal climate modes can temporarily alter the energy balance for periods of days to a several decades. • The only practical way to monitor climate change at different time scales is to continually assess the energy, mainly in the form of heat, in the climate system. Source: www.nasa.gov

3. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage: General Context EarthEnergy Budget from 1970-2011 • Since the accelerated increased concentration of greenhouse gases from human activities, energy is not balanced, leading to an accumulation of heat in the climate system Climate feedback (climatesensitivity) • Balanced by • warming of ES • increase in outgoing radiation inferredfrom changes global SST Cummulativeenergy flow into the Earth system (ES) IPCC, 2013

4. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage: General Context Earth Energy Budget from 1970-2011 • Energy stored in the climate system: • ~ 93% ocean • ~ 4% melting ice (sea and land) • ~ 3% warming of the atmosphere and land • The absolute measure of the Earth Energy Imbalance and its changes over time are vital pieces of information related to climate change as this is the single quantity defining the status of global climate change and expectations for continued global warming. Climate feedback (climatesensitivity) • Balanced by • warming of ES • increase in outgoing radiation inferredfrom changes global SST Energy accumulation within the different components of the Earthclimate system Cummulativeenergy flow into the Earth system (ES) IPCC, 2013 IPCC, 2013

5. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage: Challenge Large uncertainties in ourestimates challenge ourability to infer the absolute measure of the Earth Energy Imbalance and its changes over time • An ongoing accounting of where heat goes and its manifestations is a great need and has implications for interpreting the recent past and immediate future. • Improved knowledge and understanding of the climate system will be translated into improved climate assessments and more reliable climate models,synthesizing the observations, performing attribution of what is happening and why, and in making predictions and projections on all space and time scales.  Climate feedback (climatesensitivity) • Balanced by • warming of ES • increase in outgoing radiation inferredfrom changes global SST Energy accumulation within the different components of the Earthclimate system Cummulativeenergy flow into the Earth system (ES) IPCC, 2013 IPCC, 2013

6. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage: Motivation Developing the knowledge, and observationalcapability, necessary to “track” the energyflowsthrough the climate system iscritical to betterunderstand the relationshipsbetweenclimate forcing, response, variability and future changes.

7. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage: GOAL OceanHeat Content Radiation at TOA Loeb et al., 2012 Air-Sea fluxes radiative  Advancingourknowledgethrough budget constraints and assessmentstudies turbulent Abraham et al., 2013 Josey et al., 2014 (in prep.)

8. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage: GOAL • An overaging goal is to bringtogether 4 climateresearchcommunitiesall concernedwith the energyflows in the Earth’s System • atmospheric radiation • air-sea-flux • OceanHeat Content • oceanreanalysis and climatemodels • to advance on the understanding of the uncertaintiesthrough budget constraints. • This willincreaseourcapabilities to answer pressing issues of climaterelatedresearch.

9. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage: GOAL The main objective of the activity is to analyze the consistency between planetary heat balance and ocean heat storage estimates, data sets and information products based on different parts of the global observing systems (remote sensing (ESA/EO) and in situ) and ocean reanalysis under three tasks: • Earth Observation Measurement Constraints on Ocean Heat Budget (ESA EO) • In situ observations of ocean heat content changes (GOOS and CLIVAR/GSOP) • Ocean (or coupled) reanalysis for atmosphere-ocean heat exchange, consistency • of regional heat budgets and ocean heat content estimate (CLIVAR/GSOP, • SeaFlux)

10. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage FOCUS What is the magnitude of Earth's energy imbalance (EEI) and how does it vary over time?  Issues/Gaps: 1. We need to identify what is required to further reduce the uncertainties aiming to provide an agreed upon range for EEI (beyond just 0.5-1.0 W/m2). Best estimate from Argo OHC, but time series are short. OHC estimates show inconsistencies, in particular for the historical record TOA measurements have large unknown biases (order 6 W m-2) and uncertainty of the individual surface energy balance components are more than an order of magnitude larger than the absolute amount of the Earth imbalance. 2. We need to evaluate consistencies between in-situ and reanalyses OHC and satellite observing systems (an inventory of changes in heat that matches top-of-atmosphere (TOA) imbalance continually over time), and the different products itself, e.g. during the Argo era based on consistent and coordinated effort to intercompare the various methods (assessment and model constrains and reanalysis ensemble studies, IQuOD initiative). Still inconsistencies due to quality assurance, mapping, climatology and instrument calibration.

11. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage FOCUS How are TOA net radiation and ocean heating rate distributed regionally and vertically (OHC)? Issues/Gaps: 1. We need to evaluate the relative importance of the ice-covered ocean, marginal seas and deep ocean (> 2000m) of ocean heat content change and to understand how heat is transferred vertically and use Reanalyses to dynamically gap fill OHC estimates in space and time. 2. How do regional patterns change in time and can regional OHC tendency patterns, along with other patterns eg. sea level, be used to test/falsify Climate model variability hypotheses? Deep ocean observing system still in its initial phase. Individual Ocean Reanalyses unable to provide error estimates and most ocean reanalyses have still low resolution (1 degree).

12. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage FOCUS How can we better constrain the surface energy fluxes and their spatio-temporal variations? Issues/Gaps 1. We need to have a better quantitative knowledge of the energy fluxes at the Earth’s surface by improving the consistency amongst the different satellite-derived surface flux products by developing evaluation metrics to allow routine determination of the accuracy of different flux products: use of in situ surface radiation networks and ocean heat content constrains (Argo, reanalyses: ESA funding). They cannot be directly measured from satellites and are afflicted with large uncertainties and the level of agreement between different surface flux datasets is poor. Ocean Reanalysis transports of Heat not yet proven reliable and both mean and transient variability of transports should both be evaluated. 2. The role of air-sea fluxes in the interplay between the ocean and the atmosphere at different time scales (driving/controlling mechanisms for air-sea exchanges) and associated problems for linking heat content change with surface flux change. Long (multidecadal) homogeneous time series of surface fluxes, at least on basin scales do not exist or highly uncertain from observations and are also very uncertain in multidacadalreanalyses.

13. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage: DIscussion • “What are the expected outcome and who will use the info?” • Outcome • refinement of the global climate research community • Enhancement on uncertainty evaluation and assessment of the different components of the climate budgets by assessing already applied methods, developing new methods and inter-comparison initiatives (link to ongoing initiatives, and development of new priorities and initiate their realization) • Insight into climate research topics, and link to socioeconomic impacts • Use: • climate research community • global observing system programs, institutions, initiatives and operational centers (using recommendations and perspectives for climate research applications • internationally organized scientific initiatives and programs

14. Clivar RF: Consistencybetweenplanetaryheat balance and oceanheatstorage: DIscussion “How can the science issues be best addressed in the context of internationally coordinated science?” “How can Clivar help to mobilize the needed resources and how can Clivar best support the initiative?” “Where are the opportunities and challenges during the implementation?” “How can Clivar panels support the activity?” “Which other, e.g. Global Environnement Change (GEC) projects are involved in the activity?” What are the most appropriate governance and management structures? => Strong link with GEWEX: moving to a joint activity?