Consistency between planetary heat balance and ocean heat storage Clivar research focus team: Karina von Schuckmann, Bernard Barnier, Carol Anne Clayson, Catia Domingues, Sergey Gulev, Keith Haines, Simon Josey, Norman Loeb, Pierre-Philippe Mathieu, Mathew Palmer, Anne-Marie Treguier, Kevin Trenberth, Maria Valdivieso, Martin Visbeck, Martin Wild

 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. Clivar RF: Consistency between planetary heat balance and ocean heat storage: General Context Source:

 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 Earth Energy Budget from IPCC, 2013 Cummulative energy flow into the Earth system (ES) Climate feedback (climate sensitivity) Clivar RF: Consistency between planetary heat balance and ocean heat storage: General Context Balanced by  warming of ES  increase in outgoing radiation inferred from changes global SST

Earth Energy Budget from IPCC, 2013 Cummulative energy flow into the Earth system (ES) Climate feedback (climate sensitivity) Clivar RF: Consistency between planetary heat balance and ocean heat storage: General Context Balanced by  warming of ES  increase in outgoing radiation inferred from changes global SST Energy accumulation within the different components of the Earth climate system IPCC, 2013  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.

IPCC, 2013 Cummulative energy flow into the Earth system (ES) Climate feedback (climate sensitivity) Clivar RF: Consistency between planetary heat balance and ocean heat storage: Challenge Balanced by  warming of ES  increase in outgoing radiation inferred from changes global SST Energy accumulation within the different components of the Earth climate system IPCC, 2013  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. Large uncertainties in our estimates challenge our ability to infer the absolute measure of the Earth Energy Imbalance and its changes over time

Clivar RF: Consistency between planetary heat balance and ocean heat storage: Motivation Developing the knowledge, and observational capability, necessary to “track” the energy flows through the climate system is critical to better understand the relationships between climate forcing, response, variability and future changes.

Clivar RF: Consistency between planetary heat balance and ocean heat storage: GOAL Ocean Heat Content Radiation at TOA Air-Sea fluxes radiative turbulent Abraham et al., 2013 Loeb et al., 2012 Josey et al., 2014 (in prep.)  Advancing our knowledge through budget constraints and assessment studies

Clivar RF: Consistency between planetary heat balance and ocean heat storage: GOAL An overaging goal is to bring together 4 climate research communities all concerned with the energy flows in the Earth’s System  atmospheric radiation  air-sea-flux  Ocean Heat Content  ocean reanalysis and climate models to advance on the understanding of the uncertainties through budget constraints. This will increase our capabilities to answer pressing issues of climate related research.

Clivar RF: Consistency between planetary heat balance and ocean heat storage: 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)

Clivar RF: Consistency between planetary heat balance and ocean heat storage 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 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.

Clivar RF: Consistency between planetary heat balance and ocean heat storage 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).

Clivar RF: Consistency between planetary heat balance and ocean heat storage 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 multidacadal reanalyses.

“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 Clivar RF: Consistency between planetary heat balance and ocean heat storage: 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?