The current Earth's Energy Imbalance (EEI) is mostly the result of human activities and is driving global warming. The absolute value of EEI represents the most fundamental metric defining the status of global climate change and will be more useful than using global surface temperature. EEI can best be estimated from Ocean Heat Content changes, complemented by radiation measurements from space. Sustained observations from the Argo array of autonomous profiling floats and further development of the ocean observing system to sample the deep ocean, marginal seas, and the sea ice regions are crucial to refining future estimates of EEI. Combining multiple measurements in an optimal way holds considerable promise for estimating EEI and thus assessing the status of global climate change, improving climate syntheses and models, and testing the effectiveness of mitigation actions. Progress has been and can be achieved with a concerted international effort. Earth's energy imbalanceWeather and climate on planet Earth arise primarily from differential radiative heating and resulting movement of energy by the dynamic components of the climate system: the atmosphere and the oceans. Both of these fluids can move heat and moisture through advective processes by atmospheric winds and ocean currents, as well as through eddies, large-scale atmospheric jet streams and convection. Other major components of the climate system include sea ice, the land and its features (including albedo, vegetation, other biomass, and ecosystems), snow cover, land ice (including the ice sheets of Antarctica and Greenland, and mountain glaciers), rivers, lakes, and surface and ground water. About 30% of the incoming solar radiation is reflected and scattered from clouds and the Earth's surface back to space. The remaining absorbed solar radiation (ASR) in the climate system is transformed into various forms (internal heat, potential energy, latent energy, kinetic energy, and chemical forms), moved, stored and sequestered primarily in the ocean, but also in the atmosphere, land and ice components of the climate system. Ultimately it is radiated back to space as outgoing longwave radiation (OLR) [1][2][3] . In an equilibrium climate there is a global balance 2 between the ASR and OLR, which determines the Earth's radiation budget 1-2 . Perturbations of this budget from internal or external climate variations create EEI 4 , manifested as a radiative flux imbalance at the top of the atmosphere (TOA).The EEI is shaped by a number of climate forcings, some of which occur naturally and others that are anthropogenic in origin. A sense of the relative importance of these factors for a given timescale is obtained through estimates of their "Effective Radiative Forcing" (ERF, Fig. 1). The phenomena giving rise to changes in ERF vary regionally and over time. Internal climate variability occurs from day-to-day and month-to-month associated with weather systems and phenomena like the MaddenJulian Oscillation (MJO) that cause short-term changes in cloudiness 5 . On ...

We revisit the global mean sea level (GMSL) budget during the whole altimetry era (January 1993 to December 2015) using a large number of data sets. The budget approach allows quantifying the TOPEX A altimeter drift (amounting 1.5 ± 0.5 mm/yr over 1993–1998). Accounting for this correction and using ensemble means for the GMSL and components lead to closure of the sea level budget (trend of the residual time series being 0.0 ± 0.22 mm/yr). The new GMSL rate over January 1993 to December 2015 is now close to 3.0 mm/yr. An important increase of the GMSL rate, of 0.8 mm/yr, is found during the second half of the altimetry era (2004–2015) compared to the 1993–2004 time span, mostly due to Greenland mass loss increase and also to slight increase of all other components of the budget.

ISI Document Delivery No.: AG4PV Times Cited: 1 Cited Reference Count: 30 Cited References: Alkama R, 2010, J HYDROMETEOROL, V11, P583, DOI 10.1175/2010JHM1211.1 Balmaseda M. A., 2013, GEOPHYS RES LETT, V40, P1 Boening C, 2012, GEOPHYS RES LETT, V39, DOI 10.1029/2012GL053055 Cazenave A, 2012, MAR GEOD, V35, P82, DOI 10.1080/01490419.2012.718209 Chen JL, 2013, NAT GEOSCI, V6, P549, DOI 10.1038/NGEO1829 Church JA, 2011, GEOPHYS RES LETT, V38, DOI 10.1029/2011GL048794 Church JA, 2011, SURV GEOPHYS, V32, P585, DOI 10.1007/s10712-011-9119-1 Fasullo JT, 2013, GEOPHYS RES LETT, V40, P4368, DOI 10.1002/grl.50834 Foster G, 2011, ENVIRON RES LETT, V6, DOI 10.1088/1748-9326/6/4/044022 Gergis JL, 2009, CLIMATIC CHANGE, V92, P343, DOI 10.1007/s10584-008-9476-z Gu GJ, 2011, J CLIMATE, V24, P2258, DOI 10.1175/2010JCLI3727.1 Hallegatte S, 2013, NAT CLIM CHANGE, V3, P802, DOI [10.1038/nclimate1979, 10.1038/NCLIMATE1979] Hansen J, 2011, ATMOS CHEM PHYS, V11, P13421, DOI 10.5194/acp-11-13421-2011 Ishii M, 2009, J OCEANOGR, V65, P287, DOI 10.1007/s10872-009-0027-7 Kosaka Y, 2013, NATURE, V501, P403, DOI 10.1038/nature12534 Leuliette EW, 2009, GEOPHYS RES LETT, V36, DOI 10.1029/2008GL036010 Leuliette EW, 2011, OCEANOGRAPHY, V24, P122 Llovel W, 2011, GLOBAL PLANET CHANGE, V75, P76, DOI 10.1016/j.gloplacha.2010.10.008 Loeb G. N., 2012, NATURE GEOSCI, V5, P110 Meehl GA, 2011, NAT CLIM CHANGE, V1, P360, DOI 10.1038/NCLIMATE1229 Nerem RS, 2010, MAR GEOD, V33, P435, DOI 10.1080/01490419.2010.491031 Nicholls RJ, 2010, SCIENCE, V328, P1517, DOI 10.1126/science.1185782 Peltier WR, 2004, ANNU REV EARTH PL SC, V32, P111, DOI 10.1146/annurev.earth.32.082503.144359 Stocker T.F., 2013, CLIMATE CHANGE 2013 Trenberth K. E., 2013, EARTHS FUTURE Trenberth KE, 2005, CLIM DYNAM, V24, P741, DOI 10.1007/s00382-005-0017-4 Trenberth KE, 2010, SCIENCE, V328, P316, DOI 10.1126/science.1187272 Vergnes JP, 2012, HYDROL EARTH SYST SC, V16, P3889, DOI 10.5194/hess-16-3889-2012 von Schuckmann K, 2011, OCEAN SCI, V7, P783, DOI 10.5194/os-7-783-2011 Willis JK, 2008, J GEOPHYS RES-OCEANS, V113, DOI 10.1029/2007JC004517 Cazenave, Anny Dieng, Habib-Boubacar Meyssignac, Benoit von Schuckmann, Karina Decharme, Bertrand Berthier, Etienne CNES; CNRS; Meteo France; University of Toulon; ESA CCI project This work was supported by CNES, CNRS, Meteo France, The University of Toulon and the ESA CCI project. 1 NATURE PUBLISHING GROUP LONDON NAT CLIM CHANGEPresent-day sea-level rise is a major indicator of climate change(1). Since the early 1990s, sea level rose at a mean rate of similar to 3.1 mm yr(-1) (refs 2,3). However, over the last decade a slowdown of this rate, of about 30%, has been recorded(4-8). It coincides with a plateau in Earth's mean surface temperature evolution, known as the recent pause in warming(1,9-12). Here we present an analysis based on sea-level data from the altimetry record of the past similar to 20 years that separates interannual natural variability in sea level from the longer-term change probably related to anthropogenic global warming. The most p...

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