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Indicator Assessment
Ocean heat content calculated based on observations made in the upper 700 m of the water column
Note: Ocean heat content is defined as the integrated temperature change times the density of seawater, times specific heat capacity from the surface down to the deep ocean.
Data provenance info is missing.
Past trends
The warming of the World Ocean accounts for approximately 90 % of the warming of the Earth during the last 6 decades [i].
Figure 1 shows that the heat content of the World Ocean has increased since around 1970. The linear trend over the whole time series 1955–2010 of the uppermost 700 m and 2 000 m layer was 0.27 Wm-2 and 0.39 Wm-2 (per unit area of the World Ocean), respectively. Two thirds of the observed increase of global heat content has occurred in the upper 700 m of the ocean, with increases in the layers below 700 m depth accounting for the remaining one third [ii]. Heat content has increased in all major sea basins of the World Ocean, in particular in the Atlantic Ocean.
Several global ocean data assimilation products are available to compare observation-based estimates with independent reanalysis data. Global and basin-scale heat content warming trends in the upper 700 m of the ocean computed from a set of global ocean reanalyses fall within the range of the most recent observation-based estimates derived using different methods [iii].
Projections
Projections of OHC are very uncertain and are hence not included here.
[i] John A. Church et al., „Revisiting the Earth’s sea-level and energy budgets from 1961 to 2008“, Geophysical Research Letters 38, Nr. 18 (September 16, 2011), doi:10.1029/2011GL048794; J. Hansen et al., „Earth’s energy imbalance and implications“, Atmospheric Chemistry and Physics 11, Nr. 24 (Dezember 22, 2011): 13421–13449, doi:10.5194/acp-11-13421-2011; S. Levitus et al., „World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010“, Geophysical Research Letters 39, Nr. 10 (Mai 17, 2012), doi:10.1029/2012GL051106.
[ii] J.E. Dore et al., „Physical and biogeochemical modulation of ocean acidification in the central North Pacific“, Proceedings of the National Academy of Sciences 106 (2009): 12235–12240., doi:10.1073/pnas.0906044106; S. Levitus u. a., „Global ocean heat content 1955–2008 in light of recently revealed instrumentation problems“, Geophysical Research Letters 36, Nr. 7 (April 11, 2009), doi:10.1029/2008GL037155; Levitus et al., „World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010“; Sarah G. Purkey and Gregory C. Johnson, „Warming of global abyssal and deep southern ocean waters between the 1990s and 2000s: Contributions to global heat and sea level rise budgets“, Journal of Climate 23, Nr. 23 (Dezember 2010): 6336–6351, doi:10.1175/2010JCLI3682.1.
[iii] John M. Lyman et al., „Robust warming of the global upper ocean“, Nature 465, Nr. 7296 (Mai 2010): 334–337, doi:10.1038/nature09043; Simona Masina u. a., „Global ocean re-analyses for climate applications“, Dynamics of Atmospheres and Oceans 52, Nr. 1–2 (September 2011): 341–366, doi:10.1016/j.dynatmoce.2011.03.006.
Observed change in global ocean heat content
Ocean heat content (Joule)
In April 2013 the European Commission presented the EU Adaptation Strategy Package (http://ec.europa.eu/clima/policies/adaptation/what/documentation_en.htm). This package consists of the EU Strategy on adaptation to climate change /* COM/2013/0216 final */ and a number of supporting documents. One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which should occur through Bridging the knowledge gap and Further developing Climate-ADAPT as the ‘one-stop shop’ for adaptation information in Europe. Further objectives include Promoting action by Member States and Climate-proofing EU action: promoting adaptation in key vulnerable sectors. Many EU Member States have already taken action, such as by adopting national adaptation strategies, and several have also prepared action plans on climate change adaptation.
The European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT, http://climate-adapt.eea.europa.eu/) to share knowledge on observed and projected climate change and its impacts on environmental and social systems and on human health; on relevant research; on EU, national and subnational adaptation strategies and plans; and on adaptation case studies.
No targets have been specified.
Ocean heat content is defined as the integrated temperature change times the density of seawater, times specific heat capacity from the surface down to the deep ocean. It is calculated here base on observations from the upper 700 metres of ocean water.
The warming of the world ocean since 1955 is estimated using different kinds of observational data: historical data not previously available, additional modern data, correcting for instrumental biases of bathythermograph data, and correcting or excluding some Argo float data.
Not applicable
Not applicable
Ocean temperature data are sparse in the polar and subpolar regions of the world. In general, however, changes related to the physical and chemical marine environment are better documented than biological changes because links between cause and effect are better understood and often time series of observations are longer. For example, systematic observations of both sea-level and sea surface temperature were started around 1880 and are today complemented by observations from space that have high resolution in time and geographical coverage and by Argo floats that also automatically measure temperature and salinity below the ocean surface.
Further information on uncertainties is provided in Section 1.7 of the EEA report on Climate change, impacts, and vulnerability in Europe 2012 (http://www.eea.europa.eu/publications/climate-impacts-and-vulnerability-2012/)
No uncertainty has been specified
For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/ocean-heat-content/assessment or scan the QR code.
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