Indicator Assessment

Sea surface temperature

Indicator Assessment

Prod-ID: IND-100-en

Also known as: CSI 046 , CLIM 013

Published 20 Dec 2016 Last modified 11 May 2021

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Topics: Climate change adaptation Water and marine environment

This page was archived on 04 Dec 2019 with reason: Other (New version data-and-maps/indicators/sea-surface-temperature-3/assessment was published)

All European seas have warmed considerably since 1870, and the warming has been particularly rapid since the late 1970s. The multi-decadal rate of sea surface temperature rise during the satellite era (since 1979) has been between 0.21 °C per decade in the North Atlantic and 0.40 °C per decade in the Baltic Sea.
Globally averaged sea surface temperature is projected to continue to increase, although more slowly than atmospheric temperature.

Annual average sea surface temperature anomaly

Running average of 11 years

Data sources:

HadISST1 - Global sea ice and Sea Surface Temperature analyses provided by
Mediterranean Sea - High Resolution L4 Sea Surface Temperature Reprocessed provided by Copernicus Marine Environment Monitoring Service

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Past trends

The production of consistent, long time series of SST faces challenges owing to different measurement devices (in situmeasurements from ships and buoys, as well as remote measurements from satellites), associated different definitions (e.g. water depth and time of day of measurement), different bias correction methods, and different interpolation methods to account for incomplete spatial and temporal coverage. As a result, substantially different values for absolute SST and for SST trends may be reported for a particular ocean basin, depending on the underlying global or regional SST dataset. In fact, there is still considerable uncertainty about the trend in global SST for the recent period 1979–2012 [i]. Furthermore, observed SST trends for regional seas reflect the combined effects of anthropogenic warming and natural climate variability (e.g. Atlantic Multidecadal Oscillation) [ii]. Despite those uncertainties, it is undisputed that SST has been increasing globally and in Europe during the last century.

The current indicator primarily uses information from the Hadley Centre Sea Ice and Sea Surface Temperature (HadISST1) dataset [iii]. Information on the Mediterranean for the satellite era is complemented by data from the Copernicus Marine Environmental Monitoring Service (CMEMS). The trends, although not necessarily the absolute SST levels, are consistent between HadISST1 and available high-resolution SST datasets for the regional seas (Mediterranean Sea, Baltic Sea and North Sea). The trends reported here cannot be directly compared with those in previous versions of this indicator, which used different underlying datasets.

All European seas have warmed considerably since 1870, and the warming has been particularly rapid since the late 1970s (Figure 1). The multi-decadal rate of SST rise during the satellite era (1979–2015) has been between 0.21 °C per decade in the North Atlantic and 0.40 °C per decade in the Baltic Sea.

Projections

It is very likely that globally averaged ocean temperatures at the surface and for different ocean depths will further increase in the near-term and beyond. Owing to the thermal inertia of the ocean, global SST is projected to rise more slowly than atmospheric temperature [iv]. Quantitative SST projections are available only for some regional seas in Europe [v]. For the Baltic Sea, the increase in summer SST during the 21st century under medium to high emissions scenarios is projected to be about 2 °C in the southern parts and about 4 °C in the northern parts [vi]. An increase in harmful algal blooms, with increased risks to human health, ecosystems and aquaculture, has been projected for the North Sea and the Baltic Sea as a result of the projected warming [vii].

[i] D. L. Hartmann et al., ‘Observations: Atmosphere and Surface’, inClimate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, ed. T. F. Stocker et al. (Cambridge; New York: Cambridge University Press, 2013), 159–254, http://www.climatechange2013.org/report/full-report/, Table 2.6.

[ii] Diego Macias, Elisa Garcia-Gorriz, and Adolf Stips, ‘Understanding the Causes of Recent Warming of Mediterranean Waters. How Much Could Be Attributed to Climate Change?’,PLOS ONE 8, no. 11 (27 November 2013): e81591, doi:10.1371/journal.pone.0081591.

[iii] N. A. Rayner et al., ‘Improved Analyses of Changes and Uncertainties in Sea Surface Temperature Measured in Situ since the Mid-Nineteenth Century: The HadSST2 Dataset’,Journal of Climate 19, no. 3 (February 2006): 446–69, doi:10.1175/JCLI3637.1.

[iv] B. Kirtman et al., ‘Near-Term Climate Change: Projections and Predictability’, inClimate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, ed. T. F. Stocker et al. (Cambridge; New York: Cambridge University Press, 2013), 953–1028, http://www.climatechange2013.org/images/report/WG1AR5_Chapter11_FINAL.pdf.

[v] Macias, Garcia-Gorriz, and Stips, ‘Understanding the Causes of Recent Warming of Mediterranean Waters. How Much Could Be Attributed to Climate Change?’; Guillem Chust et al., ‘Biomass Changes and Trophic Amplification of Plankton in a Warmer Ocean’,Global Change Biology 20, no. 7 (July 2014): 2124–39, doi:10.1111/gcb.12562.

[vi] HELCOM, ‘Climate Change in the Baltic Sea Area: HELCOM Thematic Assessment in 2013’, Baltic Sea Environment Proceedings (Helsinki: Helsinki Commission, 2013).

[vii] Patricia M. Glibert et al., ‘Vulnerability of Coastal Ecosystems to Changes in Harmful Algal Bloom Distribution in Response to Climate Change: Projections Based on Model Analysis’,Global Change Biology 20, no. 12 (1 December 2014): 3845–58, doi:10.1111/gcb.12662.

Supporting information

Indicator definition

Trend in average sea surface temperature anomaly in the global ocean and in Europe’s regional seas

Units

Temperature (°C)

Rationale

Justification for indicator selection

Sea surface temperature (SST) is an important physical characteristic of the oceans. SST varies naturally with latitude, being warmer at the equator and coldest in Arctic and Antarctic regions. As the oceans absorb more heat, SST will increase (and heat will be redistributed to deeper water layers).

Increases in SST can lead to an increase in atmospheric water vapour over the oceans, influencing entire weather systems. For Europe, the North Atlantic Ocean plays a key role in the regulation of climate over the European continent by transporting heat northwards and by distributing energy from the atmosphere into the deep parts of the ocean. The Gulf Stream and its extensions, the North Atlantic Current and Drift, partly determine weather patterns over the European continent, including precipitation and wind regimes. One of the most visible physical ramifications of increased temperature in the ocean is the reduced area of sea ice coverage in the Arctic polar region.

Temperature is a determining factor for the metabolism of species, and thus for their distribution and phenology, such as the timing of seasonal migrations, spawning events or peak abundances (e.g. plankton bloom events). There is an accumulating body of evidence suggesting that many marine species and habitats, such as cetaceans in the North Atlantic Ocean, are highly sensitive to changes in SST. Increased temperature may also increase stratification of the water column. Such changes can have a significant influence on vertical nutrient fluxes in the water column, thereby influencing primary production and phytoplankton community structure. Further changes in SST could have widespread effects on marine species and cause the reconfiguration of marine ecosystems.

Scientific references

IPCC, 2013. Climate Change: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T. F., D. Qin, G.-K. Plattner, M. Tignor, S. K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P. M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.

Policy context and targets

Context description

In April 2013, the European Commission (EC) presented the EU Adaptation Strategy Package. This package consists of the EU Strategy on adaptation to climate change (COM/2013/216 final) and a number of supporting documents. The overall aim of the EU Adaptation Strategy is to contribute to a more climate-resilient Europe.

One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which will be achieved by bridging the knowledge gap and further developing the European climate adaptation platform (Climate-ADAPT) as the ‘one-stop shop’ for adaptation information in Europe. Climate-ADAPT has been developed jointly by the EC and the EEA to share knowledge on (1) observed and projected climate change and its impacts on environmental and social systems and on human health, (2) relevant research, (3) EU, transnational, national and subnational adaptation strategies and plans, and (4) adaptation case studies.

Further objectives include Promoting adaptation in key vulnerable sectors through climate-proofing EU sector policies and Promoting action by Member States. Most EU Member States have already adopted national adaptation strategies and many have also prepared action plans on climate change adaptation. The EC also supports adaptation in cities through the Covenant of Mayors for Climate and Energy initiative.

In September 2016, the EC presented an indicative roadmap for the evaluation of the EU Adaptation Strategy by 2018.

In November 2013, the European Parliament and the European Council adopted the 7^th EU Environment Action Programme (7^th EAP) to 2020, ‘Living well, within the limits of our planet’. The 7^th EAP is intended to help guide EU action on environment and climate change up to and beyond 2020. It highlights that ‘Action to mitigate and adapt to climate change will increase the resilience of the Union’s economy and society, while stimulating innovation and protecting the Union’s natural resources.’ Consequently, several priority objectives of the 7^th EAP refer to climate change adaptation.

Targets

No targets have been specified.

Methodology

Methodology for indicator calculation

The current indicator primarily uses information from the Hadley Centre Sea Ice and Sea Surface Temperature (HadISST1) dataset. Information on the Mediterranean for the satellite era is complemented by data from the Copernicus Marine Environmental Monitoring Service (CMEMS).

Methodology for gap filling

Not applicable

Methodology references

Rayner et al. (2006): Improved analyses of changes and uncertainties in sea surface temperature measured in situ since the mid-nineteenth century: The HadSST2 dataset. Rayner, N. A., Brohan, P., Parker, D. E., Folland, C. K., Kennedy, J. J., Vanicek, M., Ansell, T. J. and Tett, S. F. B., 2006, 'Improved analyses of changes and uncertainties in sea surface temperature measured in situ since the mid-nineteenth century: The HadSST2 dataset', Journal of Climate 19(3), 446–469 (doi: 10.1175/JCLI3637.1).
CMEMS: Mediterranean Sea - High Resolution L4 Sea Surface Temperature Reprocessed (SST_MED_SST_L4_REP_OBSERVATIONS_010_021). For the Mediterranean Sea- the CNR has reprocessed Pathfinder V5.2 (PFV52) AVHRR data over period Nov 1981-Dec 2012 to provide with daily gap-free maps (L4) at the original PFV52 resolution at 0.0417° x 0.0417°. The data are interpolated through an Optimal Interpolation algorithm.

Uncertainties

Methodology uncertainty

Not applicable

Data sets uncertainty

In general, changes related to the physical and chemical marine environment are better documented than biological changes. For example, systematic observations of sea surface temperature began around 1880. More recently, these manual measurements have been complemented by satellite-based observations that have a high resolution in time and a wide geographical coverage, as well as by Argo floats that automatically measure temperature and salinity below the ocean surface. In contrast, the longest available time series of plankton from the Continuous Plankton Recorder (CPR) is around 60 years. Sampling was started in the North Sea in the 1950s and today a network covering the entire North Atlantic Ocean has been established.

Our understanding is improving of how climate change, in combination with the synergistic impacts of other stressors, can cause regime shifts in marine ecosystems, but additional research is still needed to untangle the complex interactions and their effects upon biodiversity. Ecological thresholds for individual species are still only understood in hindsight, i.e. once a change has occurred.