Assessment versions
Published (reviewed and quality assured)
Rationale
Justification for indicator selection
Relevance
Sea surface temperature (SST) is closely linked to one of the strongest drivers of climate in western Europe: the ocean circulation known as the Atlantic Meridional Overturning Circulation (MOC). This circulation (also known as the great conveyor belt) carries warm upper waters north in the Gulf Stream and returns cold deep waters south. It is widely accepted that the MOC is an important driver of low frequency variations in sea surface temperature on the time scale of several decades (Griffies et al., 1997). It is also widely accepted that the NAO index (a proxy of atmospheric circulation variability) plays a key role in forcing variations in MOC as well as the northward extent of the Gulf Stream (Frankignoul and Kestenare, 2005; De Coetlogon et al., 2006). At present, changes in sea surface temperatures of the global ocean and the regional seas of Europe are consistent with the changes in atmospheric temperature (Levitus et al., 2000; Rayner et al., 2006).
The sensitivity of the MOC to greenhouse warming, however, remains a subject of much scientific debate. Observations indicate that there has indeed been a freshening of the North Atlantic since 1965 due to increased freshwater inputs from rivers, precipitation and melting glaciers (Curry and Mauritzen, 2005), and thus possibly a weakening of the Atlantic MOC. The freshening calculated by these authors occurred mainly before 1970 and does not yet appear to have substantially altered the MOC and its northward heat transport. Uncertainties regarding the rates of future climate warming and glacial melting limit the predictability of the impact on ocean circulation, but do not exclude the possibility of a weakening of the MOC. Recent observations, have, however, shown that the variability of the MOC is large. The yearlong average MOC is 18.7 ± 5.6 Sverdrup (Note: Sverdrup = 10
6 m
3s
-1) but with large variability ranging from 4.4 to 35.3 Sverdrup (Cunningham et al., 2007). A recent study has shown that the variability of the MOC may be predictable on decadal time scales, and the study predicts that North Atlantic and European sea surface temperatures will fall slightly in the next decade as natural climate variability off-sets the projected anthropogenic warming (Keenlyside et al., 2008). The plausibility of the Keenlyside et al., 2008 projections are, however, also subject to intense debate in the scientific community (see e.g.
http://www.realclimate.org).
One of the most visible ramifications of increased temperature of the ocean is the reduced area of sea ice coverage in the Arctic polar region and there is an accumulating body of evidence suggesting that many marine ecosystems are responding both physically and biologically to changes in regional climate caused predominantly by the warming of air and SST, as shown in the following sections.
Scientific references
- No rationale references available
Policy context and targets
Context description
In April 2009 the European Commission presented a White Paper on the framework for adaptation policies and measures to reduce the European Union's vulnerability to the impacts of climate change. The aim is to increase the resilience to climate change of health, property and the productive functions of land, inter alia by improving the management of water resources and ecosystems. More knowledge is needed on climate impact and vulnerability but a considerable amount of information and research already exists which can be shared better through a proposed Clearing House Mechanism. The White Paper stresses the need to mainstream adaptation into existing and new EU policies. A number of Member States have already taken action and several have prepared national adaptation plans. The EU is also developing actions to enhance and finance adaptation in developing countries as part of a new post-2012 global climate agreement expected in Copenhagen (Dec. 2009). For more information see: http://ec.europa.eu/environment/climat/adaptation/index_en.htm
Targets
No targets have been specified
Related policy documents
No related policy documents have been specified
Data specifications
EEA data references
- No datasets have been specified here.
External data references
Data sources in latest figures
Further work
Short term work
Work specified here requires to be completed within 1 year from now.
Long term work
Work specified here will require more than 1 year (from now) to be completed.
Identification
Indicator code
CSI 046
CLIM 013
Specification
Version id: 1
First draft created:
Publish date:
Last modified:
Classification
DPSIR: Impact
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
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