Climate Change Impacts

A full description of all the potential impacts of climate change on seabirds in the UK is provided by the MCCIP Annual Report Card and  the MCCIP Ecosystem Linkages Report Card.

Sea-surface temperatures in the north east Atlantic and UK coastal waters have been rising since the 1980s by around 0.2-0.9oC per decade, with the most rapid rises occurring in the southern North Sea and the English Channel1

These rises in sea temperature have already had impacts on seabirds in the UK, mainly through indirect effects via the food chain, on which they rely.  Direct impacts are likely to become more evident in response to projected rises in sea-level and in the frequency of extreme weather. Population declines are likely to result from changes in distribution that are predicted to occur in response to local changes in ambient climate. These issues are discussed in more detail below.

Reversing the recent warming of the oceans is reliant on the success of global efforts to combat climate change. In the short-term a better understanding of the interactions between seabirds and their environment may help to mitigate the impacts of climate change by identifying where other pressures can be most effectively reduced or eliminated.

 

Food chain

Climate-driven changes in the food chain have had acute negative impacts on seabirds breeding on Britain’s North Sea coast.

Rising sea temperatures caused a change in the North Sea plankton community in the late 1980s and consequently large reductions in abundance of the zooplankton on which larval fish feed2. Climate impacts on plankton may be responsible for the association between warmer sea-surface temperatures and poor sandeel productivity3.

Low breeding success of kittiwakes, and of other species that rely on sandeels such as common guillemot, has occurred with increasing frequency in recent years. Kittiwakes in eastern Britain have fledged fewer young in recent, warmer years4,5, which is thought to be linked to the relationship between temperature and sandeel productivity (see above).  

Observations at colonies monitored by the SMP confirmed seabirds were catching fewer and smaller sandeels than normal during years of poor breeding performance.  The calorific content of these sandeels was also much lower in 2004, which was one of the least successful breeding seasons for seabirds overall in recent times6.

Long-term declines in numbers of black-legged kittiwake are expected to continue unless the recent rises in sea-surface temperature are reversed4.

 

Extreme weather

Winter storms can make it difficult for seabirds to forage at sea and can result in reduced survival. At times, this impact can be dramatic and some storms have resulted in large-scale mortality events or 'wrecks',  when large numbers of dead or emaciated seabirds have been washed up on the shore. A recenty study has demonstrated that mortality during storms has had a significant negative effect on the numbers of European shags breeding at a colony in south east Scotland 7

An increase in frequency of extreme weather events, as predicted by climate-change models, could lead to population declines and an increasing probability of extinction of vulnerable species from exposed areas7.

Increased storminess and sea level rise may also reduce available breeding habitat for shoreline-nesting species (e.g. terns).

  

Distribution changes

Most seabird species in the UK are at the southern limit of their range in the Northeast Atlantic, and their distribution is likely to be limited by climate. If this is the case, as the climate in the UK changes we may expect a northwards shift in range, resulting in fewer seabird species breeding in the UK, and a possible change in overall breeding numbers, depending on the availability of nesting sites and food elsewhere. Such changes have been predicted by first describing the ‘climate envelope’ that each species currently occupies in Europe and then predicting how the shape of that envelope, and hence the breeding range of the birds, would change by the last 30 years of the 21st century 8. The climate envelope is a composite of measures of a) winter cold, b) overall warmth of growing season, and c) available moisture. 

This modelling has predicted that by the end of 21st century, changes in climate may mean that great skua and Arctic skua may no longer breed in the UK; and the range of black guillemot, common gull and Arctic tern may shrink so much that only Shetland and the most northerly tips of mainland Scotland would hold breeding colonies8.

The predicted extinction  of great skuas in the UK is of global conservation concern, given that the UK currently holds 60% of the world breeding population.

 

1 Holliday, NP, Kennedy, J, Kent, EC, Marsh, R, Hughes, SL, Sherwin, T & Berry, DI 2008. MCCIP Annual Report Card 2007-2008 Scientific Review - Sea Temperature. Marine Climate Change Impacts Partnership www.mccip.org.uk/arc.

2Beaugrand, G., Brander, K. M., Lindley, A., Souissi, S. & Reid, P. C. 2003.  Plankton effect on cod recruitment in the North Sea. Nature 426: 661-664.

3Arnott, S. A. & Ruxton, G. D. 2002. Sandeel recruitment in the North Sea: demographic, climatic and trophic effects. Mar. Ecol. Prog. Ser. 238: 199-210.

4Frederiksen, M., Harris, M. P., Daunt, F., Rothery, P. and Wanless, S (2004) The role of industrial fisheries and oceanographic change in the decline of North Sea black-legged kittiwakes. Journal of Applied Ecology, 41, 1129-1139.

5 Frederiksen M, Mavor R. A., and  Wanless S 2007. Seabirds as environmental indicators:

the advantages of combining data sets. Mar. Ecol. Prog. Ser.352: 205–211.

6 Wanless, S., Harris, M. P., Redman, P. & Speakman, J. R. 2005. Low energy values of fish as a probable cause of a major seabird breeding failure in the North Sea. Mar. Ecol. Prog. Ser. 294: 1-8.

7Frederiksen, M., Daunt, F., Harris, M.P. & Wanless, S. 2008. Stochastic weather drives survival and population dynamics in a long-lived seabird. Journal of Animal Ecology 77:1020-1029.

8Huntley B., Green R.E., Collingham Y.C. and Willis S.G. 2007. A climatic atlas of European breeding birds. Durham University, The RSPB and Lynx Edicions, Barcelona.