Puffin' Up The Global Warming Angle

Robin McKie, the Guardian's science editor, has an article up about declines in British sea bird populations.

Fair to say then that it's pretty standard Guardian fare, not only because of the (allegedly) impending apocalypse, but also because of the lack of citations to back the alarming claims up.The claims about puffins are particularly interesting, because just a few days ago, the Guardian reported on a survey of the puffin population in the Farne Islands, quoting a warden on the islands as follows:

Initial findings are concerning. Numbers could be down due to stormy or wetter weather as well as changes in the sand eel population, which is one of their staple foods.

Others reported the same thing:

Puffin numbers are 'halved by the Beast from the East': England's biggest colony is devastated by prolonged and severe winter weather.

So, not so much "global warming" as an extended period of bad weather in the North Sea.But what about those sand eels? It was once relatively undisputed that sand eel fishing was having a devastating effect on all these species, but as far as I can tell, the fisheries were closed long ago. This of course gives the Guardian the chance to bring in our old friend Global Warming again.

[Sand eel stocks] have now been disrupted again by global warming, triggered by rising carbon dioxide emissions from factories, cars and power plants that burn fossil fuels. Temperatures in the North Sea and North Atlantic have risen significantly as a result.

Significantly, eh? Last time I dipped a toe in the North Sea, it didn't seem obviously warmer than I remembered them, and unfortunately the Guardian gives no source for their claim. However, a quick glance at the HadSST map of sea surface temperatures suggests that the seas around Shetland are currently up between zero and 0.2°C warmer than the long-term average. Those in the North Sea are slightly warmer than that.Sensitive souls, these sand eels.But there's another problem with the story that the bird population changes are caused by Global Warming. A paper by Scott et al. looks at the relationship between various factors, including temperature, on the annual plankton bloom and the subsequent effect on sand eel and bird populations.

In the spring, increasing amounts of sunlight and less windy conditions allow a decrease in vertical mixing. In those areas which are deep enough or have weaker tidal currents such that the effect of tidal mixing does not reach the surface, the surface layer begins to warm up...This warming creates a difference in density between the upper and lower layers of the water column called stratification...The onset of stratification allows plankton to remain above the critical depth needed for population growth.

So for abundant plankton, and hence abundant sand eels and hence abundant sea birds, you need warmth.  The "Global Warming killed my kittiwakes" story doesn't quite stack up, does it?