SD, sorry, but they have not established that gulls eat more gull eggs when Sea Surface Temperature increases.  What they have established if their measurements are correct as to gull cannibalism and Sea Surface Temperature is that over one particular time period over which gull cannibalism increased, the sea surface temperature also increased (by apparently 0.1 degree).  No causal connection was established.  There is no evidence to suggest that gull cannibalism might not decrease with additional temperature increases.  Since almost all temperatures have increased in the last 30 years, we can expect to see that anything that happened in the last 30 years is correlated with temperature increase.  For example, crime rates have dropped in the last 30 years.  We can conclude that climate change may be driving reduced crime.  There is virtually no scientific merit to simply noting, without causal analysis, that disparate things happened during the same time period.