Global temperature has (possibly, no one is really sure) risen by about half of one degree over the last hundred years.
Given that seals have survived the last several million years of climate changes, varying from ice ages to periods considerably warmer than now, their ability to survive this miniscule change is hardly surprising.
Unless you are a raving climate catastrophist who looks for horror stories around every corner. In which case you would have been pleasantly suprised by growing numbers of protected Russian seals. Or horribly disappointed.
In further news, disobedient sea otters and polar bears also continue to increase in number.