Recent cyclic changes in climate and in abundance of marine life

Abstract

FLUCTUATIONS in temperature and rainfall are important to agriculture and human populations^1–6, and there is increasing interest in the possibility of forecasting future oscillations of climate on the basis of their apparent connection with more accurately predictable phenomena such as the sunspot cycle and planetary tidal cycles^7–11. A large part of the solar energy budget of the Earth is mediated through the surface of the oceans¹², and it is well established that interaction between the sea, the sea currents and the atmosphere has important meteorological consequences and may also have direct or indirect effects on fisheries^13–16. During the 1930s several attempts were made to link variations in solar radiation with biological and chemical events in the sea, such as the yield of certain North Atlantic fisheries and the quantity of algal nutrients present^17–19. Tentative predictions made then were clearly ahead of their time, but the longer marine biological records now accumulating show signs of both secular and short period fluctuations which seem to be related in some way to corresponding cyclic fluctuations in sea temperature, and through these, to the solar and other cycles which have been discussed recently in connection with terrestrial biological cycles^6,5,20.