Oxygen isotopic analysis and absolute dating of deep-sea cores show that temperatures as high as those of today occurred for only about 10% of the time during the past half million years. The shortness of the high temperature intervals (“hypsithermals”) suggests a precarious environmental balance, a condition which makes man's interference with the environment during the present hypsithermal extremely critical. This precarious balance must be stabilized if a new glaciation or total deglaciation is to be avoided.
Reconstruction of the salinity history associated with movements of mangrove fishes using otolith oxygen isotopic analysis