Computer simulations of global climate have shown that the planet’s oceans can mask the presence of global warming for as much as ten years.
Ocean layers deeper than 300 metres absorb enough heat to flatten the apparent rate of global warming for long periods, despite the level of greenhouse gas in the atmosphere increasing in such periods.
Satellite measurements showed that the discrepancy between incoming sunshine and radiation leaving the earth increased, showing that while global temperature appeared to stay constant, it was still, in fact, on the rise.
Read more at Bureau of Meteorology (Aus.) & National Centre for Atmospheric Research (US)