Satellite observations of global sea-surface temperature show that a 30-year upward trend has slowed down within the last 15 years. Climate scientists say this is not the end of global warming, but the result of a rearrangement in the energy flow of the climate system and, in particular, how the ocean stores heat.

Like flying thermometers, some satellites carry instruments that provide a global view of the surface temperature of oceans and seas. Measuring the sea-surface temperature is important for improving weather and ocean forecasting and climate change research.

Satellite and local readings show that sea-surface temperature has been rising rapidly since the 1970s, in line with the overall warming of our planet. But this increase has significantly slowed in the last 15 years.

In contrast, other variables such as increasing atmospheric carbon dioxide, rising sea levels and declining Arctic sea ice have not experienced the same reduction in trend and therefore demonstrate that Earth’s climate continues to change.

Scientists have speculated that one of the causes of this ‘plateau’ in sea-surface temperature could be a change in the exchange of ocean water between warm, surface waters and cold, deep waters below 700 m – as if the warming is ‘hiding’ underwater. Temperature measurements at this depth cover a relatively short period.

But the warm water won’t hide below the surface forever: scientists believe that it may re-emerge later or affect other climate indicators, such as sea level or ocean circulation.