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Warming over the last decade hidden below ocean surface

 

Richard P. Allan1, Norman Loeb2 & co-authors

1 Department of Meteorology/NCAS-Climate, University of Reading, 2 NASA Langley Research Centre

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Dr Richard Allan is a lecturer at the Department of Meteorology in the University of Reading. He works on the global water cycle and how this may change in the future.

What are the new findings?

We have detected a continued build-up of heat in Earth’s oceans, below the sea surface, since the year 2000. This suggests that the planet is steadily accumulating heat at the rate of 0.5 Watts for each metre squared of the globe (equivalent to the heating from 250 billion 1 kilowatt electric heaters spread over the planet).

Why are these findings important?

Increasing greenhouse gases are causing an imbalance between the amount of sunlight absorbed by Earth and the thermal radiation emitted back to space which is causing the climate to warm. However, warming at the surface appears to have slowed down over the last decade (see diagram, right). Our new findings show that heat is continuing to build up below the sea surface; this means global warming has actually not slowed down.

How did we discover this?

We combined satellite measurements of radiative energy at the top of Earth's atmosphere with ocean observations below the sea surface to estimate the heat entering the planet since 2000. In collaboration with scientists from the USA including from NASA we carefully accounting for margins of error in the data and found that fluctuations in the energy entering the top of the atmosphere and building up in the oceans agreed, and varied in accordance with the known climate phenomena, El Niño Southern Oscillation (large changes in temperature in the Pacific ocean affecting global rainfall patterns which occurs every 2 to 7years).

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Above: Global surface temperature has been increasing since 1950 but warming in the last decade (circled) has slowed.

 Find out more:

  • Read more...
  • see Richard Allan's webpage
  • Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
  • Take a look at the Journal article
Loeb et al. (2012) Nature Geoscience, doi:10.1038/ngeo1375
 

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This research was funded by the Natural Environment Research Council under the PREPARE project.