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Global warming is worse than we thought, according to a study that claims temperature readings in the southern hemisphere have been inaccurate.

The US research suggests that we have been sucking up more than twice as much of the heat created by greenhouse gases than previously believed.

Scientists have now recommended increasing estimates of the rate of ocean warming by between 48 per cent and 152 per cent.

Scientists at Lawrence Livermore National Laboratory in California claim climate change is worse than believed because temperature data in southern hemisphere has been inaccurate. Pictured are is a robotic profiling float which has been used to provide more accurate data on ocean temperature in recent years

Ocean warming is a key marker for global warming as they can store more than 90 per cent of man-made excess heat. Warmer oceans are also connected to rising sea levels.

Lawrence Livermore National Laboratory scientists used satellite observations to uncover long-term ocean warming in the upper 2,300ft (700 metres) of Southern Hemisphere oceans, and found old data was inaccurate.

'This underestimation is a result of poor sampling prior to the last decade and limitations of the analysis methods that conservatively estimated temperature changes in data-sparse regions,' said oceanographer Paul Durack, lead author of the study.

The team also looked at direct and inferred sea temperature measurements and compared this with the results of climate models.

This map details some of the predicted affects of climate change in different continents. Researchers now claim global warming could be much worse than we have anticipated

Together, the three types of measurements together added up for the Northern hemisphere, but the southern hemisphere showed a different picture

The study covered a period from 1970 to 2003, in which the northern hemisphere had been well charted by cargo ships, but during that time few measurements have been taken in the south.

Since 2004, automated profiling floats have been used to measure global ocean temperatures from the surface down to 6,560ft (2,000 metres).

These 3,600 Argo floats currently observing the global ocean are providing systematic coverage of the Southern Hemisphere for the first time.

Argo float measurements over the last decade, as well as data from earlier measurements, show that the ocean has been gradually warming, according to Professor Durack.

Scientists have now recommended increasing estimates of the rate of ocean warming by 48 to 152 per cent

'Prior to 2004, research has been very limited by the poor measurement coverage,' he said.

'By using satellite data, along with a large suite of climate model simulations, our results suggest that global ocean warming has been underestimated by 24 to 58 per cent.

'The conclusion that warming has been underestimated agrees with previous studies, however it's the first time that scientists have tried to estimate how much heat we've missed.'

Given that most of the excess heat associated with global warming is in the oceans, this study has important implications for how scientists view the Earth's overall energy budget, Professor Durack added.

The new results are consistent with another new paper that appears in the same issue of Nature Climate Change.

Co-author Felix Landerer, who works at Nasa and contributed to both studies, said: 'Our other new study on deep-ocean warming found that from 2005 to the present, Argo measurements recorded a continuing warming of the upper-ocean.

'Using the latest available observations, we're able to show that this upper-ocean warming and satellite measurements are consistent.'