Ponds around the world can absorb as much carbon as the world's oceans, according to the latest study, good news for attempts to tackle climate change.

For example, ponds and lakes on US farmland alone bury carbon 20 to 50 fold more than trees trap carbon. In addition, ponds were found to take up carbon at a higher rate than larger lakes.

'Aquatic ecosystems play a disproportionately large role in the global carbon budget. Despite being overlooked in the past, it's small bodies of water that are important because they take up carbon at a high rate,' said John Drowning of Iowa State University, who led the research team.

'The combined effect is that farm ponds could be burying as much carbon as the world's oceans each year.'

The study estimates there are 304 million natural lakes and ponds in the world, covering an area of 4.2 million square km, twice the area previously thought. The bulk of these water bodies are two acres or less in area.

The work has been published in the latest issue of Global Biogeochemical Cycles.

The study team included members from Europe, the US and Canada. The work was sponsored by the National Centre for Ecological Analysis and Synthesis and the Iowa Department of Natural Resources.