Scientists have suggested that burying trees might solve the global carbon dioxide (CO2) problem.
Of the current global environmental problems, the excessive release of carbon dioxide from the combustion of fossil fuels and the related global warming is one of the most pressing.
"Whereas other environmental problems can, at least in principle, be solved by the appropriate modern technology, there are no realistic solutions for the CO2 problem," said Fritz Scholz from the University of Greifswald in Germany.
At present, a daunting 32 gigatons of CO2 are released into the atmosphere every year. Previous proposals to pump the CO2 into the oceans are not practicable or are ecologically problematic.
But, according to Scholz and Ulrich Hasse from the University of Greifswald, the only possible way to bind sufficiently large quantities of CO2 from the atmosphere is photosynthesis.
However, the resulting biomass cannot be burned or composted, because this would release the bound CO2.
The trick will be to make the biomass "disappear".
Scholz recommends planting forests whose wood will subsequently be buried.
His idea involves deliberately planted forests that bind the CO2 through photosynthesis and are then removed from the global CO2 cycle by burial.
Possible burial sites include open brown coal pits or other surface mines. These should be filled with wood and covered with soil.
Cut off from the air in this manner, the wood would not change, even over long periods. It could in principle be dug up in the future and used.
"For the first time, humankind will give something back to nature that we have taken away before," said Scholz.
According to estimations made by Scholz and Hasse, a little over one billion hectares of forest needs to be planted in order to bind all of the carbon dioxide produced in a year.
"The forests should be planted in countries that are suitable for growing forest and also have the necessary sites for burial of the wood," sadi Scholz.
"Other countries, the primary consumers of fossil fuels, can pay them for it. This would produce a global trade that would benefit everyone involved," he added.