Here is a recent finding reported by BBC:

European forests are showing signs of reaching a saturation point as carbon sinks, a study has suggested.

Since 2005, the amount of atmospheric CO2 absorbed by the continent’s trees has been slowing, researchers reported.

Writing in Nature Climate Change, they said this was a result of a declining volume of trees, deforestation and the impact of natural disturbances.

Carbon sinks play a key role in the global carbon cycle and are promoted as a way to offset rising emissions.

via BBC News – European forests near ‘carbon saturation point’.

Read more here about why such reduction of nature’s ability to store the extra carbon emitted through human activities will have serious consequences.

One of the reasons for the current building up of carbon in the atmosphere is that the natural systems, which can normally handle and stow away such extra carbon are being destroyed. Carbon levels in nature have always fluctuated. Massive volcano outbursts have often added carbon dioxide to the atmosphere, but over the next years land vegetation, oceans and soils would accumulate the extra carbon and levels would soon be back to the normal level again.

This is possible when the natural systems are healthy and as long as the extra carbon is not overwhelming.

Conditions nowadays are neither of the two. The amounts of extra carbon pumped into the atmosphere are staggering. Humans have over the last one and a half century burned maybe one third of the easily accessible fossil fuels – coal, gas and oil. This corresponds to releasing to the atmosphere an amount of carbon which it took nature maybe 100 million years to accumulate (fossil fuels formed when organic matter was compressed at high temperatures over long periods in the Earth’s crust).

The part about sound natural systems is just as bad. The healthy vegetation that should be able to absorb extra carbon is in a serious crisis itself. Most of our planet’s forests have over the centuries been cleared for agricultural areas, and most of our agricultural systems are of a kind that deplete the soil more and more. Amounts of humus, which is the long-term carbon storage compound in the soil, are decreasing in the huge monoculture fields of agribusiness, so less and less carbon is stored there. In no way can such systems take up the extra carbon our consumer society is spitting out.

Oceans could then do the job. At least they are much more difficult for humans to destroy because they are so huge. But in spite of this, scientists can measure that they take up less and less atmospheric carbon, even though the amount to take from increases.

So, there is no way out. We will need to find carbon neutral energy production  methods and agricultural systems that build up a carbon rich soil.