Change in land use, and increased oxidation of nitrogen could explain the long term steady decline in atmospheric O2, and may well also account for the sharp acceleration of the downward trend since 2002 and 2003.

These years happen to coincide with record rates of deforestation. In Brazil, 10 000 square miles were lost mainly to pasture land, soybean plantations and illegal logging, a 40 percent rise over the previous year [14]. Massive deforestation has continued in the Amazon and elsewhere, spurred by the biofuels boom [15]; it is estimated that nearly 40 000 ha of the world’s forests are vanishing every day.

The crucial role of forests and phytoplankton [4] in oxygenating the earth shows how urgent it is to take oxygen accounting seriously in climate policies. Reductionist accounting for CO2 alone is insufficient, and even grossly misleading and dangerous.

A case in point is the proposal of the International Biochar Initiative (IBI). ‘Biochar’ is charcoal produced to be buried in the soil that IBI has been promoting worldwide over the past several years [16] as a means of sequestering carbon from the atmosphere to save the climate and enhance soil fertility. It involves planting fast growing tree and various other crops on hundreds of millions of hectares of ‘spare land’ mostly in developing countries, to be harvested and turned into charcoal in a process that could produce crude oil and gases as low grade fuels. There are many excellent arguments against this initiative [17], but the most decisive is that it will certainly further accelerate deforestation and destruction of other natural ecosystems (identified as ‘spare land’). In the process, it could precipitate an oxygen crisis from which we would never recover [18] (Beware the Biochar Initiative, SiS 44).