The climate models predicting the future of the planet have been imagining the natural carbon cycle. The real future may be very different.
Scientists have thought that the total bioproductivity on Earth is about 120 billion tons per dry carbon. Almost all of this carbon comes from atmospheric carbon dioxide. Subtracting from this amount the carbon released from the soil due to the decay of organic remains (87 billion tons per year), we obtained the amount of carbon bound to the biosphere per year (roughly 33 billion tons per year). Based on this parameter, the rate of growth of the CO2 concentration in the Earth’s atmosphere was estimated.
It seems now that the calculations are inaccurate. It is most likely that the terrestrial bioproductivity is underestimated by modern observational methods.
Scientists still have no answers to many basic questions about the Earth’s biosphere. For example, in 2018 it was discovered that the area of forests is not declining but, on the contrary, growing. Recently, it became known that the area burned by fires in the world is not increasing, but decreasing. Both of these discoveries are made by satellite observations.
However, satellite observations also are limited. For example, their images distinguish forest from field or savannah quite reliably, but do not allow appreciating the specific bioproductivity – in tons per hectare – of a particular forest or any other biome.
Errors are possible with this methodology. Estimating carbon dioxide emissions from soil is not easier: there are even more reasons for error.
New estimates using new method show that the real bioproductivity on the planet is 149 billion tons per year, not 120 billion tons as previously thought. Soil carbon emissions are 68 billion tons per year, not 87 billion.
The reason of errors may be the underestimation by satellites of a number of important factors. For example, it is difficult to assess the development of undergrowth in forests with closed crowns, without taking into account its biomass, it is easy to get an error.
The work may indicate that the biosphere binds anthropogenic carbon dioxide emissions faster than thought. Consequently, the contribution to this binding by non-biogenic factors – such as CO2 uptake by seawater or rocks – may not be as large as we thought.
However, the most interesting part of the study is that terrestrial life, has been seriously underestimated in terms of bioproductivity.
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