Different analyzes have shown that the plants absorbed lower amounts of carbon dioxide than expected. This implies that more stringent measures are needed to reduce our CO2 emissions and limit global warming.
Fertilization effect declining faster than expected
Although increasing levels of carbon dioxide in the atmosphere since the start of the industrial age have stimulated plant growth in recent decades, this ” fertilization effect “Tends to decline faster than expected, according to new work published in the journal Science.
Living organisms are made of carbon chains, and plants get this carbon from CO2 present in the air. When the latter have sufficient water and nutrients (especially nitrogen and phosphorus) to support them, high concentrations of CO2 generate additional growth. This explains why the land and the oceans have long continued to absorb half of the carbon dioxide produced by human activities.
Carried out on several sites around the world, this recent research suggests that the fertilization effect wears off quickly when other limits, partly conditioned by climate change, come into play. They have thus observed that in forests of ‘eucalyptus in Australia, low phosphorus levels resulted in a marked attenuation of the effect, also observed in areas with large decreases in precipitation.
Following the analysis of various satellite recordings, Yongguang Zhang, of the’nanjing university (China), and colleagues around the world have concluded that the fertilization effect is declining faster than computer models predicted, with an overall decline of around 50% since 1982.
New grim estimates
” This study based on multiple data sources reveals a significant decrease in the fertilization effect on a global scale », Note Ranga Myneni of the’boston university. ” Which means greater reductions in greenhouse gas emissions will be needed to meet climate targets.. “
In order to estimate the extent to which this decrease in plant uptake capacity is likely to affect warming in the decades to come, the Met Office (UK National Meteorological Service) has taken into account its impact on the entire carbon cycle.
” Our analyzes show that when these parameters are taken into account, the warming range is considerably wider than what is generally reported. “, Explain Richard betts. ” Emissions scenarios consistent with current global policies could lead to global warming well above 4 ° C by the end of the century. “