New Study: 2001-2020 ‘Global Greening Is An Indisputable Fact’ And It’s Driven By CO2 Fertilization

“Our results showed that the global greening was still present in 2001–2020, with 55.15% of areas greening at an accelerated rate…compared with 7.28% of browning.” – Chen et al., 2024

The CO2 fertilization effect has been dominant driver of the global-scale increase in “leaf area index” (LAI), or greening, since the 1980s. Scientists have estimated that CO2’s photosynthesis-enhancing capacity is 70% responsible for the greening trend (Zhu et al., 2016).

Using Advanced Very High Resolution Radiometer (AVHRR) data sources of questionable quality, some recent studies have suggested the greening trend has slowed or has even been reversed to browning since the 21st century began. As suggested, these data sources “should be used in caution” (Chen et al., 2024) as it is “well known that AVHRR-based NDVI and LAI have multiple sources of uncertainty,” such as “obvious artificial signals from the orbital drift.”

Using much more reliable MODIS data, scientists (Chen et al., 2024) can now say the LAI trend in the 21st century is robustly positive, and that 2001-2020 “global greening is an indisputable fact.”

The satellite data indicate 55.15% of global areas are greening “at an accelerated rate,” whereas just 7.28% have undergone a browning trend since 2001.

CO2 fertilization is still the dominant (75.63%) driver of Earth’s 21st century greening trend. Any drought trends in recent decades cannot overtake the positive CO2 fertilization effect, as all drought can do is slightly slow down the acceleration of the CO2-induced greening trend.