Ondrej wrote:Higher CO2 levels are beneficial for plants especially in very dry areas and we are currently seeing a greening of the earth (CO2 fertilization effect) https://www.nasa.gov/feature/goddard/20 ... ing-earth/
This is what one of my friends said:
A friend wrote:I completely agree with the article's premise that increases in carbon dioxide will (and does) lead to an increase in vegetation in a natural, unmanaged state - the earth is far better at addressing the imbalances we've created than humans ever could be.
However, I think the title that the earth is 'greener' is misleading in several ways - the article only states that "a quarter to half of Earth’s vegetated lands has shown significant greening over the last 35 years". So what is happening in the other half to three quarters of land? I think this article sweeps over the problem of human interference with land and vegetation, and the reality that we are actually losing valuable vegetation and tree coverage at an alarming rate due to largescale agricultural farming etc across the world. I'm sure that you, and those you are in conversation with, are aware of the significant rate of deforestation in the amazon and elsewhere.
Also this article seems to suggest that even the greening effect is less than we had thought:
The article wrote:One source of uncertainty in climate science is how the carbon fertilization effect (CFE) will contribute to mitigation of anthropogenic climate change. Wang et al. explored the temporal dynamics of CFE on vegetation photosynthesis at the global scale. There has been a decline over recent decades in the contribution of CFE to vegetation photosynthesis, perhaps owing to the limiting effects of plant nutrients such as nitrogen and phosphorus. This declining trend has not been adequately accounted for in carbon cycle models. CFE thus has limitations for long-term mitigation of climate change, and future warming might currently be underestimated.
the article only states that "a quarter to half of Earth’s vegetated lands has shown significant greening over the last 35 years". So what is happening in the other half to three quarters of land?
I can only speculate but given that these are vegetated lands already I am guessing that nothing has happened to the other half to three quarters of land. Higher CO2 concentration has a much more pronounced beneficial effect in arid regions. Plants have to open pores in their leaves to absorb CO2, when they do this they lose water through evaporation. So, increases in CO2 allow plants to absorb CO2 more quickly, letting the plants close the pores and preserve water. This enables plants to live in drier regions. It makes sense that increased CO2 may not have the same greening effect everywhere. It also make sense that in regions that are lush already, a slight increase in CO2 though still beneficial, does not have a measurable impact because our measurement techniques are rather crude (e.g. satellite images). Given these considerations it is actually quite surprising that the greening effect is measurable on a quarter to half of the vegetated land.
Also this article seems to suggest that even the greening effect is less than we had thought:
This is akin to "don't believe your lying eyes". In the previous discussion we are talking about actual observed greening.
