Global greening

Cael et al. used 20 years of satellite data to measure changes in the color of the oceans. They are getting greener as the result of more phytoplankton (microscopic plants and bacteria that live in the upper layer of the ocean). Phytoplankton form the base of – and sustain – the aquatic food web.

Global climate-change trends detected in indicators of ocean ecology
https://www.nature.com/articles/s41586-023-06321-z
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Land areas are also getting greener. From NASA:

Carbon Dioxide Fertilization Greening Earth


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Zhu et al. also used long-term satellite data to study the increase in global vegetation. Only 4% showed browning – decreasing LAI (leaf area index). Their attribution work on the causes of global greening found the following percentages:

Increased CO2      70%
N deposition        9
Warming             8
Land cover changes  4

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Remote Sensing | Free Full-Text | Greening and Browning Trends on the Pacific Slope of Peru and Northern Chile (mdpi.com)

This paper has been parroted by more than 20 sources. Most of those simply repeat the same clickbait title.

That paper presents no conclusion other than the one stated in their first observation.

They discuss method, findings and conclusion which is, put simply: “It’s getting greener.”

The “not good news” is a click bait phrase.

If you are an arid climate plant or animal and your primary sustainment relies on drier environments to keep competition down or to reduce fungal or other parasitic load, getting greener (wetter) could be bad news.

They postulate that CO2, moisture loading and temperature are possible inputs to the greening. I can almost see them sitting there in a contemplative head’s scratching state saying “…and we don’t know much else…”

There is no conclusion pointing to anything specific or general which is good or bad news.

From the discussion section:

"Although it is possible to subdivide the 20-year study period into 10 or 5 years and study short-term trends, this yields different results depending on how the period has been divided. The calculation method itself is skewed by the starting year: the result will be higher than real life if the starting year had relatively less vegetation. This could be the case if the period coincided with a particularly dry phase in the El Niño cycle. It is also possible that the observed 20-year trend is an anomalous phenomenon within much longer climatic cycles. As satellite data only cover the period from the 1980s, alternative datasets indicating vegetation changes would be needed to indicate whether these recent trends are part of such longer-term cycles or the consequence of more recent anthropogenic climate change. However, this result can form part of the basis of our interpretation of greening and browning trends in natural systems on the Pacific slope for which long-term study is required to monitor and confirm."

"Exploring causality for this phenomenon is problematic since, as one moves south, the greening strip ascends, which would seem counterintuitive. That is, plant productivity would be expected to decline as temperature declines with increasing altitude and latitude, temperature being a primary limiting factor in photosynthesis.

The increase in global CO2 contributes to the globally observed greening phenomenon and could account for greening inside and outside of the defined strip, but this cannot explain the shorter-term regionally determined fluctuations in EVI.

We must, therefore, look to moisture availability, the third driver in vegetation growth. Figure 11 and Table 3 show the correlations between the 20-year trend in EVI within the greening strip and sea surface temperature (SST), precipitation and global CO22 concentrations over the same time period.

Remote Sensing | Free Full-Text | Greening and Browning Trends on the Pacific Slope of Peru and Northern Chile (mdpi.com)

The paper presents a great observation and a nice use of satellite imagery. It will be a good support for other findings in data.

There were no conclusions offered except that, “It’s greener now than most years in the past 20 years”.

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That is for good reason as the world is more complicated than people often expect.

The argument climate change apologists like to make is that higher CO2 increases crop yields. This means global warming is a good thing so let’s keep burning coal. Oddly, however, they always leave out (as in the OP) something long known to plant biologists, increasing CO2 reduces protein and mineral content in plant tissue. That means you get more crops of poorer nutritive quality. It is estimated that rising CO2 levels will have a net negative effect on global nutrition by midcentury. https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(19)30108-1/fulltext

Crops with less protein means that the pest insects will have to eat more plant material to be satiated. Rising temperatures also means that these pests have shorter development times and so will undergo more generations during the year. That’s why many predict an increase in pest pressure on crops. And while CO2 stimulates crop growth it shouldn’t be ignored that it also stimulates weeds. Hence predictions that global warming will significantly increase the use of chemical pesticides and herbicides.

Rising CO2 may be greening the globe, but the impact on agriculture is uncertain and will be region dependent. It’s complicated.

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