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Recent Nasa Report: Humans Are Causing The Greening Of The Earth

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I think that the net effect of agriculture on atmospheric carbon dioxide levels is relatively negligible. 


Why would you think that?  What would the effect be if man just concreted over the entire surface of the earth and never again planted an agricultural plant, ya figure?

Edited by Moronium
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The population estimate is a little overblown, but the underlying premise is valid.
More than 60% of the world's population depends on agriculture
Also, according to FAO, more than 60 percent of the world’s population depends on agriculture for survival. So if the population is about 7 billion now and grows to 9 billion in 2015, 12 percent of the total available land, or about 1.5 billion hectares, would be used for agricultural crops.

Ninety percent of this land is found in Latin America and sub-Saharan Africa with half of the 90 percent concentrated in seven countries: Brazil, Democratic Republic of the Congo, Angola, Sudan, Argentina, Colombia and Bolivia. Agricultural production, globally, has been growing at a rate of between two and four percent annually over the past 50 years, while arable land has increased by only one percent per year. Farmland, in the broadest sense, i.e. land used for crops, grazing, livestock and arable land, takes up 37.6 percent of the total land available compared to forestland at 31.1 percent. In this scenario, FAO stresses, climate change poses a major challenge to the future of agriculture, an unprecedented, in that it must cope with rising temperatures, humidity and lack or scarcity of water resources; all in a context where the population continues to grow.
There’s another interesting aspect of the agricultural sector which is indicated in the "Statistical Yearbook" of the United Nations is connected to labor. Agriculture has the highest incidence of unpaid child labor, starting from the ages of between five and seven years old, and the sector with the youngest minimum work entry age.  One example illustrates the issue: about 60 percent of workers under the age of 18, of which 129 million children, are in found in the agricultural sector.
Despite the dependency and non-substitutability of agriculture within the world economy, between 2009 and 2011, this sector has counted for only 2.9 percent of increase in growth of the   global GDP (while the industrial sector accounted for about 25.3 percent growth and the services sector accounted for a 71.8 percent increase). The differences at the continental level, however, are more evident with a growth of 14 percent in Africa, 5.9 percent in Latin America, 5 percent in Asia, 10 percent in China, and just 1.6 percent in Europe, 1.2 percent in the U.S. and 3.3 percent in Oceania. 
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All very interesting, fahr, but pretty much a non-sequitur with respect to the question asked.


Here's another interesting aspect about plants as they relate to climate change.  According to American Chemical Society, Water is the largest contributor to the greenhouse effect, and constitutes about 95% of the greenhouse gases in the atmosphere.  On the surface, anyway, it would seem that the less water vapor in the air, the less warming.


In addition to serving to sequester carbon, plants can also capture and retain more water if co2 levels rise from other factors.


Rising CO2 is causing plants to release less water to the atmosphere, researchers say


BLOOMINGTON, Ind. -- As carbon dioxide levels have risen during the last 150 years, the density of pores that allow plants to breathe has dwindled by 34 percent, restricting the amount of water vapor the plants release to the atmosphere, report scientists from Indiana University Bloomington and Utrecht University in the Netherlands in an upcoming issue of the Proceedings of the National Academy of Sciences (now online).


Most plants use a pore-like structure called stomata (singular: stoma) on the undersides of leaves to absorb carbon dioxide from the air.  Stomata also allow plants to "transpire" water, or release water to the atmosphere. Transpiration helps drive the absorption of water at the roots, and also cools the plants in the same way sweating cools mammals.


While it is well known that long-lived plants can adjust their number of stomata each season depending on growing conditions, little is known about the long-term structural changes in stomata number or size over periods of decades or centuries  That model suggests that a doubling of today's carbon dioxide levels -- from 390 parts per million to 800 ppm -- will halve the amount of water lost to the air, concluding in the second paper that "plant adaptation to rising CO2 is currently altering the hydrological cycle and climate and will continue to do so throughout this century."





Since the amount of water in the atmosphere is much greater than co2, this sounds like a net decrease in warming to me.


Nature  has it's ways of balancing things out.  Many have suggested that an increase in co2 is highly desirable insofar as it could greatly increase crop yields  and photosynthesis in addition to the crops retaining co2 and water.

Edited by Moronium
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More about plants, photosynthesis and respiration from Physics.org:


Under warmer conditions, plants can take up more carbon dioxide by using carbon more efficiently for growth, shows a new study.


Plants take in – or 'fix' – carbon dioxide from the atmosphere during photosynthesis. Some of the carbon is used for plant growth, and some of it is used in respiration, where the plant breaks down sugars to get energy.


The balance between the release of carbon dioxide (CO2) during respiration and fixation of carbon during photosynthesis affects the growth of the plant. Over the globe, this balance also affects the global carbon balance – how much is stored in living things compared to free in the atmosphere. The faster the rate of photosynthesis relative to respiration, the greater the rate at which atmospheric carbon is 'sucked in' by ecosystems. By using more CO2 for growth, plants are 'fixing' more CO2 from the atmosphere as they lock it up in their leaves and stems.


Previously, scientists had measured the simple ratio between photosynthesis and respiration rate at a given temperature to estimate plant responses. However, the team have discovered a third fundamental factor that determines the ratio, called the 'carbon allocation efficiency'.  This factor determines what happens after the CO2 is taken in during photosynthesis – whether it is used for growth or respiration. The team found that as temperatures rise, plants can allocate more carbon for growth, effectively improving their net carbon gain....They also looked across diverse plant species, both on land and in water, and concluded that a warming-induced increase in carbon allocation efficiency is a general phenomenon


"Our study provides a new way to better predict the effect of warming on carbon fixation by individual plants, and ultimately whole ecosystems."




It seems like they're coming up with new realizations requiring alteration of the models all the time, eh?


And here I thought this was all "settled science" 20 years ago, ya know?

Edited by Moronium
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Models overestimate CO2


The new study estimates that over the past 110 years some climate models over-predicted the amount of CO2 that remains in the atmosphere, by about 16%....In this new study, the authors may have come up with a reason that explains why some models overestimate CO2 in the atmosphere.


It is well established that as CO2 in the atmosphere increases, the rate of photosynthesis increases...But the new study shows that models may not have quite right the way they simulate photosynthesis. The reasons comes down to how CO2 moves around inside a plant’s leaf.


Models use the CO2 concentration inside a plant’s leaf cells, in the so called sub-stomatal cavity, to drive the sensitivity of photosynthesis to increasing amounts of CO2. But this isn’t quite correct.  The new study shows that CO2 concentrations are actually lower inside a plant’s chloroplasts — the tiny chambers of a plant cell where photosynthesis actually happens. This is because the CO2 has to go through an extra series of membranes to get into the chloroplasts.


This means that photosynthesis takes place at lower CO2 than models assume.... plants are removing more CO2 in response to increasing emissions than models show.


It is a great, neat piece of science, which connects the intricacies of leaf level structure to the functioning of the Earth system. We will need to re-examine they way we model photosynthesis in climate models and whether a better way exists in light of the new findings.





How is it possible to discover anything new when you're talking about "settled science," I wonder?

Edited by Moronium
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