Global Warming: Vulnerability, Carbon Sinks, Numbers, Replenishment, & Getting Burned

Amazon Rainforest as a Significant but Highly Vulnerable Global Climate Tipping Element // Aug 27, 2019

The Amazon Rainforest is one of the very significant yet vulnerable tipping elements in the overall climate system. Willful human destruction of the rainforest by slash-and-burn techniques (trees are toppled by chainsaw or tractors with chains, allowed to dry out, and are then torched) is behind 99% of the present fires, according to some accounts. In this first of a series of 5 videos, I wade through the science and attempt to determine the most accurate numbers on the Amazon Rainforest impact as a carbon sink and oxygen producer, in the overall global context.
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Vital Significance of Amazon Rainforest as Carbon Sink // Aug 27, 2019

How significant, on a global scale, is the Amazon Rainforest? Best I can tell, correct annual numbers are: Tropical rainforests account for 34% of land-based global photosynthesis; Amazon Rainforest is almost half that, namely 16%. Total oxygen produced by land-based photosynthesis is 330 Pg, thus Amazon is 54 Pg. Ocean phytoplankton oxygen production is 240 Pg. Total global photosynthesis is 330 + 240 = 570 Pg of oxygen (58% land, 42% ocean). Amazon produces 54/570=9.5% of total global oxygen; with carbon sink being 9.5% of global plant total sink.
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Amazon Rainforest: Crunching the Numbers // Aug 27, 2019

As far as I can tell in my analysis, the most accurate numbers on carbon sink and oxygen production sizes for the Amazon Rainforest in a global photosynthesis context are in a blog by ecologist Yadvinder Malhi, which I discuss in detail within this series of 5 videos (this one is 3/5). If the entire Amazon Rainforest was to collapse (burn) then about 90 Pg of carbon would be released to the atmosphere (adding about 40 ppm, an increase of almost 10% of our present 415 ppm), using up 240 Pg of oxygen (a very small 0.02% of the oxygen level in the atmosphere).
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We Need to Plant Many New Amazon Equivalents, Not Destroy Our Existing One // Aug 27, 2019

If the entire Amazon burned down, a release of 90 Pg of carbon to the atmosphere, equivalent to a 40 ppm rise in atmospheric CO2, was mentioned in the previous video description based on Yadvinder Malhi blog. By the same token, if people on Earth got their act together and planted a new Amazon (about 390 billion trees, estimated from Amazon Wikipedia) this would drawdown about 40 ppm (90 Pg) or 10% of atmospheric concentration. At present, atmospheric CO2 rises 2-3 ppm/year, so 40 ppm is only between13-20 years worth of global emissions.
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Playing with Amazon Fire will get us all Burned // Aug 27, 2019

According to the Wiki on Amazon Rainforest: “In 2018 about 17% of the Amazon Rainforest was already destroyed. Research suggests that upon reaching about 20-25% (hence 3-8% more), the tipping point to flip it into non-forest ecosystems – degraded savannah – (in eastern, southern and central Amazonia) will be reached.” Given 3 recent century scale droughts in the Amazon Rainforest in 2005, 2010, and 2015-2016, and slash-and-burn human practices accelerating again, we are quite literally playing with fire in a game we cannot win.
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About paulbeckwith

Well known climate science educator; Part-time Geography professor (climatology, oceanography, environmental issues), University of Ottawa. Physicist. Engineer. Master's Degree in Science in Laser Optics, Bachelors of Engineering, in Engineering Physics. Won Association of Professional Engineers of Ontario gold medal. Also interested in investment and start-ups in climate solutions, renewable energy and energy efficiency. Avid chess player, and likes restoring old homes. Married with children.
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1 Response to Global Warming: Vulnerability, Carbon Sinks, Numbers, Replenishment, & Getting Burned

  1. Ronald says:

    2) In your Amazon series of videos you mention the publication by Zemp et al., (2017) that there would be a kind of deforestation tipping point, beyond which the Amazon rainforest keeps desiccating and dying back (self-amplified loss), because of vegetation-atmosphere feedbacks, the evapotranspiration feedback cycle. I have read similar hypotheses several times over the years.
    However, apart from the fact that I, of course, hope, that this will not happen, how can this hypothesis be reconciled with the fact that even during the Last Glacial Maximum (LGM) there was a residual Amazon rainforest, be it greatly reduced, from where it dispersed again after the last ice age. Apparently, there is a part of the Amazon (western?, north-western?) that is less susceptible to this vegetation-atmosphere feedback cycle. I would think, that this region should then be top priority for conservation.


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