Drought stalls tree growth and shuts down Amazon carbon sink

[OKIsItJustMe]

http://www.exeter.ac.uk/news/featurednews/title_527669_en.html

[font face=Serif][font size=5]Drought stalls tree growth and shuts down Amazon carbon sink[/font]

[font size=4]A recent drought completely shut down the Amazon Basin’s carbon sink, by killing trees and slowing their growth, a ground-breaking study led by researchers at the Universities of Exeter and Leeds has found.[/font]

[font size=3]Previous research has suggested that the Amazon – the most extensive tropical forest on Earth and one of the “green lungs” of the planet – may be gradually losing its capacity to take carbon from the atmosphere. This new study, the most extensive land-based study of the effect of drought on Amazonian rainforests to date, paints a more complex picture, with forests responding dynamically to an increasingly variable climate.

…

By using long-term measurements from the RAINFOR network spanning nearly a hundred locations across the Amazon Basin, the team was able to examine the responses of trees. In both the first drought and the second the Amazon temporarily lost biomass. But while both droughts killed many trees, the 2010 drought also had the effect of slowing the growth rates of the survivors, suggesting that many trees were adversely affected but not to the point of death.

Lead author Dr Ted Feldpausch, senior lecturer in Geography at the University of Exeter, said: “The first large-scale, direct demonstration of tropical drought slowing tree growth is extremely important. It tells us that climate changes not only increase the rate of loss of carbon dioxide to the atmosphere, by killing trees, but also slow down the rate of uptake. And yet, the Amazon clearly has resilience, because in the years between the droughts the whole system returned to being a carbon sink, with growth outstripping mortality.”

…

Date: 6 July 2016[/font][/font]

[yallerdawg]

1. Carbon sinks -reforestation and such - may save us!

Scrubbing out the greenhouse gas carbon dioxide and pumping out oxygen? What could be better?

[OKIsItJustMe]

2. Unfortunately, they don’t act all that quickly

We need to lower CO₂ levels quite quickly, and in the distant past intact ecosystems seem to be able to do that at the rate of about 1 ppm/millennium.

We need to lower them ≥ 50 ppm in about as many years.

[NNadir]

5. Well, happily the future of perovskite solar cells is brighter, rain or no rain. How many more...

Last edited Sat Jul 23, 2016, 09:16 AM - Edit history (2)

..."solar breakthroughs" do you think it will take to stop carbon dioxide increases to step away their highest rate ever? How many more will be required to make the world carbon neutral?

In my twelve years here, I must have heard of thousands of "solar breakthroughs," often from people who announced that the world's largest, by far, source of climate change energy, nuclear energy, was no damned good.

Do you have any quantitative estimate of what would be involved in removing 50 ppm of CO2 from the planetary atmosphere.

The, um, question has been the subject of quite a large discussion in the scientific literature, and, um, it's not promising. Here's an example:

Economic and energetic analysis of capturing CO2 from ambient air. (Proceedings of the National Academy of Science PNAS December 20, 2011 vol. 108 no. 51 20428–20433)


Whence is the energy to overcome the entropy of mixing going to come? Solar pervoskite cells laced with benzothiophenes and fluorocarbons?

The problem is that no one is serious about removing carbon dioxide from the atmosphere, and since the issue is so technically challenging, one would need to mobilize a seriousness that would need to go far beyond benchtop experiments that are announced as "breakthroughs."

[NickB79]

6. The scale of reforestation needed is out of our reach now

We'd need to start converting massive amounts of farmland back to forest, and with global population projected to hit 10 billion in the next 50 years, we are not going to start doing that.

[yallerdawg]

7. I don't agree at all.

The Industrial Revolution and mass deforestation for commercial purposes is only a couple centuries old. Not even a blip on the timescale of ecological history.

Most people are living in urban sprawls and megalopolis concentrations.

With a concerted will we can reverse our wasteful use of space and create offsetting green carbon sinks which can suck up the higher levels of carbon dioxide, the greenhouse gas heating us up - while pumping out more oxygen.

With or without us - it will balance out.

Of course, scaring the shit out of people may be the only way for us to be a part of the inevitable rebalancing.

[NickB79]

8. Even if we could do that, sequestration via reforestation would take millenia to reduce CO2

Natural processes can scrub CO2 at a rate of approximately 1ppm per thousand years.

We're at least 50 ppm above sustainable levels, and rising at 3-4ppm per YEAR at this point. Humanity might honestly be extinct by the time reforestation effectively stops climate change.

And in fact, reforestation to combat global warming has been studied, and the results are not good: https://www.newscientist.com/article/dn20587-planting-forests-wont-stop-global-warming/

To get a fuller picture, Vivek Arora of Environment Canada and the University of Victoria, British Columbia, and Alvaro Montenegro of St Francis Xavier University in Antigonish, Nova Scotia, Canada, used a computer model to estimate the overall effect of reforesting.

They used what they admit are “somewhat extreme” scenarios in which half or all of the world’s croplands have been converted to forests by 2060. Foresting all or half the world’s cropland reduced global temperatures in 2100 by 0.45 °C and 0.25 °C respectively.

Arora reckons that no more than 10 to 15 per cent of existing cropland is likely to be forested, so the effects will be even smaller. “The overall temperature benefits of any realistic afforestation efforts are expected to be marginal,” he says.

So, reforesting ALL of the world's cropland would reduce global temps by less than 0.5C by 2100. To put that in perspective, we're already 1C above pre-industrial levels.

[Nihil]

9. ... and, in addition to Nick's post, there is one key phrase in the whole of your post:

> With a concerted will we can reverse our wasteful use of space and
> create offsetting green carbon sinks which can suck up the higher levels
> of carbon dioxide, the greenhouse gas heating us up - while pumping out
> more oxygen.

"With a concerted will".

Even a simple scan of the headlines on any given day shows that this is
not going to happen.

If there is no "concerted will" to stop people killing, maiming & generally causing
pain to each other, no "concerted will" to stop the exponential growth in population
(despite the obvious fate of the children being born in most cases), no "concerted
will" to rebalance the obscene differential in wealth & living standards - all of which
affect millions of people every day - then there is no chance of getting any
"concerted will" focussed on a problem whose true impact is yet to hit home and
which will require total cooperation for *decades* to even turn around.

[Bill USA]

3. extremely significant finding. The prognosis keeps getting worser and worser.

[nitpicker]

4. Link to BBC article

http://www.bbc.com/news/science-environment-36856428