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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1600 on: December 14, 2016, 12:44:31 AM »
The linked reference discusses how current climate models are likely overestimating the amount of negative feedback from fire produced aerosols:

Grandey, B. S., Lee, H.-H., and Wang, C.: Radiative effects of interannually varying vs. interannually invariant aerosol emissions from fires, Atmos. Chem. Phys., 16, 14495-14513, doi:10.5194/acp-16-14495-2016, 2016.

http://www.atmos-chem-phys.net/16/14495/2016/

Abstract. Open-burning fires play an important role in the earth's climate system. In addition to contributing a substantial fraction of global emissions of carbon dioxide, they are a major source of atmospheric aerosols containing organic carbon, black carbon, and sulfate. These “fire aerosols” can influence the climate via direct and indirect radiative effects. In this study, we investigate these radiative effects and the hydrological fast response using the Community Atmosphere Model version 5 (CAM5). Emissions of fire aerosols exert a global mean net radiative effect of −1.0 W m−2, dominated by the cloud shortwave response to organic carbon aerosol. The net radiative effect is particularly strong over boreal regions. Conventionally, many climate modelling studies have used an interannually invariant monthly climatology of emissions of fire aerosols. However, by comparing simulations using interannually varying emissions vs. interannually invariant emissions, we find that ignoring the interannual variability of the emissions can lead to systematic overestimation of the strength of the net radiative effect of the fire aerosols. Globally, the overestimation is +23 % (−0.2 W m−2). Regionally, the overestimation can be substantially larger. For example, over Australia and New Zealand the overestimation is +58 % (−1.2 W m−2), while over Boreal Asia the overestimation is +43 % (−1.9 W m−2). The systematic overestimation of the net radiative effect of the fire aerosols is likely due to the non-linear influence of aerosols on clouds. However, ignoring interannual variability in the emissions does not appear to significantly impact the hydrological fast response. In order to improve understanding of the climate system, we need to take into account the interannual variability of aerosol emissions.


See also the linked article is entitled: "Climate models may be overestimating the cooling effect of wildfire aerosols"

http://news.mit.edu/2016/climate-models-may-be-overestimating-cooling-effect-of-wildfire-aerosols-1129
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1601 on: December 14, 2016, 10:23:23 PM »
The linked article is entitled: "Predicting unpredictability: Information theory offers new way to read ice cores", and it addresses the reference entitled: "A First Step Toward Quantifying the Climate's Information Production Over the Last 68,000 Years," appeared in Advances in Intelligent Data Analysis XV, the proceedings of the 15th International Symposium on Intelligent Data Analysis, Stockholm, Sweden, October 13-15, 2016.

This work demonstrates that the Earth Systems can change more rapidly than prior analysis assumed.

https://www.sciencedaily.com/releases/2016/12/161206125325.htm

Extract: "At two miles long and five inches in diameter, the West Antarctic Ice Sheet Divide (WAIS) ice core is a tangible record of the last 68,000 years of our planet's climate.
Completed in 2011, the core is packed with information, but it's also packed with noise and error, making the climate story hard to read. Figuring out whether blips in the data are evidence of humans spewing carbon into the atmosphere, odd North Atlantic weather events, or equipment malfunctions often challenges the scientists trying to read the ice cylinder's story.

Drawing from information theory, a research team led by Santa Fe Institute Omidyar Fellow Joshua Garland has proposed new, more sophisticated techniques that promise to make ongoing interpretation of the WAIS core easier and extract new kinds of data that could change the way we think about Earth's climate.

"There is information in these records that we didn't know existed until now, and it has opened doors where we didn't even know there was a door before," says James W.C. White, director of the Institute of Arctic and Alpine Research and a collaborator on the project.

In information theory, entropy is a measure of the unpredictability of information content. Permutation entropy essentially is a way to quantify the predictability of a future event.

Imagine an isolated climate system, void of game changers like supervolcanos or humans. Everything you'd need to predict the future climate would be contained in Earth's climate history. When game changers arrive, they inject new information that couldn't have been predicted from the climate's past patterns -- and that should manifest as an increase in permutation entropy (i.e., more unpredictability).

In fact, there are early signs in the WAIS record of an entropy increase roughly 10,000 years ago, at the beginning of the Holocene, suggesting human impacts on our climate began well before the Industrial Revolution.

Confirmation of that finding is pending. Meanwhile, Garland and team have already made two other surprising discoveries using their technique. The first concerns Dansgaard-Oeschger events, during which Greenland rapidly warms during glacial periods, triggering ripple effects throughout the world.

Geoscientists hypothesize that these events begin with some kind of external shock. But when Garland and team looked at another core, the North Greenland Ice Core, there didn't appear to be an increase in permutation entropy -- in other words, no external shock -- suggesting the events are likely part of the climate's standard operating procedure."
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GeoffBeacon

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Re: Conservative Scientists & its Consequences
« Reply #1602 on: December 18, 2016, 02:32:56 PM »
Most of the following is from the Sea Level Rise thread but having looked a TeaPotty's opener I think this might be appropriate here. i.e. Are Myles Allen and Ray Pierre Humbert "conservative scientists"?

My impression is that Myles Allen and Ray Pierrehumbert have been downplaying the role of Short Lived Climate Forcing [SLCF], particularly methane, for some time but it may not be obvious in their paper. (Actually, I read it last week and it did make some things clearer to me. It is well written.)

However, I have worried about their apparent leniency on methane for a few years now. See Now CO2 is short lived, cows really are bad. (I'm a bit embarrassed by the title.) Here I quote Pierrehumbert as saying in  Losing time not buying time

Suppose we are outrageously successful, and knock down anthropogenic methane emissions to zero, which would knock back atmospheric methane to a pre-industrial concentration of around 0.8 ppm… This gives us a one-time cooling of 0.4°C.

And

… since methane responds within a decade to emissions reductions, we still get the full climate benefit of reducing methane even if the actions are deferred to 2040.

In The exit strategy (2009), Myles Allen and others said

Short-term measures that reduce 2020 emissions of potent but short-lived gases but commit to greater emissions of CO2 overall could actually be counterproductive.

Strictly this is correct. “Reduce methane emissions to go easy on carbon dioxide emissions” is dangerous but it has the worrying implication “Concentrate on carbon dioxide, go easy on methane” – a message that may have been transmitted to UK Government Departments. In a reply to me, David Mackay, then Chief Scientist at DECC, wrote “[there is the] competing argument from Myles Allen et. al. that methane has too ‘high’ a rating ”. Myles may have been technically correct in some sense but the wrong message may have been received by the policy makers.

In Cutting soot and methane distracts from 2C goal, says Oxford scientist, Carbon Brief reported

Most countries are focusing on reducing CO2 and [methane and soot] at the same time. But a new policy paper by Myles Allen, professor of geosystem science at the Oxford Martin School at the University of Oxford, says that reducing [methane and soot] while CO2 emissions are still rising could make it more difficult to hit the 2C goal.

If we all consumed much less beef, lamb and dairy, methane emissions would be greatly reduced. I don't see how this would "make it more difficult to hit the 2C goal".

Also, it worries me that warming from SLCFs will have raised sea levels more-or-less independently of the efforts to keep below a peak temperature as discussed by Allen et.al., (However, the sea-level effect does get a small mention.)

Even more, I worry about the risk of positive feedbacks and tipping points not accounted for in the CMIP5 models and earlier models that were used.

Is my worry unreasonable?

P.S.  Why I think we're wasting billions on global warming, by top British climate scientist [Myles Allen] - but this needs more discussion.

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Archimid

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Re: Conservative Scientists & its Consequences
« Reply #1603 on: December 18, 2016, 02:48:06 PM »
P.S.  Why I think we're wasting billions on global warming, by top British climate scientist [Myles Allen] - but this needs more discussion.

That article was written in 2013 and the results were based mostly on the temperature measurements during the "hiatus". They fully expected for the hiatus to continue given the projected low solar cycles. They were wrong.

The next step for them will probably be to say that they were wrong about the warming, but that warming will be good. Of course if the arctic goes  in 2017 they won't be able to use that lie.

Sigmetnow

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Re: Conservative Scientists & its Consequences
« Reply #1604 on: December 26, 2016, 03:04:54 PM »
Katharine Hayhoe: Climate surprise - our stark + sobering @IOPenvironment article has been downloaded 11k times already @bobkopp ...
https://twitter.com/khayhoe/status/812735591775342593

What surprises lurk within the climate system?
Katharine Hayhoe and Robert E Kopp
Aristotle might argue that humans were not responsible for the choices made at the beginning of the Industrial Era, when collective scientific and societal knowledge limited our capacity to choose wisely and well [1]. Regardless of our original ignorance, however, over the last few centuries we have been conducting an unprecedented experiment with the Earth's climate system.

Human society is built on the implicit assumption that climate is largely stationary: that historical records can be used with confidence to determine the energy loads of our buildings, the hundred-year floodplains of our cities, and the growing zones for the crops that power our economy and feed our world. What happens when that assumption is no longer valid?
...
http://iopscience.iop.org/article/10.1088/1748-9326/11/12/120202
People who say it cannot be done should not interrupt those who are doing it.

Shared Humanity

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Re: Conservative Scientists & its Consequences
« Reply #1605 on: December 26, 2016, 06:21:23 PM »
Katharine Hayhoe: Climate surprise - our stark + sobering @IOPenvironment article has been downloaded 11k times already @bobkopp ...
https://twitter.com/khayhoe/status/812735591775342593

What surprises lurk within the climate system?
Katharine Hayhoe and Robert E Kopp
Aristotle might argue that humans were not responsible for the choices made at the beginning of the Industrial Era, when collective scientific and societal knowledge limited our capacity to choose wisely and well [1]. Regardless of our original ignorance, however, over the last few centuries we have been conducting an unprecedented experiment with the Earth's climate system.

Human society is built on the implicit assumption that climate is largely stationary: that historical records can be used with confidence to determine the energy loads of our buildings, the hundred-year floodplains of our cities, and the growing zones for the crops that power our economy and feed our world. What happens when that assumption is no longer valid?
...
http://iopscience.iop.org/article/10.1088/1748-9326/11/12/120202


Shorter Hayhoe and Kopp.....

We're more than likely fucked.

AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1606 on: January 05, 2017, 01:06:24 AM »
The linked article is entitled: "Fossil leaves suggest global warming will be harder to fight than scientists thought", and it presents new evidence about paleo-atmospheric CO₂ concentrations that indicate that climate sensitivity is likely higher than most current climate scientists assume:

http://www.sciencemag.org/news/2017/01/fossil-leaves-suggest-global-warming-will-be-harder-fight-scientists-thought


Extract: "Now, scientists have developed a new method for wringing CO2 estimates from fossilized leaves—one that can go deeper into the past, and with more certainty. “At the moment, it’s very promising and it’s probably the best tool that we’ve got,” says David Beerling, a biogeochemist at the University of Sheffield in the United Kingdom who helped develop the so-called fossil leaf gas exchange technique. Already, it is solving ancient climate puzzles and delivering some unsettling news about the future.

… in applications of the method to times between 100 million and 400 million years ago, Franks finds hints of a foreboding message. During documented episodes of global warmth, he says, the method reveals relatively low CO2 values, nothing like the levels of 2000 ppm or more suggested by other proxies. If these downward revisions hold, Earth may be even more sensitive to injections of CO2 than current models predict. “Temperatures are going to climb further for less carbon and we better be mindful of that,” Franks says."
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1607 on: January 09, 2017, 10:39:54 PM »
The linked reference concludes that:

"We propose that such centennial-millennial productivity/climate variability in the NW Pacific and sequence of sub-stadial/interstadials in the EAM from the LGM to EH are a persistent regional features, synchronous with the Greenland/North Atlantic short-term changes. We speculate that such climate synchronicity was forced also by changes in Atlantic meridional overturning circulation coupled with Intertropical Convergence Zone shifting and the northern westerly jets reorganization." 

Where: EAM = East Asian Monsoon, LGM = Last Glacial Maximum and EH = Early Holocene.

This paleo-evidence of the synchronicity of the ITCZ, the AMOC and the northern westerly jets implies to me that the Earth's climate sensitivity is likely higher than consensus science currently acknowledges:

Gorbarenko et. al. (2016), "Centennial to millennial climate variability in the far northwestern Pacific (off Kamchatka) and its linkage to East Asian monsoon and North Atlantic from the Last Glacial Maximum to the Early Holocene", Clim. Past Discuss., doi:10.5194/cp-2016-102

http://www.clim-past-discuss.net/cp-2016-102/cp-2016-102.pdf
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1608 on: January 11, 2017, 09:30:21 PM »
The linked article is entitled: "Draining huge African peatland a threat to climate: study", such GHG sources are missing from AR5.

https://www.yahoo.com/news/draining-huge-african-peatland-threat-climate-study-195730012.html

Extract: "A swampy forest in central Africa the size of England covers previously unknown carbon stocks equivalent to three years' worth of global CO2 emissions, scientists revealed Wednesday.
Draining these peatlands for agriculture, or reduced rainfall due to climate change, would release massive amounts of planet-warming greenhouse gases, they warned in a study published in Nature magazine.

"We found 30 billion tonnes of carbon that nobody knew was there," said Simon Lewis, co-lead author of the study and a professor at the University of Leeds.

"If the Congo Basin peatlands were to be destroyed, it would release billions of tonnes of CO2 into the atmosphere," he told AFP."

Edit, see also the linked article entitled: "Guest post: Vast carbon store found under Congo swamp forest".

https://www.carbonbrief.org/guest-post-vast-carbon-store-found-congo-swamp-forest
« Last Edit: January 14, 2017, 05:15:55 PM by AbruptSLR »
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jai mitchell

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Re: Conservative Scientists & its Consequences
« Reply #1609 on: January 14, 2017, 07:10:12 PM »
as a follow up to ASLRs last, this sub saharan peat is slated for increased aridity due to climate change impacts.  in this december 2015 published study of CMIP-5 model analyses

Climate change impacts in Sub-Saharan Africa:
from physical changes to their social
repercussions

http://climateanalytics.org/files/ssa_final_published.pdf

desiccation of peat is the primary driver of tropical carbon cycle emissions.
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1610 on: January 15, 2017, 07:32:26 PM »
The linked article is entitled: "It’s time to wake up to the devastating impact flying has on the environment".  Current, and coming, air travel will place higher concentrations of CO₂ into higher altitudes in the atmosphere than AR5 assumes; which will result in faster and stronger radiative forcing than AR5 assumes for this component of anthropogenic forcing.

https://theconversation.com/its-time-to-wake-up-to-the-devastating-impact-flying-has-on-the-environment-70953

Extract: " But here’s the peculiar thing: although no other human activity pushes individual emission levels as fast and as high as air travel, most of us don’t stop to think about its carbon impact.

If citizens remain blissfully unaware of aviation emissions, then airlines and governments are unlikely to do anything about them. Alternatively, if governments ever wish to place a global carbon tax on flights, then they will need to create political “buy-in” from citizens who increasingly see cheap flights as a right."

Edit, see also the following linked article entitled: "How airlines can fly around new carbon rules"

https://www.theguardian.com/environment/2017/jan/16/how-airlines-can-fly-around-new-carbon-rules

Extract: "Aircraft are gradually becoming more fuel efficient, but that’s not happening fast enough to keep up with the boom in flying".
« Last Edit: January 17, 2017, 06:08:14 PM by AbruptSLR »
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1611 on: January 23, 2017, 06:45:50 PM »
The linked article is entitled: "Forests 'held their breath' during global warming hiatus, research shows".  It shows that during periods of rapid warming that carbon uptake by land ecosystems slows down.  Thus raising the likelihood that consensus science may well be over estimating terrestrial carbon uptake for high warming scenarios:

https://phys.org/news/2017-01-forests-held-global-hiatus.html

Extract: "The study shows that, during extended period of slower warming, worldwide forests 'breathe in' carbon dioxide through photosynthesis, but reduced the rate at which they 'breathe out'—or release the gas back to the atmosphere.


However, uncertainties remain about how these ecosystems will respond to future climate change, whether by consuming more carbon or, conversely, releasing greater volumes of carbon back into the atmosphere.

The study focused on Earth's natural carbon cycle responded during both periods of rapid, and less rapid, warming that would normally be expected.

It revealed that the total amount of carbon taken up by land ecosystems slowed during periods of rapid warming, and sped up during periods of slower warming.

More significantly, the team demonstrated that while rates of photosynthesis remained constant during the periods of slower warming, the forests released less carbon back into the atmosphere - meaning the Earth is storing much more carbon during these warming hiatuses."


See the associated reference:

Friedlingstein, P. et. al. (2017) "Accelerating net terrestrial carbon uptake during the warming hiatus due to reduced respiration, Nature Climate Change, doi:10.1038/nclimate3204

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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1612 on: January 23, 2017, 06:50:41 PM »
The linked reference indicates that the terrestrial biosphere is a net source of global warming due to the high impact of methane and nitrous oxide associated with agriculture.  Unless GHG emissions associated with agriculture are reduced quickly, this may mean that AR5 is under estimating likely radiative forcing scenarios:

Hanqin Tian, et. al. (10 March 2016) "The terrestrial biosphere as a net source of greenhouse gases to the atmosphere", Nature, Volume: 531, Pages: 225–228, doi:10.1038/nature16946


http://www.nature.com/nature/journal/v531/n7593/full/nature16946.html

Abstract: "The terrestrial biosphere can release or absorb the greenhouse gases, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), and therefore has an important role in regulating atmospheric composition and climate. Anthropogenic activities such as land-use change, agriculture and waste management have altered terrestrial biogenic greenhouse gas fluxes, and the resulting increases in methane and nitrous oxide emissions in particular can contribute to climate change. The terrestrial biogenic fluxes of individual greenhouse gases have been studied extensively, but the net biogenic greenhouse gas balance resulting from anthropogenic activities and its effect on the climate system remains uncertain. Here we use bottom-up (inventory, statistical extrapolation of local flux measurements, and process-based modelling) and top-down (atmospheric inversions) approaches to quantify the global net biogenic greenhouse gas balance between 1981 and 2010 resulting from anthropogenic activities and its effect on the climate system. We find that the cumulative warming capacity of concurrent biogenic methane and nitrous oxide emissions is a factor of about two larger than the cooling effect resulting from the global land carbon dioxide uptake from 2001 to 2010. This results in a net positive cumulative impact of the three greenhouse gases on the planetary energy budget, with a best estimate (in petagrams of CO2 equivalent per year) of 3.9 ± 3.8 (top down) and 5.4 ± 4.8 (bottom up) based on the GWP100 metric (global warming potential on a 100-year time horizon). Our findings suggest that a reduction in agricultural methane and nitrous oxide emissions, particularly in Southern Asia, may help mitigate climate change."
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1613 on: January 23, 2017, 07:22:35 PM »
The linked reference indicate that current models likely do not accurately represent CO₂ ventilation from the equatorial Pacific (& Atlantic) Ocean(s) during periods of deglaciation.  The reference states: "In addition, both gradual and rapid deglacial radiocarbon changes in these Pacific records are coeval with changes in the Atlantic records.  This in-phase behavior suggest that the Southern Ocean overturning was the dominant driver of changes in the Atlantic and Pacific ventilation during deglacitions."  This does not bode well for our future.

Natalie E. Umling & Robert C. Thunell (2017), "Synchronous deglacial thermocline and deep-water ventilation in the eastern equatorial Pacific", Nature Communications, doi:10.1038/ncomms14203

http://www.nature.com/articles/ncomms14203
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jai mitchell

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Re: Conservative Scientists & its Consequences
« Reply #1614 on: January 23, 2017, 09:23:03 PM »
just a note that this study is not direclty translatable to todays conditions, most of this deeper water is not in saturation with todays (or tomorrows) atmospheric abundance.  As abundance in the atmosphere increases these non-saturated currents will, when exposed to the atmosphere, with extract CO2 from the atmosphere according to the equilibrium equations.
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1615 on: January 23, 2017, 09:47:06 PM »
just a note that this study is not direclty translatable to todays conditions, most of this deeper water is not in saturation with todays (or tomorrows) atmospheric abundance.  As abundance in the atmosphere increases these non-saturated currents will, when exposed to the atmosphere, with extract CO2 from the atmosphere according to the equilibrium equations.


As an additional note, the concentration of CO2 dissolved in deep water is not uniform throughout the ocean, and as indicated in the linked references show that biological interactions result in the Eastern Equatorial Pacific deep water having atypically high concentrations of dissolved CO2.

http://www.sciencedirect.com/science/article/pii/001174717490059X

&

http://www.pnas.org/content/108/14/5537.full

Abstract: "Understanding oceanic processes, both physical and biological, that control atmospheric CO2 is vital for predicting their influence during the past and into the future. The Eastern Equatorial Pacific (EEP) is thought to have exerted a strong control over glacial/interglacial CO2 variations through its link to circulation and nutrient-related changes in the Southern Ocean, the primary region of the world oceans where CO2-enriched deep water is upwelled to the surface ocean and comes into contact with the atmosphere. Here we present a multiproxy record of surface ocean productivity, dust inputs, and thermocline conditions for the EEP over the last 40,000 y. This allows us to detect changes in phytoplankton productivity and composition associated with increases in equatorial upwelling intensity and influence of Si-rich waters of sub-Antarctic origin. Our evidence indicates that diatoms outcompeted coccolithophores at times when the influence of Si-rich Southern Ocean intermediate waters was greatest. This shift from calcareous to noncalcareous phytoplankton would cause a lowering in atmospheric CO2 through a reduced carbonate pump, as hypothesized by the Silicic Acid Leakage Hypothesis. However, this change does not seem to have been crucial in controlling atmospheric CO2, as it took place during the deglaciation, when atmospheric CO2 concentrations had already started to rise. Instead, the concomitant intensification of Antarctic upwelling brought large quantities of deep CO2-rich waters to the ocean surface. This process very likely dominated any biologically mediated CO2 sequestration and probably accounts for most of the deglacial rise in atmospheric CO2. "
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1616 on: January 23, 2017, 11:19:27 PM »
As a follow-up to my last post, the attached image (note that at this location of the ocean the concentration of CO2 in the water is higher than in the atmosphere by a wide margin) comes from the first linked website showing that a TAO buoy at 110W in the Eastern Equatorial Pacific, EEP, shows increasing CO₂ ventilation in 2016 to 2017:

http://www.pmel.noaa.gov/co2/story/TAO+0%C2%B0%2C+110%C2%B0W

Also in the 2014 El Nino? thread, Reply #128 Bruce Steele makes the following statement & provides the second link, indicating the EEP CO₂ ventilation increases during La Nina events, and that the EEP dominates the amount of CO₂ ventilation from the world's oceans:

"The different Co2 content of the upwelled or downwelled water is due to it's different sources. The intermediate water upwelled under normal conditions in the eastern equatorial pacific is older water that has accumulated Co2 due to bacterial decomposition of organic matter. Organic matter is ballasted by calcium carbonate and sinks till it hits the saturation horizon which is at intermediate depths in the pacific. Once the calcium carbonate dissolves the organic surface supplied material is remineralized by bacteria.  The warm water in the graphs above are downwelled in the western pacific. These waters are much younger and haven't spent much time at depth so they don't have the high Co2 content.

Under normal conditions the eastern equatorial pacific contributes about 72% of all oceanic Co2 ventilation. When the warm western supplied water is pushed to the surface by the Kelvin wave is suppresses the cold high Co2 water and because the cold water no longer has surface contact with the atmosphere it stops ventilating. So the immediate effects of an El Nino are a reduction in natural supplies of oceanic derived Co2 but later as drought and terrestrial conditions increase the terrestrial supplies of Co2 dominate."

http://www.pmel.noaa.gov/pubs/outstand/feel1868/feel1868.shtml

Edit: I note that 2016-2017 has had a weak La Nina event and also the thermohaline circulation has slowed in this period.
« Last Edit: January 23, 2017, 11:30:00 PM by AbruptSLR »
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jai mitchell

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Re: Conservative Scientists & its Consequences
« Reply #1617 on: January 24, 2017, 12:08:32 AM »
If this is the case then the pre-industrial rates of co2 venting were much higher than they are today.
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Re: Conservative Scientists & its Consequences
« Reply #1618 on: January 24, 2017, 12:53:38 AM »
If this is the case then the pre-industrial rates of co2 venting were much higher than they are today.


As mentioned previously, the following linked research indicates that global warming can reduce CO₂ uptake in the oceans, particularly in areas with high upwelling (see attached image and following caption), such as the Southern Ocean:

L. E. Pichevin, R. S. Ganeshram, W. Geibert, R. Thunell & R. Hinton, (2014), "Silica burial enhanced by iron limitation in oceanic upwelling margins", Nature Geoscience doi:10.1038/ngeo2181

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2181.html

Abstract: "In large swaths of the ocean, primary production by diatoms may be limited by the availability of silica, which in turn limits the biological uptake of carbon dioxide. The burial of biogenic silica in the form of opal is the main sink of marine silicon. Opal burial occurs in equal parts in iron-limited open-ocean provinces and upwelling margins, especially the eastern Pacific upwelling zone. However, it is unclear why opal burial is so efficient in this margin. Here we measure fluxes of biogenic material, concentrations of diatom-bound iron and silicon isotope ratios using sediment traps and a sediment core from the Gulf of California upwelling margin. In the sediment trap material, we find that periods of intense upwelling are associated with transient iron limitation that results in a high export of silica relative to organic carbon. A similar correlation between enhanced silica burial and iron limitation is evident in the sediment core, which spans the past 26,000 years. A global compilation also indicates that hotspots of silicon burial in the ocean are all characterized by high silica to organic carbon export ratios, a diagnostic trait for diatoms growing under iron stress. We therefore propose that prevailing conditions of silica limitation in the ocean are largely caused by iron deficiency imposing an indirect constraint on oceanic carbon uptake. "

Image Caption: "The distribution of biogenic silica fluxes and molar biogenic silica (Si) to organic carbon (Si/Corg) ratios shows the variability in Si/Corg ratio among a wide range of oceanic provinces. Ocean Data View map and shading are derived from the US Joint Global Ocean Flux study. HNLC regions (dotted white ellipses) and the North East Pacific margin exhibit higher Si/Corg export ratio than the surrounding open ocean. Courtesy: authors and Nature Geoscience"

The following extract comes from the following linked University of Edinburgh news release:

Extract: "Researchers found that those periods when silicon was least abundant in ocean waters corresponded with relatively warm climates, low levels of atmospheric iron, and reduced CO2 uptake by the oceans’ plankton.
Scientists had suspected that iron might have a role in enabling plankton to absorb CO2. However, this latest study shows that a lack of iron at the ocean surface can limit the effect of other key elements in helping plankton take up carbon.
This effect is magnified in the southern ocean and equatorial Pacific and coastal areas."

http://www.ed.ac.uk/news/2014/0606134-oceans

See also:
http://www.nature.com/ngeo/journal/vaop/ncurrent/extref/ngeo2181-s1.pdf
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Bruce Steele

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Re: Conservative Scientists & its Consequences
« Reply #1619 on: January 24, 2017, 05:27:56 AM »


http://www.aoml.noaa.gov/ocd/ocdweb/docs/barbero.pdf

Southern Pacific surface water pCO2 is higher in the Eastern Pacific than the Western Pacific and highest in the late winter and spring. ( see Fig.7  e) pCO2 ). Although part of the year the Southern
Oceans are currently a source averaged over the year the Southern Oceans are a weak sink.
 My comments linked by AbruptSLR relate to the biologically supported transport of surface derived Co2 to intermediate depths by calcium carbonate ballasting. The saturation horizon is relatively shallow in the Pacific so as the calcium dissolves it releases it's accumulated organic matter at shallower depths than in either the Atlantic or Indian Oceans where the saturation horizon is deeper. Diatoms are silica based and organic matter ballasted by silica can sink much deeper because silica unlike calcium carbonate does not dissolve at the saturation horizon.
 How climate change will affect future oceanic iron availability relates to desertification and wind carried dust. This potential terrestrial iron will supply the different oceans at different rates. Maybe someone has better information on how desertification will distribute future iron supplies?
Where that terrestrial derived iron settles in the surface oceans depends on it's source.

 

AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1620 on: January 27, 2017, 11:07:17 PM »
The linked open access reference indicates that: "Dense algae populations in the Great Calcite Belt could cause carbon dioxide release from the ocean into the atmosphere."  This potential forcing/feedback is not included in the CMIP5 projections:

William M. Balch, et. al. (10 August 2016), "Factors regulating the Great Calcite Belt in the Southern Ocean and its biogeochemical significance", Global Biogeochemical Cycles, DOI: 10.1002/2016GB005414

http://onlinelibrary.wiley.com/doi/10.1002/2016GB005414/abstract

Abstract: "The Great Calcite Belt (GCB) is a region of elevated surface reflectance in the Southern Ocean (SO) covering ~16% of the global ocean and is thought to result from elevated, seasonal concentrations of coccolithophores. Here we describe field observations and experiments from two cruises that crossed the GCB in the Atlantic and Indian sectors of the SO. We confirm the presence of coccolithophores, their coccoliths, and associated optical scattering, located primarily in the region of the subtropical, Agulhas, and Subantarctic frontal regions. Coccolithophore-rich regions were typically associated with high-velocity frontal regions with higher seawater partial pressures of CO2 (pCO2) than the atmosphere, sufficient to reverse the direction of gas exchange to a CO2 source. There was no calcium carbonate (CaCO3) enhancement of particulate organic carbon (POC) export, but there were increased POC transfer efficiencies in high-flux particulate inorganic carbon regions. Contemporaneous observations are synthesized with results of trace-metal incubation experiments, 234Th-based flux estimates, and remotely sensed observations to generate a mandala that summarizes our understanding about the factors that regulate the location of the GCB."


See also the linked article:

Stanley, S. (2017), Tiny creatures form massive, bright ring around Antarctica, Eos, 98, doi:10.1029/2017EO066713. Published on 26 January 2017.

https://eos.org/research-spotlights/tiny-creatures-form-massive-bright-ring-around-antarctica?utm_source=eos&utm_medium=email&utm_campaign=EosBuzz012717

Extract: "Dense algae populations in the Great Calcite Belt could cause carbon dioxide release from the ocean into the atmosphere."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1621 on: January 29, 2017, 05:28:04 AM »
The linked research indicates that rice crop yields will decrease significantly more rapidly, with continued global warming, than previously (currently) assumed by food authorities:

Zhao, C., et. al. (2016), “Plausible rice yield losses under future climate warming”, Nature Plants 3, Article number: 16202, doi:10.1038/nplants.2016.202

http://www.nature.com/articles/nplants2016202


Abstract: “Rice is the staple food for more than 50% of the world's population. Reliable prediction of changes in rice yield is thus central for maintaining global food security. This is an extraordinary challenge. Here, we compare the sensitivity of rice yield to temperature increase derived from field warming experiments and three modelling approaches: statistical models, local crop models and global gridded crop models. Field warming experiments produce a substantial rice yield loss under warming, with an average temperature sensitivity of −5.2 ± 1.4% K−1. Local crop models give a similar sensitivity (−6.3 ± 0.4% K−1), but statistical and global gridded crop models both suggest less negative impacts of warming on yields (−0.8 ± 0.3% and −2.4 ± 3.7% K−1, respectively). Using data from field warming experiments, we further propose a conditional probability approach to constrain the large range of global gridded crop model results for the future yield changes in response to warming by the end of the century (from −1.3% to −9.3% K−1). The constraint implies a more negative response to warming (−8.3 ± 1.4% K−1) and reduces the spread of the model ensemble by 33%. This yield reduction exceeds that estimated by the International Food Policy Research Institute assessment (−4.2 to −6.4% K−1) . Our study suggests that without CO2 fertilization, effective adaptation and genetic improvement, severe rice yield losses are plausible under intensive climate warming scenarios.”



See also the associated linked article entitled: “Future rice yield losses due to climate change could be extreme”.

https://arstechnica.com/science/2017/01/future-rice-yield-losses-due-to-climate-change-could-be-extreme/

Extract: “Climate warming poses a major threat to rice's role in our global food security.

Rice is a staple food for more than half of the world’s population. Rice yields depend on numerous factors, such as agricultural practices, but they also depend on the temperature at which the crop is grown. Previous studies have shown that temperatures above rice's optimum physiological temperature can reduce crop yield.

As a result, the International Food Policy Research Institute has stated that the effects of rising temperatures from climate change would likely reduce rice yield by 10 percent by 2050. This could have dramatic impacts across the world, as hunger and malnutrition are already significant problems.

But little is known about the physiological mechanisms through which rice plants respond and adapt to climate change. 
...
The team ran five crop models (global gridded crop models) with daily weather outputs generated by five representative high-warming climate models; all of these set carbon dioxide emissions at the present day value (excluding relevant benefits from carbon dioxide fertilization in the future), meaning carbon would continue to accumulate in the atmosphere throughout the century. This procedure enabled the team to isolate the influence of climate warming on rice yield. The climate models predicted an increase in the mean air temperature of 3.3 to 5.0 Kelvin over rice-growing areas during growing season.

The median value of the climate-induced rice yield change that resulted was -27 percent. That's a dramatic decrease compared to today, and it would put global food security in significant danger. But the drop ranged from 6.6 percent to 42.4 percent, primarily due to the significant uncertainty inherent in climate predictions. This range encompasses everything from an utter disaster to problems that could be compensated for by improved agricultural practices.


This investigation suggests that future yield problems may be more significant than we'd been expecting. If that's right, the equally significant measures are likely required to prevent severe rice yield losses. Preventative measures such as genetic improvements that produce rice strains that are more tolerant of heat should be seriously considered to mitigate the risk inherent in the more extreme numbers seen here.”
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1622 on: February 07, 2017, 02:16:26 PM »
The linked article is entitled: "The Holocene climate experience.", and it indicates that the Holocene has generally offer mankind with Goldilocks like conditions, and on the few cases where the environment departed from such Goldilocks like conditions, mankind suffered more than experts are currently acknowledging in their consequence assessments for the rest of this century.

http://www.dailyclimate.org/tdc-newsroom/2017/feb/The-Holocene-climate-experience

Extract: "The history of climate and human health gives us a glimpse of the dramatically amplified risks we face if present trends continue.

Excursions beyond the “just right” comfort-zone temperatures, either by warming or cooling, impair biological function and well-being."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1623 on: February 11, 2017, 10:36:28 PM »
The linked reference verifies: "… that the IPO is related to one or more inherent dynamical mechanisms of the climate system."  This indicates that the IPO is subject to amplification due to anthropogenic global warming; which needs to be better modeled in future ESMs.

Benjamin James Henley, Gerald Meehl, Scott Power, Chris Folland, Andrew King, Jaclyn Brown, David Karoly, Francois Delage, Ailie Gallant & Mandy Freund (2017), "Spatial and temporal agreement in climate model simulations of the interdecadal pacific oscillation", ERL, DOI: https://doi.org/10.1088/1748-9326/aa5cc8

http://iopscience.iop.org/article/10.1088/1748-9326/aa5cc8

Extract: "Accelerated warming and hiatus periods in the long-term rise of Global Mean Surface Temperature (GMST) have, in recent decades, been associated with the Interdecadal Pacific Oscillation (IPO, Kosaka & Xie 2013; England et al. 2014). Critically, decadal climate prediction relies on the skill of state-of-the-art climate models to reliably represent these low-frequency climate variations. We undertake a systematic evaluation of the simulation of the IPO in the suite of 39 Coupled Model Intercomparison Project 5 (CMIP5) models. We track the IPO in pre-industrial (control) and all-forcings (historical) experiments using the IPO tripole index (TPI). The TPI is explicitly aligned with the observed spatial pattern of the IPO, and circumvents assumptions about the nature of global warming. We find that many models underestimate the ratio of decadal-to-total variance in sea surface temperatures (SSTs). However, the basin-wide spatial pattern of positive and negative phases of the IPO are simulated reasonably well, with spatial pattern correlation coefficients between observations and models spanning the range 0.4-0.8. Deficiencies are mainly in the extratropical Pacific. Models that better capture the spatial pattern of the IPO also tend to more realistically simulate the ratio of decadal to total variance. Of the 13% of model centuries that have a fractional bias in the decadal-to-total TPI variance of 0.2 or less, 84% also have a spatial pattern correlation coefficient with the observed pattern exceeding 0.5. This result is highly consistent across both IPO positive and negative phases. This is evidence that the IPO is related to one or more inherent dynamical mechanisms of the climate system."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1624 on: February 14, 2017, 04:13:24 PM »
The linked article is entitled: "The social cost of carbon", and it indicates that the current official estimates of the social cost of carbon, SCC, are most likely considerably too low; which distorts policy decisions.

https://www.carbonbrief.org/qa-social-cost-carbon
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1625 on: February 21, 2017, 02:14:40 AM »
The linked reference examines another positive feedback mechanism (associated with lakes & ponds) that have not been adequately considered in current climate models:

Gabriel Yvon-Durocher, Chris J. Hulatt, Guy Woodward & Mark Trimmer (2017), "Long-term warming amplifies shifts in the carbon cycle of experimental ponds", Nature Climate Change, doi:10.1038/nclimate3229

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3229.html

Abstract: "Lakes and ponds cover only about 4% of the Earth’s non-glaciated surface, yet they represent disproportionately large sources of methane and carbon dioxide. Indeed, very small ponds (for example, <0.001 km2) may account for approximately 40% of all CH4 emissions from inland waters. Understanding how greenhouse gas emissions from aquatic ecosystems will respond to global warming is therefore vital for forecasting biosphere–carbon cycle feedbacks. Here, we present findings on the long-term effects of warming on the fluxes of GHGs and rates of ecosystem metabolism in experimental ponds. We show that shifts in CH4 and CO2 fluxes, and rates of gross primary production and ecosystem respiration, observed in the first year became amplified over seven years of warming. The capacity to absorb CO2 was nearly halved after seven years of warmer conditions. The phenology of greenhouse gas fluxes was also altered, with CO2 drawdown and CH4 emissions peaking one month earlier in the warmed treatments. These findings show that warming can fundamentally alter the carbon balance of small ponds over a number of years, reducing their capacity to sequester CO2 and increasing emissions of CH4; such positive feedbacks could ultimately accelerate climate change."

See also the associated article entitled: "Warming ponds could accelerate climate change".

https://phys.org/news/2017-02-ponds-climate.html

Extract: "Rising temperatures could accelerate climate change by reducing the amount of carbon dioxide stored in ponds and increasing the methane they release, new research shows."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1626 on: February 21, 2017, 03:50:02 PM »
Continuing climate change should increase the intensity and frequency of atmospheric river events; and per the linked reference landfalling atmospheric river events are associate with about ½ of the top 2% extreme storm damage events.  Current assessments of damage from continuing climate change underestimate these impacts.

Duane Waliser & Bin Guan (2017), "Extreme winds and precipitation during landfall of atmospheric rivers", Nature Geoscience, doi:10.1038/ngeo2894

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2894.html

Extract: "Atmospheric rivers—long, narrow filaments of large integrated water vapour transport—are associated with weather and water extremes, such as precipitation extremes and flooding in western North America and northern Europe. Here we apply a global detection algorithm for atmospheric rivers to reanalysis data during 1997–2014 to investigate the impact of atmospheric rivers on wind extremes as well as precipitation extremes. We find that atmospheric rivers are associated with up to half of the extreme events in the top 2% of the precipitation and wind distribution, across most mid-latitude regions globally. Landfalling atmospheric rivers are associated with about 40–75% of extreme wind and precipitation events over 40% of the world’s coastlines. Atmospheric rivers are associated with a doubling or more of the typical wind speed compared to all storm conditions, and a 50–100% increase in the wind and precipitation values for extreme events. We also find that the majority of extreme wind events catalogued between 1997 and 2013 over Europe with billion US dollar losses were associated with atmospheric rivers. We conclude that landfalling atmospheric rivers can represent a significant hazard around the globe, because of their association with not only extreme precipitation, but also extreme winds."

See also:
http://www.techtimes.com/articles/198326/20170221/climate-change-can-supercharge-atmospheric-rivers-that-bring-drought-ending-floods-in-california.htm
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1627 on: February 21, 2017, 06:09:30 PM »
The linked reference indicates that deforestation in the Amazon rainforest has regional tipping points resulting in future hydroclimatic positive feedbacks that will accelerate future forest loss.  Such tipping points are not adequately represented in current consensus climate models:

Jaya Khanna, David Medvigy, Stephan Fueglistaler & Robert Walko (2017), "Regional dry-season climate changes due to three decades of Amazonian deforestation", Nature Climate Change, doi:10.1038/nclimate3226

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3226.html

Abstract: "More than 20% of the Amazon rainforest has been cleared in the past three decades, triggering important hydroclimatic changes. Small-scale (a few kilometres) deforestation in the 1980s has caused thermally triggered atmospheric circulations that increase regional cloudiness and precipitation frequency. However, these circulations are predicted to diminish as deforestation increases. Here we use multi-decadal satellite records and numerical model simulations to show a regime shift in the regional hydroclimate accompanying increasing deforestation in Rondônia, Brazil. Compared with the 1980s, present-day deforested areas in downwind western Rondônia are found to be wetter than upwind eastern deforested areas during the local dry season. The resultant precipitation change in the two regions is approximately ±25% of the deforested area mean. Meso-resolution simulations robustly reproduce this transition when forced with increasing deforestation alone, showing that large-scale climate variability plays a negligible role. Furthermore, deforestation-induced surface roughness reduction is found to play an essential role in the present-day dry-season hydroclimate. Our study illustrates the strong scale sensitivity of the climatic response to Amazonian deforestation and suggests that deforestation is sufficiently advanced to have caused a shift from a thermally to a dynamically driven hydroclimatic regime."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Conservative Scientists & its Consequences
« Reply #1628 on: February 22, 2017, 05:06:46 PM »
The linked open access reference indicates that tree morality (in both temperate & tropical forests) from climate change induced droughts, will act as a positive feedback mechanism that is not fully accounted for in current climate models:

Sarah Greenwood, Paloma Ruiz-Benito, Jordi Martínez-Vilalta, Francisco Lloret, Thomas Kitzberger, Craig D. Allen, Rod Fensham, Daniel C. Laughlin, Jens Kattge, Gerhard Bönisch, Nathan J. B. Kraft and Alistair S. Jump (21 FEB 2017), "Tree mortality across biomes is promoted by drought intensity, lower wood density and higher specific leaf area", Ecology Letters, DOI: 10.1111/ele.12748

http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1461-0248/earlyview

Abstract: "Drought events are increasing globally, and reports of consequent forest mortality are widespread. However, due to a lack of a quantitative global synthesis, it is still not clear whether drought-induced mortality rates differ among global biomes and whether functional traits influence the risk of drought-induced mortality. To address these uncertainties, we performed a global meta-analysis of 58 studies of drought-induced forest mortality. Mortality rates were modelled as a function of drought, temperature, biomes, phylogenetic and functional groups and functional traits. We identified a consistent global-scale response, where mortality increased with drought severity [log mortality (trees trees−1 year−1) increased 0.46 (95% CI = 0.2–0.7) with one SPEI unit drought intensity]. We found no significant differences in the magnitude of the response depending on forest biomes or between angiosperms and gymnosperms or evergreen and deciduous tree species. Functional traits explained some of the variation in drought responses between species (i.e. increased from 30 to 37% when wood density and specific leaf area were included). Tree species with denser wood and lower specific leaf area showed lower mortality responses. Our results illustrate the value of functional traits for understanding patterns of drought-induced tree mortality and suggest that mortality could become increasingly widespread in the future."

See also the associated linked article:

https://www.thecourier.co.uk/fp/news/scotland/374581/global-warming-will-speed-up-as-world-drought-hits-say-scots-researchers/

Extract: "Scots researchers are predicting a significant acceleration in global warming as a result of a major threat to the world’s forests.

They have found that forests around the world, in both tropical and temperate regions, are at risk of death due to widespread drought."

“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson