Ice Apocalypse - Multiple Meters Sea Level Rise

[AbruptSLR]

The linked article discusses evidence of a possible "early onset of industrial-era warming", which may mean that we have erred on the side of least drama about where to draw our baseline from which we measure the 2C limit:

Authors: Nerilie J. Abram, Helen V. McGregor, Jessica E. Tierney, Michael N. Evans, Nicholas P. McKay, Darrell S. Kaufman and the PAGES 2k Consortium (Published online 24 August 2016), "Early onset of industrial‐era warming across the oceans and continents", Nature, Vol. 536, pp. 411-415, doi: 10.1038/nature19082

http://www.nature.com/nature/journal/v536/n7617/full/nature19082.html

Abstract: "The evolution of industrial-era warming across the continents and oceans provides a context for future climate change and is important for determining climate sensitivity and the processes that control regional warming. Here we use post-AD 1500 palaeoclimate records to show that sustained industrial-era warming of the tropical oceans first developed during the mid-nineteenth century and was nearly synchronous with Northern Hemisphere continental warming. The early onset of sustained, significant warming in palaeoclimate records and model simulations suggests that greenhouse forcing of industrial-era warming commenced as early as the mid-nineteenth century and included an enhanced equatorial ocean response mechanism. The development of Southern Hemisphere warming is delayed in reconstructions, but this apparent delay is not reproduced in climate simulations. Our findings imply that instrumental records are too short to comprehensively assess anthropogenic climate change and that, in some regions, about 180 years of industrial-era warming has already caused surface temperatures to emerge above pre-industrial values, even when taking natural variability into account."

[AbruptSLR]

The linked reference provides satellite evidence that the CMIP5 projections substantially underestimate the positive feedback from precipitating clouds.  This is more evidence that consensus science has underestimated climate sensitivity:

J.-L. F. Li, Wei-Liang Lee, Yi-Hui Wang, Mark Richardson, Jia-Yuh Yu, E. Suhas, Eric Fetzer, Min-Hui Lo & Qing Yue (2016), "Assessing the Radiative Impacts of Precipitating Clouds on Winter Surface Air Temperatures and Land Surface Properties in GCMs Using Observations", JGR: Atmospheres, DOI: 10.1002/2016JD025175


http://onlinelibrary.wiley.com/doi/10.1002/2016JD025175/abstract


Abstract: "Using CloudSat-CALIPSO ice water, cloud fraction and radiation; CERES radiation and long-term station-measured surface air temperature (SAT), we identified a substantial underestimation of the total ice water path, total cloud fraction, land surface radiative flux, land surface temperature (LST) and SAT during Northern Hemisphere winter in CMIP5 models. We perform sensitivity experiments with the NCAR Community Earth System Model version 1 (CESM1) in fully coupled modes to identify processes driving these biases. We found that biases in land surface properties are associated with the exclusion of downwelling long-wave heating from precipitating ice during Northern Hemisphere winter. The land surface temperature biases introduced by the exclusion of precipitating ice radiative effects in CESM1 and CMIP5 both spatially correlate with winter biases over Eurasia and North America. The underestimated precipitating ice radiative effect leads to colder LST, associated surface energy-budget adjustments and cooler SAT. This bias also shifts regional soil moisture state from liquid to frozen, increases snow cover and depresses evapotranspiration (ET) and total leaf area index (TLAI) in Northern Hemisphere winter. The inclusion of the precipitating ice radiative effects largely reduces the model biases of surface radiative fluxes (more than 15 W m-2), SAT (up to 2-4 K), snow cover and ET (25-30%), compared with those without snow-radiative effects."

[AbruptSLR]

Dear AbruptSLR, I am curious about your NO-ESLD long-term view. Say for the next 20 years. Not to start a discussion, mind you. Just curious about your extrapolations of trends. Are you mainly focussed on SLR or do you also expand your view in all the other AGW/biosphere-collapse areas you generously post articles about? I think a broader view gives better general estimates/expectations.

…

…
Edit, nanny,

If you want to read about the impact of abrupt climate change on the biosphere you can track down a copy of "Abrupt Impacts of Climate Change: Anticipating Surprises" (2013):

https://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=18373

With regard to additional general discussion, the following summarizes selected considerations [including: (1) transient masking factors, (2) misinterpretations of paleo & observed climate sensitivities, (3) misinterpretations of the stability of the WAIS and (4) underestimates of the likeliness of continued high anthropogenic radiative forcing] as to why our climate change situation is more dire than the IPCC AR5 consensus currently acknowledges:

1. Masking mechanisms which allow scientists to match model results to paleo & observed conditions while calibrating for relatively low climate response (while either ignoring many masking mechanisms [such as paleo-dust & paleo-SOA], or diminishing their effectiveness in the models); and which allow decision makers to procrastinate in exactly the timeframe when it was critical that they take immediate action. 

W.R.T. GMSTA: Specific masking mechanisms include:

(a) Temporary (observed at least from roughly 1998 to 2013) atmospheric conditions in the Tropical Pacific that not only temporarily increased the frequency of lower level cloud cover with negative feedback, but also above average La Nina-like conditions and generally negative PDO values; which, accelerated the sequestration of heat in the ocean, which was partially release during the 2015-16 El Nino. 

(b) The temporary acceleration of anthropogenic aerosol emissions (largely associated with coal-fired power plants in both in China and elsewhere) that temporarily induced both negative forcing & negative feedback.

(c) A temporary acceleration of the absorption of carbon dioxide by land-based plants associate both with higher atmospheric carbon dioxide concentrations, and with global warming.

(d) Decadal scale thermal inertia fluctuations associated the ocean, atmosphere and cryosphere.
 
(f) A probable underestimation of both natural and anthropogenic negative aerosol forcing and feedback.

W.R.T. SLR: Specific masking consideration include:

(a) The tidal gauges around the world are located so as to be biased against the Greenland Ice Sheet, GIS, fingerprint contribution, likely underestimating SLR;

(b) In 2011 atypical atmospheric river event deposited large quantities of snow in Eastern Antarctica, thus underestimating SLR trends.

(c) Isostatic rebound associate with ice mass loss in the WAIS can mask the true ice mass loss measured by either gravity (GRACE) or ice surface elevation.

(d) If the WAIS is a major contributor to SLR this century, then due to the fingerprint effect this contribution could be increased by up to 40% in the NH.

W.R.T. Anthropogenic Bias: Other masking issues relate to the phrase "To err is human" in that AR5's projections contain so many caveats that it obfuscates the seriousness of our climate change challenge.  Specific anthropogenic masking factors include:

(a) The referenced standards for reporting observed GMST have been demonstrated to be biased on the low side.

(b) Anthropogenic forcing began earlier than assumed in AR5. 

(c) Common use of old values for GMSTA above pre-industrial.

(d) Common use radiative forcing scenarios that err too far on the side of least drama.

(e) Focus on linear Frequentist theory thereby underreporting the findings of chaos theory, of Bayesian analysis; of non-linear theory and of preliminary research that does yet meet the Frequentist confidence levels for evidence.

(f) Organized intimidation of climate scientists by denialists have contributed to ESLD reporting.

2. The TCR, ECS and ESS are all likely higher than consensus science is willing to currently acknowledge, due to a combination of:

(a) Masking factors biasing the recent observed climate change. 

(b) A misinterpretation of paleo-data with regard both the role of negative forcing from paleo dust and the role of Lorenz strange attractors in progressively ratcheting Earth Systems into higher states (such as an early albedo flip for the Arctic; and increased frequencies for strong El Nino events).

(c) The synergistic acceleration of non-liner positive feedback mechanisms (including Polar Amplification and permafrost degradation).

3. Instability of the WAIS could lead to a rapid acceleration of Hansen's ice-climate feedback mechanism within coming decades.  The likely earlier than expected collapse of key portions of the WAIS are due to reasons such as:

(a) The formation of the ozone hole over Antarctica accelerated the westerly winds over the Southern Ocean that together with the Coriolis effect drove warm circumpolar deep water, CDW, to the exposed ice of many key marine glaciers and associated ice shelves.

(b) The likelihood that GMSTA will approach (or exceed) 2.7C above pre-industrial conditions which per DeConto (2016) should trigger hydrofracturing and cliff failures of key WAIS marine glaciers.

(c) The rapid ocean heat uptake by the Southern Ocean's CDW (which is partially related to a climate change related increase in intense ENSO events).

4.  Anthropogenic radiative forcing would continue at higher than advisable levels, and for a longer than expected periods, due to such trends as:

(a) The transfer of industry from first world to third world countries (thus allowing high emissions to continue for some decades to come).

(b) An increase in fracking and farming led to an increase in methane emission rates.

(c) The domination of US policy by the GOP (soon including by Donald Trump) and their protection of the fossil fuel industry.

(d) The relatively rapid decline of the coal industry (particularly in China) that has accelerated aerosol forcing.

[rboyd]

A note on one of the points:

The coal industry in China is not decreasing, rather they are implementing very tight particulate emission standards that are cleaning up the air very rapidly. The Chinese government has recently restated a commitment to "clean" coal and are developing significant amounts of new coal mining and electricity generating capacity.

The Indians have massive amounts of coal-fired spare capacity, so could burn a lot more coal if necessary. The recent slowdown in coal usage growth seems to be due to a mixture of low economic growth and weather factors (benefitting hydro and wind). The extensive local air pollution may drive them to institute clean air legislation at some point.

[nanning]

Thank you AbruptSLR for your response, the links and for your list/overview. Enjoy your festive days, I wish they are full of warmth, trust, intimacy and humour.

[AbruptSLR]

A note on one of the points:

The coal industry in China is not decreasing, rather they are implementing very tight particulate emission standards that are cleaning up the air very rapidly. The Chinese government has recently restated a commitment to "clean" coal and are developing significant amounts of new coal mining and electricity generating capacity.

The Indians have massive amounts of coal-fired spare capacity, so could burn a lot more coal if necessary. The recent slowdown in coal usage growth seems to be due to a mixture of low economic growth and weather factors (benefitting hydro and wind). The extensive local air pollution may drive them to institute clean air legislation at some point.

Good point, I fully concur.

[AbruptSLR]

Deepsea mining is about to begin in earnest in order to provide minerals for the 'green economy'.  Unfortunately, this activity may likely accelerate climate change more than it slows its rate of progress, as discussed in the linked article:

Title: "The Glaring Problem With Ocean Floor Mining"

https://oilprice.com/Energy/Energy-General/The-Glaring-Problem-With-Ocean-Floor-Mining.html

Extract: "The world's nations may conclude a treaty governing undersea mining through the auspices of the United Nations as early as next year. Once that is concluded, large scale mining of ocean bottoms is expected to begin.
…
All of this will ironically be in service to the so-called "green economy." Minerals found on ocean seabeds—copper, cobalt, and manganese—are crucial to the move away from fossil fuels toward electricity as fuel for the world's transportation fleet. Will we end up devastating ocean organisms that absorb more carbon dioxide than we'll save by moving toward electrified transportation? In our blindness we can't see that our solutions lead to more problems, some of which merely compound our woes. The plumes resulting from undersea mining will contain in some cases mercury and lead liberated from the seabed that will poison the surrounding ocean and creatures large and small living there."

[Sam]

Deepsea mining is about to begin in earnest in order to provide minerals for the 'green economy'.  Unfortunately, this activity may likely accelerate climate change more than it slows its rate of progress, as discussed in the linked article:

Title: "The Glaring Problem With Ocean Floor Mining"

https://oilprice.com/Energy/Energy-General/The-Glaring-Problem-With-Ocean-Floor-Mining.html

Extract: "The world's nations may conclude a treaty governing undersea mining through the auspices of the United Nations as early as next year. Once that is concluded, large scale mining of ocean bottoms is expected to begin.
…
All of this will ironically be in service to the so-called "green economy." Minerals found on ocean seabeds—copper, cobalt, and manganese—are crucial to the move away from fossil fuels toward electricity as fuel for the world's transportation fleet. Will we end up devastating ocean organisms that absorb more carbon dioxide than we'll save by moving toward electrified transportation? In our blindness we can't see that our solutions lead to more problems, some of which merely compound our woes. The plumes resulting from undersea mining will contain in some cases mercury and lead liberated from the seabed that will poison the surrounding ocean and creatures large and small living there."

We humans keep experiencing this same problem repeatedly. — doing something because we desire and expect a certain outcome, yet once implemented we cause the reverse and add to our problems, often in intractable ways — we call it different names based sometimes on attributes, and sometimes for other reasons. But whether we call it Murphy’s law, Hanson’s razor, the Jevon’s paradox, or any of a myriad of variations - they break down to the same thing.

We humans tend to be very bad at thinking through the consequences of our actions. We desire some outcome, so we believe our actions will accomplish that outcome. The reality all too often is that clearly apparent effects of our attempts to achieve that outcome cause the opposite of what we desire, while also causing horrible impacts that we can do little to counteract or remedy.

I believe this is a reflection of our very recent evolutionary emergence into intellect. We think we are smart when actually we are only clever. We are still strongly biased by emotional responses, most particularly desire. We as a species do not yet inwardly think in terms of the future, of consequences. Rather we are caught seeing the shiny bobble, the tasty morsel, the allure of sex, assuaging our own internal bad feelings and wanting to take actions to counter those. We are often not reflective on our past actions, how those actions resulted in outcomes different than intended, and how we might change our beliefs and actions to do better. Instead we build rules to cover over our failings and to define those as good. We almost never learn from the failings of others.

Again - we have a myriad of names for this — “the road to hell is paved with good intentions” — is one of the most succinct of these. Despite some among us identifying the problem, and even suggesting workable solutions, we as a species are not yet advanced enough to actually internalize those lessons and actually learn.

Instead we marginalize those who suggest such things, or worse - we kill them. Personal gain and the desire to avoid pain from accountability or facing our own failings trap us on that road to hell.

The LED light story I related is another example of this. So to is the story of radiation and of nuclear power and nuclear weapons. The very sad stories of hepatitis C, prion disease spread, lithium batteries downing airplanes are yet others. Or the inane stories of bitcoin and its ilk, pyramid schemes, perpetual motion plans, fusion energy, etc... Chernobyl, Fukushima, Minamata, Bhopal, Michigan Bromine, Seveso, ... and on and on ... tell the same story even more tragically.

We humans refuse to learn. As a direct result climate change will destroy us and the world we know taking a million or more species with us into oblivion. Evolution will get another chance to start over. The clock is running out though. In half to three quarters of a billion years, the final alarm will begin to ring putting to an end any chance of a species escaping this earth before the solar conditions change enough to end it all.

Sam

[philopek]

Deepsea mining is about to begin in earnest in order to provide minerals for the 'green economy'.  Unfortunately, this activity may likely accelerate climate change more than it slows its rate of progress, as discussed in the linked article:

Title: "The Glaring Problem With Ocean Floor Mining"

https://oilprice.com/Energy/Energy-General/The-Glaring-Problem-With-Ocean-Floor-Mining.html

Extract: "The world's nations may conclude a treaty governing undersea mining through the auspices of the United Nations as early as next year. Once that is concluded, large scale mining of ocean bottoms is expected to begin.
…
All of this will ironically be in service to the so-called "green economy." Minerals found on ocean seabeds—copper, cobalt, and manganese—are crucial to the move away from fossil fuels toward electricity as fuel for the world's transportation fleet. Will we end up devastating ocean organisms that absorb more carbon dioxide than we'll save by moving toward electrified transportation? In our blindness we can't see that our solutions lead to more problems, some of which merely compound our woes. The plumes resulting from undersea mining will contain in some cases mercury and lead liberated from the seabed that will poison the surrounding ocean and creatures large and small living there."

We humans keep experiencing this same problem repeatedly. — doing something because we desire and expect a certain outcome, yet once implemented we cause the reverse and add to our problems, often in intractable ways — we call it different names based sometimes on attributes, and sometimes for other reasons. But whether we call it Murphy’s law, Hanson’s razor, the Jevon’s paradox, or any of a myriad of variations - they break down to the same thing.

We humans tend to be very bad at thinking through the consequences of our actions. We desire some outcome, so we believe our actions will accomplish that outcome. The reality all too often is that clearly apparent effects of our attempts to achieve that outcome cause the opposite of what we desire, while also causing horrible impacts that we can do little to counteract or remedy.

I believe this is a reflection of our very recent evolutionary emergence into intellect. We think we are smart when actually we are only clever. We are still strongly biased by emotional responses, most particularly desire. We as a species do not yet inwardly think in terms of the future, of consequences. Rather we are caught seeing the shiny bobble, the tasty morsel, the allure of sex, assuaging our own internal bad feelings and wanting to take actions to counter those. We are often not reflective on our past actions, how those actions resulted in outcomes different than intended, and how we might change our beliefs and actions to do better. Instead we build rules to cover over our failings and to define those as good. We almost never learn from the failings of others.

Again - we have a myriad of names for this — “the road to hell is paved with good intentions” — is one of the most succinct of these. Despite some among us identifying the problem, and even suggesting workable solutions, we as a species are not yet advanced enough to actually internalize those lessons and actually learn.

Instead we marginalize those who suggest such things, or worse - we kill them. Personal gain and the desire to avoid pain from accountability or facing our own failings trap us on that road to hell.

The LED light story I related is another example of this. So to is the story of radiation and of nuclear power and nuclear weapons. The very sad stories of hepatitis C, prion disease spread, lithium batteries downing airplanes are yet others. Or the inane stories of bitcoin and its ilk, pyramid schemes, perpetual motion plans, fusion energy, etc... Chernobyl, Fukushima, Minamata, Bhopal, Michigan Bromine, Seveso, ... and on and on ... tell the same story even more tragically.

We humans refuse to learn. As a direct result climate change will destroy us and the world we know taking a million or more species with us into oblivion. Evolution will get another chance to start over. The clock is running out though. In half to three quarters of a billion years, the final alarm will begin to ring putting to an end any chance of a species escaping this earth before the solar conditions change enough to end it all.

Sam

Real humans are willing to learn, only that not each creature/animal that is walking upright is human. even the term homo sapiens sapiens only applies genetically but not really.

to assume that all the creatures that look human are humans is perhaps one of the great errors.

I for sure know other primates and mammals that have way more ethical and spiritual capacity than many so called humans.

Anyone who finds this a bold statement, read history books and watch carefully what humans are capable to inflict upon each other and nature as a whole and then tell me that you disagree

[kassy]

If we would be utterly rational right now we would realize that the we live on only one planet and that we are wasting many resources. The problem is that groups of people make money with all these kind of exploitation and when they get really rich they can look for more ways in which to make money.

I read a bit of Moneyland about the offshore finance and how that allows people to steal from their countries then hide that money and be nice and rich in London and NY. Coupled this with the recent developments in wealth distribution worldwide but also in the US or most other areas you care to look ar this really undermines the democratic process. Especially since these people own (or finance owners of) much of the press we get BS stories about going green endangering our jobs´ while they never mention the amount of subsidy money thrown at fossil fuels.

The current situation is basically the end level of the old renters vs owners game because we do not have another planet.

[mitch]

If ferromanganese nodules are mined, it will be for the Co, Ni, Cu primarily, with a side of rare earth elements.  It will end up in a huge oversupply of Mn, which will have to be disposed of somehow. 

I doubt if the prices are such that a sustained mining operation could succeed. One mine of 2 million tons of nodules per year would produce roughly 2 times the current world supply of cobalt, assuming about 0.2% Co in a nodule.
https://www.tandfonline.com/doi/full/10.1080/1064119X.2017.1319448?scroll=top&needAccess=true 

If there are a bunch of operations, there would likely be wild swings in prices. Furthermore the mining is essentially strip mining--the nodules took millions of years to grow. The sediment plume would be a major environmental problem of unknown consequences.

[pietkuip]

A talk by William Lipscomb at the CCL Wild West Conference in Boulder on Sept 28, 2019:


His conclusions on the final slide:

• It seems likely that sea level rise by 2100 will not be much larger than 1 meter
• Long term: With global average warming 1.5 - 2 °C, sea level rise of about 5 m is likely (based on past climates)
• With warming of 3 °C or more, the Greenland ice sheet (7 m) and West Antarctic ice sheet (5 m) probably are not viable in the long term, and East Antarctica may be vulnerable

But in the talk he is clearly uncertain about West Antarctica.
On the next to last slide it says:
"Extreme scenarios predict up to 1 m of SLR by 2100, 12 m by 2500."

[nanning]

Sam:
Thanks for that.
I'm certain it is possible to improve your view if you want.

Your 'we' means civilisation humans, not humanity. The civilisation culture lost calibration with reality a long time ago. Dreams and fantasies rule (e.g. money, materialism) and any long term view and seeing The Big Picture (all life's interconnected ecosystems) is gone.
Supremacy over living nature induced this. It has rendered civilisation culture and humans enveloped by it, insane.

It is impossible to calibrate when thinking from inside an insane bubble. The brains don't work properly anymore. This is not some random idea, this is what has happened. I know because I succeeded in finding reality, i.e. the outside of civilisation's bubble/culture combined with the drawbacks of functional representation of reality (blind spots in interpretation space which is the space of all sensory information). My understanding is consistent and works for all lifeforms. It is how it is.
When outside living nature, high morality is the only thing stopping total destruction. The highest morality says you can't have supremacy. So automatically this high morality driver returns you to living in balance with living nature. Gives back sanity and calibration.

High technology and supremacy are the abberations. Not intelligence.
It was really wonderful to recognize exactly that in a documentary about the San tribes of southern Africa that was posted on this forum.

High morality requires rational thinking, and emotions must not steer that. Emotions are information, a sensor. Emotions must not be blocked out but taken as sensory information without being driven by it. This requires initial discipline depending on the particular culture, and vulnerability.

You are likely a great thinker Sam but you need to step outside of the civilisation bubble (e.g. all that it calls normal) to feed that thinking machine of yours true views and calibration. You will get closer to yourself and to being complete in the same effort. Bubbles give distorted views.

It is too late now but it is high technology that is the increasingly efficient instrument of destruction, it is always destructive. High tech is a dream and not a happy one (as seen from outside).
High technology is technology beyond stone age. It uses ovens and metals.

[Sam]

Nanning,

I have no idea what you are trying to convey. I am quite clear on where the world is, how it got to where it is, who precisely caused that, why they did as they did, where I am in myself, and on and on.

It is disappointing that humans individually and humanity collectively was, is and remains so blind. There are exceptions. Those who are the exceptions are in my experience a very small percentage. I see daily and even hourly most times the inanity of this animal we call man. I experience daily the inability and unwillingness of most members of the species to be willing to learn even simple lessons.

That does not deter me from continuing to try. Nor does it deter me from trying to find solutions within the constraints of the complex systems that make up the earth and our societies.

But that also does not deter me from recognizing truth and the severity of the conditions for the long term.

I am somewhat unique in that I live mostly outside the confines and limitations of emotional response. That confuses the hell out of most people. And it causes misinterpretation. Perhaps this is confusing you. My responses are not based in nor do they come from an emotional reaction or desires. They are the result of ‘cold’ analytical  analysis of where we are, what is happening, and where that takes us collectively. None of us gets to escape this system. We are all trapped in this fun house together.

Sam

[Sam]

Add to this...

Technology is neither good nor evil. Technology simply is. When we choose to use it blindly or ignorantly the consequences will often be adverse, and sometimes terrible. That the outcomes are sometimes terrible does not make the technology bad.

What it points to is our simple ignorance. That might include emotional ignorance or lack of wisdom, or ...  but in this case it means the simple lack of understanding sufficiently.

The good and safe use of technology often requires a good deal of technical understanding, a good bit of wisdom, and an openness to considering and analyzing in great depth our limitations in our understanding, as well as thoroughly exploring and challenging ourselves and the technology to truly understand what the consequences are of its use -before- using it in a major way. and and and and ...

Too often our very simple societal governing rules work counter to these requirements and put all of us at risk as a consequence. Having economics and benefit to a few govern our decisions is one such working rule. A consequence of that particular rule is the conversion of risks and impacts to externalities - i.e. to costs born by others that need not be considered in the analysis to the benefits of the person(s) making the decision.

Sam

[nanning]

Sam, you have not understood my post I'm sorry to say.

I had already observed that the civilisation bubble is too strong to break through for all humans from civilisation, but once in a while I give it a try. I am not a grown-up and don't participate in group-behaviour so maybe that's why I don't understand grown-ups' behaviour, just like the children don't understand it.

I have the definite answers but nobody wants to know. I've found some real intelligent people here but they too don't want to know. I live my life as an example but nobody follows. Oh well, I think it confirms that evil is stronger than good, that giving in to temptation is stronger than forcing discipline on yourself, that grown-ups' curiosity cannot break bubbles. (self-pity alert) Here I sit holding these fundamental and profound understanding and theories after years of intense unpaid research, here I sit alone and tortured and not believed in anything. How alone can one be? You have no idea.

https://en.wikipedia.org/wiki/Cassandra  "Apollo cursed Cassandra to always be disbelieved, in spite of the truth of her words."

Apologies for my perhaps too personal cry out and for these off-topic posts.

[AbruptSLR]

The linked article indicates that all forests are not created equal, and that we should look before we leap into geoengineering efforts to plant trees which may produce far fewer climate change benefits that people are currently likely assuming:

Title: "We Might Not be Planting the Right Kinds of Forests"

https://www.wired.com/story/we-might-not-be-planting-the-right-kinds-of-forests/

Extract: "As the world scrambles to combat deforestation, experts warn that our efforts could have far fewer benefits than we think."

[wili]

"...all forests are created equal..."

Did you mean "not all forests are created equal"?

[AbruptSLR]

"...all forests are created equal..."

Did you mean "not all forests are created equal"?

wili,

Thank you & I corrected the original post to include the 'not'

[Sam]

For anyone at all familiar with boreal or tropical forests and short rotation tree farms (less than a century between cropping) there is simply no comparison.

The ancient boreal and tropical forests, though dis-similar in many ways, are far more similar to one another in major ways than either is to tree farms. The massive complex assemblies that make up the boreal and tropical forests have multiple distinct life zones from the forest floor up through the middle layers to the high canopies. They are quite simply “cathedral forests’’.

They serve as unique complex bio systems that regulate temperature, moisture, rain, hydrologic cycling, nutrient cycling, and very much more across huge regions. Once destroyed the soils they created are rapidly degraded and destroyed making recovery of the forests extremely difficult.

To naive city dwellers and to those ignorant of these cathedral forests, a dense collection of mono cropped trees undoubtedly looks like a “forest”. It isn’t. It’s a crop. It doesn’t behave in anywhere near the same way, nor serve anywhere near the same functions.

Over short time spans a young growing crop might absorb more carbon per acre, though that seems extremely unlikely. If it does so, it does so with a huge expense in loss of nutrients from the limited soil.The giants of these forests and the complex web of life they support are referred to as the lungs of the world for good reason. They both capture immense quantities of carbon dioxide and generate equally immense volumes of oxygen.

Once cut and lost for a single generations benefit, the underlying souls degrade. As seen in Brazil and elsewhere, these lands are verdant and fertile for a very brief time. Without the restorative value of the forests, the land is rapidly denuded if nutrients. Other uses such as cattle ranching and mono-cropping for food production mine the soil of its precious nutrient load which is then exporting from the area with the crop. Once lost it must be replaced or the environmental value of the land and its abilities to support complex use is lost. Human farming techniques focus on minimum cash cost and maximum value extraction. These practices bring in nitrogen rich fertilizers devoid of nutrients other than potassium, phosphorous and occasionally other minerals like calcium. Micronutrients are lost along with soil with each crop. Soon the land is all but barren.   

The complex multi-tiered forests capture nutrients in many ways that young forests are far less able to. By supporting complex populations, oceanic fish migrate far upstream into the forests. There raptors and large carnivores capture them distributing their nutrient rich bounty far into the forests. Thin first generation small trees are simply unable to support the cool streams and complex ecosystems of the cathedral forests.

Looking at these forests through the monocles of carbon dioxide or finance completely misses and severely discounts their immense values across a thousand other measures. Doing so most particularly misses their climate impacts across huge regions.

Sam

[AbruptSLR]

The linked reference states:

"Here, we use climate model simulations to show that, for a given global temperature, most land is significantly warmer in a rapidly warming (transient) case than in a quasi-equilibrium climate.
…
Relative to differences between the 1.5 °C and 2 °C global warming limits, the differences between transient and quasi-equilibrium states are substantial. For many land regions, the probability of very warm seasons is at least two times greater in a transient climate than in a quasi-equilibrium equivalent.
…
Our study highlights the need to better understand differences between future climates under rapid warming and quasi-equilibrium conditions for the development of climate change adaptation policies. Yet, current multi-model experiments are not designed for this purpose."

Thus, it would be nice if AR6 would highlight the differences in climate response between rapidly warming and quasi-equilibrium forcing scenarios (including those assuming the use of negative emissions technology).  Also, it would be nice if CMIP7 would set-up their multi-model cases to highlight the differences between these two cases:

King, A.D., Lane, T.P., Henley, B.J. et al. Global and regional impacts differ between transient and equilibrium warmer worlds. Nat. Clim. Chang. (2019) doi:10.1038/s41558-019-0658-7

https://www.nature.com/articles/s41558-019-0658-7

Abstract
There has recently been interest in understanding the differences between specific levels of global warming, especially the Paris Agreement limits of 1.5 °C and 2 °C above pre-industrial levels. However, different model experiments have been used in these analyses under varying rates of increase in global-average temperature. Here, we use climate model simulations to show that, for a given global temperature, most land is significantly warmer in a rapidly warming (transient) case than in a quasi-equilibrium climate. This results in more than 90% of the world’s population experiencing a warmer local climate under transient global warming than equilibrium global warming. Relative to differences between the 1.5 °C and 2 °C global warming limits, the differences between transient and quasi-equilibrium states are substantial. For many land regions, the probability of very warm seasons is at least two times greater in a transient climate than in a quasi-equilibrium equivalent. In developing regions, there are sizable differences between transient and quasi-equilibrium climates that underline the importance of explicitly framing projections. Our study highlights the need to better understand differences between future climates under rapid warming and quasi-equilibrium conditions for the development of climate change adaptation policies. Yet, current multi-model experiments are not designed for this purpose.

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Better understanding of changes in upper-ocean temperature is very important for modeling future climate change, as discussed in the linked reference.  I suspect that one of likely reasons that climate sensitivity appears to be higher in CMIP6 than in CMIP5 is because the CMIP6 models are doing a better (but which still need improving) job simulating ocean dynamics.  This is particularly important for trying to better understand the implications of a potential WAIS collapse in coming decades as ice sheet forcing, & associated ice-climate feedbacks, is/are highly dependent on the interaction between the cryosphere and ocean dynamics:

R. Justin Small et al. (Dec 2019), "What Drives Upper-Ocean Temperature Variability in Coupled Climate Models and Observations?", Journal of Climate, https://doi.org/10.1175/JCLI-D-19-0295.1

https://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-19-0295.1?af=R

Abstract
A key question in climate modeling is to what extent sea surface temperature and upper-ocean heat content are driven passively by air–sea heat fluxes, as opposed to forcing by ocean dynamics. This paper investigates the question using a climate model at different resolutions, and observations, for monthly variability. At the grid scale in a high-resolution climate model with resolved mesoscale ocean eddies, ocean dynamics (i.e., ocean heat flux convergence) dominates upper 50 m heat content variability over most of the globe. For deeper depths of integration to 400 m, the heat content variability at the grid scale is almost totally controlled by ocean heat flux convergence. However, a strong dependence on spatial scale is found—for the upper 50 m of ocean, after smoothing the data to around 7°, air–sea heat fluxes, augmented by Ekman heat transports, dominate. For deeper depths of integration to 400 m, the transition scale becomes larger and is above 10° in western boundary currents. Comparison of climate model results with observations show that the small-scale influence of ocean intrinsic variability is well captured by the high-resolution model but is missing from a comparable model with parameterized ocean-eddy effects. In the deep tropics, ocean dynamics dominates in all cases and all scales. In the subtropical gyres at large scales, air–sea heat fluxes play the biggest role. In the midlatitudes, at large scales >10°, atmosphere-driven air–sea heat fluxes and Ekman heat transport variability are the dominant processes except in the western boundary currents for the 400 m heat content.

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The linked reference confirms that there is (& will continue to be) a positive feedback loop between retreating Arctic sea ice and Arctic cloud cover that contributes to Arctic Amplification:

Abe, M., Nozawa, T., Ogura, T., and Takata, K.: Effect of retreating sea ice on Arctic cloud cover in simulated recent global warming, Atmos. Chem. Phys., 16, 14343-14356, doi:10.5194/acp-16-14343-2016, 2016.

http://www.atmos-chem-phys.net/16/14343/2016/
&
http://www.atmos-chem-phys.net/16/14343/2016/acp-16-14343-2016.pdf

Abstract. This study investigates the effect of sea ice reduction on Arctic cloud cover in historical simulations with the coupled atmosphere–ocean general circulation model MIROC5. Arctic sea ice has been substantially retreating since the 1980s, particularly in September, under simulated global warming conditions. The simulated sea ice reduction is consistent with satellite observations. On the other hand, Arctic cloud cover has been increasing in October, with about a 1-month lag behind the sea ice reduction. The delayed response leads to extensive sea ice reductions because the heat and moisture fluxes from the underlying open ocean into the atmosphere are enhanced. Sensitivity experiments with the atmospheric part of MIROC5 clearly show that sea ice reduction causes increases in cloud cover. Arctic cloud cover increases primarily in the lower troposphere, but it decreases in the near-surface layers just above the ocean; predominant temperature rises in these near-surface layers cause drying (i.e., decreases in relative humidity), despite increasing moisture flux. Cloud radiative forcing due to increases in cloud cover in autumn brings an increase in the surface downward longwave radiation (DLR) by approximately 40–60 % compared to changes in clear-sky surface DLR in fall. These results suggest that an increase in Arctic cloud cover as a result of reduced sea ice coverage may bring further sea ice retreat and enhance the feedback processes of Arctic warming.

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The linked reference (& associated articles) provides evidence that the positive feedback from soil carbon emissions is stronger than previously appreciated by AR5:

T. W. Crowther et al (2016), "Quantifying global soil carbon losses in response to warming", Nature, DOI: 10.1038/nature20150

http://www.nature.com/nature/journal/v540/n7631/full/nature20150.html

Abstract: "The majority of the Earth’s terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming. Despite evidence that warming enhances carbon fluxes to and from the soil, the net global balance between these responses remains uncertain. Here we present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia. We find that the effects of warming are contingent on the size of the initial soil carbon stock, with considerable losses occurring in high-latitude areas. By extrapolating this empirical relationship to the global scale, we provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections. Our empirical relationship suggests that global soil carbon stocks in the upper soil horizons will fall by 30 ± 30 petagrams of carbon to 203 ± 161 petagrams of carbon under one degree of warming, depending on the rate at which the effects of warming are realized. Under the conservative assumption that the response of soil carbon to warming occurs within a year, a business-as-usual climate scenario would drive the loss of 55 ± 50 petagrams of carbon from the upper soil horizons by 2050. This value is around 12–17 per cent of the expected anthropogenic emissions over this period. Despite the considerable uncertainty in our estimates, the direction of the global soil carbon response is consistent across all scenarios. This provides strong empirical support for the idea that rising temperatures will stimulate the net loss of soil carbon to the atmosphere, driving a positive land carbon–climate feedback that could accelerate climate change."

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The linked reference discusses paleo findings related to variabilities in the carbon-climate feedback during the Miocene Climatic Optimum (MCO); which may have bearing on what climate sensitivities to calibrate to for future climate change projections, as the MCO had atmospheric CO₂ concentrations comparable to today and GMSTA of about 4C.  The presented evidence implies that when the two polar ice caps are absent, or severely restricted, the associated impacts on the oceans likely resulted in significant (& relatively rapid) carbon emissions from the ocean.  Such feedback mechanisms are not included in AR5 projections and they raise the prospect that the Earth Systems could ratchet up to a higher climate state if the WAIS were to collapse in coming decades:

Karlos G. D. Kochhann, Ann Holbourn, Wolfgang Kuhnt, James E. T. Channell, Mitch Lyle, Julia K. Shackford, Roy H. Wilkens & Nils Andersen (17 September 2016), "Eccentricity pacing of eastern equatorial Pacific carbonate dissolution cycles during the Miocene Climatic Optimum", Paleoceanography, DOI: 10.1002/2016PA002988

http://onlinelibrary.wiley.com/doi/10.1002/2016PA002988/full

Abstract: "The Miocene Climatic Optimum (MCO; ~16.9 to 14.7 Ma) provides an outstanding opportunity to investigate climate-carbon cycle dynamics during a geologically recent interval of global warmth. We present benthic stable oxygen (δ18O) and carbon (δ13C) isotope records (5–12 kyr time resolution) spanning the late early to middle Miocene interval (18 to 13 Ma) at Integrated Ocean Drilling Program (IODP) Site U1335 (eastern equatorial Pacific Ocean). The U1335 stable isotope series track the onset and development of the MCO as well as the transitional climatic phase culminating with global cooling and expansion of the East Antarctic Ice Sheet at ~13.8 Ma. We integrate these new data with published stable isotope, geomagnetic polarity, and X-ray fluorescence (XRF) scanner-derived carbonate records from IODP Sites U1335, U1336, U1337, and U1338 on a consistent, astronomically tuned timescale. Benthic isotope and XRF scanner-derived CaCO3 records depict prominent 100 kyr variability with 400 kyr cyclicity additionally imprinted on δ13C and CaCO3 records, pointing to a tight coupling between the marine carbon cycle and climate variations. Our intersite comparison further indicates that the lysocline behaved in highly dynamic manner throughout the MCO, with >75% carbonate loss occurring at paleodepths ranging from ~3.4 to ~4 km in the eastern equatorial Pacific Ocean. Carbonate dissolution maxima coincide with warm phases (δ18O minima) and δ13C decreases, implying that climate-carbon cycle feedbacks fundamentally differed from the late Pleistocene glacial-interglacial pattern, where dissolution maxima correspond to δ13C maxima and δ18O minima. Carbonate dissolution cycles during the MCO were, thus, more similar to Paleogene hyperthermal patterns."

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The linked reference discusses how the AR5 generation of models likely overestimated the amount of negative feedback from fire produced aerosols; which indicates that the range of ECS is likely higher than assumed by AR5:

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.

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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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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."

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The linked reference examines another positive feedback mechanism (associated with lakes & ponds) that were not adequately considered in the AR5 generation of 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."

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The linked open access reference indicates that tree mortality (in both temperate & tropical forests) from climate change induced droughts, will act as a positive feedback mechanism that was not fully accounted for in the AR5 generation of 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."

[sidd]

Re: tree morality

While the morals of trees are an interesting discussion, perhaps a better word for this is "mortality" ?

sidd

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Re: tree morality

While the morals of trees are an interesting discussion, perhaps a better word for this is "mortality" ?

sidd

Thanks, I fixed the original.

[pietkuip]

Trees have a hard time in a changing climate: fires, droughts, windstorms, flooding, insects, fungi, etc, etc.

They cannot walk away from it.

[AbruptSLR]

The linked reference indicates that models indicate that rainfall will increase rapidly in the Arctic in coming years.  This should increase Arctic Amplification to higher levels than previously assumed in AR5 (if for no other reason than that rain will markedly increase methane emissions from Arctic permafrost).

R. Bintanja et al. Towards a rain-dominated Arctic, Nature Climate Change (2017). DOI: 10.1038/nclimate3240

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3240.html

Abstract
Climate models project a strong increase in Arctic precipitation over the coming century, which has been attributed primarily to enhanced surface evaporation associated with sea-ice retreat. Since the Arctic is still quite cold, especially in winter, it is often (implicitly) assumed that the additional precipitation will fall mostly as snow. However, little is known about future changes in the distributions of rainfall and snowfall in the Arctic. Here we use 37 state-of-the-art climate models in standardized twenty-first-century (2006–2100) simulations to show a decrease in average annual Arctic snowfall (70°–90° N), despite the strong precipitation increase. Rain is projected to become the dominant form of precipitation in the Arctic region (2091–2100), as atmospheric warming causes a greater fraction of snowfall to melt before it reaches the surface, in particular over the North Atlantic and the Barents Sea. The reduction in Arctic snowfall is most pronounced during summer and autumn when temperatures are close to the melting point, but also winter rainfall is found to intensify considerably. Projected (seasonal) trends in rainfall and snowfall will heavily impact Arctic hydrology (for example, river discharge, permafrost melt), climatology (for example, snow, sea-ice albedo and melt)8, 9 and ecology (for example, water and food availability).

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The linked reference indicates that forests play a more important role in keeping the planet cool than was previously appreciated by AR5 vintage models:

Ryan M. Bright et al. Local temperature response to land cover and management change driven by non-radiative processes, Nature Climate Change (2017). DOI: 10.1038/nclimate3250

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3250.html

Abstract: "Following a land cover and land management change (LCMC), local surface temperature responds to both a change in available energy and a change in the way energy is redistributed by various non-radiative mechanisms. However, the extent to which non-radiative mechanisms contribute to the local direct temperature response for different types of LCMC across the world remains uncertain. Here, we combine extensive records of remote sensing and in situ observation to show that non-radiative mechanisms dominate the local response in most regions for eight of nine common LCMC perturbations. We find that forest cover gains lead to an annual cooling in all regions south of the upper conterminous United States, northern Europe, and Siberia—reinforcing the attractiveness of re-/afforestation as a local mitigation and adaptation measure in these regions. Our results affirm the importance of accounting for non-radiative mechanisms when evaluating local land-based mitigation or adaptation policies."

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The linked research indicates that as the Arctic Sea Ice becomes thinner, portions of the ice become thin enough to allow sufficient light to pass through the ice to support phytoplankton blooms beneath the zones of think ice.  This trend is increasing faster than previously assumed and it is decreasing the albedo of the affected ice zones; which is a positive feedback mechanism that was not adequately accounted for in AR5.

Christopher Horvat, David Rees Jones, Sarah Iams, David Schroeder, Daniela Flocco and Daniel Feltham (2017), "The frequency and extent of sub-ice phytoplankton blooms in the Arctic Ocean", Science Advances, Vol. 3, no. 3, e1601191, DOI: 10.1126/sciadv.1601191

http://advances.sciencemag.org/content/3/3/e1601191

Abstract: "In July 2011, the observation of a massive phytoplankton bloom underneath a sea ice–covered region of the Chukchi Sea shifted the scientific consensus that regions of the Arctic Ocean covered by sea ice were inhospitable to photosynthetic life. Although the impact of widespread phytoplankton blooms under sea ice on Arctic Ocean ecology and carbon fixation is potentially marked, the prevalence of these events in the modern Arctic and in the recent past is, to date, unknown. We investigate the timing, frequency, and evolution of these events over the past 30 years. Although sea ice strongly attenuates solar radiation, it has thinned significantly over the past 30 years. The thinner summertime Arctic sea ice is increasingly covered in melt ponds, which permit more light penetration than bare or snow-covered ice. Our model results indicate that the recent thinning of Arctic sea ice is the main cause of a marked increase in the prevalence of light conditions conducive to sub-ice blooms. We find that as little as 20 years ago, the conditions required for sub-ice blooms may have been uncommon, but their frequency has increased to the point that nearly 30% of the ice-covered Arctic Ocean in July permits sub-ice blooms. Recent climate change may have markedly altered the ecology of the Arctic Ocean."

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The linked open access reference indicates that: "… sea ice will completely disappear in the Barents and Kara Seas by around 2025"; which is clearly an indication that Arctic Amplification is greater than AR5 acknowledges:

Kim, K.-Y., Kim, J., Yeo, S., Na, H., Hamlington, B. D., and Leben, R. R. (2017), "Understanding the Mechanism of Arctic Amplification and Sea Ice Loss", The Cryosphere Discuss., doi:10.5194/tc-2017-39

http://www.the-cryosphere-discuss.net/tc-2017-39/

Abstract. Sea ice reduction is accelerating in the Barents and Kara Seas. Several mechanisms are proposed to explain the accelerated loss of polar sea ice, which remains an open question. In the present study, the detailed physical mechanism of sea ice reduction in winter is identified using the daily ERA interim reanalysis data. Downward longwave radiation is an essential element for sea ice reduction, but can only be sustained by excessive upward heat flux from the sea surface exposed to air in the region of sea ice loss. The increased turbulent heat flux is used to increase air temperature and specific humidity in the lower troposphere, which in turn increases downward longwave radiation. This feedback process is clearly observed in the Barents and Kara Seas in the reanalysis data. A quantitative assessment reveals that this feedback process is amplifying at the rate of ~ 8.9 % every year during 1979–2016. Based on this estimate, sea ice will completely disappear in the Barents and Kara Seas by around 2025. Availability of excessive heat flux is necessary for the maintenance of this feedback process; a similar mechanism of sea ice loss is expected to take place over the sea-ice covered polar region when sea ice is not fully recovered in winter.

[AbruptSLR]

The linked reference presents new findings that the retreat of the Barents Sea Ice Sheet at the end of the last ice age resulted in the explosive release of methane from Arctic seafloor hydrates as overpressure from the ice sheet disappeared.  The researchers findings serve as a good past analogy of what may likely happen in the near-term future if the WAIS were to collapse, and/or if marine terminating glaciers in Greenland were to retreat rapidly.  As methane has a GWP100 of about 35 such explosive releases of methane could have a significant impact on global warming this century, which has not been considered in either AR5 or CMIP5:

K. Andreassen, A. Hubbard, M. Winsborrow, H. Patton, S. Vadakkepuliyambatta, A. Plaza-Faverola, E. Gudlaugsson, P. Serov, A. Deryabin, R. Mattingsdal, J. Mienert & S. Bünz (02 Jun 2017), "Massive blow-out craters formed by hydrate-controlled methane expulsion from the Arctic seafloor",Science, Vol. 356, Issue 6341, pp. 948-953, DOI: 10.1126/science.aal4500

http://science.sciencemag.org/content/356/6341/948

Abstract: "Widespread methane release from thawing Arctic gas hydrates is a major concern, yet the processes, sources, and fluxes involved remain unconstrained. We present geophysical data documenting a cluster of kilometer-wide craters and mounds from the Barents Sea floor associated with large-scale methane expulsion. Combined with ice sheet/gas hydrate modeling, our results indicate that during glaciation, natural gas migrated from underlying hydrocarbon reservoirs and was sequestered extensively as subglacial gas hydrates. Upon ice sheet retreat, methane from this hydrate reservoir concentrated in massive mounds before being abruptly released to form craters. We propose that these processes were likely widespread across past glaciated petroleum provinces and that they also provide an analog for the potential future destabilization of subglacial gas hydrate reservoirs beneath contemporary ice sheets."

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The linked article suggests a future feedback between biomass fires in the Southern Hemisphere and decreasing albedo in Antarctica, with continued global warming.  To the best of my knowledge such a feedback is currently not included in any AR5 projections:

M. M. Arienzo et. al. (11 June 2017), "Holocene black carbon in Antarctica paralleled Southern Hemisphere climate", Journal of Geophysical Research -  Atmospheres; DOI: 10.1002/2017JD026599

http://onlinelibrary.wiley.com/doi/10.1002/2017JD026599/abstract?utm_content=bufferad755&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

Abstract: "Black carbon (BC) and other biomass-burning (BB) aerosols are critical components of climate forcing but quantification, predictive climate modeling, and policy decisions have been hampered by limited understanding of the climate drivers of BB and by the lack of long-term records. Prior modeling studies suggested that increased Northern Hemisphere anthropogenic BC emissions increased recent temperatures and regional precipitation, including a northward shift in the Inter-Tropical Convergence Zone (ITCZ). Two Antarctic ice cores were analyzed for BC and the longest record shows that the highest BC deposition during the Holocene occurred ~8-6k years before present in a period of relatively high austral burning season and low growing season insolation. Atmospheric transport modeling suggests South America (SA) as the dominant source of modern Antarctic BC and, consistent with the ice-core record, climate model experiments using mid-Holocene and preindustrial insolation simulate comparable increases in carbon loss due to fires in SA during the mid-Holocene. SA climate proxies document a northward shifted ITCZ and weakened SA Summer Monsoon (SASM) during this period, with associated impacts on hydroclimate and burning. A second Antarctic ice core spanning the last 2.5k years documents similar linkages between hydroclimate and BC, with the lowest deposition during the Little Ice Age characterized by a southerly shifted ITCZ and strengthened SASM. These new results indicate that insolation-driven changes in SA hydroclimate and BB, likely linked to the position of the ITCZ, modulated Antarctic BC deposition during most of the Holocene and suggests connections and feedbacks between future BC emissions and hydroclimate."

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The linked reference indicates that AR5 vintage models to not adequately account for the impacts (i.e. they underestimate the impacts) of internal climate variability (ICV) on ice mass loss from ice sheets:

Chii-Yun Tsai, et. al. (12 June 2017), "Assessing the contribution of internal climate variability to anthropogenic changes in ice sheet volume", Geophysical Research Letters, DOI: 10.1002/2017GL073443

http://onlinelibrary.wiley.com/doi/10.1002/2017GL073443/abstract?utm_content=bufferc7113&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

Abstract: "Understanding ice sheet response to different sources of uncertainty in projecting the climate is essential for assessing long-term risk of sea-level rise (SLR). The impact of uncertainty caused by internal climate variability (ICV) on future ice sheet changes has not been assessed explicitly. Here we estimate how ICV affects ice sheet projections using a three-dimensional ice sheet model driven by climate fields from two large-ensembles of climate model simulations differing in initial climate states. We find that ICV causes approximately 2mm uncertainty in the estimated SLR due to Greenland ice sheet mass loss during 1992–2011, which is nearly double the observational uncertainty. Additionally, SLR difference due to ICV is about 17% of the mean total change of SLR in 2100. This study highlights a critical need to assess uncertainties of projecting ice sheet loss due to ICV to obtain robust estimates of both historical and future SLR."

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The linked reference uses discriminant analysis and the Bayesian theorem to reduce the uncertainty that anthropogenic radiative forcing is driving climate change.  Hopefully, AR6 will use similar analyses to decrease their uncertainty ranges; which should clarify that we are headed towards the upper end of the confidence ranges cited in AR5:

Heiko Paeth, Felix Pollinger, and Christoph Ring (2017), "Detection and attribution of multi-variate climate change signals using discriminant analysis and Bayesian theorem", Journal of Climate, https://doi.org/10.1175/JCLI-D-16-0850.1

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0850.1?utm_content=bufferc3e80&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

Abstract: "Detection and attribution methods in climatological research aim at assessing whether observed climate anomalies and trends are still consistent with the range of natural climate variations or rather an indication of anthropogenic climate change. In this study, we pursue a novel approach by using discriminant analysis to enhance the distinction between past and future climates from state-of-art climate model simulations. The method is based on multi-variate fingerprints that are defined in the space of several prominent climate indices representing the thermal, dynamical and hygric aspects of climate change. Attribution is carried out by means of a Bayesian classification approach.

The leading discriminant function accounts for more than 99 % of total discriminability, with temperature variables, extratropical precipitation and extratropical circulation modes mainly contributing to the discriminant power. The misclassification probability between probability density functions of past and future climates is substantially reduced by the discriminant analysis: from >50% to <15%. Since the mid-1980s, the observed anomalies of the considered climate indices are more or less consistently attributed to a climate under strong radiative forcing, projected for the first half of the 21st century. We also assess the sensitivity of our results to different emissions scenarios from the CMIP3 and CMIP5 multi-model ensembles, seasons, prior probabilities for the early 21st-century climate, estimates of the observational error, lowpass filters, variable compositions, group numbers and reference data."

[AbruptSLR]

Per the linked reference, methane radiative forcing is about 25% higher than previously estimated in AR5 for shortwave forcing:

M. Etminan et al. Radiative forcing of carbon dioxide, methane, and nitrous oxide: A significant revision of the methane radiative forcing, Geophysical Research Letters (2016). DOI: 10.1002/2016GL071930

http://onlinelibrary.wiley.com/doi/10.1002/2016GL071930/abstract;jsessionid=4BD7EE5DBE1525CC15B5806E5EBEC6F4.f03t01

Abstract: “New calculations of the radiative forcing (RF) are presented for the three main well-mixed greenhouse gases, methane, nitrous oxide, and carbon dioxide. Methane's RF is particularly impacted because of the inclusion of the shortwave forcing; the 1750–2011 RF is about 25% higher (increasing from 0.48 W m−2 to 0.61 W m−2) compared to the value in the Intergovernmental Panel on Climate Change (IPCC) 2013 assessment; the 100 year global warming potential is 14% higher than the IPCC value. We present new simplified expressions to calculate RF. Unlike previous expressions used by IPCC, the new ones include the overlap between CO2 and N2O; for N2O forcing, the CO2 overlap can be as important as the CH4 overlap. The 1750–2011 CO2 RF is within 1% of IPCC's value but is about 10% higher when CO2 amounts reach 2000 ppm, a value projected to be possible under the extended RCP8.5 scenario.”

Plain Language Summary
“Radiative forcing” is an important method to assess the importance of different climate change mechanisms, and is used, for example, by the Intergovernmental Panel on Climate Change (IPCC). Increased concentrations of greenhouse gases, such as carbon dioxide, methane and nitrous oxide, are the major component of the human activity that led the IPCC, in its 2013 Assessment, to conclude that “it is extremely likely that human influence is the dominant cause of warming since the mid-20th century.” In this letter, we report new and detailed calculations that aimed to update the simpler methods of computing the radiative forcing that have been used in IPCC assessments, and elsewhere. The major result is that radiative forcing due to methane is around 20-25% higher than that found using the previous simpler methods. The main reason for this is the inclusion of the absorption of solar radiation by methane, a mechanism that had not been included in earlier calculations. We examine the mechanisms by which this solar absorption causes this radiative forcing. The work has significance for assessments of the climate impacts of methane emissions due to human activity, and for the way methane is included in international climate agreements.”

[AbruptSLR]

Low cloud cover (LCC) is associated with negative climate change feedback; thus the finding of the linked reference that LCC decreases with continued warming indicates that ECS is likely higher than assumed by AR5:

Daniel T. McCoy, Ryan Eastman, Dennis L. Hartmann, and Robert Wood (2017), “The Change in Low Cloud Cover in a Warmed Climate Inferred from AIRS, MODIS, and ERA-Interim”, Journal of Climate, https://doi.org/10.1175/JCLI-D-15-0734.1

http://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0734.1

Abstract: “Decreases in subtropical low cloud cover (LCC) occur in climate model simulations of global warming. In this study 8-day-averaged observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS) spanning 2002–14 are combined with European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis to compute the dependence of the observed variability of LCC on various predictor variables. Large-scale thermodynamic and dynamic predictors of LCC are selected based on insight from large-eddy simulations (LESs) and observational analysis. It is found that increased estimated inversion strength (EIS) is associated with increased LCC. Drying of the free troposphere is associated with decreased LCC. Decreased LCC accompanies subsidence in regions of relatively low EIS; the opposite is found in regions of high EIS. Finally, it is found that increasing sea surface temperature (SST) leads to a decrease in LCC. These results are in keeping with previous studies of monthly and annual data. Based upon the observed response of LCC to natural variability of the control parameters, the change in LCC is estimated for an idealized warming scenario where SST increases by 1 K and EIS increases by 0.2 K. For this change in EIS and SST the LCC is inferred to decrease by 0.5%–2.7% when the regression models are trained on data observed between 40°S and 40°N and by 1.1%–1.4% when trained on data from trade cumulus–dominated regions. When the data used to train the regression model are restricted to stratocumulus-dominated regions the change in LCC is highly uncertain and varies between −1.6% and +1.4%, depending on the stratocumulus-dominated region used to train the regression model.”

[Florifulgurator]

Trees have a hard time in a changing climate: fires, droughts, windstorms, flooding, insects, fungi, etc, etc.

They cannot walk away from it.

Let's make them walk!
Like here: https://treesforlife.org.uk/

[Tom_Mazanec]

AbruptSLR, how has the early part of AR1 corresponded with the actual events since it was put out? Have the last several decades shown that they underestimated the situation when their first report came out, like they seem to be doing now?

[pietkuip]

Video of the public lecture by Carrie Lear at the Geological Society in September 2019:

"This lecture will firstly explain how we use indirect methods to reconstruct changes in the size of the Antarctic ice sheet which happened millions of years in the past. We will then see how the formation of the ice sheet - approximately 34 million years ago - made its mark in marine geochemical proxy records. Caroline will show that these records reveal a surprisingly dynamic history of the Antarctic ice sheet, with worrying implications for future ice sheet stability."



At the first question she says that she feels the MICI mechanism is necessary to explain rapid sea level rises during the Miocene but that more work needs to be done to say this convincingly.

[nanning]

Thanks piet.

AR5 vintage models

ripened? 

[AbruptSLR]

AbruptSLR, how has the early part of AR1 corresponded with the actual events since it was put out? Have the last several decades shown that they underestimated the situation when their first report came out, like they seem to be doing now?

That depends on what parameter you want to consider.  As the attached image shows, FAR (AR1) was more accurate than AR5 was about SLR; which I attribute to political pressure that was applied to SAR (AR2), TAR (AR3), AR4 and AR5.

[AbruptSLR]

The linked reference indicates that the important feedback mechanism of GHG emissions form wetland anaerobic peat decomposition is sensitive to the rate of warming; where faster rates of warming results in an increase in effective ECS this century:

Debjani Sihi, Patrick W. Inglett, Stefan Gerber and Kanika Sharma Inglett (26 July 2017), "Rate of warming affects temperature sensitivity of anaerobic peat decomposition and greenhouse gas production", Global Change Biology, DOI: 10.1111/gcb.13839 

http://onlinelibrary.wiley.com/doi/10.1111/gcb.13839/abstract?utm_content=buffer22bfd&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

Extract: "Temperature sensitivity of anaerobic carbon mineralization in wetlands remains poorly represented in most climate models and is especially unconstrained for warmer subtropical and tropical systems which account for a large proportion of global methane emissions. Several studies of experimental warming have documented thermal acclimation of soil respiration involving adjustments in microbial physiology or carbon use efficiency (CUE), with an initial decline in CUE with warming followed by a partial recovery in CUE at a later stage. The variable CUE implies that the rate of warming may impact microbial acclimation and the rate of carbon-dioxide (CO2) and methane (CH4) production. Here, we assessed the effects of warming rate on the decomposition of subtropical peats, by applying either a large single-step (10°C within a day) or a slow ramping (0.1°C day−1 for 100 days) temperature increase. The extent of thermal acclimation was tested by monitoring CO2 and CH4 production, CUE, and microbial biomass. Total gaseous C loss, CUE, and MBC were greater in the slow (ramp) warming treatment. However, greater values of CH4-C:CO2-C ratios lead to a greater global warming potential in the fast (step) warming treatment. The effect of gradual warming on decomposition was more pronounced in recalcitrant and nutrient-limited soils. Stable carbon isotopes of CH4 and CO2 further indicated the possibility of different carbon processing pathways under the contrasting warming rates. Different responses in fast versus slow warming treatment combined with different endpoints may indicate alternate pathways with long-term consequences. Incorporations of experimental results into organic matter decomposition models suggest that parameter uncertainties in CUE and CH4-C:CO2-C ratios have a larger impact on long-term soil organic carbon and global warming potential than uncertainty in model structure, and shows that particular rates of warming are central to understand the response of wetland soils to global climate change."

[AbruptSLR]

The linked reference indicates that tropical peatlands are likely three times larger than previously recognized.  Peatlands currently represent a net carbon sink, but continuing global warming and Anthropogenic activities (like agriculture & deforesting) could change these net carbon sinks into net carbon sources, that are largely unaccounted for in CMIP5/AR5:

Thomas Gumbricht, Rosa Maria Roman-Cuesta, Louis Verchot, Martin Herold, Florian Wittmann, Ethan Householder, Nadine Herold & Daniel Murdiyarso (9 May 2017), "An expert system model for mapping tropical wetlands and peatlands reveals South America as the largest contributor", Global Change Biology, DOI: 10.1111/gcb.13689

http://onlinelibrary.wiley.com/doi/10.1111/gcb.13689/abstract

Abstract: "Wetlands are important providers of ecosystem services and key regulators of climate change. They positively contribute to global warming through their greenhouse gas emissions, and negatively through the accumulation of organic material in histosols, particularly in peatlands. Our understanding of wetlands’ services is currently constrained by limited knowledge on their distribution, extent, volume, interannual flood variability and disturbance levels. We present an expert system approach to estimate wetland and peatland areas, depths and volumes, which relies on three biophysical indices related to wetland and peat formation: (1) long-term water supply exceeding atmospheric water demand; (2) annually or seasonally water-logged soils; and (3) a geomorphological position where water is supplied and retained. Tropical and subtropical wetlands estimates reach 4.7 million km2 (Mkm2). In line with current understanding, the American continent is the major contributor (45%), and Brazil, with its Amazonian interfluvial region, contains the largest tropical wetland area (800,720 km2). Our model suggests, however, unprecedented extents and volumes of peatland in the tropics (1.7 Mkm2 and 7,268 (6,076–7,368) km3), which more than threefold current estimates. Unlike current understanding, our estimates suggest that South America and not Asia contributes the most to tropical peatland area and volume (ca. 44% for both) partly related to some yet unaccounted extended deep deposits but mainly to extended but shallow peat in the Amazon Basin. Brazil leads the peatland area and volume contribution. Asia hosts 38% of both tropical peat area and volume with Indonesia as the main regional contributor and still the holder of the deepest and most extended peat areas in the tropics. Africa hosts more peat than previously reported but climatic and topographic contexts leave it as the least peat-forming continent. Our results suggest large biases in our current understanding of the distribution, area and volumes of tropical peat and their continental contributions."