Carbon Feedback

​  ONLY ZERO CARBON ONLY ZERO CARBON ONLY ZERO CARBON ONLY ZERO CARBON ONLY ZERO CARBON ONLY ZERO CAR

The rapidly warming Arctic has already been leaking methane from both thawing terrestrial permafrost for many years (global surface warming) and sub sea methane hydrates (some times called ocean  floor permafrost) for several years (ocean warming and surface warming).

The methane emissions from thawing permafrost is the result of bacteria in the presence of water digesting the thawed soil carbon and emitting methane. So its slow process that happens some years after a level of permafrost is thawed.

Methane hydrate on the other hand is pure methane that forms under conditions of cold and pressure. If pressure is reduced or temperature increased sufficiently, the methane is released and bubbles up through the sea water and from the East Siberian Arctic shelf, it is actually venting to the atmosphere. As the methane gas has over 100 times the volume of the solid hydrate it can release explosively. Methane hydrates are widely distributed around all continental coastal shelves but are most vulnerable to global warming in the Arctic.

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In the Arctic, they are most vulnerable to global warming because they have formed nearer the ocean surface level in coastal sediments. They are also potentially vulnerable on the sea bed off the Siberian coastal shelf where the solid methane hydrate caps methane gas below the sea bed.

Runaway Hothouse Earth

The ultimate planet catastrope is what has been referred to as runaway and published in. 2018 as Hothouse Earth. 

Carbon feedback is the cause of  so-called runaway' global warming and climate change and Hothouse Earth

It is the ultimate vicious cycle.

Industrial GHG emissions- cause global warming- that leads to feedback emissions- that increases global warming- that leads to even more feedback emissions etc etc.

The IPCC 6th Assessment said we had no time left on reducing emissions-to avoid climate catastrophe. To avoid global catastrophic 2°C, global emissions had to be in decline immediately rapidly.

The longer the delay the more  (higher degree) global warming is committed, and the greatest the amplifying feedbacks will be. Already all these feedbacks are operant 

These amplifying feedbacks, like permafrost thaw, are irreversible- they can only increase.

This is another reason we cannot afford to add more carbon to the atmosphere.

The so-called allowable carbon budget (to burn more carbon) does not include any of these enormous carbon feedback sources. 

  Arctic carbon feedbacks

The most dangerous effect of global warming is carbon feedbacks and the most dangerous of the carbon feedbacks by far is the carbon feedback from the Arctic.

The Arctic permafrost contains twice as much carbon as in the atmosphere. Most of this is emitted as methane (CH4) as the Arctic warms rapidly due to global warming. 

​​Methane only lasts in the atmosphere as methane for 12 years as by then it disappears because it's oxidized in the atmosphere to other greenhouse gases- notably including carbon dioxide, making methane feed back emissions a carbon dioxide source.

Terrestrial carbon feedback.

'Terrestrial' carbon feed back is CO2 or methane emitted by warmed living soils and decaying vegetation.

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Since a 2000 paper by Peter Cox (Acceleration of global warming due to carbon-cycle feedbacks) , the upper range of terrestrial carbon projected warming is 1.5C by 2100. Other researchers calculate it as low as 0.5C by 2100. ​​The difference is mainly due to the Cox model predicting the dieback of the Amazon forest by drying drought and fire.

The latest 2012 terrestrial carbon feedback research by B. Both (High sensitivity of future global warming to land carbon cycle processes)  projects it to be high at 1.7C.

Already on the many continents that increased forest fires as a result of global warming.

The fossil fuels are burnt to produce fossil fuel energy and in doing so they emit carbon dioxide that causes global warming. The burning forest fires also emit carbon dioxide which then adds to the global warming.

There is another example for carbon feedback from dying forests. This one is caused by increased insect infestation of forest trees under warmer temperatures. As the trees die they stop absorbing CO2 and the forests emit a lot of carbon dioxide released by the dying trees.

More drying, more heat waves, more toxic ground level ozone

more insect infestation and more diseases combined together will result in large forested regions of the planet burning away under increasing global warming.

By their very nature amplifying feedbacks the single most dangerous disastrous potentially catastrophic effect of global warming. The 

This is because of the many enormous sources of amplifying feedbacks on the planet.

At some degree of warming each of these feedback sources will be triggered. Some of the feedbacks have tipping points. True avoid catastrophic feedbacks being triggered it is necessary to assess and plan mitigation of global climate change by the total committed degree of global warming at any particular time.

Presently the land and oceans absorb ('sink' or rather store) about half of industrial carbon emissions, but that cannot last indefinitely. The sinks are not permanent, but will both weaken over time. This is explained by the IPCC 5th Assessment. has probably started already (Global Carbon Project)
 

Ocean changes as well as land changes may lead to positive carbon feedbacks.

Before industrialization natural planetary carbon emissions were balanced by carbon uptake- by the photosynthesis of

green plants, on land and sea. Ocean surface plankton (minute green plants) take up the most CO2.  

Carbon feedbacks by planetary source

This illustration of the perturbed carbon cycle, shows three planetary general sources of carbon feedback emissions.

From left to right we have: Terrestrial- Ocean-Arctic

Terrestrial feed backs

o Increased decomposition and respiration by soil organisms in a warming soils.

o Extreme weather events- reduce carbon uptake by green vegetation       photosynthesis. This is caused by heat waves and drought.

o​ Increased green plant toxic ground level ozone increase- reduced photosynthesis.

o Increased forest fires - emit black carbon, CO2 and methane.

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Ocean carbon feed backs.

o Increased water temperature dissolves less CO2.

o Increased ocean acidification dissolves less CO2.

o Reduced phytoplankton growth reduces ocean photosynthesis.

o Impaired Capacity of shell bearing organization to make calcium carbonate. ​

Arctic cryosphere carbon feedbacks

o Thawing permafrost

o Melting ocean floor methane hydrates

Ocean carbon feedbacks

Carbon cycle feedback

As the land is warmed, it becomes a source of additional

carbon emissions as carbon dioxide (CO2) or as methane (CH4) emissions.

This effect is called carbon feedback. The largest amount of carbon is in soil and

the largest amount in the soils is peatland- northern and tropical.

Arctic Permafrost holds the very largest amount of carbon.

Methane is a powerful GHG and a relatively small amount of it is converted

to CO2 in the atmosphere by chemical reaction. Most of a methane emission is removed

by  chemical reactions by 10 years. However as methane increases in the atmosphere

it is not removed as fast, so more methane is left in the atmosphere,

methane has its own feedback. 

Time-scales 

The carbon stores respond to warming on various time-scales

Terrestrial carbon feedback First climate science calls the most rapidly responding feedbacks terrestrial carbon carbon feedbacks.

The only carbon feedback included in the model projections is some terrestrial

carbon back, but as it assumed the carbon sinks will keep taking up more

CO2 as CO2 in the atmosphere increases, projections of global warming do

not include extra warming from these sources, even though they will respond.

The IPCC just calls them uncertainties not accounted for .

There are large ranges projected by the models for amount aof emissions

and extra warming of these feedbacks. Only the 2007 4th IPCC Assessment gave a figure for terrestrial carbon feedback of over 1"C.

Terrestrial carbon feedback warming by 2100 has been estimated to be as high as 1.8°C

(Booth 2012).

This excludes the largest planetary carbon stores which are:

o Large forest fires

o Amazon die-back (subarctic and tropical)

o Wetland peat (methane),

o Arctic permafrost (methane, CO2)

o Sub seafloor methane gas hydrate

Peatlands About half the world's wetlands are carbon-rich peatlands

They are estimated to hold double all the world's forest carbon. 

Arctic 

Most of the largest feedback sources are Arctic, particularly the potest greenhouse gas methane. Arctic wetland peat and permafrost are already emitting more methane into the atmosphere. Adding the estimates of all Arctic carbon sources the Arctic holds four times atmospheric carbon.

Permafrost  holds double atmospheric carbon.

All permafrost regions are thawing 

This is releasing all three GHGs methane, CO2, nitrous oxide

Far more CO2 is being than expected because it keeps emitting in the Autumn to early Arctic winter 

Arctic sink to source

As a result of the permafrost carbon emissions of methane and CO2 , the Arctic has switched from carbon sink to source (NOAA Arctic Report Card 2016,

confirmed Arctic Report Card 2019)

The Arctic holds most of the largest feedbacks sources

Arctic summer sea ice extent  (albedo-loss feedback)

Northern snow cover  (albedo-loss  feedback)

This leads to a multiple feedback carbon cascading dynamic 

Carbon dioxide emissions due to carbon feed back is a additional source of carbon and as such should be accounted for in zero carbon climate change mitigation.

Peatlands and permafrost

​​Carbon from warming peatlands (Arctic and tropical), and from thawing permafrost (permanently frozen soils in the Arctic) is emitted mainly as methane and some CO2. Neither are included among the terrestrial carbon feedbacks and These sources hold double of all the carbon in the atmosphere.

​Arctic methane hydrate carbon (frozen solid methane gas) in the ocean floor sediment of the Arctic

​is already being released into the ocean and from the East Siberian Arctic shelf it is bubbling up to

​emit methane into the atmosphere. Methane released into the ocean will add to ocean acidification.

​This is double the carbon in the atmosphere

Oceans absorbing less CO2

Warm water dissolve less atmospheric CO2 than cold water.

​Acidified ocean water will absorb less CO2.

Forests

Forest fires are already increasing under global warming and are a carbon feedback emitting mainly carbon dioxide as they burn but also methane.

Forest insect infestations increase under global warming so this is +ve feedback by killing forests.

​​Arctic frozen solid methane hydrates under the ocean floor, which also hold possibly up twice as much carbon as the atmosphere.

​(Soil organic carbon pools in the northern circumpolar permafrost region C. Tarnocai J. G. Canadell et al 27 June 2009)

The far north and Arctic have been warming up twice as faster than the rest of the planet In Siberia , that holds by far the most of the Arctic's huge store of frozen carbon, some regions have been warming three times as fast. This is all much faster than the scientists had predicted from their computer models and the Arctic is now warming four times as fast as the rest of the planet.

Tropospheric (ground level) ozone​​ is projected to be the cause of a major carbon feedback with further global warming. Ground level ozone is well known to be toxic to human health and it is also toxic to green plants reducing their capacity for capturing carbon from the air by photosynthesis. This ozone air pollution is formed by a chemical reaction from fossil fuel pollutants and the reaction is catalyzed by the warmth of sunlight. Therefore this toxic ground level ozone will increase with global warming, and plants will become less efficient at fixing carbon from the ambient carbon dioxide, leaving more carbon dioxide in the air- a positive amplifying carbon feedback.

Extreme  weather events that are increasing is a source of carbon feedback, because the capacity of the damaged vegetation to take up CO2 is impaired (Climate extremes and the carbon cycle M Reichstein Nature 2013) terrestrial ecosystems absorb approximately 11 billion tons less carbon dioxide every year as the result of the extreme climate events. That is equivalent to approximately a third of global CO2 emissions per year.

Carbon Feedbacks

Positive (+ve) feedbacks to global warming

are Amplifying- they increase the warming 

Global warming induces effects on the climate system that increase global warming. Ffor example more forest fires increased by global surface warming emit CO2 that increases warming.

This may result in a feedback self sustaining loop. 

Warming of vulnerable carbon stores releases CO2 and/or methane (CH4)

This has been known for a great many years

Global warming vulnerable carbon

feedback stores 2006

The enormous omission of amplifying  carbon feedbacks by the IPCC has been put down to 'uncertainty'- but it is a certainly that is already happening. It's a fundamental fatal flaw that renders all IPCC projections 

huge underestimates, or inthe cse of the carbon budget over estimate.

In 2012 UNEP published 'Policy implications of warming permafrost'