Beyond the Point of No Return — Imminent Carbon Feedbacks Just Made the Stakes for Global Warming a Hell of a Lot Higher

“It’s fair to say we have passed the point of no return on global warming and we can’t reverse the effects, but certainly we can dampen them,” said biodiversity expert Dr. Thomas Crowther.

“I’m an optimist and still believe that it is not too late, but we urgently need to develop a global economy driven by sustainable energy sources and start using CO2, as a substrate, instead of a waste product.” — Prof Ivan Janssens, recognized as a godfather of the global ecology field.

“…we are at the most dangerous moment in the development of humanity. We now have the technology to destroy the planet on which we live, but have not yet developed the ability to escape it… we only have one planet, and we need to work together to protect it.” — Professor Stephen Hawking yesterday in The Guardian.


The pathway for preventing catastrophic climate change just got a whole hell of a lot narrower.

For according to new, conservative estimates in a scientific study led by Dr. Thomas Crowther, increasing soil respiration alone is about to add between 0.45 and 0.71 parts per million of CO2 to the atmosphere every year between now and 2050.

(Thomas Crowther explains why rapidly reducing human greenhouse gas emissions is so important. Namely, you want to do everything you can to avoid a runaway into a hothouse environment that essentially occurs over just one Century. Video source: Netherlands Institute of Ecology.)

What this means is that even if all of human fossil fuel emissions stop, the Earth environment, from this single source, will generate about the same carbon emission as all of the world’s fossil fuel industry did during the middle of the 20th Century. And that, if human emissions do not stop, then the pace of global warming of the oceans, ice sheets, and atmosphere is set to accelerate in a runaway warming event over the next 85 years.

Global Warming Activates Soil Respiration Which Produces More CO2

This happens because as the world warms, carbon is baked out of previously inactive soils through a process known as respiration. As a basic explanation, micro-organisms called heterotrophs consume carbon in the soil and produce carbon dioxide as a bi-product. Warmth is required to fuel this process. And large sections of the world that were previously too cold to support large scale respiration and CO2 production by heterotrophs and other organisms are now warming up. The result is that places like Siberian Russia, Northern Europe, Canada, and Alaska are about to contribute a whole hell of a lot more CO2 (and methane) to the atmosphere than they did during the 20th Century.

When initial warming caused by fossil fuel burning pumps more carbon out of the global environment, we call this an amplifying feedback. It’s a critical climate tipping point when the global carbon system in the natural environment starts to run away from us.

Sadly, soil respiration is just one potential feedback mechanism that can produce added greenhouse gasses as the Earth warms. Warming oceans take in less carbon and are capable of producing their own carbon sources as they acidify and as methane seeps proliferate. Forests that burn due to heat and drought produce their own carbon sources. But increasing soil respiration, which has also been called the compost bomb, represents what is probably one of the most immediate and likely large sources of carbon feedback.


(A new study finds that warming of 1 to 2 C by 2050 will increase soil respiration. The result is that between 30 and 55 billion tons of additional CO2 is likely to hit the Earth’s atmosphere over the next 35 years. Image source: Nature.)

And it is also worth noting that the study categorizes its own findings as conservative estimates. That the world could, as an outside risk, see as much as four times the amount of carbon feedback (or as much as 2.7 ppm of CO2 per year) coming from soil if respiration is more efficient and wide-ranging than expected. If a larger portion of the surface soil carbon in newly warmed regions becomes a part of the climate system as microbes activate.

Amplifying Feedbacks Starting to Happen Now

The study notes that it is most likely that about 0.45 parts per million of CO2 per year will be leached from mostly northern soils from the period of 2016 to 2050 under 1 C worth of global warming during the period. To this point, it’s worth noting that the world has already warmed by more than 1 C above preindustrial levels. So this amount of carbon feedback can already be considered locked in. The study finds that if the world continues to warm to 2 C by 2050 — which is likely to happen — then an average of around 0.71 parts per million of CO2 will be leached out of soils by respiration every year through 2050.


(When soils lose carbon, it ends up in the atmosphere. According to a new study, soils around the world are starting to pump carbon dioxide into the atmosphere. This is caused by increased soil respiration as the Earth warms. Over the next 35 years, the amount of carbon dioxide being pumped out by the world’s soils is expected to dramatically increase. How much is determined by how warm the world becomes over the next 35 years. Image source: Nature.)

The upshot of this study is that amplifying carbon feedbacks from the Earth environment are probably starting to happen on a large scale now. And we may be seeing some evidence for this effect during 2016 as rates of atmospheric carbon dioxide accumulation are hitting above 3 parts per million per year for the second year in a row even as global rates of human emissions plateaued.

Beyond the Point of No Return

What this means is that the stakes for cutting human carbon emissions to zero as swiftly as possible just got a whole hell of a lot higher. If we fail to do this, we will easily be on track for 5-7 C or worse warming by the end of this Century. And this level of warming happening so soon and over so short a timeframe is an event that few, if any, current human civilizations are likely to survive. Furthermore, if we are to avoid terribly harmful warming over longer periods, we must not only rapidly transition to renewable energy sources. We must also somehow learn to pull carbon, on net, out of the atmosphere in rather high volumes.

Today, Professor Ivan Janssens of the University of Antwerp noted:

“This study is very important, because the response of soil carbon stocks to the ongoing warming, is one of the largest sources of uncertainty in our climate models. I’m an optimist and still believe that it is not too late, but we urgently need to develop a global economy driven by sustainable energy sources and start using CO2, as a substrate, instead of a waste product. If this happens by 2050, then we can avoid warming above 2C. If not, we will reach a point of no return and will probably exceed 5C.”

In other words, even the optimists at this time think that we are on the cusp of runaway catastrophic global warming. That the time to urgently act is now.


Quantifying Soil Carbon Losses in Response to Warming

Netherlands Institute of Ecology

Earth Warming to Climate Tipping Point

This is the Most Dangerous Time for Our Planet

Climate Change Escalating So Fast it is Beyond the Point of No Return


Soil Respiration

Hat tip to TodaysGuestIs

Hat tip to Cate

Hat tip to Colorado Bob

Hat tip to Wili

James Hansen and the Three Categories of the Runaway Greenhouse: Earth Uninhabitable for Humans at ~5,000 Gigatons Fossil Fuel Burned

Runaway Global Warming

The Arctic’s Contribution to Runaway Global Warming (hypothetical worst-case runaway) . The above image provides a potential worst-case scenario for amplifying Arctic methane feedbacks to human-caused climate change. James Hansen’s research shows that a mini-runaway, pushing global temperatures to 10-12 degrees C above the Holocene, is all but certain under continuous, business as usual, fossil fuel burning through 2100. It is important to note that the current non CO2 forcing is equal to about 1/3 of the total CO2 forcing and that atmospheric methane releases are at 1/20th the level we would see during a runaway of the kind depicted in this image.

( Image source: Arctic News)

Forget for a moment that we can still emit about 530 gigatons of CO2 and still keep human warming in the ‘safe range’ of less than 2 degrees (Celsius) temperature increases this century. Forget for a moment how important to the sustenance of human civilization and the prevention of ever-worsening conditions this strict limit on carbon emissions is. Now think for a moment what will happen if Republicans in Congress and fellow conservatives aligned with fossil fuel companies across the country and around the world get their way.

In the past month, Republicans in the House of Representatives have pushed to increase US coal burning, approve the Tar Sands Keyston XL Pipeline, remove energy efficiency standards, and to slash US government (ARPA -E) R&D funding for new renewable energy technology by 80 percent. Fully 55% of all Republicans in the US Congress deny that human caused warming even exists. And the rest clearly are deluded enough to believe that it represents the climate version of a mild summer storm. Their legislative action over the past month, the past year, and for many years following that has been to enforce US dependence on oil, gas, and coal and to delay, diffuse and deny US access to new energy sources that may effectively serve as their replacements. And the millions of dollars in oil, gas and coal company largess they enjoy in the form of contributions is just the final proof that these members aren’t working for the best interests of the American people. They’re working for the international corporate state called Big Oil (BO).

So let’s consider for a moment what would happen if these BO lackeys in Congress were successful in their efforts to kill off alternative energy, to remove efficiency standards, and to shackle the US Energy future to Tar Sands, Coal, and Fracked Shale Oil and Gas.

What would happen?

It’s difficult to argue, given the current extreme and worsening state of the world’s climate, that blind Republican attempts to enforce dependence on BO would result in much in the way of US prosperity. It, essentially, would turn the entire North American Continent into a giant petro-state. It is possible that, for some years, the US will make some energy independence gains, possibly removing a larger fraction of imports from most states except Canada. But the loss of efficiency standards would do ongoing damage by increasing consumption of high-cost unconventional fuels, which would put a drag on the economy. The even greater drag would come from shackling US and North American economies to ever greater degrees to fuel sources, at best, that create a 6 to 1 energy return, where wind and solar could have supplied between 10 and 20 to 1 at ever-lower costs.

Worse still, is the fact that US and Canadian carbon emissions would go through the roof. Tar Sands, Coal, and Tight Shale Fracking are three horsemen of the apocalypse when it comes to climate change change (the fourth being fossil fuel company greed). Coal has always been the worst emitter. But both Tar Sands and Tight Shale Fracking are not far behind. The Republicans would have us depend on these, arguably vast, unconventional sources to the exclusion of all others. They wouldn’t care one whit about capturing the carbon (costs too much and reduces the energy return on already low energy fuels). And, adding yet one more insult, they allow BO to export the fracking and tar sands technologies to other countries consigning them and the world to similar fates.

Total carbon emissions in 2012 (including non CO2 sources) was 45 gigatons. But on the path Republicans set, this level of emission will look minor. Peak emissions would probably pair with peak human civilization at some time around 2050 near 80-90 gigatons per year. At this point, emissions are put in check by mother nature’s outrage at our insults. By 2050, the ‘burn everything’ strategy put in place by Republicans and enforced by conservatives around the world has resulted in near 600 ppm atmospheric CO2. Life in the oceans is in terminal collapse, major cities and island nations are being devoured by a combination of powerful storms and rising seas. The coastlines, for so long productive, have become unstable. And large regions of once fertile land are now being devoured by deserts. Water stress has caused entire countries to collapse. Mass migrations from both the coastlines and from desertified regions has already set in. Human population peaks at about this time near 10 billion.

But over the next 50 years humans maintain enough vestige of prior fossil-fuel based civilization to keep burning. They expend massive efforts to encircle coastal cities with walls. They try to farm indoors more and more. Miami is placed on giant oil platforms (we have more than enough in surplus) whose bases are driven into the limestone beneath the city. The New Orleans’ tidal wall is heightened to 30 feet. New York and the all important Wall Street is surrounded by increasingly high flood barricades. But the massive storms of this age are freakish, wrecking entire regions and knocking out power for weeks to months. Storms and heatwaves kill millions each year and millions more are rendered homeless. Entire countries collapse for want of food or under a tide of refugees they cannot support.

By 2100, CO2 is at 1000 ppm and global temperatures are 7 degrees (Celsius) hotter. Fossil fuel based industry has emitted about 5,000 gigatons of carbon, enough to set off the stages for a mini runaway global warming scenario (Category 1). Sea levels have risen 12 feet and Earth’s population has been reduced to 6 billion. 40% of ocean species are extinct and 10% of land species have suffered the same fate. Summer time results in the emergence of large heat death zones experiencing wet bulb temperatures in excess of 35 degrees Celsius (hot enough to kill most large mammals, including humans, through heat stress alone). Even if all emissions ceased, global temperatures would still rise to around 12-14 degrees Celsius hotter than the Holocene. There is almost no chance, in this case, for human civilization to survive such an insult for more than another 50-100 years. And the chances for humans, long term, are dire indeed.

But the world’s fossil fuel companies are still around, still clawing coal, fracked oil and gas, tar sands, oil shale, and methane hydrates  from the Earth with whatever new high tech process they’ve invented. These manage to survive for another 50 years or so selling off enough dirty fuels to set world CO2 levels to 1500 ppm. And that’s when game over really sets in for just about everything that can’t run to a high mountain range.

Fossil fuel based industry had managed to survive just long enough to emit more than 8,000 gigatons of carbon into the atmosphere. Just long enough to kill off the rest of us and themselves too.

Three Categories of Runaway Warming

The above scenario isn’t science fiction. According to some hard science done by the world’s top climate scientists, it is entirely likely if Republican burn, baby burn policy and the fossil fuel companies that push it survive in their current forms for much longer.

Hansen’s new paper is a more in depth study of Earth Systems Climate Sensitivity to a given level of CO2 forcing. The study looks, with greater detail, into both how much Earth will warm, long term, given a certain level of CO2 emission and how much of this emission is required to set off one of three categories of a runaway greenhouse.

In a less than ideal scenario, Hansen investigates what will happen if we burn all or nearly all the fossil fuels currently included in the unconventional reserves. All, or nearly all, according to Hansen represents between 5,000 to 10,000 gigatons of carbon equivalent fuels. Chillingly, if we tap the most extreme sources, such as methane hydrates, that number could rocket to 20,000 gigatons or more. So even Hansen’s study isn’t an extreme worst case.

Category 1: The Mini-Runaway

The Hansen paper finds that burning between 3,500 and 6,500 gigatons of carbon based fuels is enough to raise world CO2 levels to between 800 and 1200 parts per million. This level of CO2 would set up climate conditions similar to those experienced during the Paleocene-Eocene Thermal Maximum (PETM) in which temperatures were between 10 and 12 degrees Celsius hotter (average) than today.

Hansen finds that this level renders much of the Earth mostly uninhabitable for humans. Hansen notes:

Earth was 10-12 °C warmer than today in the early Eocene and at the peak of the PETM (Fig. 4). How did mammals survive that warmth? Some mammals have higher internal temperatures than humans and there is evidence of evolution of surface-area-to-mass ratio to aid heat dissipation, e.g., transient dwarfing of mammals (Alroy et al., 2000) and even soil fauna (Smith et al., 2004)during the PETM warming. However, human-made warming will occur in a few centuries, as opposed to several millennia in the PETM, thus providing little opportunity for evolutionary dwarfism to alleviate impacts of global warming. We conclude that the large climate change from burning all fossil fuels would threaten the biological health and survival of humanity, making policies that rely substantially on adaptation inadequate.

It is also worth noting that much of the world’s land masses would experience average summer temperatures above the mammal-killing level of 35 degrees Celsius (wet bulb) in a PETM-like world. The added heat of this regime would swiftly soften and obliterate any ice on the planet. But given the killing heat and a hydrological cycle driving droughts and rainfall events that are 80% more extreme, a rapid sea level rise of 200+ feet would likely come as a harsh afterthought. (To this point, it is worth mentioning that most planetary ice disappears when CO2 levels hit and maintain between 500 and 620 parts per million over a number of centuries).

Nearly all climate scientists agree that a return to PETM conditions and CO2 levels, especially on so short a time-scale would be a mass extinction event on the land and in the ocean. Which is why policies that extend the burning of fossil fuels combine the travesties of ecocide, genocide, and suicide in equal measures and to ever greater degrees as time moves forward.

Category 2: The Moist Stratosphere Runaway

If the fossil fuel companies manage to stick around long enough, they may be able to burn through between 8,000 and 15,000 gigatons of additional carbon-based fuels. Such an event would almost certainly spell the end for human beings and probably most of the complex life on Earth as well.

In such a situation, average global temperatures rise by between 15 and 20 degrees Celsius. A 15 degree Celsius temperature rise increases temperatures over land by around 20 degrees C. This puts Earth’s average land temperatures at around 35 degrees Celsius with average daily (wet bulb) highs in the range that is hot enough to kill humans. The entire Earth, in this case, is an enormous human killing field.

The only regions able to even marginally support human life or agriculture would be the high mountains. But even these regions would be under threat. Global heating of around 15 degrees Celsius or greater would pump ever greater levels of moisture into the stratosphere. The added H20 would substantially degrade stratospheric ozone. The added UV radiation would severely hamper both plant and animal life in the remaining habitable regions. Human food crops are highly sensitive to excess UV radiation. So it is seriously doubtful if humans could continue cultivation even on the Himalayan Plateau during a Category 2 Runaway.

Category 3: Evaporated Oceans, Baked Crusts

Thankfully, even the fossil fuel companies aren’t likely to bring about even the worst of the climate change nightmares — Earth transitioning to a state more like Venus. In order to do that, global heating would have to evaporate all of Earth’s oceans and then bake the remaining carbon out of the Earth’s crust. According to new models constructed by Hansen, such conditions would take between 100 million and one billion years to develop. Hansen’s models also show that climate sensitivity is not enough, at the higher CO2 levels, to finally set off the kind of runaway that would force such catastrophic events to occur.

That said, the first two categories of global warming runaway are well within the reach of current fossil fuel reserves. And the fact that all fossil fuel companies are doing everything they can to burn all the reserves on their books and to find ever greater quantities of these fuels is not at all comforting, especially when they have a number of hired trolls in Congress and elsewhere (Republicans) to do their dirty work for them…


New Hansen Paper on Climate Sensitivity, CO2 and Sea Level Rise

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