1.5 C warming will trigger 1,000 gigaton release of methane and carbon

By Jeremy Hance / Mongabay

While nations around the world have committed to keeping temperatures from rising 2 degrees Celsius (3.6 degrees Fahrenheit) above the pre-industrial era, new research published in Science suggests that the global climate could hit a tipping point at just 1.5 degrees Celsius (2.5 degrees Fahrenheit). Studying cave stalactites and stalagmites in Siberia, scientists found that at about 1.5 degrees Celsius the Siberian permafrost melts, potentially releasing a greenhouse gas bomb of 1,000 giga-tonnes, according to some experts.

Turning to cave formations—stalactites and stalagmites—to reconstruct past climates in Siberian Russia, the scientists found that Russia had little permafrost around 400,000 years ago when the world was about 1.5 degrees warmer than the past 10,000 years (or the length of human civilization).

“The stalactites and stalagmites from these caves are a way of looking back in time to see how warm periods similar to our modern climate affect how far permafrost extends across Siberia,” lead author Anton Vaks of Oxford University’s Department of Earth Sciences explains. The stalactites and stalagmites do not grow under permafrost conditions, but only when ice melt or rain is available. Therefore these cave formations act as signals for what past climate looked like.

According to the study, the only time the permafrost melted in the last half million years was between 424,000 and 374,000 years ago when temperatures globally hit the 1.5 degree Celsius mark. So far global temperatures have risen 0.8 degrees Celsius (1.4 degrees Fahrenheit) in just the last two hundred or so years with two thirds of that rise coming since 1980.

“As permafrost covers 24 percent of the land surface of the Northern hemisphere significant thawing could affect vast areas and release giga-tonnes of carbon,” Vaks says. Once permafrost melts, sunlight and bacteria will attack previously-frozen plant material, releasing carbon and methane into the atmosphere. Though at this point there is considerable debate about how much greenhouse gas emissions would actually hit the atmosphere.

Despite such concerns, experts say that reaching, and surpassing, 1.5 degrees Celsius is practically inevitable given that global greenhouse gas emissions continue to rise year-after-year. Many emissions are considered “locked-in” since fossil fuel-driven power plants have already been built or are currently being constructed. Still, many vulnerable and island nations have called on the global target to be reduced from 2 degrees Celsius to 1.5 degrees. But even making the 2 degree target is looking increasingly unlikely, unless, perhaps, scientists literally start pulling carbon out of the atmosphere or the world’s fossil fuel plants are shut-down.

Whatever comes, the experts say it’s time to start incorporating permafrost melt into current climate models.

Read more at Mongabay: “Rise in 1.5 degrees Celsius likely to spark massive greenhouse gas release from permafrost

2 thoughts on “1.5 C warming will trigger 1,000 gigaton release of methane and carbon”

  1. So, let me get this right…if the temperature rises from the current .8C to 1.5C the permafrost will hit a tipping point and melt, releasing roughly 1,000 giga-tones of methane (which is 22 times more potent a greenhouse gas than C02) into the atmosphere. Since the global temperature is currently being raised via the rise of anthropogenic greenhouse gases (GHG’s), and there is a time-lag between temperature rise and GHG levels (temperature catching up to where these gases have set the bar, roughly a 20-30 yr. time-lag), then all we need to do to find out how close we are to this tipping point is to look at current levels of GHG’s and projections of correlating temperature rise, right? Come walk with me for a moment.

    Current C02 levels are at 394 ppm (the main factor in the last 180 yrs. of forcing temperature rise, most of which has increased in the last 30 yrs.). The last time C02 levels were this high was roughly 15 million years ago (mya), with temperatures roughly 3-6C above current levels. It would be good to note here that projected emissions and C02 levels by 2030, if “business as usual” continues, will be around 516-774 ppm; levels closer to those of the Eocene 54-50 mya when temperatures were roughly 5-7C higher than today.

    Since there is a time-lag between temperature rise and levels of C02 we can be certain that the temperature will rise 3-6C over the next 20-30 yrs. solely based on current levels of C02 alone. This of course would be the case without adding in any positive feedbacks like the melting of permafrost, arctic sea ice, ice caps, glaciers, and rapid forest die offs due to drought/deforestation etc. The thing is, the world has changed quite a bit in the last 15 myr. A lot more carbon has been stored in the earths surface due to the resumption of glacial cycles (since 13 mya the earth has plummeted into glacial cycles-5 mya and rapid glacial cycles-2.5 mya), increasing the capability/possibility with which to warm the globe if it were ever to be fully released. You see, the tricky thing about this time-lag is that if there was a huge spike in GHG’s over a shorter period of time, lets say 5-10 yrs. (which would definitely be reached if permafrost and forest die off positive feedbacks were to be pushed over their tipping points), the global temperature rise would also increase at an exponential rate.

    So, a more realistic picture would be: current GHG levels will undeniably rise temperatures enough in the next 10-15 yrs. to push the permafrost over its tipping point, hurling it into a rapid positive feedback loop and thus drastically escalating the already exponential rate of global temperature rise. During this short process every other positive feedback will come into play (this is because they are all just as sensitive to temperature rise), forcing the global temperature to rise beyond any conservatively or reasonably projected model. What’s really concerning in all this is that the arctic sea ice, permafrost, glaciers and ice caps have already begun their near rapid melt, and we continue to increase our output of fossil fuel GHG emissions and deforest the earth. Does anyone know what more than a 5-7C temperature rise looks like? Near-term extinction for the majority of biological life, including humans. This is the part where most people start formulating rebuttals that usually begin with the word “alarmist!”. Well, if the bare facts of our current situation is not alarming then I would think we have an even bigger problem.

    The last sentence in the last paragraph of the article posted couldn’t be more to the point. The only chance of survival is to immediately end the consumption (on all levels, and in every way) of fossil fuels, and to quickly begin sequestering GHG’s from the atmosphere. Best way to end this consumption would be to shut down all fossil fuel extractions, and to lock up all ready-to-be-used fossil fuels: gasoline, coal, and stored natural gas. Best way to sequester the GHG’s (semi-naturally) would be to plant native-to-bioregional plants/trees wherever they had been destroyed, and to grow our own food locally. Time is almost up!

    So, things look bad, but it all depends on your perspective. On the one hand it doesnt look too good for civilization (actually good) if people decide to rise up and act, but on the other hand, well…not so good for anyone. Also, another good thing is that civilization does not represent the whole of humanity…nor does it represent any other species of life on earth. So, some good news 🙂


    Daniel Whittingstall

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