A Fearful Glance at the Global Carbon Stores — Weekly CO2 Values Hit 404 Parts Per Million a Little Too Soon

mlo two years April 15

(Big jump in weekly CO2 averages during second week of April bring 2015 concentrations into the range of 404 parts per million a month earlier than expected. Image source: The Keeling Curve.)

Over the past decade, annual rates of atmospheric CO2 increase have remained in a range of around 2.2 parts per million (ppm) each year. It’s a geologically blinding pace of increase driven by a human carbon emission on the order of around 11 billion tons each and every year. Primarily driven by fossil fuel burning, this massive dumping of carbon into the atmosphere is steadily filling up a number of the world’s key carbon stores.

The oceans are brimming full with carbon — as we see in a rapidly rising rate of acidification.  The oceans are warming, steadily losing their ability to keep a higher fraction of greenhouse gasses stored in solution. The trees are lagging in their ability to draw carbon from the atmosphere — a symptom of a combined deforestation, wildfire proliferation, and endemic outbreaks of invasive species that prey on key trees. And the carbon store in the Arctic is showing signs that it may be actively venting higher volumes of greenhouse gasses back into the atmosphere and oceans.

As a leading indicator that some of these carbon stores are starting to fill up, or worse, dump a significant portion of their sequestered carbon back into the atmosphere, we would expect to see spiking levels of CO2 and CH4 in the global measures. Which is why when, starting on April 5 of 2015, Mauna Loa CO2 values shot up to around 404 to 405 parts per million in some of the hourly records, a few eyebrows were raised.

Implications of Hitting Expected Peak Values a Bit too Soon

Typically, atmospheric CO2 peaks around mid-May. And, for this year, following the 2.2 ppm increase trajectory, we would expect a May monthly value of around 404 parts per million. So readings in the range of 404 to 405 parts per million in early April are a significant jump well ahead of the expected marks. If this increase remained consistent and showed continued seasonal rise on through mid-May, it could skew April and May readings upward — well beyond a 2.2 ppm annual increase at peak.

mlo_one_month

(Consistently High CO2 values show up at the end of the monthly measure. Note the frequent hourly departures above 405 ppm. Image source: The Keeling Curve.)

Typically, the difference between April and May monthly values is in the range of 0.5 to 1 ppm CO2. So an April Average near 404 ppm could yield a May average of 404.5 to 405 ppm or a 2.7 to 3.2 ppm increase over 2014 peak values. A significant high departure that could be a leading indicator of a bad response from the global carbon stores. This possibility was raised as daily Mauna Loa CO2 values ranged from 403.2 ppm through 404.9 ppm from April 5 to 14 and as weekly values for April 8-14 hit 403.9 ppm.

Signal or Noise?

Of course, these admittedly worrisome spikes could well be noise in the overall carbon system. CO2 values have tended to vary more wildly in the Mauna Loa measure recently. And average rates of increase from peak to peak could still fall into the standard range.

It is also worth noting that any major disruption in the global carbon system as it relates to CO2 would also show up as a trailing indicator in the CO2 airborne fraction measure. A higher level of emitted CO2 would remain in the atmosphere as sinks began to fail and as stores became sources. Such a carbon sink failure would eventually show up as a higher airborne CO2 fraction.

Overall, the airborne fraction measure is an indicator of how much of the carbon human beings emit into the atmosphere is being taken up by the global environment:

CO2 Airborne Fraction

(Airborne CO2 fraction showing global carbon dioxide emissions [as gigatons of carbon without oxygen molecular weight added] since 1960 through 2012 and amount of emitted CO2 that has remained in the atmosphere. Image source: James Hansen and The University of Columbia.)

Currently, the amount of carbon from CO2 remaining in the atmosphere is in the range of 45% of the human emission — or around 5 gigatons.

If carbon sinks are retaining their ability to uptake CO2, then the fraction will remain relatively low. If carbon sinks are over-topping and bleeding substantial volumes of their carbon back into the atmosphere, then the airborne fraction measure will tend to rise as a trailing indicator.

During recent decades, the airborne fraction has actually fallen as emissions ramped up — probably due to a combined increase in ocean surface exposure to CO2 and to an initial bump in the rate of CO2 respiratory uptake by photosynthetic life. But considering the very high volume of carbon being dumped into the global system coordinate with a wide variety of stresses to carbon stores resulting from both added heat and chemistry changes, these carbon sinks are under ever-increasing stress. A number of scientific studies have indicated a likely rise in CO2 airborne fraction, under business as usual fossil fuel emissions, to as much as 80 percent through 2100 — with start of carbon store failures during the current decade.

If carbon stores do begin to fail, we would first see atmospheric spikes in the global CO2 and CH4 measures. Then, as a trailing indicator, the CO2 airborne fraction measure would begin to ramp up. In this context, weekly CO2 spikes at Mauna Loa are some cause for concern, but we can’t make any strong calls of a larger carbon system response without a more consistent spike and, eventually, a jump in the airborne fraction.

To this final point, I’ll leave you with the somewhat related Mauna Loa CH4 measure which has, lately, also been showing an increasing rate of accumulation for that greenhouse gas:

Mauna Loa Methane Measure 2004 to 2015

(Mauna Loa Methane measure shows ramping up of atmospheric CH4 readings at that station. Image source: NOAA ESRL.)

Links:

The Keeling Curve

Doubling Down on Our Faustian Bargain

Modeling The Atmospheric Airborne Fraction in a Simple Carbon Cycle Model

NOAA ESRL

Scientific Hat tip to Dr. James Hansen

Hat tip to Wili

Hat tip to Kevin Jones

Yedoma Region of Russia Showing Significant Methane Pulse

August 7 Methane Pulse, Yedoma

August 7 Methane Pulse, Yedoma

(Image source: Methane Tracker)

August 4-7 saw a large and growing pulse of methane emerging from the Yedoma region of Russia and the Siberian Arctic over the past week. By Wednesday, about 30 percent of the Yedoma region was covered in methane readings exceeding 1950 parts per billion, according to measurements published through the online resource — Methane Tracker.

This pulse emerged in conjuction with late summer fires and heatwaves scorching this massive region of permafrost above or near the Arctic Circle. Yedoma includes a broad expanse of permafrost ranging from Siberia to a shallow sea known as the East Siberian Arctic Shelf. In total, this region is estimated to hold 500 gigatons of carbon locked in, now thawing, tundra.

The region has come under increased scrutiny and study during recent years as temperatures throughout the Arctic and especially in this area have rapidly risen due to human warming. While global temperatures have increased by an average of around .2 degrees Celsius per decade, temperatures in Yedoma have increased by more than twice that rate at a whopping .5 degrees Celsius per decade. As a result, most of the tundra, both land and shallow sea, is subjected to increasing heat forcing and is at greater risk of releasing large volumes of carbon into the atmosphere.

The geographic region of Yedoma and its related loess layers are indicated on the map below. Note the large off-shore region extending into the East Siberian Arctic Shelf:

Yedoma Map with loess deposits.

Yedoma Map with loess deposits.

(Image source: Ole Log)

Originally, it was estimated that Yedoma released about 4 megatons of carbon each year. Instead, recent expeditions have found that the region releases a staggering 44 megatons of CO2 and an estimated 4 megatons of methane. The CO2 emission alone is greater than that pumped out by 1 million automobiles and, since methane is so powerful a greenhouse gas, the forcing provided by the 4 megaton methane emission is nearly twice that.

Recent studies conducted by N. Shakhova have estimated that as much as 50 gigatons of the methane locked in the East Siberian Arctic Shelf could rapidly destabilize and emit over a brief period of 1-50 years. The Shakhova paper is refuted by another scientific paper produced by C. Ruppel who claims that the global .2 degree Celsius temperature increase each decade is not enough forcing for a rapid release. Peter Wadhams, who produced a recent article for Nature, refutes these findings noting that temperatures in the Arctic are warming faster than the global average and that sea ice losses can result in very strong, if briefer, temperature spikes during summer months that provide a powerful forcing to the sub-sea methane. Wadhams observations are refuted by other scientists — notably Gavin Schmidt and David Archer, who favor a slow release scenario based on what they have seen in various climate models.

In context to this scientific argument is the well supported theory that methane release contributed to rapid warming during past global heating events such as the PETM and the Permian-Triassic.

Nevertheless, we have seen a rising methane emission from the Arctic over the past decade. These increases are not indicative of the extraordinarily rapid release Shakhova has warned is possible. But they are still rapid enough to raise local methane levels by a rate of 5-10 parts per billion each year — nearly twice the global rate of increase. What this rate shows is that Arctic methane emissions are occurring at a faster pace and at relatively higher volumes than those in the rest of the world.

The Yedoma spike chronicled above by Methane Tracker is a troubling, though not catastrophic, occurrence. It appears during a time when high temperatures and wildfires are affecting a large region of Yedoma where we see the methane pulse. It is possible that methane seeping up through the tundra from anaerobic pockets where methane-producing bacteria can thrive are venting into the atmosphere as the tundra thaws. During times of high heat forcing, such as periods of late summer at times when human warming has induced more and more Arctic heatwaves, higher volumes of this methane are at risk of venting into the atmosphere. In some places, the methane concentrations are high enough to ignite in fires, as we have seen in numerous melt ponds across the Arctic. In the presence of wildfires driven by Arctic heatwaves, a high rate of methane emission creates a volatile additive to an already anomalous situation.

Major Wildfire Outbreak in the Region of Yedoma and Siberian Russia

Major Wildfire Outbreak in the Region of Yedoma and Siberian Russia

(Image source: NASA/Lance-Modis)

Whether or not catastrophic methane spikes of the kind Shakhova and Wadhams warn of will result from human forcing, it is likely that methane and related CO2 emissions will continue to increase throughout the Arctic and at rates far faster than is correlated in the climate record over the past 800,000 years. The carbon store there is vast, and the rate of forcing increase is far faster than at any time in the geological record. For reference, it took about 8,000 years for the Earth to warm out of the last ice age. Temperature increases averaged at a rate of .006 degrees Celsius per decade during this time. The current rate of human-cased warming is more than 30 times that. Yet even with this very slow level of forcing we find atmospheric CO2 and methane levels rising significantly over the ice age to interglacial transition period — with CO2 rising by 100 ppm and methane rising by 300 ppb.

The fact that even such slow forcings can result in such significant responses should serve as a warning when we consider the current, very rapid human temperature forcing. A related, more rapid, Earth Systems methane feedback could quickly overwhelm sinks and provide a much higher relative atmospheric methane level. Meanwhile, as we consider this, very valid, concern, we observe significant and rising methane emissions from the Arctic’s most vulnerable stores. Given these two very valid concerns, it is both prudent and rational to identify rising methane emissions as a current and growing threat.

***

Related: Arctic Methane and Why Sea Ice Matters

Links:

Methane: From Obscurity to Super-Stardom, by Gavin Schmidt

It’s All About Frozen Ground — NSIDC

Extensive Methane Venting to the Atmosphere by Natalie Shakhova

Methane Hydrates and Contemporary Climate Change by Carolyn Ruppel

The Vast Costs of Arctic Change by Chris Hope, Peter Wadhams and Gail Whiteman

Dissolved Organic Carbon Loss From Yedoma Amplified by Ice Wedge Thaw

Kudos to:

Colorado Bob

Prokaryotes

A4R (Methane Tracker)

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