Perturbed Earth: Why is Heat-Trapping Methane on the Rise?

Globally, atmospheric methane levels have been on the rise over recent years. And though the rate of rise is not as dramatic as seen during the late 1980s (yet), the relative rise of atmospheric methane has caused concern among scientists.

Methane is a major heat trapping gas. And it is the #2 driver of human-forced global warming behind fossil fuel burning based CO2 according to NOAA’s Earth Systems Research Lab. It also has an out-sized potential to swing global heat trapping values higher due to the fact that a single molecule of methane can trap around 86 times more heat than a single molecule of CO2 over the same period of time.

ch4_trend_all_gl

(Global trends in methane show a concerning jump in atmospheric values since leveling off in the mid-2000s. A combination of earth environment feedbacks to warming and fossil fuel related extraction, burning and transport activity are primary suspects for this increase. Image source: NOAA ESRL.)

Methane is a much shorter lived gas (one molecule lasts 8 years in the atmosphere while a molecule of CO2 lasts 500 years), and atmospheric concentrations of methane are far, far lower than CO2 (measured in parts per billion, not parts per million), however. Which is one of the reasons why CO2 (primarily from fossil fuel based burning) is the gas in the driver’s seat of the majority of present warming.

Given this context, the new upward swing in methane is troubling for a number of reasons. Which begs the question — where is the excess methane coming from?

One primary suspect is that the Earth System, warmed by fossil fuel burning, is starting to produce its own feedback carbon emissions. The way this works is that warmer wetlands (a major source of methane) become more biologically active and, in turn, produce more methane. Heavier rains might provide more flooded regions in which microbes become productive. And thawing permafrost in the far north may be providing new wetland based methane sources. So the nascent methane emissions could be coming from such varied sources as tropical wetlands (as some experts point out), from thawing and expanding biologically active permafrost zones, from increasing wildfire activity, from increasing methane emissions due to drought, or any combination of the above.

Add in potentially very leaky and large-scale, fossil fuel infrastructure related to gas and legacy infrastructure related to coal and the list of suspects grows very long indeed. A hint at where the larger sources of methane show up, at least at present, is provided by the atmospheric observatories. In particular, I’m going to turn to the Copernicus Atmospheric Monitoring System (CAMS) for this part of today’s discussion:

Atmospheric Methane Hot spots

(Global atmospheric methane hot spots indicated by CAMS.)

What we find from looking at this map is that the highest concentrations of methane presently correspond with the densest collections of fossil fuel based industrial activity. This jibes with findings that 60 percent of the presently elevated atmospheric methane value is due to human activity — leaky gas infrastructure, leaky coal mines, and various human-based farming practices that produce methane (rice farming, cow belches etc). It also highlights the recently discovered fact that fossil fuel based leaks are 60 percent more extensive than previously indicated. Confusing this point is the recent Nature finding that though leaky gas and coal infrastructure were more leaky than expected, the large fossil fuel based infrastructure methane emission was not increasing over time.

So the visible, top-down readings in the CAMS monitor may mask a larger feedback delta, or change, in how the the Earth System itself is producing methane. In other words, the new bump in methane may be coming from a perturbed Earth.

As noted by NOAA research scientist Lori Bruhwiler in a recent Wired article:

“The most important science question we face now is the question of carbon-climate feedbacks. The question that’s really important is, what’s coming down the road?”

In other words, is the recent methane spike coming from changes to the Earth System driven by the longer term fossil fuel based warming? And if so, how much will it continue to feed back? How much more methane can we expect from tropical wetlands, fires, droughts and thawing permafrost? This is a big question with wide-ranging implications for our climate future.

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Possible Record Methane Spike at Barrow, Alaska — What Does it Mean?

There’s no avoiding it — climate change is a controversial subject; a threat that should unify us all that, due to reticence, denial, fear, and a basic lack of understanding, is instead often quite divisive. But among the subjects that stand out as real fodder for acidic controversy, the issue of methane feedbacks from the global climate system — the oceans, thawing permafrost, and especially the Arctic — is one of the worst. There’s a noted tendency to either downplay or overplay risks. Though this polarization is likely fed by the general mysteriousness and complexity of the subject, its potential existential nature also feeds into the heat that methane feedback-related discussions tend to draw.

It all makes one hope for improved discussion on the subject. Given the fact that catastrophic methane feedback appears unlikely (but would have a high overall impact if it did emerge), it’s probable that the subject will continue to generate a difficult conversation for as long as human-forced warming is an issue, and so long as the science continues to remain uncertain.

copernicus-observatory

(The Copernicus Observatory shows surface methane hot spots in China, Africa, South America, the U.S., Canada, Europe, Russia and the Arctic. Note that generally high concentrations still tend to center over the Arctic. Meanwhile, the various hot spots seem to indicate major sources like fossil-fuel industry wildfires, wetlands, droughts, the Arctic Ocean and glacial and permafrost thaw. Also note that current readings indicate a serious rise in global methane concentrations, but not a spike that significantly exceeds peak 20th-century additions. It’s worth considering that, during recent years, expanded natural gas exploration and extraction through fracking has likely contributed a substantial new human methane source addition to the global atmosphere. Meanwhile, there is some concern that the Earth System may be starting to mildly feed back by bleeding additional carbon from warming lands, forests, oceans and permafrost.)

It’s not really a question of whether or not some scientists are concerned or if there is a risk, however ill-defined. Dr. James Hansen has often indicated that a strong methane feedback from the Arctic or world ocean system would be a climate nightmare that could well eliminate the time window to respond to prevent catastrophic warming. Methane and other carbon feedbacks are prime suspects for past hothouse event triggers — potentially playing a role in setting off events like the Permian-Triassic Extinction and/or greatly contributing to the loss of ocean health that was a key feature of these extinction events. Neil deGrasse Tyson alluded to this risk in his 2014 rerendering of the science series Cosmos.

Polar researchers, including those at the National Snow and Ice Data Center (NSIDC), often point to varying risks and potentials for methane feedback from numerous sources such as permafrost thaw. Others fear releases coming from seabed stores — claims that often meet stiff resistance from more established areas of the science. But given how close we are to locking in 2-degree-Celsius or greater amounts of warming this century, it doesn’t take a lot of carbon feedback, methane or otherwise, from the Earth System to generate a problem. Even a moderate feedback would cut the time necessary for carbon emissions draw-downs. It is for this reason that monitoring of the methane, and overall carbon feedback, situation is a necessary part of developing a comprehensive climate change situational awareness (which I have worked hard to develop here at this blog). Which is why, today, we are going to talk a little bit about a big methane spike appearing in the hourly readings near Barrow, Alaska.

Apparent Record Methane Spike in the Hourly Readings at Barrow

Yesterday, climatologist Brian Brettschneider, whose Twitter feed provides a good stream of informed climate change-related updates, posted a truncated version of this NOAA ESRL graph:

hourly-methane-spike

The graph tracks hourly methane readings at the data collection location for Barrow, Alaska. As shown, the recent (and unconfirmed) data set shows what appears to be a record methane spike for that location. Also note that big spikes appear in the hourly data at certain points many times since 2000, as is typical during this time of year. Most notably, a similar very large spike occurred in 2004, one that the recent 2016 spike just edges out.

Looking at the graph, there’s a lot that it doesn’t tell us. Firstly, what is the source of this methane spike? If the spike was an outlier with no periodicity it might indicate the potential for some kind of anomaly or human source. However, since seasonal spikes seem to show up in this graph, this hints that the current spike is environmental. In addition, since Alaska as a whole and Barrow in particular both recently experienced some of their warmest weather on record, there’s some reason to suspect that this added heat played a part in the 2016 spike. And, 2004 also saw a period of then-record warmth during summer in Alaska. So Alaska warming is in line as a suspect cause for the 2016 methane spike.

As anomalous spikes go, this one is pretty big — it apparently set a new hourly record methane reading around 2370 parts per billion for the recording station. But since this Barrow spike isn’t visibly part of some big regional methane plume and since the global monitors aren’t recording a big methane jump as well, we can be pretty certain that this particular spike, if confirmed, is a local and probable short-term issue, and not a sudden, huge methane release issue of global importance. However, it does represent another point in a context that seems to include some big local methane sources popping up in the Arctic environment and possibly indicating a larger, if comparatively moderate, regional feedback taking place in response to the warming and thawing ongoing there. (No consensus scientific study has yet fully confirmed such a preliminary observation, which is a threat analysis-based potential identification on my part.)

So, overall, something to add to the big pot of bubbling concerns — but nothing to light your hair on fire over yet.

Conditions in Context

During the 20th century, large-scale industrialization linked to fossil-fuel burning and extraction helped to drive rapid rates of atmospheric methane increase. These rates peaked during the late 1980s and early 1990s when global policy measures helped curtail methane leakage from fossil fuel infrastructure. According to NOAA, annual rates of global atmospheric methane increase peaked in 1991 at a 14.32 ppb yearly jump.

ch4-trend

(Global methane is again hitting a rapid rate of rise. Though the Earth System appears to be providing some ominous rumblings that feedbacks may be on the way, the present spike is likely primarily due to increased fossil-fuel extraction activity, particularly due to fracking. Image source: NOAA.)

Such curtailments helped to produce a mid-1990s to mid-2000s plateau in the rate of atmospheric methane accumulation. Now, with the advent of fracking and with global warming appearing to generate a number of possible new methane sources (or amplify traditional sources) from the Earth System, rates of annual methane increase are again on the rise. In 2014 and 2015, annual increases hit 12.53 ppb (the third highest annual rate of increase in the NOAA record) and 10.07 ppb respectively (tenth highest). Preliminary reports show that 2016 appears to be on track to hit near 10 ppb worth of atmospheric increase.

As a result, it appears that fracking, primarily, and warming-related feedback (possibly secondarily) are contributing to annual rates of atmospheric methane increase that are comparable to peak periods of increase during the late 1980s and early 1990s. However, these rates of increase, though significantly adding a heat forcing that about equals one quarter to one third of the annual CO2 addition, show no current indication of a catastrophic rate of methane increase that would point toward the major environmental releases some have feared. As such, the greatest part of our ability to currently prevent further rising rates of atmospheric methane comes in the form of rapidly reducing all fossil fuel use and particularly to contain and reduce coal mining and oil and natural gas fracking. And if we do that, there will be less heat stress on the environmental methane stores and less overall long-term pressure for the kinds of feedbacks some of us have come to fear.

Links:

NOAA ESRL

All About Frozen Ground

The Arctic Turns Ugly

Hydrate Catastrophe Unlikely

The Copernicus Observatory

Brian Brettschneider

Toward Improved Discussions: Methane

An Update on Fracking Emissions

Cosmos

Hat tip to Griffin

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