Is Human Warming Prodding A Sleeping Methane Monster off Oregon’s Coast?

We’ve talked quite a bit about the Arctic Methane Monster — the potential that a rapidly warming Arctic will force the release of disproportionately large volumes of methane from organic material locked in permafrost and in frozen sea bed hydrates composing volumes of this powerful greenhouse gas large enough to significantly increase the pace of human-forced global warming. But if we consider the globe as a whole, the Arctic isn’t the only place where large methane stores lurk — laying in wait for the heat we’ve already added to the world’s oceans and atmosphere to trigger their release. And a new study out of the University of Washington provides yet another indication that the continental shelf off Oregon and Washington may be one of many emerging methane release hot spots.

For all around the world, and beneath the broad, blue expanse of the world’s seas, rest billions and billions of tons of frozen methane hydrate.

A kind of methane and ice combination, frozen hydrate is one of the world’s most effective natural methods of trapping and sequestering carbon. Over long ages, organic material at the bottom of the oceans decompose into hydrocarbons, often breaking down into methane gas. At high pressure and low temperature, this methane gas can be locked away in a frozen water-ice hydrate lattice, which is then often buried beneath the sea bed where it can safely remain for thousands or even millions of years.

Plume2_nolabels_cropped

(Plume of methane bubbles rising from the sea floor off the Oregon Coast. This image shows methane bubbles originating from the sea bed about 515 meters below the surface before dissolving into the water column at about 180 meters depth. Image source: American Geophysical Union.)

Most of these deposits lay well beneath the sea bed or at extreme ocean depths of one mile or greater. And so far, human forced warming hasn’t been great enough to risk the destabilization of most of these deep ocean carbon stores. But some hydrate deposits rest in the shallower waters of continental slope systems and at depths where current warming may now be causing them to destabilize.

Scientists Think Methane Hydrates May be Destabilizing off Oregon

Enter a new study by University of Washington scientists which found “an unusually high number of bubble plumes at the depth where methane hydrate would decompose if seawater has warmed.” The scientists concluded that these bubble plumes were likely evidence of methane hydrate destabilization due to a human forced warming of the water column in the range of about 500 meters of depth.

The warm waters, ironically, come from a region off Siberia where the deep waters have, over recent decades, been heated to unprecedented temperatures. These waters have, in turn, through ocean current exchange, circulated to the off-shore region of Washington and Oregon where they appear to have gone to work destabilizing methane hydrate in the continental slope zone. A paper published during 2014 hypothesized that these warm waters would have an impact on hydrates. And the new paper is the first potential confirmation of these earlier predictions.

In total about 168 methane plumes are now observed to be bubbling out of the sea bed off the Washington and Oregon coasts. Of these, 14 are located in the 500 meter depth range where ocean warming has pushed temperatures to levels at which hydrate could begin to destabilize. University of Washington researchers noted that the number of plumes at this depth range was disproportionately high, which also served as an indirect indicator that human heating may be causing this methane to release.

PlumesMap

(Locations of methane plumes in the continental slope zone off Washington and Oregon. The location of a disproportionate number of these plumes in a zone now featuring a warming water column is an indication that the human-forced heating of ocean currents is starting to drive some methane hydrate structures to destabilize. Image source: AGU.)

Lead author H. Paul Johnson, a University of Washington professor of oceanography noted in AGU:

“So it is not likely to be just emitted from the sediments; this appears to be coming from the decomposition of methane that has been frozen for thousands of years… What we’re seeing is possible confirmation of what we predicted from the water temperatures: Methane hydrate appears to be decomposing and releasing a lot of gas. If you look systematically, the location on the margin where you’re getting the largest number of methane plumes per square meter, it is right at that critical depth of 500 meters.””

Implications For Ocean Health, Carbon Cycle

Most methane released at this depth never reaches the atmosphere. Instead, it either oxidizes to CO2 in the water column or is converted by ocean bacteria. That said, expanding zones of methane release can rob the surrounding ocean of vital oxygen even as it can saturate the water column with carbon — increasing ocean acidification and reducing the local ocean’s ability to draw carbon out of the atmosphere. Such a response can indirectly increase the volume of heat trapping gasses in the atmosphere by reducing the overall rate of ocean carbon uptake. In more extreme cases, methane bubbles reach the surface where they then vent directly into the atmosphere, proportionately adding to the human-produced greenhouse gasses that have already put the world into a regime of rapid warming.

It has been hypothesized that large methane releases from ocean hydrate stores contributed to past hothouse warming events and related mass extinctions like the Permian and the PETM (See A Deadly Climb From Glaciation to Hothouse). But the more immediate consequences of smaller scale releases are related to declining ocean health.

According to AGU and Dr. Johnson, the study author:

Marine microbes convert the methane into carbon dioxide, producing lower-oxygen, more-acidic conditions in the deeper offshore water, which eventually wells up along the coast and surges into coastal waterways. “Current environmental changes in Washington and Oregon are already impacting local biology and fisheries, and these changes would be amplified by the further release of methane,” Johnson said.

Instances of mass sea life die-off have already occurred at a very high frequency off the Washington and Oregon Coasts. And many of these instances have been associated with a combination of low oxygen content in the near and off shore waters, increasing ocean acidification, increasing dangerous algae blooms, and an overall warming ocean system. It’s important to note that ocean acidification, though often cited in the media, is just one of many threats to ocean life and health. In many cases, low oxygen dead zones and large microbial blooms can be even more deadly. And in the most extreme low oxygen regions, the water column can start to fill up with deadly hydrogen sulfide gas — a toxic substance that, at high enough concentrations, kills off pretty much all oxygen-based life (See Hydrogen Sulfide in the World’s Warming Oceans).

During recent years, mass sea life deaths have been linked to a ‘hot blob’ forming in nearby waters (See Mass Whale Death in Northeast Pacific — Hot Blob’s Record Algae Bloom to Blame?). However, indicators of low oxygen in the waters near Washington and Oregon have been growing in frequency since the early 2000s. Though the paper does not state this explicitly — increasing rates of methane release in the off-shore waters due to hydrate destabilization may already be contributing to declining ocean health in the region.

Slope Collapse, Conditions in Context

A final risk associated with methane hydrate destabilization in the continental slope zone is an increased prevalence of potential slope collapse. As methane hydrate releases, it can deform the sea bed structures within slope systems. Such systems become less stable, increasing the potential for large underwater landslides. Not only could these large landslides displace significant volumes of water or even set off tsunamis, slope collapse events also risk uncovering and exposing more hydrate systems to the warming ocean in a kind of amplifying feedback.

In context, the total volume of methane being released into the off-shore environment is currently estimated to be about 0.1 million metric tons each year. That’s about the same rate of hydrocarbon release seen from the Deepwater Horizon blowout. A locally large release but still rather small in size compared to the whopping 10+ billion tons of carbon being dumped into the atmosphere each year through human fossil fuel burning. However, this release is widespread, uncontrolled, un-cappable and, if scientists are correct in their indications of a human warming influence, likely to continue to increase as the oceans warm further.

Links:

Bubble Plumes off Washington and Oregon Suggest Warmer Ocean May be Releasing Frozen Methane

Geochemistry, Geophysics, Geosystems

Warming Oceans May be Spewing Methane off US West Coast

Concern Over Catastrophic Methane Release

Hydrogen Sulfide in the World’s Warming Oceans

Mass Whale Death in Northeast Pacific — Hot Blob’s Record Algae Bloom to Blame?

A Deadly Climb From Glaciation to Hothouse

Hat tip to Humortra

2013 4th Hottest Year on Record, Deep Ocean Warming Fastest, NASA, NOAA Find No Pause in Long-Term Warming Trend

2013 4th Hottest On Record

(Global temperature anomalies for 2013. Image source: NOAA)

With the readings coming in for 2013 — atmosphere, ocean surface and the deep ocean — it becomes increasingly obvious that anyone saying planetary warming has slowed down is clearly misinformed.

Criticisms of the misinformed aside, according to reports from NOAA’s National Climate Data Center, 2013 was the world’s 4th hottest on record since temperature measures began in 1880. All this despite ENSO conditions remaining neutral in the Eastern Pacific and deep ocean heat content continuing to rapidly rise while sucking a portion of that heat out of the atmosphere.

The NCDC measure found numerous regions in which temperatures were the hottest ever recorded including a large swath of Australia, a broad stretch of the Pacific Ocean adjacent to New Guinea and the Philippines, an area larger than Texas at the heart of the Asian Continent, and multiple other locations ranging from south of Svalbard to East Africa to the Indian Ocean to the Northern and Southern Pacific. Aside from these record hot zones, over 70 percent of the land and ocean surface measured came up either hotter than average or much hotter than average while 28% of the globe experienced average temperatures and less than 2% of the Earth’s surface experienced cooler than average temperatures.

Notably, no regions of the globe saw record coldest temperatures and the only zone coming up cooler than normal cropped up in the Southern Ocean just north of Antarctica.

NASA found 2013 to be the 7th hottest on record and the 2nd hottest non El Nino year on record.

Helpfully, NASA also put together a graph of global temperature averages as measured since 1950 showing that atmospheric warming has continued unabated despite much false and inaccurate press coverage of a ‘global warming hiatus.’

gistemp_nino_s

(GISS temperature measurements with trend lines for El Nino, La Nina and all years. It’s worth noting that this temperature graph indicates no pause in warming since 1950. Instead, what we see are inexorable global surface temperature increases. Image source: NASA GISS)

Deep Ocean Warming Measures Far More Dire

Recent news reports have also falsely claimed that more heat going into the deep ocean, as measured by NASA, NOAA, the Trenberth study, and others, is an indication of lowered global climate sensitivity. To the contrary, a warming ocean contains two very dire consequences that, if set into play, could both enhance warming, and create an ecological nightmare for first the oceans and finally the surface world.

The first, a growing risk of subsea methane release, is greatly enhanced by a rapidly warming ocean. We have covered the risks and consequences of methane release (both seabed and terrestrial methane) in numerous posts over the past year. For your convenience I’ve linked them below. But, suffice it to say that a warming ocean puts at risk the more rapid release of hundreds of gigatons of methane, an amount that could greatly amplify the already powerful and ongoing signal of human warming. More worrisome, initial indications show that at least some of this methane is already destabilized and venting into the world ocean system and atmosphere.

The second consequence involves growing ocean hypoxia and anoxia as the oceans warm, become more stratified and as major ocean current systems are disrupted and altered. Growing ocean hypoxia and anoxia results in, among other terrible impacts, ocean sea bottoms that are less and less able to support a diversity of life and that, more and more, come to support dangerous hydrogen sulfide producing bacteria.

A third consequence includes the basal melting of ocean contacting ice sheets. Such melting has already destabilized the massive Pine Island Glacier which, according to a recent scientific study, is on the path to an inevitable collapse into the Southern Ocean.

Yet, according to these excellent graphs produced by Larry Hamilton for The Arctic Ice Blog, world ocean heat content has been rising by leaps and bounds over the past few years, especially in the deep ocean where warming puts at risk the most dangerous of outcomes — methane release and anoxia.

OHC_7an

OHC_2an

(Image source: L Hamilton. Image data: NOAA. Produced for The Arctic Ice Blog. Note the extraordinarily steep slope indicating deep ocean warming since 1985.)

The top graph shows ocean heat content increases in the first 700 meters of ocean water. The bottom graph shows ocean heat content in the first 2000 meters of ocean water. Note that ocean heat content gains for the deep ocean (2000 meter graph) are more rapid by 25% than heat content gains in the shallower ocean. Meanwhile, both graphs show a very rapid accumulation of heat, especially through recent years during which the so-called global warming hiatus was in effect.

If we could find a place to put the majority of heat from human-caused climate change, the deep ocean would be the last place any sane ecologist would look. Warming the deep ocean is a worst-case disaster in the making. It puts added stress on methane hydrate stores and it pushes the very dangerous consequences of ocean stratification and anoxia along at a much more rapid pace.

These are not optimistic measures. In my view, this is much closer to an absolute worst case.

Mixed Outlook for 2014

Early indications for 2014 show an increased chance of La Nina for the first three months of the year. That said, ocean surface heat in the Eastern equatorial Pacific appears to be on the rise, especially in areas closest to coastal South America.

sst.daily.anom

(Image source: NOAA)

Should ENSO tip the scale to El Nino, it is almost certain we will see a hottest year on record for surface temperatures during 2014. Should conditions remain neutral or tip to La Nina, we’ll still likely experience a top ten hottest year on record (atmosphere) even as ever more heat is transferred to the deep ocean.

Links:

NASA Finds 2013 Sustained Long-Term Warming Trend

National Climate Data Center Global Analysis

Larry Hamilton CA The Arctic Ice Blog

The Arctic Methane Monster Continues its Ominous Rumbling

Arctic Methane Monster Shortens Tail

The Arctic Methane Monster Stirs

Through the Looking Glass of the Great Dying

Awakening the Horrors of the Ancient Hothouse — Hydrogen Sulfide in the World’s Warming Oceans

Warming Ocean, Upwelling to Make an End to Pine Island Glacier

Hat Tip to Colorado Bob

%d bloggers like this: