Methane Levels Early 2015

The image below shows highest mean methane readings on one day, i.e. March 10, compared between three years, i.e. 2013, 2014 and 2015, at selected altitudes. The comparison indicates that the increase of methane in the atmosphere is accelerating, especially at higher altitudes.

The table below shows the altitude equivalents in mb (millibar) and feet.

56925 feet44689 feet36850 feet30569 feet25543 feet19819 feet14383 feet8367 feet1916 feet
74 mb147 mb218 mb293 mb367 mb469 mb586 mb742 mb945 mb

This rise in global mean methane levels appears to go hand in hand with much higher peak readings, especially at higher altitudes.

From January 1 to March 20, 2015, methane levels reached levels as high as 2619 ppb (on January 12, 2015), while peak daily levels averaged 2373 parts per billion (ppb). At the start of the year, global mean methane levels typically reach their lowest point, while highest mean levels are typically reached in September. Highest daily global mean methane levels for the period from January 1, 2015, to March 20, 2015, ranged from 1807 ppb (January 6, 2015) to 1827 ppb (March 5, 2015).

Further study of the locations with high methane levels indicates that much of the additional methane appears to originate from releases at higher latitudes of the Northern Hemisphere, in particular from the Arctic Ocean, from where it is over time descending toward the equator (methane will typically move closer to the equator over time as it rises in altitude, as discussed in this earlier post).

The largest source of additional methane appears to be emissions from the seabed of the Arctic Ocean. Annual emissions from hydrates were estimated to amount to 99 Tg annually in a 2014  post (image below).

The image below, based on data from the IPCC and the World Metereological Organization (WMO), with an added observation from a NOAA MetOp satellite image, illustrates the recent rise of methane levels and the threat that methane levels will continue to rise rapidly.

What causes these methane eruptions?

Methane eruptions from the seafloor of the Arctic Ocean appear to be primarily caused by rising ocean heat that is carried by the Gulf Stream into the Arctic Ocean. The image below shows sea surface temperatures of 20.9°C (69.62°F, green circle left) recorded off the coast of North America on March 14, 2015, an anomaly of 12.3°C (36.54°F).

[ click on image to enlarge ]
Furthermore, both methane eruptions from the Arctic Ocean seafloor and demise of the Arctic sea ice and snow cover are feedbacks that can interact and amplify each other in non-linear ways, resulting in rapid and intense temperature rises, as illustrated by the image below.

Diagram of Doom - for more background, see Feedbacks
How high could temperatures rise?

Worryingly, a non-linear trend is also contained in the temperature data that NASA has gathered over the years, as described in an earlier post. A polynomial trendline points at global temperature anomalies of over 4°C by 2060. Even worse, a polynomial trend for the Arctic shows temperature anomalies of over 4°C by 2020, 6°C by 2030 and 15°C by 2050, threatening to cause major feedbacks to kick in, including albedo changes and methane releases that will trigger runaway global warming that looks set to eventually catch up with accelerated warming in the Arctic and result in global temperature anomalies of 16°C by 2052.

[ click on image to enlarge ]

The situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan blog.

Comparison between three years, i.e. 2013, 2014 and 2015, of highest mean methane readings at selected altitudes on...
Posted by Sam Carana on Friday, March 27, 2015

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