ARCTIC CLIMATE EMERGENCY C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ATMOSPHERIC METHANE

Scientists  think that the post 2007 increase in atmospheric methane was due to planetary feedback emissions. The planet has large organic stores of methane that when warmed up emit methane. The scientists think the atmospheric methane increase is methane feedback is due to : a) greater than average wetland CH4 emissions at  high northern latitudes during 2007 owing to exceptionally warm temperatures; and b) tropical emissions during 2007 and 2008 related to greater than normal precipitation in wetland regions during a La Niña (WMO report).

 

Though it is crucial to know from where exactly and how fast these feedback type methane emissions are, due to inadequate monitoring coverage the scientists are still uncertain.

 

2009 E. J. Dlugokencky GRL

... after a decade of near-zero growth, globally averaged atmospheric methane increased during 2007 and 2008. During 2007, CH4 increased by 8.3 ± 0.6 ppb. CH4 mole fractions averaged over polar northern latitudes and the Southern Hemisphere increased more than other zonally averaged regions. In 2008, globally averaged CH4 increased by 4.4 ± 0.6 ppb; the largest increase was in the tropics, while polar northern latitudes did not increase. The most likely drivers of the CH4 anomalies observed during 2007 and 2008 are anomalously high temperatures in the Arctic and greater than average precipitation in the tropics. Near-zero CH4 growth in the Arctic during 2008 suggests we have not yet activated strong climate feedbacks from permafrost and CH4 hydrates.

 

2011  E. Fisher  GRL Arctic methane sources:

The results imply the dominant Arctic summer CH4 source in 2008 and 2009 was biogenic, from wetland. This is consistent  with evidence from Siberia  from Siberia of the importance

of wetland CH4 [Tarasova et al., 2009]. Submarine emissions along the West Spitsbergen slope currently input negligible CH4 to the air in summer, despite the clear evidence for gas

plumes in the water column. However, this could change  rapidly if a warming Atlantic warms the West Spitsbergen  current [Westbrook et al., 2009]. Gas hydrates are widespread in thick sediments in the Fram Strait between Spitsbergen and Greenland. If the sea bottom warms, the gas hydrate stability zone will move further down the continental slope. Given the steep slopes, earthquakes triggered by ice‐melt unloading could produce submarine landslides, triggering further emissions [Berndt et al., 2009]. [17]

Wetland CH4 emissions respond rapidly to warming, such that the warming can feed the warming [Nisbet and Ingham, 1995], as evidenced by their importance in glacial

terminations [Nisbet and Chappellaz, 2009].

In particular, Arctic and boreal wetlands are likely to respond immediately to sustained heatwaves and increases in precipitation.

 

Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions

Ivar S. A. Isaksen et al  Global Biogeochemical Cycles  2011

 

The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the large potential for future methane releases calls for improved understanding of the interaction of a changing climate with processes in the Arctic and chemical feedbacks in the atmosphere. Here we apply a “state of the art” atmospheric chemistry transport model to show that large emissions of CH4 would likely have an unexpectedly large impact on the chemical composition of the atmosphere and on radiative forcing (RF). The indirect contribution to RF of additional methane emission is particularly important. It is shown that if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone. Assuming several hypothetical scenarios of CH4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry. In particular, the impact of CH4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO2 as a result of atmospheric chemical processes.

Atmospheric methane increased two and a half times with industrialization and then leveled off at year 2000.

 

Since 2007 it has been on the rise again, but this time scientists say increased emissions are from the surface of the planet — a carbon feedback due to global warming.  In the Arctic (Barrow Alaska) where methane is the highest the level has reached 1900 ppb (see right).

 

The atmospheric methane has never been higher than 800 ppb over the past 800,000 years

 

The methane increase started first in Northern hemisphere subarctic wetlands (2007) follwed by southern hemisphere tropical wetlands. The increase is from peat rich wetlands.

 

This should be recognized as a planetary emergency because global warming will unavoidably increase to due to inertias, and this methane increase from feedback (caused by global warming) is happening at today's 0.8C warming.

 

The NOAA record shows the highest methane concentrations are in the Arctic.

 

The highest methane ever recorded was from is Lac La Biche in northern Alberta right on the lower edge of the Canadian wetlands, at 2000 ppb with spikes up 2500 ppb.

Methane's atmospheric lifetime of 12 years is much shorter than CO2  but its global effect is much higher at 86 XCO2 (global warming potential IPCC 2014 AR5).

 

Methane's global warming effect is complicated because unlike CO2 it is reactive with other chemicals  in the atmosphere. Research by  NASA's  Drew Shindell has estimated that reactions with atmospheric chemical aerosols may means methane is 30% stronger again as a global warming gas.

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However methane is oxidised to water vapor and CO2 (both GHGs)

Lac La Biche with map Atmos methane AIRS Atmos methane global AZug 2013

Satellite SCIAMACHY low altitude methane conentration for emissions.

 

Satellite AIRS methane concentration

 

Arctic methane concentrations and emissions are available daily from Copernicus methane forecasts.

 

By far the most is emitting from warming wetlands, some from thawing permafrost, and a relatively small amount from Arctic subsea floor methane hydrate