- When will Arctic sea ice disappear?
- What makes Arctic sea ice retreat so rapidly?
- Why is Arctic sea ice decline so important?
- Are temperatures already rising in the Arctic?
- What are the consequences of large methane releases? What is the cost of (not) taking action?
- What are methane hydrates?
- Did methane hydrates ever release much methane in history?
- Why is the situation in the East Siberian Arctic Shelf (ESAS) so threatening?
- How much methane could be released from the East Siberian Arctic Shelf (ESAS)?
- How much methane could be released, say, within a few years?
- Is it possible for heat to reach hydrates deep down in the sediment underneath the ESAS?
- How much methane is/was there in the atmosphere, how much is added annually?
- What is the global warming potential of methane?
- What is the lifetime of methane?
- Is methane already venting in the Arctic from hydrates?
- What should be done to reduce the risk that methane hydrates will trigger runaway warming?
- What are the costs of this proposed action (to reduce the risk of runaway warming)?
- Shouldn't we wait with geo-engineering until more research is done?
- Won't geo-engineering take the pressure off the need to reduce emissions?
- Why should drilling be banned in the Arctic? Why is a spill or blow-out particularly bad in the Arctic?
1. When will Arctic sea ice disappear?
Most sea ice looks set to disappear in September within a few years. For other months, it may take a few more years for most sea ice to disappear. This is the conclusion when calculating an exponential trendline using annual sea ice volume minima,
- Why volume? It makes sense to look at volume, because the thinner the sea ice will get, the bigger the chance will be that the increasingly intense and frequent storms will smash it to pieces, leaving only a small rim of ice along the edges of Greenland and Ellesmere island.
- Why minima? Clearly, when examining the danger of disappearance of Arctic sea ice, it makes sense to compare annual moments when volume is at its minimum.
- Why an exponential trendline? A linear trend would be inappropriate, given the increased impact of feedbacks that can each be expected to reinforce sea ice decline, while there can also be interaction between these feedbacks, further accelerating sea ice decline. Albedo change is one such feedback, but there are numerous other ones, such as storms that have more chance to grow stronger as the area with open water increases. In conclusion, an exponential trendline is more appropriate than a linear trendline, as also illustrated by the image below that illustrates that a linear trendline has 9 years fall outside its 95% confidence ionterval, versus 4 years for an exponential trendline.
The data were produced by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS, Zhang and Rothrock, 2003) developed at Polar Science Center, Applied Physics Laboratory, University of Washington.
An exponential trendline shows that sea ice looks set to disappear in 2019, while disappearance in 2015 is within the margins of a 5% confidence interval, reflecting natural variability.
2. What makes Arctic sea ice retreat so rapidly?
Emissions result in global warming, as warmer water flows into the Arctic from ocean currents and rivers. Melting permafrost causes even more emissions, while there are further feedbacks such as wildfires raging in tundras and peatlands. The Arctic is especially vulnerable to black carbon (soot), which darkens the ice, resulting in more sunlight being absorbed rather than reflected back into space. This albedo effect accelerates as sea ice retreats and amplifies warming in the Arctic.
Without action to cool the Arctic, methane releases threaten to further amplify warming, triggering runaway warming.
From: The need for geo-engineering - by Sam Carana
For more feedbacks, see the feedbacks page.
3. Why is Arctic sea ice decline so important?
Permafrost and sea ice keep methane hydrates stable. Arctic sea ice and permafrost still reflect a lot of sunlight back into space, while a lot of heat also goes into the process of melting the ice. As the sea ice declines and permafrost melts, this light and heat is instead absorbed in the Arctic, further accelerating warming in the Arctic, which is already several times larger than elsewhere on Earth (see next question).
The image directly above shows the threat of feedbacks further accelerated warming in the Arctic and triggering methane releases, escalating into runaway global warming.
For more on feedbacks that are accelerating warming in the Arctic, see the feedbacks page.
4. Are temperatures already rising in the Arctic?
The image below shows observed temperature anomalies - global in blue and for higher latitudes in red, with trend added.
As above image shows, temperatures in the Arctic are rising exponentially and without action anomalies look set to reach 10 degrees Celsius within decades. Once that kind of warming starts penetrating sediments, it will be very hard to reverse the process.
The need for geo-engineering - by Sam Carana
Earlier versions of the above two images appeared on the posted made by Sam Carana for display at AGU 2011
For an updated version (2013) of the above temperature projection, see:
How much will temperatures rise? - by Sam Carana
Taking no action risks extinction for many species, including humans, possibly within one generation. With so much at stake, the cost of taking action is dwarfed by the price we pay when no action is taken. The longer we wait, the larger the risk becomes and the more difficult, expensive and risky it will become to take measures to try and reduce the risk.
Vast costs of Arctic change - by Gail Whiteman, Chris Hope & Peter Wadhams
The need for geo-engineering - by Sam Carana
Ten dangers of global warming - by Sam Carana
6. What are methane hydrates?
Methane hydrates are crystal-like structures that hold methane. They are likely to remain intact as long as they are not disturbed (e.g. by landslides or earthquakes) and temperatures and pressures remain within certain bounderies.
For more details, see:
- The need for geo-engineering - by Sam Carana
- Methane hydrates - by Sam Carana
7. Did methane hydrates ever release much methane in history?
Pockmarks up to 11 km (6.8 mi) wide off the coast of New Zealand indicate that large abrupt emissions from methane hydrates did occur in the past.
Since the location of these pockmarks is prone to earthquakes, seismic activity may have contributed to the release.
In the past, hydrates did likely become destabilized as Earth became warmer during interglacial periods. But while Earth - during such periods - may have been several degrees warmer than today, warming in the Arctic probably was not as amplified as it is today. In the Eemian period, for example, there were no ice-free summers in the Arctic. Ice sheets remained largely frozen, in part because ocean currents were quite different from the situation today.
Even where large amounts of methane did get released from hydrates, this may not have left a mark in ice cores. Paul Beckwith explains:
Furthermore, methane that did get trapped in ice may have returned to the atmosphere as temperature rose and the ice melted. Higher temperatures for thousands of years ensured that the methane was over time oxidized, leaving only carbon dioxide traces in later ice, and thus in the ice cores that we examine today. For more on this point, also see the comments and responses at:
In conclusion, there's no reason to doubt that there have been large emissions from methane hydrates in the past. Furthermore, the current situation is unprecedented and looks more dangerous in many ways than in previous periods. Firstly, the rate at which temperatures are rising, particularly in the Arctic, is without precedent. Furthermore, the levels of pollutants in the atmosphere today are extremely high (and rising), which is the more dangerous given the presence of huge amounts of methane in the shallow seas of the Arctic. For further reasons why the current situation in the Arctic is so dangerous, see point 8. below and:
8. Why is the situation in the East Siberian Arctic Shelf (ESAS) so threatening?
At the last glacial maximum (LGM), at the height of the ice age about 20,000 years ago, the sea level was approximately 120 metres lower than it is today. The ESAS was well above sea level and the cold air temperature would have cooled the land surface to considerable depth, freezing water around organic matter into permafrost. Then the sea level rose, and the land and permafrost were inundated. Some of the organic matter would have decomposed, producing methane which could, at certain pressures and temperatures, combine with groundwater to form methane hydrate (a "lattice" of ice and gas). Thus, below the permafrost is now a mixture of hydrate and free methane gas.
Methane release from the East Siberian Arctic Shelf and the Potential for Abrupt Climate Change - by Natalia Shakhova and Igor Semiletov (2010)
On carbon transport and fate in the East Siberian Arctic land–shelf–atmosphere system - by Semiletov et al. (2012)
A recent paper in Oceanology says that the ESAS is not only the broadest and shallowest shelf of the World Ocean, but also undergoes pronounced transformations under the change of climatic epochs. The shelf is also characterized by the location of over 80% of the existing submarine permafrost, as well as of the bulk of shallow water gas hydrates. The most distinctive characteristics of the Arctic compared to oceanic gas hydrates are the following:
- high density of the spatial deposition; the thickness of the layer of pure gas hydrates may be as high as 100m or more, unlike the oceanic hydrates occurring mainly in disseminated form;
- the presence of deposits is more likely by several times at the Arctic shelf compared to the Arctic land;
- the high inter stitial saturation with gas hydrate (from 20 to 100% of the interstitial volume against 1–2% for oceanic gas hydrates);
- the lower thermal capacity of the phase transition (a third of that for oceanic hydrates); and
- high sensitivity to further warming, because of the profound changes in thermal conditions of the subma rine permafrost proceeding as long as 5000–6000 years.
Sam Carana discusses further points at the Methane-hydrates blog.
9. How much methane could be released from the East Siberian Arctic Shelf (ESAS)?
To get an idea of how much methane could be released, selected parts are added below from: JICS Annual Report 2010-2011 (page 25):
Recent geochemical and geophysical evidence demonstrates that the ESAS subsea permafrost has been showing signs of destabilization (Shakhova et al., 2010a, b). If this permafrost further destabilizes, emissions could be significantly larger than teragram-sized.10. How much methane could be released, say, within a few years?
The amount of CH4 that could theoretically be released in the future is enormous. The volume of gas hydrates that underlie the Arctic Ocean seabed is estimated to be 2,000 Gt of CH4 (Makogon et al., 2007). About 85% of the Arctic Ocean sedimentary basins occur within the continental shelf; therefore, within the ESAS alone, which comprises ~30% of the area of the Arctic shelf, hydrate deposits could contain ~500 Gt of CH4. An additional two-thirds of that amount (~300 Gt) is stored in the form of free gas (Ginsburg and Soloviev, 1994). Because submarine permafrost is identical to on-land permafrost, the carbon pool held within submarine permafrost can be estimated to include not less than 500 Gt of carbon within a 25-m-thick permafrost body (Zimov et al., 2006). Thus the total amount of carbon preserved within the Arctic continental shelf could total ~1300 Gt of carbon, of which 800 Gt is previously formed CH4 ready to be suddenly released when appropriate pathways develop (Shakhova and Semiletov, 2009; Shakhova et al., 2010b). Release of only 1% of this reservoir would more than triple the atmospheric mixing ratio of CH4, probably triggering abrupt climate change, as predicted by modeling results (Archer and Buffett, 2005).
A new model of subsea permafrost degradation
The Arctic Ocean is surrounded by offshore and onshore permafrost, which is being degraded at increasing rates under warming conditions. This warming is most pronounced in the East Siberian part of the Arctic, where surface air temperature increased by about 5°C during 2000–2005 compared to 20th century temperature patterns (Figure 4). In response to this anomalous warming, shrinkage of onshore permafrost is projected to double by 2090 (ACIA, 2004).
At the same time, no attention has been paid to that part of the onshore permafrost that is the most sensitive to warming. This sensitive permafrost was inundated during the last 10–15 Kyr, when the ocean level rose by ≤ 100 m. The thermal regime of the surrounding environment changed drastically as the sea intruded, warming by as much as 12–17°C; gradually, the temperature of the submerged permafrost responded.
ACIA. 2004. Impacts of a warming Arctic: Arctic Climate Impact Assessment. Cambridge University Press, Cambridge, 139 pp.
Archer, D.E. and B. Buffett. 2005. Time-dependent response of the global ocean clathrate reservoir to climatic and anthropogenic forcing. Geochem., Geophys., Geosys., 6(3), doi: 10.1029/2004GC000854.
Ginsburg, G.D. and V.A. Soloviev. 1994. Submarine Hydrates. VNIIOkeangeologia, Sankt- Peterburg, 1999.
Makogon, Y.F., S.A. Holditch, and T.Y. Makogon. 2007. Natural gas-hydrates – A potential energy source for the 21st Century. J. Petrol. Sci. Engineering, 56, 14-31.
Shakhova, N.E. and I.P. Semiletov. 2009. Methane Hydrate Feedbacks. In Martin Sommerkorn & Susan Joy Hassol, eds., Arctic Climate Feedbacks: Global Implications, Published by WWF International Arctic Programme August, 2009, ISBN: 978-2-88085-305-1, p. 81-92.
Shakhova, N., I. Semiletov, A. Salyuk, V. Joussupov, D. Kosmach, and O. Gustafsson. 2010a. Extensive methane venting to the atmosphere from sediments of the East Siberian Arctic Shelf. Science 327, 1246-1250.
Shakhova, N., I. Semiletov, I. Leifer, P. Rekant, A. Salyuk, and D. Kosmach. 2010b. Geochemical and geophysical evidence of methane release from the inner East Siberian Shelf. J. Geophys. Res. -Oceans, in press
Zimov, S.A., E.A.G. Schuur, and F.S. Chapin III. 2006. Permafrost and global carbon budget. Science, 312, 1612-1613.
Shakhova et al. estimate the accumulated methane potential for the Eastern Siberian Arctic Shelf alone as follows:
- organic carbon in permafrost of about 500 Gt;
- about 1000 Gt in hydrate deposits; and
- about 700 Gt in free gas beneath the gas hydrate stability zone.
From: Methane release from the East Siberian Arctic Shelf and the Potential for Abrupt Climate Change - by Natalia Shakhova and Igor Semiletov (2010)
". . . we consider release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time."
11. Is it possible for heat to reach hydrates deep down in the sediment underneath the ESAS?
It is possible for heat to reach hydrates in a short period. Waters in the Arctic can be very shallow, which makes that they can heat up quite rapidly, especially in summer when the sun hardly sets in the Arctic.
Drastic sea ice shrinkage causes increase in storm activities and deepening of the wind-wave-mixing layer down to depth ~50 m that enhance methane release from the water column to the atmosphere.
The ESAS is very shallow averaging < 50 m depth over its 2x10ˆ6 km2 area, 80% of which is predicted to contain originally sub-areal permafrost unit, now submerged due to transgression. Associated with transgression was a new thermal regime including enhanced heat transfer from warming Arctic Oceans and terrestrial riverine waters to the submerged permafrost, as well as from exothermic oxidation reactions and geothermal sources. As a result, large areas of integrity loss have been identiﬁed from widespread bubble ebullition and enhanced aqueous methane levels well above atmospheric equilibrium. The resulting thaw sediments (taliks) and structural breaches facilitate ﬂuid
and gas migration within the permafrost to overlying sediments where some microbial methane oxidation occurs. These destabilizing features may also provide a mechanism for enhanced heat transfer to methane hydrate deposits.
From: Submarine pingoes: Indicators of shallow gas hydrates in a pockmark at Nyegga, Norwegian Sea Hovland et al., Marine Geology 228 (2006) 15–23
The danger is that heat will travel down cracks, fractures, channels and conduits in the perfafrost, and reach methane held in the form of free gas and hydrates in the sediment. A team of scientists studying methane emissions in the Laptev Sea point at the observed massive methane outburst from the bottom sediments in the image below as an indication that methane must be rising through channels in the sediment.
Because the waters are so shallow, much of the methane that rises up through these waters will not get oxidized. As the methane causes further warming in the atmosphere, this will causing further release of methane that further accelerates warming, in a vicious cycle leading to runaway global warming.
12. How much methane is/was there in the atmosphere, how much is added annually?
The above figure for radiative forcing (RF of about 0.5 W per square meter) does not include indirect effects of methane, such as water vapor. These effects are included in the images below.
13. What is the global warming potential of methane?
IPCC AR5 (2013) figures for methane's Global Warming Potential (GWP) are in the table below.
Note that Shindell et al. pointed out in 2009 that when including some important direct and indirect effects, methane's GWP is 105 over 20 years. Over shorter periods, the GWP is even higher, as illustrated by the image below. At a 10-year timescale, the current global release of methane from all anthropogenic sources exceeds all anthropogenic carbon dioxide emissions as agents of global warming; that is, methane emissions are more important than carbon dioxide emissions for driving the current rate of global warming.
Unlike carbon dioxide, methane's GWP does rise as more of it is released. For more on methane's global warming potential, see:
Methane Hydrates - by Sam Carana
14. What is the lifetime of methane?
Methane can persist in the atmosphere for as little as 8 years, but its lifetime can be extended to decades, particularly due to lack of hydroxyl in the atmosphere.
Methane's GWP and lifetime depend on variables such as the size of emissions and the location of emissions (hydroxyl depletion already is a big problem in the Arctic atmosphere), the wind, the time of year (when it's winter, there's less hydroxyl), etc. Another variable is the indirect effect of large emissions and what's often overlooked is that large emissions will trigger further emissions of methane, thus further extending the lifetime of both the new and the earlier-emitted methane, which can make the methane persist locally for decades.
For more on methane's lifetime, see:
Methane Hydrates - by Sam Carana
15. Is methane already venting in the Arctic from hydrates?
Evidently, it is, given the high levels of methane in the Arctic. Above NASA image shows methane levels of 1870+ in the Arctic for January 2012.
From: Sam Carana, Methane venting in the Arctic
The image below compares methane levels for the period 21-31 January for the years from 2009 to 2013.
[ click on image to enlarge ]
The two images below, produced by Sam Carana with NASA GES DISC Giovanni data system, show methane levels for early April 2012.
The top image below shows where methane levels exceed 1.9 parts per million.
The image below is a polar projection; note the different scale on the right, which is the one automatically calculated as the default one and exceeds 2 parts per million.
High methane levels in Arctic - April 2012
More monitoring should take place to analyze details of such venting. Furthermore, data should be more easily available online, while more should be done to interpret the data and assess the risks. A recent private initiative to do so has started at http://methanetracker.org
To some extent, the question how much methane is already venting in the Arctic is no longer relevant. Action can no longer be postponed. It is clear that it's necessary to reduce the risk that large amounts of methane will be released abruptly in future. We need to reduce this risk while we still can.
Methane in the Arctic is monitored through flask and in situ measurements at only three sites, i.e. Barrow (Alaska), Alert (Nunavut, Canada) and Svalbard (Norway), as discussed at:
Meanwhile, funding for continued in situ measuments at Barrow have been terminated.
At times, balloons and aircraft also take measurements at higher altitudes, e.g. HIPPO.
Furthermore, there are satellite measurements, such as discussed at:
Methane in the sea is monitored by buoys, by submarines (Peter Wadhams) and by ships, e.g. at expeditions as discussed at:
16. What should be done to reduce the risk that methane hydrates will trigger runaway warming?
Large-scale geo-engineering, afforestation and dramatic reduction of emissions are necessary to bring the atmosphere and oceans back to their pre-industrial state as soon as possible. Additionally, further geo-engineering is necessary to reflect more sunlight back into space, break down or capture methane, etc.
"[Measures identified to reduce black carbon and tropospheric ozone] could reduce warming in the Arctic in the next 30 years by about two-thirds . . ."
Dr. Drew T. Shindell et al. in: Summary for Policy Makers, UNEP/WMO 2011
"Increases in global methane emissions have caused a 26% decrease in hydroxyl; global carbon monoxide emissions have caused a 13% decrease in hydroxyl."
Dr. Drew T. Shindell et al. in: NASA Research News, from: Science, October 30, 2009
PART B. The atmosphere and oceans need to be brought back to their pre-industrial state.
This will take many years and will require the help of a range of geo-engineering methods including large-scale afforestation, biochar and enhanced weathering.
PART C. Geo-engineering methods must also be deployed as part of emergency measures to avoid runaway warming, for starters to replace the cooling effect of aerosols now released through combustion. Further geo-engineering will be necessary, particularly ways to capture or break down methane in the Arctic.
For further discussion of what needs to be done, see the Climate Plan at
17. What are the costs of this proposed action (to reduce the risk of runaway warming)?
Again, as discussed under question 5.,we cannot afford not to act. Each policy that seeks to accomplish the necessary shifts comes with costs and benefits, and they will be greater for some people than for others, but generally we will all be much better off if we act. To get the atmosphere and oceans back to their pre-industrial state, feebates are the most effective policy instruments, they can be budget-neutral, have the least leakage and are best implemented locally. Such local implementation means that one doesn't have to wait for policy implementations elsewhere. While a global commitment to act is imperative, the exact shape of such policies is best decided and implemented locally. In many cases, this increases health, job and investment opportunities, while prices of products will come down over time.
Furthermore, geo-engineering methods must be deployed to reflect more sunlight back into space, break down or capture methane, etc. The direct cost of this are estimated to be under $1 billion per year. Additionally, there may be some undesirable side effects of geo-engineering, but - again - the cost of that would be dwarfed by the cost of taking no action.
For further details on what action is needed, see the Climate Plan at:
The impact of global warming could destroy civilization as we know it, taking away the tools and knowledge necessary to reduce further escalation, as discussed at: Earth is on the edge of runaway warming
There are risks associated with any chosen policy; a business-as-usual scenario carries the highest risk of extinction of many species, including humans. With so much at stake, the cost of taking no action is incalculable. The longer we wait, the larger the risk becomes and the more difficult, expensive and risky it will become to take measures in efforts to reduce the risk.
Of course, research should continue to find the safest methods, but there's enough evidence that decisive action is necessary now, and there are many measures that can be taken that are safe and that are beneficial in many ways. There are sufficient technologies and resources available to start acting now. The one thing we don't have enough is time. We are rapidly running out of time. We cannot afford not to act.
20. Why should drilling be banned in the Arctic? Why is a spill or blow-out particularly bad in the Arctic?
Given the risk of oil spills and disturbing methane hydrates, drilling in the Arctic should be banned. Since a rapid shift to clean energy is necessary globally, there's no need to drill for fossil fuel in the Arctic in the first place. Rather than drilling for oil and natural gas, oil companies should use their experience with drilling and with hydrates to help out in dealing with the problems.
Circumstances in the Arctic are different from most other places in the world. There is hardly any response capacity ready for launch in the Arctic, while arrival of winter ice would make it even harder to reach many places. Standard responses such as drilling relief wells or using booms are hard to apply when the ice thickens. An oil spill in the Arctic would risk that oil gets underneath the sea ice, from where it will be very hard to recover. Low temperatures mean there are less bacteria to break down the oil. In other places, currents may bring bacteria back to the location of the spill repeatedly. Currents in the Arctic are long, so once bacteria flow away from the location of the spill, it may take a long time for them to return, too long to survive in the cold water and often with little or no sunshine.
Methane won't get broken down easily in the Arctic, as this requires oxygen, which isn't quickly replenished in the Arctic, once depleted. Furthermore, hydroxyl levels in the Arctic are very low, so methane that reaches the atmosphere won't get broken down there easily either.
"It seems clear that in a warming world (for whatever reason), methane will be released in increasing quantities, e.g. from warming permafrost, thus augmenting global warming. Disturbances on the sea bed may also cause the decomposition of methane-hydrate. It is known that drilling into methane hydrate poses a hazard to oil prospecting operations, and it is also thought that decomposition of methane hydrate with an eruption of methane could trigger a tsunami."
Professor Chris Rhodes in: Methane Gas Hydrates. . Feb 1, 2012
Peter Wadhams - written evidence submitted to UK Environmental Audit Committee
Greenpeace - written evidence submitted to UK Environmental Audit Committee