Are the Factors Present Which Could Lead to a Runaway?
- The incredible warming power of methane as a greenhouse gas (already quantified)
- The phenomenally huge volume of methane present in the continental shelf areas of the Arctic
- The quite shallow depth of these seabeds, which allows direct venting to the surface and atmosphere (methane otherwise safely oxidizes in deep water)
- Their location in the most rapidly warming region on earth, where such is accelerating due to the "albedo flip" (open water now absorbing solar heat rather than having it reflected away by ice cover) and warmer water infiltrating at the river mouths
- Direct observations confirming that large scale methane plumes are venting to the surface and into the atmosphere, and
- Direct observations confirming that seabed bottom temperatures are hovering at the thaw point. 
With the Arctic warming so much faster than the rest of the world and arriving at such incredible temperatures within this century, it is clear that the "writing is on the wall" in terms of the future of methane in the shallow Arctic seabeds. Unless there is a major shift away from the "business as usual" scenario, it is inevitable that they will thaw and vent into the atmosphere.
Six Direct Challenges to David Archer
Preparation of Safe Geo-Engineering Options Should Humanity Need to Use Them
The concept of geo-engineering has attracted a spectrum of opinions ranging from support to opposition and many shades in between. However, there is a fundamental reality staring in our face. If humanity waits until the point of no return is crossed and a runaway is unleashed, it will be too late to develop any such options. In the opinion of this writer, the prudent position is to work now on developing safe geo-engineering options so that there might at least be a chance to implement them should the world become convinced that a runaway is imminent.
Perceiving a threat that Arctic ice could conceivably collapse as soon as 2013, John Nissen (chairperson of the Arctic Methane Emergency Group)  offers a statement in support of urgent development of safe modes of geo-engineering:
The Arctic Methane Emergency Group (AMEG) has been set up for the express purpose of drawing the world’s attention to the danger arising from astonishingly rapid retreat of sea ice, accelerated warming of the Arctic and escalating methane emissions from the seabed, especially in the area off the Siberian coast. It is the methane that can produce abrupt climate change, but it is the retreat of sea ice that has triggered this crisis... We are approaching a likely point of no return, and therefore it is essential that emergency measures are taken to avoid passing this point. This involves intervention on a large scale to cool the Arctic, either directly or indirectly by cooling currents and rivers flowing into the Arctic. By definition such intervention constitutes what is called 'geoengineering,' but, whereas geoengineering has generally been considered on a global scale to counter global warming rising over decades, we need geoengineering geared to cool the Arctic with a timescale of just months, to prevent a possible collapse in sea ice extent in September 2013.
Critical Need for the Scientific Community to Speak Out More Forcefully
In the case of methane, we are not dealing with a dramatic image of an atomic fireball and its capacity to render immediate destruction. But extended over a longer range of time, the global devastation it would inflict would be no less sweeping. The spectre of a methane runaway is real and it is an existential threat to humanity.
In our society, the scientific community holds a position of great respect. In order to protect scientific "objectivity," our tradition has been to separate the institution of science from the realm of public policy. I do not call upon RealClimate to violate its internal agreement and issue specific policy directives. However, I do call upon it to release a generic warning to policy makers that humanity must break out of its state of denial, recognize that the laws of physics do not operate on a political calendar, realize we are dealing with a powerful force that can spin out of control, and therefore quickly educate ourselves as to the severity of the threat. It is my hope that RealClimate -- as well as the larger community of climate scientists -- will rise to the occasion and show the way.
- by Gary Houser, co-producer and writer of the documentary film "Sleeping Giant of the Arctic: Could Thawing Methane Trigger Runaway Global Warming?"