Something Else To Worry About
I went to a talk this evening about Methane hydrates. “What are they?” you ask “and why should I care?” Methane hydrates are deposits of CH4 molecules frozen inside an ice-like crystal called a Clathrate Cage. Here is one:
Methane Hydrate: A Methane molecule (red) in Clathrate Cage (blue)
Deposits of methane hydrates are abundant in Earth’s oceans – they freeze over the surface of ocean shelves. The molecule above is stable (remains frozen) over a given range of temperature and pressure. Going deeper in the ocean means a higher pressure, making it more stable. Increasing the temperature for a given pressure de-stabilises it: so methane deposits which are stable at a given depth of ocean can become destabilised if the temperature there rises.
Here’s the phase diagram (showing whether the molecule is in the hydrate or gas phase for a given point in the temperature-pressure plane) – above the blue line is the stable methane hydrate region, whereas below it methane deposits are released into the ocean as gas bubbles:
Now why should you care? Well, the methane bubbles rise to the surface, becoming atmospheric methane. Methane gas is a potent greenhouse gas – around 20 times more potent per molecule than atmospheric CO2. There is potential here for a positive feedback: the ocean temperature increases, therefore releasing some methane gas into the ocean then the atmosphere, which further increases the ocean’s temperature, which releases more methane gas – and so on.
A lot of ocean floor methane deposits might be released via this mechanism, over a geologically short time period (a few decades perhaps). This has happened in the past – it’s thought during the Paleocene-Eocene Thermal Maximum, around 55 million years ago, with global average temperatures increasing then by around 6 degrees over a 20,000 year period. Humans may yet “accomplish” this in a much shorter time frame, given that we are releasing a lot of extra greenhouse gases over a very short (in geological terms) timescale:
Today there is huge uncertainty over the amount of methane hydrate depoits in the oceans. In the talk I went to, we were told that estimates range over more than two orders of magnitude, from 1000 to 120 000 trillion cubic metres. Also not well known is what percentage of this total is liable to become destabilized by an increase in temperatures. Is it 1%? 10%? And if so, 10% of what – 1000 trillion cubic metres? 120 000? Even more? We don’t know – not particularly comforting!
Even less comforting is recent observations that deposits are already being released. In 2008, research teams discovered methane gas bubbling up from the Siberean ocean shelf. We were shown plots indicating that sites where bubbles are observed have been increasing in number since then. It’s worth bearing in mind that the IPCC’s recommendation to keep under a “safe” 2 degree rise in temperatures refers to a global average. Even if we manage this (unlikely, given that parting with economic growth is thought-crime) temperatures could well go up by much more in critical ocean regions where meta-stable methane deposits reside. So the IPCC’s “safe” recommendations are not really very safe, in light of our current level of ignorance about positive feedback such as this one. The sensible strategy at this point would be to hit the brake. The insane strategy would be to hit the accelerator. Alas, we do the latter.
If you want a sense of just how vain it is to hope for a sensible response, consider how our economic system is currently responding. Already this potential crisis is being re-branded as a glorious new investment opportunity – the methane can be burned as a new source of fuel: a solution to peak oil. Never mind that this will release more CO2 into the atmosphere (not as bad as merely letting the more potent methane gas go, but still not exactly helping). Never mind that we are merely postponing by a few more years the inevitable, painful collision with reality, whereupon we are confronted with the realization that our global economic system is fundamentally and catastrophically unsustainable. And never mind that when we finally arrive to this epiphany we shall find ourselves painted into an even tighter corner, having kept the grow forever, kill everything economy hobbling along on its last legs for a few years longer.
Sorry if that ruined your day, but seriously, human beings need to get with the program and fast! When crisis after crisis being directly caused by the current economic model is talked up as a shiny new investment opportunity under that same model, something is quite drastically awry. Another example of this that amused me (in a gallows-humor sort of way) was when the scary post-millennial data on arctic sea ice was seized upon as an opportunity for new shipping lanes and arctic oil drilling. You couldn’t make this shit up. Best wise up humanity, or your days are numbered.
freedom this time 