Geoengineering the Planet

By Mark Crutchley

Following on from my last column in which I described the unprecedented extent of the sea ice melt in the Arctic this summer, I want to take you to a dark place that you may never have considered going to before. I want to suggest that we may need to undertake some limited Geoengineering in the immediately foreseeable future. I realise this is a radical suggestion, particularly coming from a committed green like myself, but there is a good reason as I will explain.

To set the stage I want to start by challenging the idea that it would never be right to geoengineer our planet. If it were an ice age we were facing, with great ice sheets set to cover most of Europe, Russia, Canada and a large part of the USA. Crop production would be devastated and hundreds of millions of people would become homeless or starve to death. Would we accept geoengineering then to keep the planet warm enough for our civilisation to continue? I know I would and I suspect so would most other people. 

So now let’s turn our attention to the current situation. The reason I want to suggest we should consider geoengineering is because of methane. It is generally stated that methane has a global warming potential (GWP) which is around 21 times that of CO₂, but while this is the figure used by the UNFCCC, it doesn’t tell the whole story. This is the 100 year averaged figure, but methane only stays in the atmosphere for around 12 years and in that time it has a GWP in the region of 90 times that of CO₂.

At the moment the CO₂ concentration in the atmosphere is around 392 parts per million (ppm). Methane is the next most important global warming gas, with a concentration of around 1800 parts per billion (ie 1.8ppm), this having risen around 150% since the start of the industrial revolution compared to an increase of around 40% in CO₂.

Recent articles have highlighted the risks of significant methane releases triggered by the well above average rate of warming in the more northerly latitudes. On land methane is being released in the tundra as the permafrost thaws and wetland peat bogs warm, and in the oceans lie vast quantities of the gas in the form of frozen methane clathrates, which if mobilised could dramatically impact on our climate. The references in my last column to the Arctic Methane Emergency Group and the interview with Peter Wadhams both highlighted these risks.

Significantly increased methane emissions run the risk of pushing us into unstoppable runaway warming. But crucially their impact would be felt over a relatively limited time period. Within 12-15 years the released methane would disappear from the atmosphere. A temporary programme of geoengineering – I’m not going to discuss of what form, that’s another whole issue – might be necessary to prevent this scenario from becoming a disastrous reality.

But there is one crucial caveat which I would add. A key concern of opponents of geoengineering is that it would be used to avoid addressing the underlying problem of our excessive carbon emissions. Reducing the amount of incoming solar radiation for example might limit the warming of the planet, but unless we cut emissions it will do nothing to address ocean acidification; and without emission cuts the extent of geoengineering required would continually increase. This is a recipe for disaster.

So my suggestion is that if we were to go down this route, it would only be acceptable if it were accompanied by a massive global programme to transform our energy systems permanently to low or zero carbon forms. Otherwise all we are doing is delaying the inevitable. Without this we would be applying a temporary palliative, just pushing back the date of the disaster by a few years.

I can’t pretend that I like this scenario. As a species we have a poor record of taking action to benefit the environment on a large scale, but we may be on the verge of developments for our climate so dramatic that we have little option other than to consider such drastic measures. At least this time we would be doing it for the right reasons rather than the thoughtless geoengineering we have inflicted on the planet so far.