Climate Change may be worse then anyone expects
Unknowns in climate system could bring change with more rapidity and severity than predicted
The recent release of the IPCC’s latest draft report has revealed increased certainty that human activity is driving climate change, and well as a range of future scenarios and probable impacts. These have spurred calls for greater action worldwide, even from previously sceptical quarters.
Although the scenarios detailed in the reports are devastating enough, there is a very real probability that the situation will actually be far worse.
Vast stores of methane are trapped in the permanently frozen ground or permafrost around the arctic circle in Canada and Siberia. Over short periods of time, Methane has a far stronger effect on climate then carbon dioxide, with around twenty-five times the effect on warming.
As the arctic continues to warm, this permafrost is melting on a huge scale. Many far Northern settlements, structures, and landscapes are being disrupted by the shifting of the ground beneath them as the ice gives way.
Methane Clathrates are ice-like structures comprised of methane and water, located on and just under the sediment on the bottom of oceans and lakes. As the waters warm this is being released and bubbling to the surface in vast plumes. Russian scientists were recently shocked at the scale of methane outgassing off Siberia, with areas of venting measuring kilometres across.
Coal seams are full of methane as well. This is also referred to as ‘coal seam gas’. When you dig an enormous hole through a bunch of coal seams, a lot of this methane is released into the atmosphere but monitoring and reporting of this is very rare. Some underground mines use it as a power source but this process is nigh impossible at an open cut mine.
The IPCC has a figure for how much methane will likely come from natural sources, which is a range from 5 to 25 times the global annual emissions of 2011. The first problem with this, asides from it being a huge range, is the figure is expressed with low confidence. They aren’t as sure about this as they are about a lot of other conclusions such as humans effecting the climate. The second problem is that due to the slow process of the IPCC, new data such as that found by the Russian scientists off Siberia hasn’t been included in the result. The actual quantity and rate of methane that could be released is unknown. There are estimates but in science, as in life, surprises abound. Although the IPCC process means that they can stand by what they have said thus far with a high degree of confidence, it isn’t conducive to rapidly responding to new data or addressing new and unexpected events in the climate system.
This is important because the assumptions the IPCC are making are based on a gradualist model of change, which don’t factor in major changes in equilibrium in the climate, also know as tipping points. This is largely because such events are very complex and difficult to model. A very recent study claims to have found that in the most analogous historical climate scenario, the Paleocene-Eocene Thermal Boundary (PETM) 55 million years ago, temperatures may have risen 5 degrees and oceans may have turned acidic in just 13 years (!) following a massive 3000 gigaton addition of carbon to the atmosphere.
Although we’re not sure what caused this release, we are sure about the human causes of the current more gradual release of carbon dioxide. It is also well established that in the climate system there are a number of feedback loops that can magnify small changes until the system is uncontrollably moving towards a new state of equilibrium. A huge release of methane could trigger one such feedback loop, rapidly accelerating global warming.
Another important factor in feedback loops is the Albedo effect, which refers to the reflectivity of a surface. A perfectly black surface reflects no light, while a perfectly white surface can reflect close to all of the light that falls on it. This effect is very important in polar and glaciated regions. As snow and ice melts it exposes the dark rock and soil beneath it, which absorbs more light and heat and further increases the melting of ice nearby. This effect gains momentum as time goes on and is known as a positive feedback loop.
When the albedo effect is applied to the broader issue of melting permafrost this becomes a particularly fearsome loop. The more the permafrost melts, the more methane is released, increasing the warming of the atmosphere which melts more ice which leads to more heat being absorbed by the land and oceans beneath until a new steady state is reached. This effect is what people are referring to when they talk about runaway climate change, and it has the potential to cause all sorts of unknown and unknowable effects. If there are large frozen deposits of methane out there that we don’t know about, warming the planet until this feedback loop occurs is the best way to find out.
Ultimately this amounts to a giant experiment on the entire planet. We can run all the models we want and publish all the papers but science is limited in its scope of dealing with dynamic systems in realtime, and the amount of computing power required to model Earth in all it’s glorious complexity is still a long way off. Thats not to cast any doubt on what has been published, but the length of time it takes to put together an IPCC report greatly lags the time in which changes may start to happen over the next few decades, and even were it fast enough science is inherently conservative in its predictions.
In light of these unknown factors the best global response is to reduce emissions as rapidly as we can, and then reduce them even faster in the hope that we haven’t already tipped the balance too far. Its the least we can do to give those who come after a chance to live in the beautiful world we know.
