Offsetting and Feedback: Do the Books Balance?

Achieving a state of so-called ‘carbon neutrality’ has long been the Holy Grail for individuals, businesses, and even nations that have an eye fixed on the threat posed by global climate change. It’s a phrase that evokes the idea of a balanced equation, where the emissions we produce can be, in one way or another, counteracted by actions that cause an equivalent reduction in our environmental impact elsewhere, thus offsetting their effect.

These actions can take many forms, from funding research in renewable technologies in the hope of lowering future emissions, to planting trees as a way of increasing the earth’s capacity to naturally sequester carbon.

As these examples show, ‘offsetting’ strategies don’t actually have to involve lowering current levels of emissions, and indeed, very often they don’t. As a result, the trend for ‘offsetting’ has occasionally come in for criticism by environmentalists for encouraging a potentially short-sighted ‘have your cake and eat it’ sort of attitude. Whilst there are a variety of reasons that relying on offsetting rather than actually lowering emissions could be seen as a flawed way to tackle climate change, the phenomenon of greenhouse gas ‘feedback’ is quite possibly the most troubling.

(Just as it does in the fields of electronics or biology, when applied to climate science, the term ‘feedback’ refers to a situation where a self-perpetuating loop occurs. A great example of this is where greenhouse gases (GHGs), simply by their presence in the atmosphere, directly cause more GHGs to be released.)

Accurately calculating the potential for a situation where a global warming ‘feedback’ loop might start occurring is a highly complex and extremely challenging task, even for those who make understanding the issue their life’s work. By comparison, measuring emissions is relatively straightforward.

It comes as little surprise, then, that the potential for further emissions caused by a feedback scenario are not factored into offsetting programmes. Instead, a sort of balance sheet logic is generally employed, whereby emissions directly caused by a certain activity are estimated so as to give an idea of the amount that needs to be compensated for.

Undoubtedly, this method of thinking provides a great way for individuals and organisations to recognise and subsequently take responsibility for their emissions, and it will go a long way to reduce the impact of their practices. However, whilst tackling the historically high levels of carbon emissions that modern civilisation currently produces is an achievable, though somewhat daunting task, if — as a result of ‘feedback’ — GHGs that have been naturally sequestered from before the advent of the human species are released into the atmosphere, achieving ‘neutrality’ would become practically impossible.

Unfortunately, this scenario is far from unimaginable. Current estimates suggest that the amount of carbon sequestered in organic material trapped within the northern hemisphere’s permafrost is roughly double that of the world’s atmosphere taken as a whole. Should this ice thaw, it could lead to a huge rise in emissions. A recent survey of 41 international scientists, conducted with a view to assessing the risk posed to these regions of permafrost, predicted that, on the basis of current trends, as much as 15% of the top layer of all permafrost could be degraded within the next 38 years.

To make matters worse, much of this carbon will not be released as carbon dioxide, but as methane, owing to the fact that the bacteria that break down organic material and convert it to carbon dioxide can only do so in conditions where oxygen is plentiful. If this is not the case, and it won’t be for a large amount of the thawing material, bacteria called methanogens will instead turn them into methane.

This further compounds the problem as methane, though less abundant, is a far more potent greenhouse gas than carbon dioxide. Indeed, according to The Environmental Protection Agency, it’s 23 times as harmful as CO2 in terms of its contribution to global warming per weight.

The prospect of higher methane emissions is made even more worrying by the fact that a high presence of methane in the atmosphere also amplifies the effects of other greenhouse gases. For example, nitrogen dioxide and carbon monoxide can both be neutralized by binding with hydroxyl molecules in the lower atmosphere. According to Arlene Fiore of the National Oceanic and Atmospheric Administration, if more methane were released, it would bond with many of these molecules, rendering them unable to mitigate other gases’ effects.

Needless to say, should these emissions occur, they’d be expected to hasten the thawing process, leading to a positive feedback loop. And this is without considering other contingencies, such as the high levels of carbon that could be released into the atmosphere if larger areas of tundra start to become susceptible to widespread blazes such the Anaktuvuk River fire of 2007.

All these potential issues surrounding the loss of permafrost and frozen lands, which have recently gained a high level of prominence, are just one example of a number of positive feedback loops that could be triggered by a warmer planet.

To avoid such an event, it is important to recognise that whilst offsetting is assuredly a good way to lessen the impact of emissions, it doesn’t negate their immediate impact on the atmosphere. If that impact should be to trigger the release of prehistoric GHGs that have been locked out of the atmosphere for aeons, our attempts to ‘balance the books’ will be thrown perilously off.

Edward A. G. Schuur, of the University of Florida, commenting on the release of ancient carbon observed during his field work in Alaska, said that: “[it’s] the fingerprint of a major disruption, and we aren’t going to be able to turn it off someday.” In other words, even the emissions we do offset take us closer to a situation where offsetting is no longer a viable solution.

Steve Waller is an environmental blogger on a journey to improve the sustainability of his lifestyle. He uses his Green Steve blog to document his efforts and educate himself and others on all sorts on environmental issues.

Image Credit: legislation balancing concept via Shutterstock

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