Ecologists to the rescue
Posted October 22, 2009 in Solving Global Warming
A group of prominent ecologists and climate scientists have an important article coming out in tomorrow's issue of Science, in which they call for "fixing a critical climate accounting error." The error is ignoring a significant source of global warming pollution related to using biomass for energy ("bioenergy").
I know that most people's eyes glaze over whenever "accounting" is mentioned and others tune out when discussion turns to "climate," so the number of people interested in "climate accounting" may be vanishingly small. But this article is important and not as obscure as it sounds. Getting the accounting wrong means that more CO2 is going into the air than we are acknowledging; and that worsens global warming. CO2 has the same effect whether we count it or not, but we can't reduce emissions that we don't admit are happening. Global warming is too serious of a problem for us to use incomplete balance sheets.
The Science article points out that the climate legislation pending in Congress hasn't yet accounted properly for emissions from bioenergy. We need to get this right so that climate legislation promotes bioenergy that helps us fight global warming rather than costs us forests.
This is where the principles of ecology come in. Barry Commoner annunciated five laws of ecology during the 1970s. The first two are:
- Everything is connected to everything else.
- Everything has to go somewhere, or there is no such place as away.
The first law means that to understand the implications of using biomass for energy we can't just look at the impact on the land where the biomass came from, we also have to consider the ripple effects, whether on neighboring farms or forests half way across the world that are connected through global commodities markets. Remember, everything is connected to everything else.
A corollary of the second law is that everything has to come from somewhere. In the case of biomass, the carbon it contains comes from CO2 in the atmosphere. That's why there is an environmental opportunity in replacing fossil fuels with biofuels. But whether there are in fact net environmental benefits or costs depends on what would have happened to that carbon if it wasn't used for energy. Remember, everything has to come from somewhere.
The key sentence in the Science article is:
Bioenergy therefore reduces greenhouse emissions only if the growth and harvesting of the biomass for energy captures carbon above and beyond what would be sequestered anyway, thereby offsetting emissions from energy use.
In other words, the clean energy merits of biomass depend on the specifics of how it is harvested and how the land it comes from is managed.
The climate bills currently under consideration in Congress, however, fail to distinguish between the carbon footprint of burning biomass from a mature forest and burning crop waste. Instead, all "renewable biomass" is assumed to be carbon neutral and any biomass that isn't considered renewable is assumed to have no environmental benefits. As a result, there is a huge, if obscure, fight going on over exactly how "renewable biomass" should be defined in the legislation. The need for a more nuanced approach was flagged by House Energy and Commerce Committee Chair Henry Waxman and Agriculture Committee Chair Collin Peterson, and needs to be addressed as clean energy and climate legislation moves through the Senate.
We have to get biofuels right to get the pollution reductions the clean energy bill is designed to achieve. Otherwise there will be a perverse incentive to clear forests for bioenergy production even if the net emissions are actually higher than from continuing to burn fossil fuels. This incentive will get larger over time as the cost of emitting fossil fuel CO2 rises as long as net emissions from bioenergy CO2 remain free.
The solution is to stop assuming that burning biomass is always carbon neutral and fix this climate accounting error by recognizing that everything is connected to everything else.
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