In order to keep global temperatures under 2°C, the threshold generally accepted as the best way to avoid the most catastrophic impacts of climate change, there must be a limit on cumulative CO2 emissions. For those of you not tracking mitigation negotiations closely at COP21, there is some hot debating surrounding long-term signals maintaining this threshold. Delegates are looking at two potential options, decarbonization and climate neutrality. But what’s the difference?
While the two options may seem rather similar, they carry with them significantly different implications. Climate neutrality would require that countries achieve annual zero net anthropogenic greenhouse gas emissions (GHG) by a specified date. What this means is that for every ton of anthropogenic GHG emitted, an equivalent amount must be removed from the atmosphere. This sounds great in theory. However some parties are concerned, and for good reason, that climate neutrality equates to more of a political move around than effective action.
Here’s why. Climate neutrality allows for those emitted GHG emissions to be compensated with removals via carbon offsets such as sequestration, carbon capture and storage. To actually keep global temperatures under 2°C with carbon offsets, large-scale uptake of negative emission technology will have to be implemented. According to Kevin Anderson of the University of Manchester, there are problems with relying on negative emission technologies to achieve an under 2°C global temperature target. Anderson noted that these technologies have never worked at scale, have huge technical and economic unknowns, and have major efficiency penalties. These technologies are often not worth the hype.
In essence, climate neutrality means that CO2 may still be produced, but not all parties think this is a bad thing. It may leave room for developing countries to continue emitting GHG and thus enable them to continue essential sustainable development projects. However, a concern is that developed countries may purchase carbon offsets for their emissions from developing countries with natural carbon sinks. This allows for developed countries to continue with a “business as usual” approach to emission mitigation efforts rather than encouraging them to radically change their consumption patterns.It allows for the possibility that wealthy developed countries may pay for their emissions by buying carbon offsets from developing countries with lower emissions and natural carbon sinks.
Alternatively, decarbonization tends to be understood as a process that results in a decarbonized global economy with no anthropomorphic CO2 emissions. Amongst the scientific community, it is widely accepted that to successfully achieve climate stabilization, full decarbonization of our energy systems is likely our only option. While this idea seems rather straight forward, there is confusion about how decarbonization may be interpreted and implemented. While full decarbonization tends to mean zero unabated CO2 emissions, it is possible that decarbonization within the Paris Agreement would allow for emissions to be balanced with adequate reductions and carbon sinks. There are also concerns that a decarbonization option would not account for non-CO2 GHG emissions.
What is clear is that whichever option ends up in the Paris Agreement, further clarification and definition of terms should be made first. For either option to be effectively implemented, they should be accompanied by specific timeframes, definitions, rates, and standardized accounting measures.