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When Net-Zero Really Means Just Zero

Madeleine Hardy
Apr 22, 2021

Guidehouse Insights

This blog was coauthored by Viktorija Stojcheva and Caspar Noach.

The net-zero in net-zero targets refers to the zero sum of residual greenhouse gas (GHG) emissions and CO2 removals that neutralize these emissions. What are residual emissions, and which residual emissions are expected to remain in 2050? This blog discusses different sectors in net-zero scenarios and what this could mean for organizations setting net-zero targets.

This blog is part of a series on net-zero targets by Guidehouse’s decarbonization experts. Review the first two blogs, "A Corporate Perspective on Net-Zero Targets and the Use of Carbon Credits" and "First Steps in Setting a Net-Zero Target," and look for upcoming blogs on carbon removals, how net-zero will affect value chains, and how the Supplier Leadership on Climate Transition collaborative can help these efforts.

Residual Emissions in 2050

Residual emissions are GHGs that are unlikely to be eliminated due to technical and economic constraints. The Intergovernmental Panel on Climate Change’s Special Report: Global Warming of 1.5ºC shows mitigation pathways to reach net-zero emissions by mid-century and limit global warming to 1.5ºC. In these pathways, some sectors such as power and buildings are projected to nearly or entirely decarbonize, while others such as agriculture, heavy industry, and transport still have difficult residual emissions beyond 2050. 

Process emissions from heavy industry is one source of residual CO2 emissions forecast in these scenarios. These emissions are inherent to chemical processes, such as limestone calcination in cement production. Although carbon capture and storage is an option to abate some of these emissions, for smaller distributed sources this may not be economically feasible. In the transport sector, passenger cars and rail are expected to reach net-zero in 2050 mainly via electrification; however, aviation, heavy duty vehicles, and shipping are more difficult to decarbonize, with most scenarios showing residual emissions in 2050. 

CO2 is typically the star of the show when it comes to GHGs, but nitrous oxide and methane play a larger role when it comes to residual emissions. They are harder to abate and have a higher global warming potential compared to CO2. They are expected to represent the largest part of residual emissions in 2050 for 1.5ºC scenarios. These emissions largely come from the agricultural sector, with nitrous oxide emissions arising from manure and fertilizers and methane arising from manure and livestock digestive processes (see figure below). 

Residual Emissions by Sector in Net-Zero Scenarios in 2050

Residual Emissions by Sector in Net-Zero Scenarios in 2050

(Source: Guidehouse)

Sectors Where Net-Zero Really Means Zero

For sectors expected to fully decarbonize, such as power and buildings, net-zero really means zero in 2050. For organizations with supply chains where electricity, heat, and road passenger transport dominate the carbon footprint, such as those in the service sector and manufacturing (excluding steel and cement), this means net zero targets will need to be achieved through complete emission reduction, with little option to neutralize residual emissions.

However, organizations with supply chains reliant on aviation or agriculture need CO2 removals to neutralize their residual emissions and reach net-zero targets. This applies to those active in the food and beverage, apparel, or logistics sectors. Our next blog in this series will discuss the different removal options and market development.

Reductions Over Removal

Carbon removals have an important role to play, but only in specific sectors and for organizations with net-zero targets earlier than 2050. Climate modelling shows that for many sectors, emissions will need to be driven down to zero by 2050, rather than net-zero. For these sectors, long-term net-zero targets should not rely too heavily on promises of future CO2 removals but should focus on the more urgent need of reducing emissions in the near- and mid-term future.

Without sufficient reductions, we can't remove ourselves from the climate crisis.