href="#fb3_img_img_525d054f-8b4a-5773-a3c5-7d0e2b8f55dd.png" alt=""/>
Figure 1.4 C40 analysis: consumption-based GHG emissions of C40 cities. (Source: Consumption-based GHG emissions of C40 cities, March 2018. C40 Cities Climate Leadership Group, Inc. https://www.c40.org/researches/consumption-based-emissions.)
Figure 1.5 C40 methodology showing overlap and distinction between sector-based and consumption-based emissions. (Source: Consumption-based GHG emissions of C40 cities, March 2018. C40 Cities Climate Leadership Group, Inc. https://www.c40.org/researches/consumption-based-emissions.)
In the corporate realm, for example, Unilever’s “Wash at 30” campaign arose from internal analysis that showed most of their “full-scope” emissions were caused by consumers using their products – in this case washing with hotter water than needed to clean clothes given the detergent technology Unilever now provides. Volkswagen, bouncing back from their diesel-emissions scandal, presented at the World Climate Summit 2019 a fully comprehensive value chain analysis showing that only 15% of their targeted emissions reductions to comply with the Paris Agreement are from their vehicle production and supply chain. Meanwhile, emissions from fuel supply and customers driving vehicles accounted for 79%. For Volkswagen, assuming responsibility for scopes 1–3 is propelling a more ambitious corporate strategy (with cleaner, electric-powered cars at its heart) and in turn a beneficial impact on world CO2 emissions.
If cities are to truly lead on climate action, ideally we would define “Fully Scoped” as assuming responsibility for scopes 1, 2, and 3, upstream and downstream – sector-based and consumption-based.17 The C40 analysis shows how the consumption-based method “offers complementary insights into the drivers of GHG emission – recognizing cities as both consumers and producers of goods and services – and can help cities identify a broader range of opportunities to reduce global GHG emissions”.18
In addition to “all scopes”, “Fully Scoped” should clearly include all GHGs19 and not just carbon dioxide. We recommend that this is made explicit within the concept of “Fully Scoped”: i.e. all activities, all gases. A recent report in McKinsey Quarterly 20 shows – in Figure 1.6 – how important assuming responsibility for all gases is for any city that has significant industrial and agricultural sectors; but it also demonstrates that all cities should consider targeting all GHGs, considering waste has such a strong global warming potential outside the effects of carbon dioxide.
Figure 1.6 Anthropogenic GHG emissions per sector and type of gas. (Source: Based on Emissions databases for Global Atmospheric Research (EDGAR), 2015; FAOSTAT, 2015; IEA, 2015; Mc Kinsey Global Energy Perspective 2019; Reference case 1.5c Scenario Analysis.)
“Science-Based”: What Does This Mean?
The Science-Based Targets Initiative (SBTi) has focused on providing the corporate sector “with a clearly defined pathway to future-proof growth by specifying how much and how quickly they need to reduce their greenhouse gas emissions”.21 The targeting process involves a widely accepted methodology from the World Resources Institute, CDP, UN Global Compact, and World Wildlife Fund to calculate reduction pathways for different sectors. That methodology apportions the Paris Agreement’s emissions-reduction goals to each entity according to their capacity to reduce. The methodology helps organizations calculate the emissions reductions to target in accordance with any of three aligned approaches: a sector-based division of the global carbon budget; an absolute approach based on emissions reductions required; and an approach that uses an entity’s relative economic contribution to determine its emissions reduction target. As of December 2019, over 740 companies had committed to science-based targets.
The SBTi has not yet created similar pathways and guidance for cities but (1) points to the C-FACT methodology as a useful corollary of the method22 and (2) has inspired a science-based approach.
Importantly for our summary here, it provides a principle for cities when targeting “Net-Zero”: looking to the best-available science to help inform the appropriate share of emissions reductions for the city and defining how quickly the reduction should occur to be in line with global climate stabilization targets.
The contraction and convergence approach developed by the Global Commons Institute back in the 1990s, but championed more recently by C40 in its Climate Action Plan guide,23 helps cities measure and “converge” on an emissions per capita that is becoming equal to its relevant peers and also “contracting” enough for global net-zero emissions to be achieved by 2050.
Keeping global temperature rise under 1.5–2°C requires leaders to focus their strategies on both the total amount of global emissions reductions and detailed accountability for each city’s appropriate share of their relevant national total. To say a city’s net-zero target or pathway is science-based communicates that the city has considered its appropriate obligations under the Paris Agreement and has set is emissions-reduction target accordingly. Of the many strong examples of “science-based” leadership to net-zero emissions, the Mayor of London’s “Zero carbon London: A 1.5oC compatible plan”24 explicitly links the plan to the global temperature goal in the Paris Agreement.
“Paris-Agreement-Compliant”: What Does This Mean?
Many cities may approach the idea of reducing to zero emissions and conclude that with best efforts and all available technology they will not be able to get there on their own. There will be an emissions gap. This gap may be a hard-to-abate industrial sector within the city’s boundary or it may just be the need to be connected to a grid that is not on a zero-carbon trajectory and lies outside the city’s sphere of control.
As with leaders in the corporate world, these municipal leaders may conclude the need to purchase carbon credits, or invest in negative emissions technologies, in order to offset the emissions that they cannot reduce on their own account. These outside-entity investments can help us all along the journey to a net-zero world if they are tied to the global carbon budget. To achieve this, the unit of carbon credit supply needs to be counted in the appropriate nation’s single, unified GHG inventory. Only then will the credit be netted against the nation’s other carbon sources (e.g. logging and carbon-emitting factories) and sinks (e.g. forest preservation, afforestation); and only then will there be a unified picture of reality at the global level. Most organizations fund these sinks, though, by purchasing carbon credits in a flawed marketplace. Subnational, project-based carbon credits may often have a variety of real-world benefits but fall short from the point of view of atmospheric integrity because they do not form part of the relevant nation’s GHG inventory.
However, encouraging directions announced at COP25 – for example, by REDD.plus – point to some fixes on the horizon.25 Powered by the Coalition for Rainforest Nations, this platform will be making United Nations Framework Convention on Climate Change (UNFCCC)-registered REDD+ forest carbon credits issued by nations under the Paris Agreement, and these will be made available to subnational and private actors such as cities to purchase for the first time. This could trigger
