The second intended orientation of setting “Net-Zero and Beyond” goals is leaving the “Net-Zero” market behind in the past. Cities hopefully become “Climate Positive” rather than just aiming for “Net-Zero”. “Climate positive” is an increasingly used alternative to “carbon negative” that emphasizes the benefits of aggressive climate action. “Net-Zero” hopefully becomes a well-defined marker that many cities leave behind – and ideally well before 2050.8
Ambition and Clarity at the Global Level
Providing net-zero context at the global level, the Paris Agreement, agreed in 2015 and ratified the following year, created a vital destination-based target for the world. It set the objective of “Holding the increase in the global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C …” by achieving “a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of the century, on the basis of equity, and in the context of sustainable development and efforts to eradicate poverty”.9
While the first phrase, from Article 2, outlines the temperature target, Article 4 effectively defines net-zero GHG emissions as reducing human-caused emissions to the level that natural climate solutions and other methods of CO2 storage and removal can effectively absorb. It succinctly describes a global state of ecological balance, even if the results of past emissions have not been fully absorbed. If this state is achieved by mid-century, and if emissions decline further to net-negativity in the back half of the century, maintaining a 1.5°C world becomes likely.10
Paris-Agreement goals build on strong conclusions from the Intergovernmental Panel on Climate Change’s recent assessment11 and the US government’s own 4th National Climate Assessment.12 A recent report released in BioScience 13 listing 11,000 scientists as contributing authors was equally unequivocal. We must adjust course dramatically and achieve net-zero emissions by 2050 if we are to avert the worst impacts of climate change and remain on target for 1.5°C of warming. These global goals transmit across language, culture, and ideology. They are vital to the transition to a sustainable world, but their applicability and measurability tend to burn off on impact as they enter a single enterprise.
Ambition at the City Level
City mayors have been stepping up and leading through a variety of fora, most notably the Global Covenant of Mayors for Climate & Energy, C40, and the International Council for Environmental Initiatives (ICLEI). In the former, 9,000 municipalities could potentially achieve savings of 1.4–2.8 GtCO2e versus “business as usual” if their combined pledges are achieved. C40’s “Deadline 2020” is a commitment from the world’s leading cities to urgently pursue high-ambition climate and has attracted 119 committed cities at time of writing.
Where and how does “net-zero” appear in these commitments? Some of these commitments clearly articulate goals, techniques, and timing. Many do not. Some of the commitments include room for flexibility, often by design, to create a wide net of inclusivity and attract more signatories. Well and good; but with four UN climate conferences behind us since Paris and COP26 in Glasgow this year (2021), it is time to tighten definitions – especially concerning the mid-century destination of net-zero. For the “Race to Zero”, 449 cities have already joined this campaign.
The risk is that these campaigns are intentionally broad and open-sided tents. Only 12 of the 119 committed cities to C40’s Deadline 2020 have Paris-Agreement-compatible climate action plans.14
Race to Zero lists a “Minimum Criteria for participation in Race to Zero”15 but does not display as obviously a vanguard of bold, best-in-class targets and a “lead peloton” willing to show others how this is done.
Ultimately, the hope is that a clear, bold, ubiquitous definition will empower the world’s most progressive cities to lead the world’s just transition past “Net-Zero” to true sustainability and a climate-positive, restorative back-half of the century. So how can we describe “net-zero” better to be both clear and bold?
“Fully Scoped”: What Does This Mean?
There is a flexibility and power in the net-zero concept. It can apply at all levels, from the globe down through nations and states to cities, communities, households, and individuals. For the world to achieve global net-zero emissions, all relevant entities should assume responsibility for direct emissions caused by sources they directly own and control (scope 1). For cities, this has been translated as emissions created within their boundaries.
Scope 2 includes targeting GHG emissions occurring as a consequence of the use of grid-supplied electricity, heat, steam, and/or cooling within the city boundary. This is typically the electricity and heat generation from utilities that may supply the city but not be located within the boundary.
Scope 3 emissions for a city are all other GHG emissions that occur outside the city boundary as a result of activities taking place within the city boundary. This may be upstream activities such as emissions going into the production of materials consumed in the city, as well as downstream activities – emissions caused by the consumption of goods/services produced inside the city but consumed elsewhere.
If every city in the world achieves net-zero emissions for scopes 1 and 2, the urban world should expect to realize an equilibrium among sources and sinks of emissions. But this leaves no margin for error and also relies on other communities to target net-zero too. A more airtight approach would acknowledge that some entities are not targeting boldly enough and would task those that can act more assertively to take responsibility for scope 3.
C40 analysis conducted with the University of Leeds, the University of New South Wales, and Arup adopted a consumption-based approach to investigate GHG emissions of 79 cities, capturing both direct and lifecycle GHG emissions (Figure 1.4).16 This usefully captures the upstream effect of emissions arising in supply chains outside the city to meet the demand and consumption for goods and services inside the city; but from a “high-ambition” point of view it is unfortunate that it subtracts the downstream effect. It gives the city a (double) break on the emissions – both by netting out emissions created by producing goods and services inside the city that are consumed elsewhere and the emissions associated with the actual consumption (Figure 1.5).
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