If you are a keen carbon tracker you will have noticed the City of Toronto’s TransformTO Implementation Update shows a large drop in greenhouse gas emissions since last year: an astounding 11 per cent between 2017 and 2018. For context, this is equivalent to taking 740,000 cars off the road. Wow!
Overall, the report pegs city-wide carbon reductions at 44 per cent measured against a 1990 baseline, putting Toronto well ahead of its 2020 reduction target of 30 per cent. TAF was surprised by this reported number and thought others might be wondering about it too, so we dug into the data to see what accounted for this big dip.
In fact, very little of the reduction reported this year is associated with specific climate actions or policies undertaken in the last year in Toronto. Rather, it is due to improvements to the methodology the City uses to calculate its greenhouse gas inventory. City staff have been working hard in recent years to strengthen the methods used to quantify local greenhouse gas outputs. Calculating local carbon emissions is a notoriously challenging task (just ask your local GHG quantification nerd!) and the efforts to build more accuracy into City of Toronto numbers is something that is happening behind the scenes on an ongoing basis. This work is essential to gaining a clear understanding of local emissions sources and how to tackle them.
New calculation methods for waste and transportation
For the current emissions report, new insights were applied the City’s approach to calculating emissions associated with waste management and local transportation.
The lion’s share of the one-year 11 per cent reduction is associated with a change in the method used to calculate Toronto’s emissions from waste. Previously, the City had little information upon which to base its assumptions about the quantity and type of waste being sent to private landfills, because these are sites the City is not in charge of managing. But with access to new information from a study undertaken in 2019 by the provincial government, the City has discovered that the waste numbers used in previous annual calculations were over-estimating the emissions from private landfills.
Secondly, City staff have been working with researchers at the University of Toronto, with funding support from TAF, to get more accurate local transportation data. Previously, transportation emissions were estimated by using traffic count data from 2004-2009 to estimate total vehicle-kilometres travelled, and then estimating the average fuel efficiency of vehicles based on reported data from other cities. The collaboration with U of T has allowed for the use of more recent traffic count data, combined with more local data about the vehicle stock and traffic speeds. The use of more local and up-to-date data is providing a much more accurate picture. When applied to this year’s GHG inventory calculation it resulted in a significant downward adjustment in reported emissions.
The accuracy vs clarity conundrum
Making adjustments to calculation methods on an ongoing basis to improve emissions data is a smart and necessary activity. However, making these changes plays havoc with the ability to track the year-over-year progress in driving down local emissions. Technically, if you change the way you calculate current emissions, you need to apply those same changes to the way you calculated the baseline, so you are comparing apples to apples. But the data available for Toronto’s baseline year are not sufficient to retroactively apply the new methodologies. However, providing updated numbers without baseline correction can give the mistaken impression that local programs are making a significant dent in emissions. For example, 71 per cent of the reported 2016-2017 reduction takes place in the waste sector and is due a change in methodology. Without the change to the methodology, waste emissions for the time period would have increased by a bit less than one per cent.
Toronto produced one of the earliest city-wide greenhouse gas inventories, with the first report, a collaboration between TAF and the City of Toronto completed in 2007 using 2004 data. Since then a standardized international protocol has been established concerning the methodologies used for this task, and Toronto has adopted this standard retroactively – embracing one more complexity of being a trailblazing player in this field of work.
Practically speaking, the whole target and baseline issue a bit of a weird mix-and-match situation that can hamper understanding of whether we are making progress on greenhouse emissions reductions or not, and why, which is the real reason these measurements are done in the first place. While improving calculation methods is important, the bottom line remains the same: let’s honour local commitments to make meaningful and sustained reductions to our urban carbon footprint.
How we embrace these new methods while ensuring clear information about our local emission reduction progress is an important question. We know it is being considered very carefully by City staff, who must balance methodological updates and changes in baselines with a commitment to transparent progress reporting. As a key stakeholder in emissions reduction across the Greater Toronto and Hamilton Area, TAF is interested in sharing ideas on how to address this tracking and reporting challenge – we welcome your thoughts – so please keep them rolling in, and watch for a future blog on this important topic.