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On November 4, 2016, the most recent international treaty to reduce global greenhouse gas (GHG) emissions went into force; the goal is to limit the average global temperature rise below 2˚ C. Emissions can linger in the atmosphere for centuries after being produced and trap more heat from the sun. The average global temperature has already risen 0.87˚ C above pre-industrial levels according to a 2015 report from NASA; it has increased by more than 3˚ C in the Arctic and Antarctic regions. With the future of our planet riding in the balance, it is important to accurately capture emissions.

GHG data is self-reported by each country, but there is not an easy nor consistent approach to record or track emissions over time. Emissions come from a variety of sources, however human activity, particularly the burning of fossil fuels, has significantly increased the volume of GHG emissions entering the atmosphere. Measuring these volumes is often estimated based on an underlying factor, for instance the number of kilowatt hours of energy produced via specific fuel types, with fossil fuels such as oil and coal contributing more than renewable sources. Similarly, miles traveled by car, train or airplane are aggregated, or the number of cows per acre, to determine emissions produced. There are other metrics that are harder to quantify, including emissions from buildings which may be the leading source in dense-urban areas. The variety of housing stock, including age, insulation, energy consumption and fuel source, can vary significantly from building to building, never mind city to city. Waste is another factor that has wide variance on methane production. Complicating these measurements are the various carbon sinks that absorb emissions, which are being rapidly depleted. How can all of these various sources be quantified into one national total?

If any real effort is to be made to reduce GHG emissions, we need a consistent method for calculating an accurate estimate. The Global Protocol for Community-Scale GHG Inventories (GPC) responds to this challenge by establishing guidelines and methodology. The inventory outlines three primary factors: establishing the boundary within which the measurements will be conducted, an overarching and sector-specific account method, and a way to track performance over time. Sources for GHG emissions are grouped into six sectors, including stationary energy, transportation, waste, industrial processes and product use, agriculture and forestry, and out-of-boundary emissions (GHG emissions that take place outside the prescribe boundary); these are divided into sub-sectors. Finally the emissions are categorized by scope, with Scope 1 covering emissions created within the boundary, Scope 2 capturing all energy/heat related emissions, and scope 3 capturing the out-of-boundary emissions. Breaking down the complexities of what and how to measure each factor creates a consistent approach on how each sub-sector can be calculated into the total. This also helps identify the larger contributors, including energy production in Scope 2, so that they can be prioritized for remediation. Additionally, these measurements can be more easily tabulated to create a baseline and revisited to ensure reduction targets are being met.

New York City has successfully implanted effective measurement and GHG reduction efforts under differently titled, but similarly themed, programs under mayors Bloomberg and DeBlasio. New York is already a green leader due to its concentrated development, mass transit system, and lack of a manufacturing sector. However, there are still many ways to reduce emissions including the expansion of bike lanes for alternative bipedal transportation, increased green space, and building policies that call for tighter emissions standards in new construction and retrofits. New York’s Governor Cuomo also has a goal of adding more renewable energy to the mix to decrease emissions and reliance of fossil fuels. Without reliable reporting methods none of these successes could be captured or computed against a baseline. New York City also leads by example and shares its plans via the Compact of Mayors, which includes leaders from over 400 cities.

Measuring GHG emissions is going to become increasingly critical as we move into an uncertain future. By establishing a method for capturing these numbers, and continuing to modify it for ease of use, will help all parties, especially those in the developing world who may not have the resources to measure their impact. A takeaway is how to ensure this measurement is universally adopted so that self-reporting is as accurate as possible; perhaps it should be a condition established by COP23 in 2017. By facilitating the capture of this vital statistic will make it easier to accurately capture updates and determine areas for remediation.

Image Credit: NASA Global Climate Change

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