By Ricardo Cepeda-Márquez, Head of C40’s Solid Waste Initiative

Historically, waste management has been seen more as a development challenge rather than an area with great potential to reduce greenhouse gas (GHG) emissions. Current accounting methodologies attribute only 3-5% of overall GHG emissions to the “waste” sector, with these emissions coming primarily from methane from landfills[1].

However, a refined understanding of the behaviour of methane in the atmosphere estimates that 25% of current global warming is caused by methane, which is 27 times more powerful than CO2 in retaining heat in the atmosphere over a 100-year period. Over a 20-year period methane becomes  85 times more powerful at retaining heat in the atmosphere[2], which means that actions to reduce methane emissions will have an impact over a much shorter timescale. It is estimated that aggressive mitigation of methane across all sectors can reduce global warming over the next 50 years by as much as 0.5˚C[3], with most of these reductions delivered by 2040, with added benefits around crop yield loss reduction, improved public health and air quality[4].

Additionally, when waste actions beyond disposal are taken into account, including waste collection and transportation, recycling, carbon storage and chemical fertilizer offset from composting, and fossil fuel offsets from energy recovery, the contribution of these actions in addition to methane reduction and avoidance from landfills can reduce 10-15% of the city’s GHG emissions. When actions related to waste reduction and minimization are considered, this contribution can reach 20-25%[5].

The C40 Waste to Resources Network is working with progressive cities looking to transition to a more sustainable management of materials and resources, with actions focused on reducing residual waste generation, prevention, reuse and recycling to keep valuable materials from entering the residual waste stream.

Cities like Auckland, New Zealand are taking the lead in this transition by focusing on the top of the waste management hierarchy and transitioning from a waste management vision towards a resources management vision. Auckland has established a bold target to reach zero waste disposal by 2040. Their plan includes deploying ambitious volume-based collection fees and city-wide segregated collection programs; working closely with their communities to develop resource recovery networks through recycling, reuse and repair fairs; creating job opportunities for vulnerable sectors; and reducing discarding of valuable resources.

This visionary strategy has made Auckland an ideal city to lead the C40 Waste to Resources Network, which will work closely with cities around the world to take more ambitious action around waste and materials management. The Network will also help cities improve segregated collection, resource recovery, minimization and diversion initiatives, and the transition towards a more integrated, circular economy.

“I am delighted that Auckland has been selected to lead the C40 Waste to Resources Network. The way in which we deal with waste is challenging cities in every part of the globe and Auckland is no exception. As a city, we have a target of zero waste by 2040. We are making good progress; household waste is down by 10% and we have also diverted 30% of inorganic waste from landfills. Our involvement with C40 provides a great opportunity to share ideas and knowledge gained from our waste reduction programmes and learn from other cities.”

– Phil Goff, Mayor of Auckland

The C40 Waste to Resources Workshop currently taking place in Guangzhou, China aims to advance and accelerate waste management targets in cities across the globe. City officials and sector experts from 10 cities across 6 different regions are meeting to discuss the challenges of maintaining well performing collection programs, reducing resource loss and disposal and engaging with communities to maintain and increase programs for source separation, recycling and reuse, and raising political will and ambition for more impactful action.

“To deal with the overwhelming amount of waste and further reduce greenhouse gas emissions, Guangzhou has promoted waste disposal with a major focus on waste segregation. A series of measures have been taken, including improving facilities for segregated waste collection and transfer, promoting recycling, facilitating construction of waste treatment facilities, introducing a legal framework for waste separation, and perfecting the management system for waste sorting. This workshop will be an opportunity for Guangzhou to deepen cooperation with C40 and learn from international best practices of solid waste management. It will be beneficial to the establishment of a solid waste management system of internationally high standards in Guangzhou."

– Mr. Zeng Kaizhang, Deputy Secretary General of Guangzhou Municipal Government.

Hosting the Waste to Resources workshop in Guangzhou represents a unique opportunity to engage rapidly growing Chinese cities, which are facing the challenges of increased consumption associated with their rapid economic development. However, this also presents an historic opportunity to leapfrog traditional development paths and implement a resource management vision to keep resources in the economic cycle for longer, increasing their competitiveness and resiliency to resource and food scarcity, delivering significant local social, economic and environmental benefits, and considerably reducing direct and indirect GHG emissions.

[1] IPCC, 2007b

[2] Methane Matters: Scientists Work to Quantify the Effects of a Potent Greenhouse Gas. NASA Earth Observatory, 2016

[3] The Climate and Clean Air Coalition to Reduce Short Lived Climate Pollutants (

[4] Simultaneously Mitigating Near-Term Climate Change and Improving Human Health and Food Security, Shindell, et al. 2012

[5] The International Solid Waste Association – Global Waste Management Outlook:


Share article

More Articles