(Excerpted from The Ecology of Recycling by Marian Chertow, Director of the Program on Solid Waste Policy, School of Forestry and Environmental Studies, Yale University.)

Study after study in the last five years from Brazil to Canada and from Europe to Asia affirms the ability to quantify greenhouse gas emissions from household waste on a lifecycle basis. Each of these lifecycle studies finds a clear, positive impact of recycling and reuse on reducing greenhouse gasses, principally because of recapturing, rather than discarding, the embedded energy, water, and materials used to make the products in the first place. These studies have included "upstream" (production stage) impacts, such as the effect of replacing virgin materials with recycled ones, as well as "downstream" (waste management) impacts that result from alternative strategies such as landfilling, incineration, composting and recycling. The sum of upstream and downstream amount to a dual benefit from recycling. Even when the emissions from collection trucks and additional transport to recycling facilities are included, greenhouse gas savings prevail.

The scale and mechanism of greenhouse gas reductions for a particular location, however, depend on the specific materials involved, the extent of recovery, the availability of markets, and the mix of fuels avoided through recycling of resources. Recycling metals carries a large energy benefit, while paper recycling often contributes to forest carbon sequestration benefits. Replacing power generated by oil or coal, two carbon-intensive fuel sources, adds more greenhouse gas benefits to recycling than replacing power generated from renewables or hydro energy. Thus, there are no universal claims, but significant regional differences occur when measuring comparative climate impacts from waste recycling and disposal.

There are now many tools to calculate greenhouse gas impacts of different solid waste management options and materials. One example is the Environmental Benefits Calculator of the Northeast Recycling Council in the United Sates, which estimates the environmental benefits of a selected study area based on the tonnages of materials that are source reduced, reused, recycled, landfilled, or incinerated. The Calculator, a Microsoft Excel-based tool, incorporates findings from several lifecycle studies based on "typical" facilities and operating characteristics in the United States.3 The Brazil study measured in detail the greenhouse gas impacts of individual materials, including aluminium, plastic, paper, steel and glass.4

With some exceptions for mixed or contaminated materials that are difficult to categorize or recycle, a broad array of policy programmes is available to reduce climate-related impacts of waste management. Some of the most successful programmes include recycling pick-up from homes or drop-off at district centres; requiring residents who generate a lot of waste to pay more than those who generate less ("pay as you throw"); instituting policies that originated in Europe and are diffusing quickly in Asia that require producers of goods to play a larger role in taking back products (extended producer responsibility); and assessing fees and taxes on categories of goods such as tyres or batteries, or on landfill use overall.

Source: UN Chronicle, Volume 46, Issue 4, April 2012, pp.56-60