A bunch of cool cities across the globe have some kind of ban on plastic bags: Los Angeles, San Francisco, Portland, Seattle, Mumbai, Buenos Aires and Mexico City, to name a few. Last week, Toronto joined this admirable list after a surprise vote by the City Council.

Plastic bags cause serious problems for the environment, taking centuries to break down and threatening sea life; they can even make natural disasters, such as floods, much worse. With major cities like these taking action, it's time for others to come on board.

Plastic not so fantastic

In 2002, Bangladesh became the first country to ban plastic bags, after devastating floods were blamed in part on storm drains being clogged with them. Since then, China, Italy, South Africa, Rwanda, Kenya, and others have followed suit.

Despite the bans, plastic bag production continues to rise – at least in the United States, where the Environmental Protection Agency estimates that from 2009 to 2010 use of plastic film and bags increased by nearly 100,000 tonnes (220m pounds). According to the Worldwatch Institute, 4 to 5 trillion plastic bags were produced worldwide in 2002. Roughly 80% of those bags were used in North America and western Europe.

All those bags damage the environment. Most are made from polyethylene, a synthetic compound that degrades over hundreds of years into a "plastic dust" that contaminates soils and waterways, and eventually enters the food chain. According to WWF, nearly 200 species of sea life are damaged by plastic bag pollution. In all, plastics account for 60-90% of marine debris. (Perhaps that is why Hawaii became the first US state to ban plastic bags earlier this year.)

In addition to bans, there are other ways to cut down on plastic bag use. A study in the journal Environmental and Resource Economics found that after Ireland imposed a €0.15 ($0.20) tax on plastic bags in 2002, consumption fell by 94%.

Further Reading: Learn more about plastic bag laws at plasticbaglaws.org