Breathing dirty air is not good for anyone. Air pollution can aggravate asthma and now a new study finds that it triggers more heart attacks than cocaine. In addition to public health concerns, some forms of air pollution can trap atmospheric heat, producing a greenhouse-type effect. These planet-warming pollutants, called greenhouse gases (GHGs), are primarily produced from the combustion of fossil fuels, methane releases and flaring and through the production of cement. The build up of GHGs in the atmosphere causes the earth to warm.
A ubiquitous molecule created as a byproduct of combustion, carbon dioxide (CO2 ) is a GHG that has been the center of attention for policymakers. Since the beginnings of the fossil-fueled industrial revolution, the concentration of CO2 in the atmosphere has risen from around 280 parts per million (ppm) to about 390 ppm today. While CO2 in the atmosphere does not have a direct adverse effect on human health (we exhale carbon dioxide, a result of respiration), it does have an impact on the climate; therefore, policymakers concerned about climate change want to limit CO2 concentrations to 450 ppm to avoid higher global temperatures. (Some organizations and scientists would prefer that CO2 concentrations be reduced to 350 ppm.)
According to climate models, a CO2 concentration of 450 ppm would limit the increase of average global temperature to 2 degrees C above pre-industrial levels, the goal set by the United Nations Framework Convention on Climate Change. In order to meet that target, CO2 emissions must be stabilized and reduced. Unfortunately, unlike ozone layer depleting chemicals, fossil fuels that generate CO2 don’t have cheap and easy substitutes.
Complicating matters, as The Economist recently noted, is that “the emission of carbon dioxide is a fundamental part of today’s industrial infrastructure.” Because CO2 emissions are tied closely to the global economy, international agreements on how to stabilize and reduce CO2 emissions will likely take some time. According to the article, while it is still important to reduce CO2, policymakers can begin to reduce other GHGs through alternative methods. The article offers three alternative approaches that may be appealing to policymakers in the near term, while negotiations over how to reduce CO2 levels take place.
First, certain types of GHGs released in industrial processes may have substitutes or could be eliminated altogether with improved technology. These GHGs can have a larger warming effect than CO2 ; for example, the GHG HFC-134a is 1,000 times more potent than CO2.
Second, reducing emissions of black carbon (think ‘soot'), which is a byproduct of cooking fires and dirty diesel engines, offers rapid, huge and tangible public health benefits along with mitigation of its warming effects.
Third, some GHGs could be managed under existing regulations. For example, the Obama administration has attempted to regulate carbon dioxide under the Clean Air Act. Also, HFC-134a and related industrial chemicals could be regulated by expanding the Montreal Protocol, the treaty designed to protect the ozone layer, to include GHGs that may also destroy stratospheric ozone.
In addition, a new report [pdf] from the United Nations Environment Program (UNEP) and the World Meteorological Organization says that cutting black carbon and tropospheric ozone will reduce warming in the first half of this century and will have immediate benefits for public health. The report states that reducing these emissions, “could immediately begin to protect climate, public health, water and food security, and ecosystems.” If reduction measures are fully implemented, projected temperature increases could be curtailed by 0.5 degrees C.
Given the current goal of limiting average global temperature increases to 2 degrees C, reducing black carbon and ozone emissions will likely be key strategies, along with mitigating carbon dioxide production, in achieving that goal. As The Economist muses “let the good be the friend of the better.”