A striking new report was released yesterday showing diesel pollution’s significance in climate change. In fact, the report shows that black carbon is the second most important individual climate-warming agent after carbon dioxide (CO2) and a much more potent source than previously reported.
Black Carbon (BC) results from the incomplete combustion of fossil fuels, biofuels and biomass. Black carbon absorbs visible light, which disturbs the planet’s radiation balance and leads to increased warming. Sources of black carbon include diesel engines, cook stoves, brick kilns and open biomass burning.
Scientists have known for more than a decade that black carbon contributes to climate change, but the extent to which it warms, the role from various sources, and the targets and role of mitigation have been unclear. This new report, “Bounding the role of black carbon in the climate system: A scientific assessment,” provides new evidence and clarity that we believe should encourage additional action to reduce this pollution.
Some significant findings from the black carbon study include:
● The direct climate impacts of BC are nearly twice as great as previously believed (2007 IPCC’s Fourth Assessment), ranking BC “as the second most important individual climate-warming agent after carbon dioxide”.
● The study finds that diesel engines are the best target for mitigation, followed by brick kilns and residential stoves, and that cleaning up diesel engines could slow warming immediately.
● Confirmation that BC causes significantly higher warming over the Arctic from a combination of the warming effect on the atmosphere and the additional effect of black carbon darkening snow and accelerating the melting of Arctic snow and ice.
Our partners at the Clean Air Task Force have more details here and here.
We believe the evidence from this report underscores the critical need to continue the fight to reduce diesel pollution. For close to a decade, SACE has advocated for diesel emissions reductions to protect public health, which is still very critical. But, with the growing evidence of the role of black carbon in climate change, it is increasingly important that we focus on a comprehensive, targeted plan to cut emissions from diesel engines and other black carbon sources for the protection of both our health and the climate.
Some of the various actions already undertaken in our region include:
● the retrofitting, replacement and refueling of diesel school buses, trucks and equipment
● the establishment of the Southeast Diesel Collaborative that works to expand knowledge, build connections, and promote solutions to diesel emissions; and
● the establishment of state clean up programs and numerous idling reduction goals by municipalities, schools and businesses
These have all had a significant role in reducing diesel emissions. However, in recent years, interest and commitment nationally to funding diesel clean up has been waning, with the assumption that fleet turnover is happening and cleaner diesels are now in operation. Unfortunately, the recession caused a steep decline in the turnover rate, leaving many older – often decades older – diesel engines still in operation. Much more action is needed.
We call on large businesses, universities, fleets and other entities that contract or own diesel equipment to commit to only using new or retrofitted diesel equipment and vehicles. Our elected officials also must not back down from support for diesel clean up programs, but rather increase their commitment and funding to existing and new diesel clean programs in the most recent transportation bill, MAP-21, and the Diesel Emissions Reduction Act that have proven their benefits in cutting emissions from this sector, specifically in construction equipment, shipping and across our logistics chains that heavily employ diesel equipment.
Along with our partners in the Diesel Clean Up Campaign, we also recommend reducing the excise tax on new diesel engines to accelerate fleet turnover, creating a model for curbing emissions from aging diesel fleets globally, driving faster global deployment of flaring technologies for natural gas systems to achieve complete combustion of flared gas (another source of black carbon), and working towards greater public-private partnerships and multinational collaboration (e.g. the State Department’s Climate and Clean Air Coalition), which would have positive economic benefits throughout the U.S. economy.
As evidenced from this new study and others, attention to reducing black carbon could play a vital role over the next few years in curtailing the pace of climate change and its resulting impacts. We cannot and should not wait, as we have in addressing carbon dioxide. Action on these pollutants now can have an immediate impact.