Black carbon, a form of particulate air pollution most often produced from biomass burning, cooking with solid fuels and diesel exhaust, has a warming effect in the atmosphere three to four times greater than prevailing estimates, according to scientists in an upcoming review article in the journal Nature Geoscience.

Scripps Institution of Oceanography at UC San Diego atmospheric scientist V. Ramanathan and University of Iowa chemical engineer Greg Carmichael, said that soot and other forms of black carbon could have as much as 60 percent of the current global warming effect of carbon dioxide, more than that of any greenhouse gas besides CO2. The researchers also noted, however, that mitigation would have immediate societal benefits in addition to the long term effect of reducing greenhouse gas emissions.

“Observationally based studies such as ours are converging on the same large magnitude of black carbon heating as modeling studies from Stanford, Caltech and NASA,” said Ramanathan. “We now have to examine if black carbon is also having a large role in the retreat of arctic sea ice and Himalayan glaciers as suggested by recent studies.”

In the paper, Ramanathan and Carmichael integrated observed data from satellites, aircraft and surface instruments about the warming effect of black carbon and found that its forcing, or warming effect in the atmosphere, is about 0.9 watts per meter squared. That compares to estimates of between 0.2 watts per meter squared and 0.4 watts per meter squared that were agreed upon as a consensus estimate in a report released last year by the Intergovernmental Panel on Climate Change (IPCC), a U.N.-sponsored agency that periodically synthesizes the body of climate change research.

Ramanathan and Carmichael said the conservative estimates are based on widely used computer model simulations that do not take into account the amplification of black carbon’s warming effect when mixed with other aerosols such as sulfates. The models also do not adequately represent the full range of altitudes at which the warming effect occurs. The most recent observations, in contrast, have found significant black carbon warming effects at altitudes in the range of 2 kilometers (6,500 feet), levels at which black carbon particles absorb not only sunlight but also solar energy reflected by clouds at lower altitudes.

Between 25 and 35 percent of black carbon in the global atmosphere comes from China and India, emitted from the burning of wood and cow dung in household cooking and through the use of coal to heat homes. Countries in Europe and elsewhere that rely heavily on diesel fuel for transportation also contribute large amounts.

“Per capita emissions of black carbon from the United States and some European countries are still comparable to those from south Asia and east Asia,” Ramanathan said.

In south Asia, pollution often forms a prevalent brownish haze that has been termed the “atmospheric brown cloud.” Ramanathan’s previous research has indicated that the warming effects of this smog appear to be accelerating the melt of Himalayan glaciers that provide billions of people throughout Asia with drinking water. In addition, the inhalation of smoke during indoor cooking has been linked to the deaths of an estimated 400,000 women and children in south and east Asia.

Elimination of black carbon, a contributor to global warming and a public health hazard, offers a nearly instant return on investment, the researchers said. Black carbon particles only remain airborne for weeks at most compared to carbon dioxide, which remains in the atmosphere for more than a century. In addition, technology that could substantially reduce black carbon emissions already exists in the form of commercially available products.

Ramanathan said that an observation program for which he is currently seeking corporate sponsorship could dramatically illustrate the benefits. Known as Project Surya, the proposed venture would provide some 20,000 rural Indian households with smoke-free cookers and equipped to transmit data. At the same time, a team of researchers led by Ramanathan would observe air pollution levels in the region to measure the effect of the cookers.

Carmichael said he hopes that the paper’s presentation of the immediacy of the benefits will make it easier to generate political and regulatory momentum toward reduction of black carbon emissions.

“It offers a chance to get better traction for implementing strategies for reducing black carbon,” he said.

The National Science Foundation, the National Oceanic and Atmospheric Administration and the National Aeronautics and Space Administration funded the review.

carbonfree.co.uk
13th March 2008

Promoting the green design, construction, renovation and operation of buildings could cut North American greenhouse gas emissions that are fuelling climate change more deeply, quickly and cheaply than any other available measure, according to a new report issued by the trinational Commission for Environmental Cooperation (CEC).

North America’s buildings cause the annual release of more than 2,200 megatons of CO2 into the atmosphere, about 35 percent of the continent’s total. The report says rapid market uptake of currently available and emerging advanced energy-saving technologies could result in over 1,700 fewer megatons of CO2 emissions in 2030, compared to projected emissions that year following a business-as-usual approach. A cut of that size would nearly equal the CO2 emitted by the entire US transportation sector in 2000.

It is common now for more advanced green buildings to routinely reduce energy usage by 30, 40, or even 50 percent over conventional buildings, with the most efficient buildings now performing more than 70 percent better than conventional properties, according to the report.

Despite proven environmental, economic and health benefits, however, green building today accounts for a only small fraction of new home and commercial building construction—just two percent of the new non-residential building market, less than half of one percent of the residential market in the United States and Canada, and less than that in Mexico.

The report, Green Building in North America: Opportunities and Challenges, is the result of a two-year study by the CEC Secretariat. It was prepared with advice from an international advisory group of prominent developers and architects, sustainability and energy experts, real estate appraisers and brokers, together with local and national government representatives.

“Improving our built environment is probably the single greatest opportunity to protect and enhance the natural environment. This report is a blueprint for dramatic environmental progress throughout North America—mostly using the tools and technology we have on hand today,” says CEC Executive Director Adrián Vázquez. “Green building represents some of the ripest ‘low-hanging fruit’ for achieving significant reductions in climate change emissions.”

Even with rapid growth projected in the green building market across all three countries, the report says public and private sectors must embrace substantial changes to the planning, development and financing of commercial and residential buildings to overcome what it says are significant barriers to the widespread adoption of high-performance buildings throughout North America.

Jonathan Westeinde, managing partner of The Windmill Development Group in Ottawa and the CEC’s advisory group chair, states “As a developer, I rely on the fact that green building is a proven concept—with construction costs and market benefits that are rapidly improving. This report shows what is needed to scale up and put green building at the heart of a healthy, energy-secure North America.”

The report highlights the importance of green building in urban development. Seattle Mayor Greg Nickels, whose city hosted a CEC symposium on green building in May 2007, states, “Green building is a cornerstone for creating strong, sustainable communities. In Seattle, we are convinced that cities that make the commitment and investment in green development now will have a significant advantage in the long run.”

Report authors describe a number of disincentives to green building to be overcome. For example, how to encourage developers to incur the marginal cost of green building features when the long-term energy-saving benefits will be passed on to the new owners or tenants.

They recommend ways to accelerate the market uptake of green building and make it the standard practice for all new construction and renovation of existing buildings in North America. Among its recommendations, the report calls upon North American government, industry and nongovernmental leaders to:

Create national, multi-stakeholder task forces charged with achieving a vision for green building in North America;

Support the creation of a North American set of principles and planning tools for green building;

Set clear targets to achieve the most rapid possible adoption of green building in North America, including aggressive targets for carbon-neutral or net zero-energy buildings, together with performance monitoring to track progress towards these targets;

Enhance ongoing or new support for green building, including efforts to promote private sector investment and proper valuation methods; and

Increase knowledge of green building through research and development, capacity building, and the use of labels and disclosures on green building performance. The recommendations complement ongoing efforts by federal, state/provincial and local governments as well as industry and trade associations and nongovernmental organizations.

The CEC study notes several government and industry initiatives that promote aggressive energy performance improvements in the building sector. One study completed for the report signals the potential of green building to yield tremendous energy improvements and greenhouse gas emissions reductions in the building sector by 2030, and suggests a path toward zero net-energy and carbon-neutral buildings.