Black Carbon: Not just pollutant, but also driver of global warming

By Biriz Ozbakir

ISTANBUL (AA) - Black carbon is responsible for a warming effect of about 0.6 watts per square meter on the Earth's surface amid the pressing global discourse on climate change.

While not typically classified among greenhouse gases, black carbon, commonly known as soot, is recognized as a significant factor in climate change and human health issues.

Burcu Onat, a lecturer in the environmental engineering department at Istanbul University-Cerrahpasa, delved into the multifaceted effect of black carbon emissions on the planet's climate dynamics and public health, in an interview with Anadolu.

Onat said in Antarctica, nearly 3 nanograms of black carbon were detected in 1 gram of snow.

The emissions predominantly arise from various sources, including the incomplete combustion of coal, diesel fuel, gasoline and biomass, said Onat.

According to data from the Climate and Clean Air Coalition (CCAC), nearly 5.8 million tonnes (6.3 tons) of black carbon were emitted in 2019, with household energy consumption contributing to 43% of the emissions globally.

She said carbon dioxide ranks first among greenhouse gases causing global warming, and methane is second. Onat emphasized that black carbon ranks third.

- Black carbon causes global warming through three different mechanisms

Unlike greenhouse gases, which primarily affect the atmosphere through a single mechanism, black carbon exerts its influence through three distinct pathways, she stressed.

"If there is black carbon in the atmosphere, it directly absorbs sunlight and causes the atmosphere to warm. This is the first mechanism.

“The second mechanism is when black carbon in the atmosphere settles on surfaces like snow and ice, it contaminates the surface and changes the surface's reflectivity of sunlight. A clean surface of snow reflects about 90% of sunlight coming from space, but when it's contaminated with black carbon, this reflection rate decreases, and the surface absorbs more sunlight, causing more heat. Therefore, it accelerates the melting of glaciers and snow surfaces,” she said.

The third is when there is black carbon inside a cloud, it also affects the reflectivity, the duration of clouds and alters precipitation, leading the air to warm, added Onat.

Speaking about monitoring and tracking black carbon concentrations in different cities worldwide, Onat noted that the average concentration of black carbon in cities varies between 5 and 20 micrograms per cubic meter.

- Necessity of using black carbon capture filters in mobile sources

Onat evaluated the effects of black carbon on health.

"If the proportion of black carbon in particulate matter is high, it increases the negative effects on health. It triggers asthma risk in children, causing respiratory diseases to be more severe,” she said.

To protect oneself from black carbon pollution, Onat advised minimizing outdoor activities on days when air quality is poor and using masks when going outside, if necessary.

She also emphasized the necessity of using black carbon capture filters, especially in mobile sources, to prevent black carbon pollution from fuel combustion.

Onat added that the widespread use of rail systems and electric vehicles in urban public transportation would reduce the burden of black carbon.

*Writing by Seda Sevencan