Why measuring black carbon is key to climate change mitigation

Black carbon is a climate pollutant and a major contributor to global warming. Its harmful particles are released into the atmosphere when fossil fuels and biomass are not burned thoroughly, such as from diesel exhaust fumes, coal power plants, and household cooking and heating. Its significant impact can be reduced, but urgent action is required to move to cleaner alternatives.

The video below explains the impact of black carbon on the planet and what can be done to change things.

Black carbon is dangerous for the environment and our health. It's therefore important to properly measure it for the following reasons:

Since black carbon can have strong short-term climate impacts, accurate measurements and black carbon emission estimates contribute to short-term climate improvement when policies are implemented that effectively reduce black carbon. In addition, since black carbon has different sources, emission characteristics vary from country to country and region to region.

Accurate measurements of regional emission characteristics will help establish the most effective policy response to climate change and related problems. Many countries currently do not have specific regulatory measures for black carbon and regulate it as part of broader categories, such as PM2.5. However, there are growing calls for independent regulation of black carbon. Accurate measurements and emission estimates of black carbon can provide the basis for black carbon-specific regulation and will play a key role in establishing effective regulatory policies.

Unlike some other pollutants, black carbon has various effects on climate, health, and air quality. It causes lung and cardiovascular diseases in humans and plays an important role in global climate change, such as changes in glacial melting and cloud formation patterns. In addition, in terms of air quality, identifying its sources and emission characteristics will allow us to effectively predict impacts on human health and the surrounding ecosystem.

Accurate measurements of black carbon will play a major role in understanding and responding to these complex effects more comprehensively.

There are various techniques for measuring black carbon, but the main measurement techniques used are thermal/optical methods and absorption methods.

Thermal/optical methods are one of the indirect measurement methods for elemental carbon (EC) in the atmosphere. Although EC and black carbon are strictly different concepts, they have very similar properties in the atmosphere, so we use EC measurements as an approximation of black carbon. The thermal/optical method measures the carbon component that is vaporized after first collecting particles in the atmosphere on filter paper and then heating them step by step.

Organic carbon (OC), another form of carbon in the atmosphere, may also be vaporized during the heating process, which leads to distorted measurement values when attempting to measure EC. To solve this problem, EC and OC are distinguished by optical calibration where the filter contents are subsequently measured optically by using lasers or light to differentiate between OC and EC. The advantages of this method are that it can clearly distinguish between EC and OC and provides high accuracy. However, it has the disadvantage of requiring a relatively higher initial investment cost, taking a lot of time, and being difficult to measure in real-time.

The absorption method measures black carbon through laser absorption by collecting particles on filter paper. Black carbon absorbs light at 880nm, which is a wavelength few other particles absorb. Therefore, if we measure the amount of light at 880nm that passes through the filter before and after the sample is observed and calculate the reduced amount, we can assume that the amount of material that absorbs that light is black carbon.

These values can be transformed by the Beer-Lambert Law (that relates the amount of light extinction and concentration of the absorbing entity) to estimate the mass of black carbon particles. Although there are various absorption-based measurement methods, the most widely used one is the Aethalometer method due to cost, practicality, and real-time measurement capabilities.

There is no internationally agreed-upon standard measurement method for black carbon, making data comparison and integration difficult. To address this issue, related international organizations present guidelines on black carbon measurement. In addition, international measurement protocols are being developed through the Global Atmosphere Watch (GAW) program, and EURAMET is working on a project to standardize black carbon aerosol measurement standards.

The incomplete combustion of carbonaceous substances emits not only black carbon but also various other substances. Black carbon often coexists with other aerosols, making it difficult to separate and measure accurately. Advanced technologies such as multi-wavelength Aethalometer and single-particle analyzers (SP2) are being developed to solve this problem. These new methods will provide more accurate measurement results of black carbon.

When measuring black carbon, there are technical and physical difficulties measuring in remote areas such as polar regions or oceans. These include difficulty in direct use of the measuring equipment due to extreme conditions and management issues involved with obtaining continuous measurement data. Various methods, such as satellite technology and unmanned aerial vehicle measurements, are being used to overcome these problems.

Measurement methods of black carbon vary, but each method differs in terms of initial investment and operating cost. In the case of developed countries, it is not difficult to introduce the various measurement methods stated above, but in the case of developing countries, methods that require high cost and expertise in terms of initial investment, operating costs, and professional workforce can be difficult to incorporate. Therefore, it is an important challenge to choose the appropriate method that suits each country or region's economic and technical situation.

Accurate measurement and analysis of black carbon are key challenges that must be met for a proper climate change response. Despite the development of various measurement methods and technologies, many challenges still remain. Overcoming these obstacles will provide more reliable data on black carbon, ultimately contributing significantly to establishing and implementing effective climate change response policies. Therefore, continued development of black carbon measurement technology and international cooperation should receive greater attention in the future.