Carbon neutrality, which mainly refers to the "balance between income and expenditure" of carbon emissions, refers to the direct or indirect greenhouse gas emissions calculated by enterprises, groups or individuals within a certain period of time, offset by afforestation, energy conservation and emission reduction and other forms to achieve zero carbon emissions. According to this concept, there are two main methods to achieve carbon neutralization:
Carbon emission reduction: curb carbon emissions, save energy and reduce emissions, and build a low-carbon industrial system
Carbon absorption: maintain natural resources and ecological environment, plant trees and absorb carbon emissions
Since it is a process of balance between "carbon emission" and "carbon absorption", quantitative monitoring and tracking is a very important link and means. It requires accurate monitoring and management methods to explore the ability and tools to optimize development. From this point of view, remote sensing satellite imagery is a good macro tool.
Satellite remote sensing can not only monitor, trace and improve carbon "emissions", but also play a role in quantitative supervision, providing digital guidance for the construction of green renewable energy industry system; In the direction of carbon "absorption", it can also play a role in timely finding ecological problems and protecting ecological balance. Its main functions are as follows:
Carbon emission monitoring: through satellite remote sensing monitoring and inversion of the earth's atmosphere, quantitative and objective monitoring and traceability of carbon emissions, spatial distribution and intensity are carried out.
Ecological protection and climate research: monitor and record natural resource data, protect and promote carbon sink, and conduct in-depth research on the earth's climate ecology;
Next, we will introduce the main work contents of satellite remote sensing:
When calculating carbon emissions, each country in the world calculates the amount and efficiency of fossil fuel combustion, with great uncertainty. By using specific remote sensing satellites, the generation, distribution and diffusion of greenhouse gases and the range of influence can be objectively monitored from the earth's atmosphere, and the changes of gas concentration gradient and carbon flux can be quantitatively retrieved.
When sunlight passes through the atmosphere, some specific spectral frequency points are absorbed by the accumulated carbon dioxide. If the specific frequency point in the reflected or scattered light of an area is very weak, it can be inferred that the carbon dioxide molecules in the area are relatively dense; On the contrary, if the specific frequency point is very strong, it can be inferred that there are fewer carbon dioxide molecules. This inference and quantification process is commonly referred to as "quantitative inversion of atmospheric remote sensing". Moreover, not only carbon dioxide, different spectral characteristics can infer different concentrations of greenhouse or harmful gases, such as methane (CH4), sulfur dioxide (SO2), nitrogen dioxide (NO2), aerosols, etc.
In December 2016, China's first scientific experimental satellite used to monitor the global atmospheric carbon dioxide content successfully reached the space more than 700 kilometers away from the earth and began to monitor the global carbon dioxide emissions. Using multi-source spatio-temporal data such as multiple hyperspectral satellites and vehicle borne lidars, based on the inversion algorithm, the operational monitoring of atmospheric environmental conditions can also be carried out in real time and accurately.
Remote sensing inversion can go deep into bare land, urban roads, construction bare land and key emission units for dynamic monitoring of carbon emissions. Once abnormal carbon emissions are found, they can be confirmed and repaired in a timely manner; Use the geographic grid to generate the distribution map of carbon emission hotspots, support urban managers to make more scientific decisions from the macro level, and reasonably adjust the location and time of carbon emissions.
According to estimates, forests around the world have absorbed about 15.6 billion metric tons of carbon dioxide (171.6 tons) from the atmosphere every year in the past decade, which means that healthy forests can absorb and neutralize some carbon emissions. However, on the other hand, events such as deforestation, forest fires and loss have resulted in the release of about 8.1 billion metric tons (89.1 tons) of carbon dioxide every year.
Forest carbon sink is one of the most important carbon neutralization approaches at present. Through high-resolution remote sensing satellite network and real-time data acquisition and analysis, high-frequency monitoring and maintenance of forest ecology, timely warning of forest fires, limiting human activities, and maintaining and developing forest stocks are the key links to achieve carbon neutralization.
At the same time, using the processed satellite remote sensing image data, a more accurate global framework for estimating carbon flux and local regional impact calculation can be constructed, reflecting the dynamic spatio-temporal changes between carbon absorption and release modes as forests are destroyed.
In addition to forests, the healthy development of natural resources, including grasslands, land, mineral resources, oceans, wetlands, and water, is an important acceleration to move towards carbon neutrality. The real-time and dynamic acquisition of their change information by remote sensing satellite and other spatio-temporal monitoring means will play a role in efficient regulation to maintain ecology and promote carbon absorption.