CO2 Absorption

The most evident manifestation of global climate change is global warming. Over the past 300 years, the global temperature has risen by more than 0.7°C, indicating that climate change is already occurring. The 20th century alone saw a temperature increase of 0.5°C. The most severe warming occurred between 1910-1940 and from 1976 to the present. The 1990s, within the last 1000 years, were the warmest decade, with four of the five warmest years occurring in the 1990s. The year 1998 was the warmest year on record since 1861. In 1995, there were more hot days than in any year in the past 225 years, with the number of days with an average temperature exceeding 20°C reaching 26 days. Meanwhile, the number of cold days (average temperature below 0°C), which used to be 15-20 days per year before the 20th century, has decreased to about 10 days per year in recent years.

Global warming has become an irreversible reality. In the coming decades—10, 20 years, or even longer—humanity will increasingly perceive the impacts of global warming. Without proactive measures to reduce emissions, the global average temperature is projected to rise by an additional 1.4 to 5.8°C from now until 2100. The persistent trend of global climate change poses a significant threat to global biodiversity and the ecosystems upon which they depend, accelerating the degradation of ecosystems, depletion of ecological services, and loss of biodiversity.

Forests play a crucial role in absorbing carbon dioxide and converting it into oxygen through photosynthesis, a process known as carbon sequestration. Carbon sequestration primarily refers to the amount of carbon dioxide that forests can absorb and store, or the capacity of forests to sequester carbon. It is noted that although forests cover only one-third of the Earth's land area, the carbon stored in forest vegetation accounts for nearly half of the carbon reserves on land. Hence, forests are vital due to their direct link to climate change. Trees absorb large amounts of carbon dioxide from the atmosphere through photosynthesis, mitigating the greenhouse effect. This is commonly referred to as the carbon sink function of forests. Green plants convert solar energy into chemical energy through photosynthesis and transform atmospheric carbon dioxide into organic matter, providing the biosphere with leaves, stems, fruits, and seeds, which are the most basic sources of material and energy. This transformation process results in the carbon sequestration effect of forests. The growth of forests absorbs and fixes carbon dioxide, acting as absorbers, storage facilities, and buffers for carbon dioxide. Conversely, once forests are destroyed, they become sources of carbon dioxide emissions.

Shellac insect host plants are widely distributed across Southeast Asia and South Asia, playing a significant role in absorbing CO2. Taking Yunnan Province as an example, survey results from the 1960s indicated that there were over 80 million shellac insect host plants distributed across the province. These host plants are predominantly wild and suitable for shellac production, thus they are generally quite large. Calculating with a dry weight of 30kg per plant and estimating that carbon constitutes 50% of the biomass (Fang Jingyun, 2000), these host plants have absorbed approximately 1.2 million tons of CO2.

In the late 1980s, the felling of some host plants led to a reduced carbon sequestration capacity of the shellac production system. Around 2002, with the support of the national project to convert farmland back to forest, there was a certain recovery in the number of shellac insect host plants. The area of man-made forests increased by more than 40,000 hectares, of which about 20,000 hectares were Dalbergia odorifera (South China rosewood) and the remaining 20,000 hectares comprised various local host species. The estimated carbon sequestration from this recovery is approximately 900,000 tons.