This blog post examines the causes of rapidly increasing atmospheric CO₂ and the worsening climate crisis, exploring both the potential and limitations of artificial photosynthesis as a new solution gaining attention.
CO₂ is the substance that first comes to mind when we think of environmental issues like climate change and global warming. It’s easy to mistakenly view CO₂ as a ‘substance that must be eliminated,’ but to be precise, it’s not something that ‘must disappear’ but rather a substance that ‘must be reduced to an appropriate level.’ In fact, it is precisely because carbon dioxide exists that photosynthesis utilizing it became possible. Thanks to this, plants adapted to the Earth’s environment, allowing organisms to continue their normal evolution based on oxygen respiration. The idea of converting the carbon dioxide emitted by organisms back into nutrients is truly ingenious, and the Earth’s ecosystem has maintained itself for over a billion years through this cyclical structure. However, the ‘excess’ carbon dioxide that humanity began emitting as it evolved and industrial activity exploded has started to disrupt the ecosystem’s balance, and its quantity has now increased to a level that is difficult to ignore.
I have been paying attention to the seriousness of atmospheric CO₂ concentrations, which have been at the center of global debate since the latter half of the 20th century. The Earth naturally absorbs and emits solar radiation to maintain its average temperature. The phenomenon where CO₂ absorbs emitted radiation, trapping heat and preventing it from escaping into space, is called the ‘greenhouse effect’. This is now recognized as a primary driver of recent climate change. According to data from the U.S. National Oceanic and Atmospheric Administration (NOAA) and the Scripps Institution of Oceanography, atmospheric CO₂ concentrations had remained balanced between 170 and 280 parts per million (ppm) over the past 800,000 years. However, they increased sharply after industrialization, reaching 315 ppm in the first recorded measurement in 1958 and surpassing 400 ppm in 2013. The rate of increase has since accelerated, with atmospheric CO₂ concentrations reaching approximately 421 ppm (Mauna Loa standard) by 2024. This represents an increase of approximately 33% compared to the 1960s. Over the same period, the global average temperature has risen by about 1.2°C compared to pre-industrial levels (IPCC AR6, 2023 Supplementary Report), causing significant changes across the entire planet.
The root cause of this situation lies in the Industrial Revolution, which began in mid-18th century Britain and initiated large-scale fossil fuel use. Indiscriminate deforestation by countries worldwide also significantly contributed to this. According to the FAO’s Global Forest Resources Assessment 2020 and Global Forest Watch 2023, the world has lost an average of approximately 10 million hectares of forest annually since 1990, with cumulative losses far exceeding 100 million hectares. This represents a far more severe long-term decline than the 13 million ha mentioned in the original text for the 1990-2010 period. The critical reason for this severe forest loss is the corresponding reduction in the capacity to absorb increased CO₂. Based on South Korea’s forest standards, a simple calculation assumes each hectare absorbs approximately 9 tons of CO₂ annually. This implies the cost of processing tens of millions of tons of CO₂ is estimated to be astronomical. Assuming it costs about $20 to store or convert one ton of CO₂, the cumulative global cost due to forest loss soars to astronomical figures.
Furthermore, forests cannot immediately process CO₂ simply by planting trees. No matter how thorough the forest management plan, it takes at least 30 years for trees to grow sufficiently to absorb the level of CO₂ we require. The average CO₂ processing capacity mentioned in the original text (based on 60-year-old trees) remains applicable today. Factoring in regional variables like soil quality, rainfall, and sunlight exposure makes solving the CO₂ problem solely through natural forests practically impossible.
Compounding this is the pine wilt disease, whose spread has accelerated due to climate change. First reported in Korea in 1988, it has steadily expanded. This disease, caused by nematodes parasitizing the pine sawyer beetle that kill trees by drying them out, still has no complete cure. According to 2024 statistics from the Korea Forest Service, the area affected by pine wilt disease has shown a continuous expansion trend recently, with a very high mortality rate, earning it the nickname ‘pine and Korean pine AIDS’. Particularly, as the temperature rises, the spread of pine wilt disease accelerates, making it highly likely to cause greater damage alongside global climate change. In Japan, after its introduction in 1905, the disease has spread for over 100 years, now threatening the collapse of the pine ecosystem. Similarly, in South Korea, approximately 40% of the 6.34 million hectares of forest consists of conifers, exposing the country to significant risk. If most conifers become infected and die from pine wilt disease, the carbon absorption base will weaken, greatly increasing the nation’s vulnerability to climate change.
Among the various ideas to prevent such a global catastrophe, one is ‘artificial photosynthesis’. The concept of ‘artificial photosynthesis’ was first mentioned in 1912 by Italian photochemist Dr. Giacomo Cacciamani in the journal ‘Science’, and was first experimentally realized in 1972 by Professor Akira Fujimara of the University of Tokyo. Since then, technological development has rapidly progressed at research institutions worldwide. In Korea, Professor Chan-Beom Park’s team at the Korea Institute of Science and Technology (KIST) successfully developed a technology that combines solar cell technology with redox enzymes to mimic the light and dark reactions of natural photosynthesis. Unlike natural photosynthesis, which produces glucose, artificial photosynthesis can convert CO₂ into various fuels and polymer materials like methane and ammonia depending on reaction conditions. Its potential for CO₂ utilization is exceptionally broad, making it a subject of significant attention.
One of the greatest advantages of artificial photosynthesis is its wide range of applications. While natural photosynthesis requires fertile soil, water, and sunlight, artificial photosynthesis replaces the light reaction with solar cells and implements the dark reaction using catalysts. This enables photosynthesis even in harsh environments like deserts. It is not constrained by soil conditions and can be installed on urban building exteriors or large-scale facilities, dramatically increasing spatial utilization. It is truly a ‘wonderful’ technology, as it can become a new platform for converting CO₂ even in urban environments.
Until now, humanity has been absolutely dependent on natural photosynthesis to replenish oxygen and absorb CO₂. However, the costs of maintaining and managing natural forests are extremely high; the Forest Service alone spends tens of millions of won per hectare just to purchase private forests. The annually increasing management costs are so large they are difficult to estimate. ‘Artificial photosynthesis’ holds significant potential as a technology that can substantially reduce this burden. Above all, its value is immense due to its ability to dramatically reduce atmospheric CO₂ concentrations.
Existing CO₂ conversion technologies primarily involve chemical and biological conversion, with the most widely used being the conversion of CO₂ into building materials. In South Korea, Daewoo E&C has secured technology to partially replace cement, and its stability has also been proven. However, this technology also carries the fundamental limitation that the building materials can become a pollution source when discarded. Microalgal photosynthesis exhibits a photosynthetic rate 2.3 times faster than sugarcane and 15 times faster than pine trees, but it has the disadvantage of requiring specialized cultivation facilities.
In contrast, artificial photosynthesis enables CO₂ conversion even outside forested areas, provided only enzymes, water, and facilities supplying a certain level of light are available. Artificial photosynthesis produces not only oxygen but also various storable compounds like hydrogen and methanol. It can convert substances with 1-2 carbon atoms, such as carbon monoxide, ethanol, and formic acid, into diverse compounds, making it highly advantageous for replacing fossil fuels and establishing a CO₂ cycle structure. Notably, recent studies indicate the efficiency of artificial photosynthesis is rapidly increasing. Unlike the previously mentioned efficiency levels (0.1–4%), multiple research teams achieved efficiencies exceeding 10% between 2022 and 2024, with some experimental environments reporting up to 17%. This represents significant progress toward commercialization, and the pace of development is steep.
Of course, the final hurdle to overcome is the catalyst. The silver-carbon-based catalyst under development at KIST is a cutting-edge material, but its efficiency is lower than that of experimental gold catalysts. Furthermore, improvements are still needed in the production scale and stability of the catalyst. However, recent research on various transition metal catalysts based on nickel, cobalt, and copper, as well as nitride complexes, is progressing rapidly. Catalyst technology is also advancing in a direction that is significantly more economical and efficient than before. Although still in the early adoption phase, considering the current pace of scientific progress and its potential, the future positive impact of artificial photosynthesis on nature is so significant it is difficult to predict. Natural photosynthesis has an efficiency of only 0.2%, is vulnerable to pests and diseases, and requires demanding conditions. However, if artificial photosynthesis becomes commercialized, its advantages—including high efficiency exceeding 10% and no spatial constraints—will enable it to play a crucial role in solving the atmospheric CO₂ problem. It could achieve the same absorption effect using an area just 1/50th the size of the Amazon rainforest. Efficiency could be maximized by deploying balloons over desert regions or areas with thin ozone layers to perform targeted photosynthesis.
The recurring heatwaves and record droughts each year demonstrate the urgent necessity with which we must address this problem. In November 2015, the global average temperature rose exactly 1°C above pre-industrial levels, and by August 2016, it had increased an additional 0.38°C in just one month. Recent studies warn that the Earth has already warmed by over 1.2°C compared to pre-industrial levels, and if warming continues at the current pace, it is highly likely to exceed the 1.5°C threshold by the 2030s. Research findings remain valid: a 1°C rise in global average temperature puts one-third of all species at risk of extinction and could destroy 15% of the world’s forests through natural disasters. Despite a population exceeding 7 billion, global forest area continues to decline steadily, management costs are rising, and CO₂ concentrations keep increasing. Considering the extreme weather and natural disasters occurring annually, there is effectively no clear solution other than directly removing or converting CO₂. To create a virtuous cycle structure capable of recycling CO₂ in terms of practicality and efficiency, ‘artificial photosynthesis’ is clearly an indispensable technology for humanity.
Photosynthesis is the very first survival technology devised since life emerged on Earth. Through photosynthesis, a planet once thought uninhabitable now glows green. The stability of this technology has been sufficiently proven; it is no exaggeration to say no life form can survive without photosynthesis. Yet, this system built by nature over roughly 2 billion years now faces collapse due to human activity.
Saying it’s not too late might sound like an excuse for humanity. But what is clear is that there is no reason for things to get worse than they are now. ‘Artificial photosynthesis’ has not yet reached completion, but given that South Korea holds a leading position in this field, with sustained interest and investment from the government and society, it has the potential to be worthy of a Nobel Prize. The Nobel Prize is not solely awarded for discovering undiscovered theories. As seen in the 2014 case where three Japanese researchers won the Nobel Prize in Physics for developing gallium-based blue LEDs, technological innovations that directly contribute to human life can be recognized as having sufficient value.
“Award it to those who have contributed most concretely to the welfare of mankind.”
This is the will of Nobel, who amassed global wealth through dynamite, and the fundamental spirit the Nobel Prize aspires to. With the hope that a Nobel Prize in Science, unprecedented until now, will be awarded in this very field, I conclude this article.
