Jun's Blog

I previously wrote a blog post expressing a skeptical view on the impact of CO2. I’ve since reviewed this through generative AI and will continue to verify it.

[1]. Skeptical View

The theory that increasing CO2 causes global warming is based on a correlation between rising CO2 and global warming. However, there’s no scientific evidence demonstrating that CO2 hinders the radiation of Earth’s temperature.

If CO2 were to hinder the radiation of temperature into space, it would also impede incoming radiation, creating a contradiction. Analysis of CO2 concentrations from sources like fossils indeed shows an increase in CO2 since ancient times. However, the idea that a 2-degree Celsius change in Earth’s temperature could be caused by variations in the Earth’s distance from the 5,700°C sun or changes in the Earth’s axial tilt is persuasive.

Increased human activity (population growth, economic activity, etc.) leads to increased energy consumption. In other words, heat consumption rises. Heat transfer occurs through conduction and radiation, and Earth’s heat radiates into space through the atmosphere. However, the increased heat is not released all at once. It accumulates on the Earth’s surface and is slowly released, causing the Earth’s temperature to rise.

Heat is primarily generated by combustion, which produces CO2. Therefore, it’s natural for CO2 to increase if Earth’s temperature rises. It’s not that increased CO2 caused global warming; rather, global warming caused CO2 to increase.

Other energy sources include nuclear power and solar power, which also contribute to global warming (hydroelectric, tidal, and wind power, being conversions of solar energy, do not cause global warming). Therefore, as human activity increases, global warming will progress regardless of CO2. However, this may not be the only cause. An ice age would be a different story (in the past, volcanic ash caused cooling).

[2]. Verification of the Skeptical Argument

The presented text puts forth claims about the relationship between CO2 and global warming that differ from general scientific consensus. Below is a verification of each claim based on scientific evidence.

“There’s no scientific evidence demonstrating that CO2 hinders the radiation of Earth’s temperature.”

This is incorrect. CO2 (carbon dioxide) is one of the primary greenhouse gases in Earth’s atmosphere and has the property of absorbing and re-emitting heat (longwave radiation) from the Earth. This property is based on the physical principles of molecular vibrational-rotational spectra and has been confirmed through laboratory measurements and satellite observations. The scientific consensus on global warming is based on this greenhouse effect of CO2.

“If CO2 were to hinder the radiation of temperature into space, it would also impede incoming radiation, creating a contradiction.”

This is based on a misunderstanding. CO2 absorbs very little shortwave radiation (like visible light) from the sun but absorbs longwave radiation (infrared) emitted from the Earth. This is because CO2 molecules have different absorption characteristics for different wavelengths of light. Therefore, showing different behavior for incoming (solar radiation) and outgoing (heat from Earth) radiation is not a contradiction. Earth’s “greenhouse effect” relies on this selective absorption.

“Analysis of CO2 concentrations from sources like fossils indeed shows an increase in CO2 since ancient times. However, the idea that a 2-degree Celsius change in Earth’s temperature could be caused by variations in the Earth’s distance from the 5,700°C sun or changes in the Earth’s axial tilt is persuasive.”

It’s true that ancient CO2 concentrations fluctuated, which suggests that changes in Earth’s orbital parameters (variations in distance from the sun, axial tilt, and orbital eccentricity), known as Milankovitch cycles, have influenced past climate change. However, current global warming cannot be explained by these natural factors alone. The rapid increase in CO2 concentrations over the past few decades is clearly attributable to human activities, such as the burning of fossil fuels, as evidenced by carbon isotope ratio analysis. Many studies have shown that the impact of solar activity changes on Earth’s temperature is too small to explain the scale of current warming.

“Increased human activity (population growth, economic activity, etc.) leads to increased energy consumption. In other words, heat consumption rises. Heat is primarily generated by combustion, which produces CO2. Therefore, it’s natural for CO2 to increase if Earth’s temperature rises. It’s not that increased CO2 caused global warming; rather, global warming caused CO2 to increase.”

This argument presents two theories: that “global warming is caused by direct heat release from human activity, not CO2,” and that “global warming causes CO2 to increase.” Both lack strong scientific basis.

Regarding direct heat release: While heat released by human activities (e.g., waste heat from buildings and factories) can cause localized urban heat island effects, the amount of heat contributed to global warming compared to heat trapped by greenhouse gases is shown to be very small.

Regarding “global warming caused CO2 to increase”: In past climate changes, there have indeed been cases where CO2 concentrations rose during warming periods. This is thought to be due to feedback mechanisms, such as CO2 release from oceans, where warming triggered further increases in CO2 concentration. However, the current increase in CO2 concentration is primarily due to human-caused CO2 emissions far exceeding natural CO2 absorption. Graphs of CO2 concentration and temperature rise since industrialization suggest that the increase in CO2 concentration has preceded the temperature rise.

“Other energy sources include nuclear power and solar power, which also contribute to global warming (hydroelectric, tidal, and wind power, being conversions of solar energy, do not cause global warming). Therefore, as human activity increases, global warming will progress regardless of CO2.”

Regarding nuclear power generation: Nuclear power generation does not directly emit CO2, making it attractive for global warming countermeasures. However, it does release heat through cooling water discharge. There is no scientific evidence that this heat release is a primary cause of global warming.

Regarding solar power generation: Solar power is considered a clean energy source that does not emit CO2. While CO2 is emitted during the manufacturing process of solar panels, the emissions during power generation and over the entire lifecycle are significantly lower compared to fossil fuel power generation. There is no scientific basis for the claim that solar panels themselves “cause global warming.”

“However, this may not be the only cause. An ice age would be a different story (in the past, volcanic ash caused cooling).”

Earth’s climate is complex, and various natural factors (volcanic activity, solar activity, ocean circulation, etc.) contribute to its fluctuations. Large amounts of aerosols (fine particles) from volcanic activity can block sunlight and cause temporary cooling. Also, Earth has experienced multiple ice ages and interglacial periods in the past. While these natural factors are essential for understanding climate change, the current rapid warming deviates from the range of past natural variations, and there is a scientific consensus that human activities are the primary cause.

Summary

The presented text largely deviates from the mainstream scientific understanding of current global warming. In particular, denying the greenhouse effect of CO2, attributing the primary cause to direct heat release from human activities, and claiming that CO2 increase is a result of warming, are either scientifically unsubstantiated or based on misunderstandings.

Scientific understanding of global warming is thoroughly assessed by international organizations like the IPCC (Intergovernmental Panel on Climate Change), which regularly publish reports. These reports reflect a broad scientific consensus based on numerous scientific papers.

[3]. Supplement

To what extent has the impact of global warming gas concentrations on global warming been scientifically demonstrated?

The impact of global warming gases (greenhouse gases) on global warming has been extensively scientifically demonstrated, and its mechanisms are well-understood. This understanding is based on years of research and consensus among scientists worldwide, including those affiliated with the Intergovernmental Panel on Climate Change (IPCC).

Scientific Evidence

Physical Properties of Greenhouse Gases:

Greenhouse gases such as CO2 (carbon dioxide), CH4 (methane), N2O (nitrous oxide), and CFCs (chlorofluorocarbons) have the property of absorbing and re-emitting infrared radiation (heat) emitted from the Earth’s surface. This property is based on molecular structure and quantum mechanics and has been confirmed through laboratory measurements.

Without these gases, Earth’s average temperature is calculated to be around -18°C. The current average temperature of about 15°C is due to the natural greenhouse effect. As the concentration of greenhouse gases increases, this heat-trapping effect strengthens, leading to a rise in surface temperature.

Correlation with Observational Data:

Simultaneous rise of CO2 concentration and temperature: Since the Industrial Revolution, atmospheric CO2 concentrations have increased rapidly, and Earth’s average temperature has risen almost concurrently. In particular, the rapid warming over the past few decades cannot be explained by natural climate variability alone.

Carbon isotope ratio analysis: Analysis of carbon isotope ratios in atmospheric CO2 shows an increasing proportion of CO2 originating from human activities (such as the burning of fossil fuels). Fossil fuels have a specific carbon isotopic composition, and their “fingerprint” is visible in atmospheric CO2.

Comparison with past climate changes: Paleoclimate data from ice cores, for example, show a close correlation between temperature changes and CO2 concentration changes during past glacial and interglacial cycles. However, the current rate of CO2 concentration increase is abnormally fast, unprecedented in past natural fluctuations.

Climate Model Predictions and Verification:

Climate models, developed based on the physical properties of greenhouse gases and past observational data, predict that rising greenhouse gas concentrations will cause global warming. These models have been shown to reproduce past climate changes quite accurately, which validates their predictive reliability.

IPCC reports present future temperature rise predictions based on various emission scenarios, indicating that higher greenhouse gas emissions lead to greater temperature increases.

Contribution of Each Greenhouse Gas

According to IPCC reports, the majority of the impact of anthropogenic greenhouse gases on global warming comes from the following gases (contribution percentages may vary slightly depending on the report and period):

Carbon Dioxide (CO2): It is the most abundantly emitted gas and has the largest contribution to warming, about 76%. It is primarily emitted through the burning of fossil fuels and deforestation.

Methane (CH4): While its warming potential is about 25 times stronger than CO2, its atmospheric lifetime is shorter than CO2. It is emitted from agriculture (livestock, rice cultivation), fossil fuel extraction, landfills, and other sources. Its contribution to warming is about 14%.

Nitrous Oxide (N2O): Its warming potential is very strong, about 300 times that of CO2. It is emitted from agriculture (fertilizers), industrial processes, and other sources. Its contribution to warming is about 8%.

Fluorinated Gases (CFCs, HCFCs, etc.): These are ozone-depleting substances and also very potent greenhouse gases. They were formerly used as refrigerants in refrigerators and air conditioners, but emissions are declining due to international regulations.

Conclusion

The rise in greenhouse gas concentrations being the primary cause of global warming is a scientifically established view, supported by physical principles, extensive observational data, and sophisticated climate model simulations. This evidence clearly indicates that human-caused greenhouse gas emissions are significantly impacting Earth’s climate system.

To be continued.