In this blog post, we’ll examine the causes and processes of global warming, its various impacts, and the different perspectives surrounding it.

What Is Global Warming?

The decline in the wild panda population due to reduced bamboo growth in China’s Qinling Mountains, the opening of the Arctic shipping route connecting Asia and Europe, and the frequent occurrence of powerful typhoons with maximum wind speeds exceeding 50 m/s. These phenomena, which seem completely unrelated, share a common cause: global warming.
Global warming refers to the long-term rise in average temperatures near the Earth’s surface. However, people who have experienced record-breaking cold snaps in winter might wonder, “If it’s global warming, shouldn’t winters be warmer too?” This can be understood when considering that global warming simply means a rise in average temperatures, while temperature variability by region and season may actually increase. In other words, global warming does not necessarily mean that winters will be warmer in every region. While winters in some areas may be warmer than average, other regions could experience record-breaking cold snaps during the same period.
In the movie ‘Spider-Man 2’, there is a scene where objects around the nuclear fusion device created by the villain Doctor Octopus melt and drip down as if they were ice cream. The nuclear fusion device in the movie is a machine that generates enormous amounts of energy. Similarly, the more energy an object possesses, the higher its temperature becomes. The rise in the Earth’s average temperature is ultimately due to the fact that the Earth now holds more energy than before. This occurs because either the amount of energy entering the Earth has increased, or the amount of energy escaping from the Earth has decreased.
Causes of increased energy entering the Earth include changes in solar activity, changes in the Earth’s orbital path, and precession. Conversely, causes of the decrease in energy emitted from Earth include the intensification of the greenhouse effect due to rising greenhouse gas levels and the reduction in glacier area. The primary cause of the climate warming currently being observed is attributed to the increase in greenhouse gases resulting from human activities; let’s first examine these factors.

How do the greenhouse effect and glacier retreat raise temperatures?

Let’s start with the greenhouse effect. Some of the light emitted by the Sun is reflected by the atmosphere, oceans, and glaciers, while the rest passes through the atmosphere, with a significant portion being absorbed by the Earth’s surface and oceans. This absorbed energy is re-emitted in the form of invisible infrared radiation. The phenomenon in which certain gases in the atmosphere absorb this infrared radiation, trapping heat on Earth, is known as the greenhouse effect. Not all gases absorb infrared radiation; those that do are called greenhouse gases.
When greenhouse gases are present at appropriate levels, the Earth’s average temperature is maintained at a level suitable for life. However, if the concentration of greenhouse gases becomes excessively high, energy that should be released into space remains trapped in the atmosphere, causing the average temperature to rise.
Major greenhouse gases include water vapor, methane, and carbon dioxide. Water vapor cannot continuously increase beyond a certain concentration due to the precipitation cycle. In contrast, methane and carbon dioxide are significantly influenced by human activities, and their concentrations can continue to rise. Although methane has a very strong greenhouse effect per molecule, its atmospheric concentration is relatively low; conversely, carbon dioxide has a relatively weak greenhouse effect per molecule, but its very high atmospheric concentration results in a significant impact on climate change.
Next, let’s examine the reduction in glacier area resulting from rising temperatures. Glaciers play a crucial role in reflecting sunlight, thereby reducing the amount of energy absorbed by the Earth. However, as average temperatures rise, glaciers melt, exposing the soil or ocean beneath them. While ice reflects light well, soil and the ocean absorb relatively large amounts of solar energy. As a result, the Earth stores more energy, and average temperatures rise even further.
As average temperatures rise, glaciers shrink even faster, and this, in turn, causes temperatures to rise further—a cycle that repeats itself. This phenomenon is called positive feedback. Positive feedback refers to a process in which a result acts to further reinforce its cause.

Why is the energy entering the Earth increasing?

Most of the energy reaching Earth comes from the Sun. If the Sun’s energy output increases or if Earth receives more solar energy, the amount of energy flowing into Earth also increases.
Solar activity fluctuates on an average cycle of about 11 years, and the amount of energy emitted rises and falls accordingly. Additionally, the amount of solar energy received by Earth can vary over the long term due to astronomical factors such as changes in Earth’s orbital path and precession. These natural factors are known to have influenced climate change in the past.

What consequences will global warming bring?

Many people believe that sea-level rise occurs simply because glaciers floating on the ocean melt. However, this explanation is only half correct. If you fill a cup with water and ice, you’ll see that even when all the ice melts, the water does not overflow. By the same principle, the melting of ice floating on the ocean alone does not significantly raise sea levels.
On the other hand, the situation is different when glaciers on land melt. The melted water flows into the ocean, causing sea levels to rise. In addition, seawater expands as its temperature rises—a phenomenon known as thermal expansion. Therefore, sea levels can rise even if the total volume of seawater does not change significantly.
Rising sea levels increase the risk of flooding in low-lying areas. Tuvalu is one of the places most severely affected by this phenomenon. With most of the country’s territory affected by rising sea levels, residents have lost their homes, and Tuvalu is often cited as a prime example of environmental refugees caused by climate change.

How will climate change alter ecosystems and weather patterns?

Due to global warming, climate change is manifesting in various ways. From a global perspective, the most notable change is that climate zones are gradually shifting northward. Temperate regions are beginning to exhibit subtropical characteristics, while an increasing number of subtropical regions are gradually taking on tropical characteristics. As climate zones shift, the distribution of organisms that have adapted to those environments is also changing. Taking South Korea as an example, while the catch of cold-water fish species has decreased compared to the past, the proportion of warm-water fish species such as mackerel and squid is showing an upward trend. Furthermore, the presence of subtropical and tropical marine life is gradually increasing.
On a national scale, the most noticeable change is the increase in extreme weather events. Representative examples include powerful typhoons and winter cold snaps. Recently, extremely powerful typhoons with maximum wind speeds exceeding 50 m/s have been occurring in various regions. Typhoons develop by absorbing large amounts of energy from warm oceans, and the higher the sea surface temperature, the greater the likelihood that they will become more powerful. As sea surface temperatures rise due to global warming, the likelihood of extremely powerful typhoons forming is also increasing. Such typhoons cause massive loss of life and property damage.
Record-breaking cold waves are also not phenomena entirely unrelated to global warming. Recent studies suggest that rapid warming in the Arctic affects atmospheric circulation, potentially increasing the likelihood of cold waves in certain regions. Furthermore, warmer oceans supply more water vapor, which can intensify heavy snowfall in some areas. However, the causes of these cold waves are highly complex, and active research is currently underway in this field.

Does global warming necessarily lead only to negative outcomes?

Global warming does not necessarily lead only to negative outcomes. As Arctic sea ice decreases, the feasibility of using the Arctic route connecting Europe and Asia is gradually increasing. Previously, ships traveled from Busan to Europe via the Indian Ocean and the Suez Canal, but using the Arctic route could significantly shorten the voyage distance. This is seen as an advantage that can reduce shipping time and logistics costs. Furthermore, the Arctic region is believed to hold various natural resources, such as oil, natural gas, and rare earth elements. As sea ice retreats, access to these resources is likely to improve. However, resource development involves a complex interplay of international law, environmental protection, economic viability, and geopolitical issues, meaning there are various constraints on actual development.

Who is responsible for global warming?

There is a scientific consensus within the international community that global warming is occurring. However, in the past, various opinions were put forward regarding the extent to which human activities have contributed to this phenomenon.
Those who argue that human influence is limited explain that the climate has historically changed over long periods due to natural factors such as solar activity and changes in the Earth’s orbital path. They point to the fact that the Earth has cycled through ice ages and interglacial periods for hundreds of thousands of years, and that natural climate variability has played a significant role in these changes.
On the other hand, the view that human activity is the primary cause of current climate change is the most widely accepted perspective internationally today. Prior to the Industrial Revolution, atmospheric carbon dioxide concentrations were around 280 ppm, but they have now surpassed 430 ppm and continue to rise. This increase has been attributed to human activities such as the use of fossil fuels, industrial activities, and deforestation. Major global scientific institutions, including the Intergovernmental Panel on Climate Change (IPCC), have concluded that most of the global warming observed in recent decades is due to greenhouse gas emissions caused by humans.

How will global warming unfold in the future?

The future climate is expected to vary significantly depending on the extent to which humanity reduces greenhouse gas emissions. The Intergovernmental Panel on Climate Change (IPCC) has presented various emission scenarios; if greenhouse gas reductions are actively implemented, the rise in temperature could be relatively limited. However, if emissions continue to increase, the average temperature by the end of this century is likely to rise by several degrees Celsius compared to pre-industrial levels.
If temperatures continue to rise, sea levels are also expected to continue rising. Consequently, the risk of flooding in low-lying coastal areas will increase, and the frequency and intensity of extreme weather events—such as heat waves, droughts, torrential rains, and wildfires—are likely to rise. Furthermore, shifts in climate zones, changes in ecosystems, and alterations in the production environments for agriculture and fisheries are projected to become even more pronounced.
Currently, South Korea may also face new opportunities in certain areas, such as expanded access to the Arctic shipping route and the increased cultivation of some subtropical crops. In fact, as temperatures rise, the cultivation of subtropical crops is expanding in some regions, and the distribution of fish species is changing due to shifts in marine ecosystems. However, since these changes are accompanied by various risks—including heat waves, torrential rains, droughts, and rising sea levels—it is difficult to assess them solely in positive terms.
Climate warming is no longer a future possibility but a phenomenon already underway. Accurately understanding its causes and impacts is the first step toward responding to the various changes that will emerge in the future.