At the end of the 18th century, the Industrial Revolution emerged in England. The advent of the steam engine transformed all walks of life, and the machines in factories worked day and night. So far, the energy for many production activities still comes from the combustion of fossil fuels such as coal, oil, and natural gas. Most industrial activities inevitably generate and emit gases such as carbon dioxide. However, for more than a hundred years, human activities have seriously affected the composition of the atmosphere.
On June 29, 2021, the village of Lytton in western Canada set the country’s highest temperature record with a temperature of 49.5 ℃, arousing global attention. According to scientists’ analysis, the occurrence of such extreme high temperature weather may be a manifestation of global warming caused by atmospheric changes. Compared to the eve of global industrialization in the early 20th century, the average surface temperature today is at least 1.1°C warmer.
In fact, humans discovered carbon dioxide’s ability to change the temperature of the environment as early as a century and a half ago. It wasn’t until the second half of the 20th century, however, that scientists began meticulously measuring greenhouse gases in the atmosphere to extrapolate carbon emissions from human activity. The global climate change seems to have happened suddenly and violently, but it also seems to have given enough time for mankind to pull back from the precipice.
The omen is dark, and I don’t care
One day in 1856, a scientist in the United States placed two glass jars in the sun, one filled with air and the other with only carbon dioxide. She found that when exposed to sunlight, the CO2-only jars heated up faster than the air-filled jars; when both jars were moved to the shade, the CO2-only jars cooled more slowly. She went on to speculate that a carbon dioxide-rich atmosphere would cause the planet to heat up. Three years later, an Irish physicist came to similar conclusions through more sophisticated experiments, and went further to find the reason for carbon dioxide’s insulating properties — carbon dioxide’s ability to absorb infrared radiation so well.
At the end of the 19th century, the Swedish scientist Arrhenius became interested in changes in carbon dioxide levels in the atmosphere. At first, he just wanted to know whether the reduction in carbon dioxide levels caused by fewer volcanic eruptions heralded an ice age on Earth. As his research progressed, he gradually became disturbed by the large amount of carbon dioxide emitted by industrial activities, and established a mathematical model of the greenhouse effect. Based on this model, he speculates that if the amount of carbon dioxide in the atmosphere doubles, the global temperature will increase by 5 to 6 degrees Celsius.
Scientists studying the endothermic phenomenon of carbon dioxide
The factory emits a lot of waste gas
A British meteorologist took Arrhenius’s findings very seriously. After collecting and arranging weather data from various places, he found that the local temperature recorded by 147 weather stations around the world showed an upward trend year by year. In 1938, he pointed out in a paper that the massive burning of fossil fuels was inseparable from the rise in Earth’s temperature; he also deduced that the burning of fossil fuels had released about 150 billion tons of carbon dioxide into the atmosphere from the end of the 19th century to the year of the paper.
However, these findings did not attract much attention from other scientists at the time. Most of them believe that the climate system is large and complex, and its changes must be slow, for example, evidence from geological studies shows that an ice age spanned tens of millions of years. From the perspective of human beings, it is impossible to appreciate the impact of gasification changes. So, what’s there to worry about?
The evidence is conclusive, wake up
Shortly after Arrhenius published the above paper, World War II broke out, the war reshaped the world scientific research pattern, and the research needs of military technology gave birth to the concept of “big science”. High-target, high-investment, multidisciplinary scientific research projects bring together researchers from all over the world, who work side by side to solve intractable global scientific problems. Climatology research has also entered a new stage. Throughout the second half of the 20th century, massive observational data have made scientists gradually realize that human activities do have a profound impact on climate.
From July 1957 to December 1958, the International Geophysical Year, an 18-month joint global observation of geophysical phenomena, allowed scientists to make key advances in Earth’s climate research. The generous research funding provided by the event has allowed scientists to implement some of the research projects they aspired to but were shelved due to high investment, such as the long-term and precise recording of atmospheric carbon dioxide levels in many regions of the world.
During this period, the United States established atmospheric composition observation systems at Mauna Loa in Hawaii and Antarctica respectively. With the data collected systematically, scientist Keeling published the most powerful paper at the time to prove that “human activities affect the natural world”. In the article, he drew the famous “Keeling curve”, which initially described the annual variation of carbon dioxide content in the atmosphere. The curve shows that, although changes in atmospheric carbon dioxide levels are seasonal, there is an overall upward trend.
It is worth mentioning that not long before Keeling started this research, scientists have pointed out that the ocean as a “carbon sink” has a limited capacity and is not as infinitely capable of absorbing carbon dioxide as previously thought. This provides a part of the theoretical basis for the academic interpretation of the “Keeling curve”.
Keeling curve depicting the change of carbon dioxide content in the atmosphere
Analyzing ice cores drilled from inside glaciers is a common tool for understanding past climates. The material in the atmosphere will reach the glacier with the atmospheric circulation and settle on the surface of the ice and snow, and finally form the ice core record. The ice layers formed by snow cover at different periods have significant structural differences, like the rings of trees. Scientists can infer the temperature at the time of formation based on the isotopic ratio of hydrogen and oxygen in the ice core, and can also infer the atmospheric composition of the bubbles when they are formed based on the composition of the bubbles in the ice core. Ice core drilling is also an important way for Chinese scientists to study climate change on Mount Everest. As of 2021, the Chinese and foreign research teams, mainly in China, have analyzed the ice cores of more than 20 glaciers in the Qinghai-Tibet Plateau.
Beneath the glacier’s ice cap is a book of history. By reading this “book”, scientists have discovered that some aspects of the earth are changing at an alarming rate. About three-quarters of Greenland’s area is within the Arctic Circle, which has long been an important location for weather monitoring. In just a few decades, the island’s average temperature has soared by more than 20 degrees Celsius. Such drastic climate change has dealt a heavy blow to mankind’s “procrastination” in dealing with global warming.
There are also many meteorological observations from satellites. Satellite observation data shows that the earth’s sea water is warming; polar glaciers are melting significantly, with more than 400 billion tons of glaciers disappearing every year; the current global sea level is rising by an average of 3.4 mm per year.
After the sheep is gone, those who come can be chased
The impacts of climate change are large and widespread.
The ocean continues to absorb carbon dioxide, and the acidity of seawater will become stronger and stronger. Since the main component of the shells of most “shellfish” marine life is calcium carbonate, which is easily corroded by acid, this change in seawater acidity will first affect “shellfish” marine life. And many “crustaceans” marine organisms play a pivotal role in the marine food chain, and the ecosystem is bound to affect the whole body. In addition, excessive seawater temperatures can accelerate the expulsion of colorful symbiotic algae from corals, causing coral bleaching. Bleached corals lack the ability to obtain nutrients and are extremely vulnerable to death. Many species will gradually “escape” from high-temperature waters and create new habitats. The risks brought by this move are not yet known.
Acidified seawater will corrode animal shells
Many areas have suffered severe drought due to warming temperatures; vegetation has dried up, resulting in frequent mountain fires; the polar permafrost has gradually melted, and many houses and roads in the Arctic Circle countries have been damaged as a result. In the past, offshore sea ice often acted as a shield for coastal areas during storm surges; now, this protection is diminishing, and many coastal people are considering moving inland.
Global warming is a foregone conclusion, and what human beings can do is to slow down its warming process as much as possible. Achieving this goal depends on how many countries are involved in reducing emissions. Scientific researchers must take responsibility in emission reduction actions, such as improving climate models, explaining climate change in more detail, and providing theoretical basis for relevant departments to regulate.