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The greenhouse effect is usually discussed in connection with climate change. Is the greenhouse effect really harmful to us, and what do we need to know about it?
What is the greenhouse effect?
The greenhouse effect is a natural phenomenon that increases the temperature on our planet for comfortable existence.
How does it occur? Solar radiation reaches our planet, which heats the surface. The radiation from the sun is short-wave, so greenhouse gases that are around the Earth freely pass it. Some insignificant part of the sunlight can be reflected back by aerosols that are in the Earth’s atmosphere, together with greenhouse gases.
In turn, when the planet heats up, it gives off thermal radiation — infrared radiation (long waves). But since the radiation is long-wave, greenhouse gases do not allow it to completely fly away into space. Part of the thermal radiation still manages to bypass the greenhouse gases, but a significant share is reflected, which increases the temperature on Earth.
The first person to describe the greenhouse effect was the French scientist Jean-Baptiste Joseph Fourier in 1824, who is also considered the author of the term.
What are the main greenhouse gases on earth?
• Carbon dioxide (CO2) is considered the most important greenhouse gas of anthropogenic origin. Carbon dioxide also occurs naturally in the carbon cycle, but it is man who has increased its concentration in the atmosphere by 47% since the Industrial Revolution
• Methane (CH4) — in terms of its greenhouse effect, methane is considered even stronger than carbon dioxide, but there is significantly less of it in the atmosphere. Natural sources are swamps and termite mounds. Anthropogenic origin — landfills, agriculture, coal, and natural gas mining
• Nitrous oxide (N2O) is formed during the combustion of solid waste and fossil fuels. A significant portion of N2O comes from agriculture
• Synthetic chemicals such as hydrofluorocarbons, halogenated hydrocarbons, sulfur hexafluoride, and other synthetic gases. The main source is the chemical industry
• Ozone (O3) — occurs naturally in the Earth’s stratosphere and troposphere and does not cause a significant greenhouse effect
• Water vapour ranks first among all greenhouse gases by volume, but direct emissions of water vapour have the least effect on the greenhouse effect
The greenhouse effect itself is a blessing for us, since without it, there would be no life on Earth. If it did not exist, the average temperature on Earth would be -18℃, meaning rivers and oceans would always be frozen, and plants would not grow anywhere. With its help, the average temperature on our planet reaches +15℃.
The strongest greenhouse effect in the Solar System exists on Venus. The planet’s atmosphere consists almost entirely of carbon dioxide, so the temperature on the surface of Venus reaches 475℃.
Causes of the greenhouse effect
The Earth constantly receives and gives off energy. According to the law of conservation of energy, all this should be in radiation balance. But man has thrown the system out of balance with his actions. As the volume of greenhouse gases increases, they increasingly prevent heat from leaving the Earth’s atmosphere. It turns out that even the infrared radiation that once flew into space now partially remains with us — the global temperature is rising.
Scientists have concluded that the average temperature on Earth has increased by 1.1 ℃ since the end of the 19th century. A difference of only 4 ℃ previously led to ice ages, so this figure is not so small. There is a scientific consensus that human economic activity is to blame for the sharp increase in greenhouse gases in the atmosphere.
What increases the greenhouse effect:
• Industrial emissions
• Mining
• Coal power plants
• Car exhaust
• Extensive agriculture
• Building maintenance
• Forest fires
• Deforestation
The greatest greenhouse effect is caused by fuel combustion, its extraction and transportation, production of raw materials (cement, steel, and other metals), food industry, landfill, and waste incineration. They account for approximately 70% of all global anthropogenic emissions.
Scientists have derived the global warming potential, which allows comparing the climatic effects of greenhouse gases over different periods. For example, 1 kg of methane absorbs thermal radiation 84 times better than 1 kg of CO2, if we take a 20-year period.
Gases have different lifetimes; for example, methane has a lifetime of about 12 years, while N2O has a lifetime of 114 years. Some anthropogenic carbon dioxide emissions are removed from the atmosphere within a few decades, but a significant portion remains in the atmosphere for up to several millennia.
Consequences of the greenhouse effect
Temperature change is directly proportional to radiative forcing. Scientists have already calculated that if the amount of CO2 doubles, it will cause warming from 1.5°C to 4.5°C — this is the so-called climate sensitivity. The concentration of carbon dioxide is already 1.5 times higher than the pre-industrial level.
The non-profit research centre Oxford Economics has published a study on the impact of global warming on the economy. Scientists based their study on the optimal temperature at which people work most productively and agricultural crops yield the greatest harvest. Experts have determined this figure to be 15°C. Countries with an average annual temperature below this value may receive small benefits from warming. Countries with a hotter climate, on the contrary, will suffer damage.
In the course of the study, specialists from Oxford Economics analysed data on the situation in 203 developed and developing countries and predicted a 20% drop in global GDP by 2100. This conclusion is based on the assumption that the average temperature will continue to rise at the same rate as it does now (by about 0.2°C per decade). The findings of experts from Oxford Economics confirm the results of an earlier study published in 2015 by scientists from Stanford University and the University of California, Berkeley.
According to experts from Oxford Economics, the Indian economy will suffer the most: the country’s GDP per capita will fall by 90% by 2100 if greenhouse gas emissions into the atmosphere do not decrease. The experts also assumed what this indicator could be in different countries if the average temperature were 1.1°C lower. According to the forecast, it would be significantly higher. For example, Nigeria’s GDP per capita could be 35% higher than it is now.
Solutions
There are many ways to solve the problem, which can be divided into fantasy and reality.
Fantasist ones include the proposal to spray silver particles in the stratosphere so that they reflect as much sunlight as possible. This way, the Sun will not heat our planet, and it, in turn, will give off less heat. For the same reason, some scientists suggest artificially causing clouds, since they are able to reflect sunlight coming to Earth.
What can actually be done now so that the greenhouse effect does not harm us in the future:
• Reduce the use of fossil fuels and switch to renewable energy sources
• Increase energy efficiency and modernise energy-saving technologies
• Engage in sustainable forest management and control forest fires
• Move to environmentally friendly agriculture
• Restore the soil cover, since the loss of humus directly affects the greenhouse effect
• Give up personal transport and switch to bicycles, public transport, and electric cars
illuminem Voices is a democratic space presenting the thoughts and opinions of leading Sustainability & Energy writers, their opinions do not necessarily represent those of illuminem.
