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Greenhouse effect

The greenhouse effect is a natural phenomenon that regulates the temperature of the planet's surface through the accumulation of thermal energy within the atmosphere. This thermal energy mainly comes from the Sun. Sunlight reaches the Earth's surface, is absorbed by the Earth, and then re-emitted in the form of infrared radiation (heat) back into space. However, some of the infrared radiation is also absorbed by certain gases present in the atmosphere, known as greenhouse gases, which makes the Earth's temperature warmer.

Explanation. Greenhouse gases in the Earth's atmosphere, including carbon dioxide (CO2), methane, and water vapor, filter harmful solar radiation for human health and prevent the escape of infrared radiation. The sunlight that reaches the Earth is partially reflected upward by the Earth's surface, and partially absorbed by the Earth itself, before being emitted in the form of infrared radiation (IR) or heat. Infrared radiation, represented in the figure below with the color orange, is partially sent back towards the Earth by the greenhouse gases present in the atmosphere. This effect of trapping heat within the Earth's atmosphere leads to a further increase in the average temperature on Earth.
spiegazione dell'effetto serra naturale

However, an excess of greenhouse gases in the Earth's atmosphere can also cause negative effects. The heat trapped in the atmosphere causes a gradual increase in the Earth's temperature, resulting in serious imbalances to ecosystems and the biosphere, as well as variations in climate and extreme weather phenomena. Therefore, this effect represents a matter of global significance. If global warming continues to increase, there will be increasingly severe consequences for the environment and human life, such as:

  • Melting glaciers
  • Rising sea levels
  • Acidification of the oceans
  • Climate change
  • Desertification of agricultural areas
  • Increased frequency and intensity of extreme weather events such as storms, hurricanes, wildfires, heat waves, and floods alternating with long periods of drought.

In order to better understand the delicate balance of the greenhouse effect and the causes of global warming, it's important to distinguish between natural and anthropogenic greenhouse effects - the latter being the one resulting from human activities. Human activity is the main cause of the excessive increase in greenhouse gases in the atmosphere, putting at risk the climate balance of our planet. Over the last century, the use of fossil fuels such as oil, coal, and natural gas has released an enormous amount of CO2 into the atmosphere. At the same time, deforestation has reduced the Earth's ability to absorb the CO2 present in the atmosphere.

Types of greenhouse effect

There are two types of greenhouse effect:

  • The natural greenhouse effect. The Earth releases greenhouse gases (such as CO2, methane, etc.) into the atmosphere through various natural sources such as the plant world, organic decomposition of animals and plants, volcanism, and more. The natural accumulation of greenhouse gases in the atmosphere raises the temperature of the planet. This natural process makes life possible on Earth, warms our planet, and contributes to its habitability.

    The environment is responsible for producing ten times more CO2 than human activities. A significant amount, certainly, but the natural system has developed an effective counter-strategy: the chlorophyll photosynthesis of plants. Thanks to this process, "natural" CO2 is immediately reabsorbed and used for the growth of the plants themselves. In this way, the natural greenhouse effect is able to maintain a sustainable balance over time, except for exceptional natural events such as volcanic eruptions.

  • The anthropogenic greenhouse effect. The anthropogenic greenhouse effect is caused by the excessive presence of greenhouse gases in the atmosphere, which results from the release of CO2 and methane emissions from human activities such as industry, agriculture, livestock, and transportation. These anthropogenic greenhouse gases have caused an increase in the average temperature on the planet, posing a serious threat to life on Earth. Global warming is one of the most pressing environmental issues of our time.

    The rise in anthropogenic greenhouse gas emissions dates back to the 19th century, following the first industrial revolution. This increase was mainly due to the widespread use of coal as fuel in industry, transportation, and domestic heating. Throughout the 20th century, emissions grew exponentially with the advent of the automobile, the use of gasoline and petroleum derivatives, and the production of electricity. Anthropogenic CO2 emissions into the atmosphere increased by 40% in the 20th century, mainly due to the combustion of oil, methane, and coal in transportation, domestic heating, industrial production, and electricity generation. In the last century, emissions of methane, another greenhouse gas, have also increased exponentially due to intensive livestock farming. It is estimated that CO2 emissions have increased by 30% in the last two centuries, while methane emissions have increased by 200%.

Over the past few decades, there has been a steady increase in the average temperature on Earth, but the problem of climate change is much more severe than previously thought. Carbon dioxide, responsible for the greenhouse effect, remains suspended in the atmosphere for a minimum of one hundred years before falling to the ground. The effects are unpredictable because the accumulation of CO2 in the atmosphere produces effects in a discontinuous manner, and the consequences on the environment can become sudden and irreversible. The planet Earth is a complex system, similar to a chaotic system, in which even small initial variations can cause enormous upheavals over time. Today, the effects of climate change are visible in the form of extreme weather phenomena, such as hurricanes, storms, and floods, but also through the melting of polar ice caps, the reduction of the surface area and thickness of mountain glaciers, and the desertification of land. The consequences of these phenomena, in the long run, risk destabilizing the balance of the ecosystem on which the life of our planet is based, putting its very survival at risk.

The Causes of Global Warming

The global warming of the planet caused by the anthropogenic greenhouse effect is mainly due to the following reasons:

  • The use of fossil fuels by humans. The utilization of fossil fuels by humans is one of the primary causes of overheating. The modern economy is primarily based on the extraction and exploitation of fossil resources such as coal, oil, and natural gas. The combustion of these resources releases large amounts of carbon dioxide (CO2) into the atmosphere, which have been trapped underground for millions of years.
  • Deforestation. Deforestation is accelerating desertification and the loss of green areas on our planet. Urban and agricultural expansion in wooded areas is reducing the planet's green lung. Deforestation reduces the environment's natural ability to absorb CO2 through the chlorophyll photosynthesis of plants, undermining the stability of the ecological balance.

In general, global warming caused by the greenhouse effect can also have natural causes, such as solar activity, natural climate cycles, and volcanic eruptions. However, according to most of the scientific community, the global warming observed in recent decades is mainly caused by human activities, such as the emission of greenhouse gases into the atmosphere.

How to Reduce the Greenhouse Effect

Reducing CO2 emissions and adopting sustainable lifestyle choices are essential to combat the greenhouse effect. Both companies and individual citizens can contribute by adopting responsible behaviors, such as:

  • Choosing renewable energy
  • Using public transportation or green mobility options
  • Reducing electricity waste
  • Recycling correctly
  • Using eco-friendly products
  • Using long-lasting and energy-saving light bulbs

However, it is equally important for a global agreement to be signed by all the countries in the world to reduce greenhouse gas emissions caused by industries and transportation.

The first attempt to reduce greenhouse gases dates back to the 1990s with the Kyoto Protocol. The phenomenon of the greenhouse effect began to be known in the 1970s and 1980s. In the following decade, the international community tried to put a brake on greenhouse gas emissions through a binding agreement called the Kyoto Protocol, aimed at the countries that signed it. States committed to reducing greenhouse gas emissions by 5.2% by 2012 compared to 1990 levels. However, despite being signed in 1997 in Kyoto, Japan, by all developed countries, in the following years some major countries, such as the USA and Australia, did not ratify the agreement. Therefore, the Kyoto Protocol never became operational.

Why did the Kyoto Protocol fail? The Kyoto Protocol excluded developing or emerging countries from the commitment, in order not to prejudice their economic and social development. However, in the last 30 years, some of these countries, such as China, have experienced rapid economic and industrial growth. This has led some developed countries not to ratify the agreement for fear of losing their competitiveness.

Despite repeated attempts, there is still no international agreement that obliges all industrialized countries to reduce greenhouse gas emissions. Currently, in fact, only States voluntarily subscribe to reduction commitments. Recently, the European Union has set the goal of reducing greenhouse gas emissions by 80% by 2050 with the Paris Agreement.