Global warming is the phenomenon of increasing average air temperature near the Earth's surface caused by the accumulation, in large quantities, of polluting gases in the atmosphere.
This accumulation leads to greater retention of solar heat radiation on the earth's surface.
Experts indicate that the Earth's temperature has changed over almost all time scales.
This increase also has great influence of human activities, mainly from the first Industrial Revolution.
Global temperature: comparison of the averages verified between 2014 and 2018 and between 1950 and 1980 (source: NASA).
The greenhouse effect and global warming
Before understanding the causes of global warming, it is important to understand what the greenhouse effect is and how it happens.
The greenhouse effect phenomenon is a natural process that heats the Earth's surface.
When the sun's energy hits the Earth's atmosphere, some is reflected back to space and the rest is absorbed and radiated again by greenhouse gases.
Among the greenhouse gases are:
- Steam;
- carbon dioxide;
- methane;
- nitrous oxide;
- ozone;
- some artificial chemicals such as chlorofluorocarbons (CFCs).
The absorbed energy heats the Earth's atmosphere and surface. This process keeps the Earth's temperature about 33° Celsius warmer than it would otherwise be, allowing life to exist on the planet.
Without the greenhouse effect, the Earth would reach -18° Celsius, which would not allow the existence of life.
The problem we face now is that human activities are increasing concentrations of greenhouse gases.
Some of these activities are:
- burning fossil fuels such as coal, oil and natural gas;
- agriculture;
- the deforestation.
Understand how global warming occurs
global warming occurs when polluting gases accumulate in the atmosphere and absorb sunlight and solar radiation that return to the Earth's surface. Some of these gases are methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O).
Normally, this radiation would escape into space, but these pollutants, which can last for years or even centuries in the atmosphere, “trap” the heat and make the planet warmer. Greenhouse gases have increasingly absorbed this energy thrown back into space. This is largely responsible for global warming, that is, for the increase in global temperature on the planet.
The sun emits electromagnetic radiation at different wavelengths, transforming itself into energy of different intensities. The atmosphere acts as a multilayer shield that protects the Earth from dangerous solar radiation.
In this case, ozone is found in two different parts of our atmosphere:
- Ground-level ozone (bad ozone) is harmful to human health and a component of smog (mixture of dust, fog and polluting gases). It is found in the lower atmosphere (troposphere) and has nothing to do with the "ozone hole".
- High-level ozone or (good ozone) occurs in the stratosphere and is responsible for the vast majority of atmospheric ozone.
Learn more about greenhouse effect.
What is the growth in global temperature?
According to NASA, the Earth's temperature increase has been approximately 0.17°C every ten years between the 1970s and 1990s.
In measurements from 1990 onwards, the record is even greater: 0.21º C every ten years.
NASA also reported that in the last hundred years, between 1910 and 2010, the temperature increased by 0.88°C.
Earth's temperature rise from 1880 to 2019 (source: NASA).
The main causes of global warming
Global warming can come from any number of causes. All of them increase the concentration of greenhouse gases in the atmosphere, mainly due to human activities such as burning fossil fuels, deforestation and agriculture.
Some of the main causes of global warming are:
- Burning fossil fuels such as coal, oil and gas to create electricity or fuel cars. By burning this type of fuel, we release CO2 pollution into the atmosphere;
- Deforestation: Plants and trees play an important role in climate regulation because they absorb carbon dioxide from the air and release oxygen back into it. Therefore, the greater the number of deforestation, the faster global warming advances;
- Agriculture and livestock: Animals, particularly sheep and cattle, produce methane, a greenhouse gas. When cattle are grazed on a large scale, the amount of methane produced is a major contributor to global warming.
Pollution, fires and deforestation are some of the causes of global warming.
consequences of global warming
Experts on the subject always warn of the countless consequences of global warming for the planet. Some of the best known are:
Sea level rise and constant flooding in coastal areas
New Orleans flood after Hurricane Katrina.
Global warming is now accelerating the rate of sea level rise, increasing sea levels. flood risks for low-lying communities and high-risk coastal properties.
Global mean sea level is rising much faster off the east coast of the United States and the Gulf of Mexico. And, according to experts, it has increased to 8 inches since 1880.
Longer and more constant forest fires
Fires are increasingly constant in different places on the planet.
Due to rising temperatures, forest fire seasons are getting longer and more intense in some places like the United States and some countries in Europe.
Higher spring and summer temperatures result in warmer, drier forests for longer periods, providing favorable conditions for forest fires to ignite and spread.
most destructive hurricanes
Destruction after Hurricane Irma, Florida, United States.
While hurricanes are a natural part of our climate system, recent research indicates that its destructive power has been growing since the 1970s, particularly in the Atlantic region. North.
More frequent and intense heat waves
Intense heat waves can pose health risks.
Dangerously hot weather is already occurring more often than it was 60 years ago. Scientists warn that heat waves could become more frequent and severe as global warming intensifies.
This increase in heat waves creates serious health risks and can lead to exhaustion from heat stroke and aggravate other existing medical conditions.
Consequences for human health
Respiratory problems can be intensified with global warming.
Climate change has significant implications for our health.
The increase in temperature on the planet has some consequences, such as the increase in air pollution that generates, for example, respiratory and dermatological allergies and the spread of diseases transmitted by insects.
Destruction of marine ecosystems
Marine ecosystems also suffer from global warming.
Higher concentrations of CO2 in the atmosphere, due to the burning of fossil fuels, are making the oceans warmer and more acidic.
These two factors threaten the survival of marine life. Corals, molluscs and phytoplankton, which are the base of the food chain, are particularly at risk.
Meet the phytoplankton.
The ozone layer and global warming
The stratospheric ozone layer absorbs ultraviolet (UV) radiation, preventing harmful UV rays from reaching the Earth's surface and harming living organisms. UV rays cannot be seen or felt, but they are very powerful and change the chemical structure of molecules.
This same radiation plays a small role in global warming because its quantity is not enough to cause excess heat trapped in the atmosphere.
But ozone depletion is also worrying because it directly affects the health of humans and other living organisms.
Ozone depletion and global warming
Global warming is mainly caused by the excessive emission of carbon dioxide into the atmosphere, as mentioned above.
Carbon dioxide spreads around the planet like a blanket and is one of the main gases responsible for the absorption of infrared radiation (felt as heat), which comprises most of the solar energy.
Ozone depletion occurs when chlorofluorocarbons (CFCs) are released into the atmosphere. Ozone stays in the upper atmosphere and absorbs ultraviolet rays, another type of solar energy that is harmful to humans, animals and plants.
CFCs cause chemical reactions that break down ozone molecules, reducing ozone's ability to absorb ultraviolet radiation.
Also read the meanings of ozone layer and radiation.
How to prevent global warming?
To prevent the advance of global warming, it is necessary to reduce and control the activities that cause it: gas emissions, pollution and deforestation.
There are big moves around preventing and stagnating global warming. Some world treaties have been established so that the pollution caused by humanity is reduced and that there is an awareness of the matter.
One of the best known agreements is the Montreal Protocol, with 32 years in force, and which aims to unite countries in favor of the elimination of 31 substances that deplete the ozone layer.
This whole movement was started when experts alerted the major political authorities about the risks that the environment and, consequently, humanity will suffer due to the increase in the temperature of the planet.
See too:
- Atmospheric pollution
- Carbon dioxide
- Atmosphere layers
