CLIMATE CHANGE
What is climate change?
Climate change refers to long-term shifts in temperatures and weather patterns.
All this talk about climate change...
What are we actually
talking about?
What is the cause of climate change?
Around the world, human activities cause the emission of greenhouse gases (gases present in large numbers in the Earth's atmosphere, which trap heat on Earth). These human activities mainly include energy production, transport, manufacturing goods, growing food and cattle farming. Energy production, transport and manufacturing goods all demand fossil fuels, all non-renewable energy sources, such as petrol, coal and gas, which, once combusted (burned), produce large quantities of greenhouse gases. Agricultural soils release a greenhouse gas named nitrous oxide, whilst livestock emits methane, as it digests grasses and plants. In addition to that, agricultural production being a main cause of deforestation (the action of clearing a wide area of trees), large spaces are cleared to host agricultural sites, reducing the quantity of plants removing carbon dioxide, a greenhouse gas, from the atmosphere.
From 1960 to 2020, the quantity of carbon dioxide in the atmosphere in particles per million has grown from 310 particles per million to 410 particles per million; in other words the quantity has grown by 100 particles per million in 80 years. Studies show that, if no modifications are made to our daily consumption methods, global atmospheric carbon dioxide concentrations could reach 550 particles per million by 2050.
With the growth of the global population, countries demand more and more from human activities, emitting more and more greenhouse gases.
Why are greenhouse gas emissions the main cause of climate change?
The Earth’s surface, warmed by the Sun, radiates heat into the atmosphere. Most of this heat makes its way out of the atmosphere and into space. In an environment in which the presence of greenhouse gases is moderate and natural, the heat can take three different paths: it can directly make its way to space, be absorbed by greenhouse gas molecules and radiated outside of the atmosphere, or it can be absorbed by greenhouse gas molecules and radiated back to the Earth’s surface. With the continuous increase of greenhouse gases in the Earth’s atmosphere, a rising amount of heat is absorbed by these, resulting in the heat being redirected to the planet’s surface, then radiated back towards space, only to be absorbed by a greenhouse gas molecule again. Due to this vicious circle, heat remains trapped in the Earth’s atmosphere, warming the planet.
Above: (Left) The Earth’s surface, warmed by the Sun, radiates heat into the atmosphere. Some heat is absorbed by greenhouse gases like carbon dioxide and then radiated to space (A). Some heat makes its way to space directly (B). Some heat is absorbed by greenhouse gases and then radiated back towards the Earth’s surface (C). (Right) With more carbon dioxide in the atmosphere later this Century, more heat will be stopped by greenhouse gases, warming the planet. (Image: L.S.Gardiner/UCAR)
The consequences of climate change
Rising temperatures
With heat remaining trapped in the Earth’s atmosphere, the global surface temperature is rising. “According to an ongoing temperature analysis led by scientists at NASA’s Goddard Institute for Space Studies (GISS), the average global temperature on Earth has increased by at least 1.1° Celsius (1.9° Fahrenheit) since 1880. The majority of the warming has occurred since 1975, at a rate of roughly 0.15 to 0.20°C per decade,” announces NASA Earth Observatory. 2024 has been recorded as the warmest year on record, whilst the 2015-2024 decade has been named the warmest decade on record, with the global mean temperature being 1.19 to 1.22°C warmer than pre-industrial level.
Image: Climate Central
Extreme weather
Higher temperatures cause worldwide climatic issues. Not only are nearly all of Earth’s land areas experiencing more hot days and heat waves, but the risk of wildfires has been multiplied by 3.
Rising temperatures increase the quantity of water and moisture being evaporated. This leads to heavy rainfall. Tropical storms such as hurricanes, cyclones and typhoons develop from warm ocean surface waters. Storms’ strong winds and rainfall result in flooding, sewage overflow, the blockage of water supplies and destroy buildings and infrastructures, including power lines, leading to power outages. Such effects often destroy communities, and cause important economic losses, as well as injuries and deaths.
Image: Thousands Evacuated on Greek Island of Crete as Winds Fan Wildfire
The New York Times
3 July 2025
Warming oceans
It is estimated that the ocean stores about 91% of excess heat trapped in the atmosphere. As a result, the ocean is warming faster than ever recorded. This provokes an increase in the ocean’s volume as water expands as it gets warmer and as ice melts, making the ocean levels rise and low-lying lands disappear. Studies show that Arctic ice is melting so fast it could entirely disappear by 2040. Furthermore, the ocean also absorbs carbon dioxide, a greenhouse gas. This gas lowers the ocean’s pH, making it more acidic. Many marine species use minerals present in ocean water to build their shells. The amount of these minerals, such as carbonate, present in the water is reduced by ocean acidification. This makes it more difficult for species such as plankton to build their shells, and already existing shells may begin to dissolve. On top of absorbing carbon dioxide, ocean plankton provide the primary food source for the oceanic food web. Without them, the Earth would experience a significant decrease in atmospheric oxygen and most ocean life would be impossible.
Image: Average Global Sea Surface Temperature, 1880–2023
United States Environmental Protection Agency
Water scarcity, unpredictability and pollution
Rising temperatures disrupt precipitation patterns as evaporation rates increase, and soil erosion (the process of being worn away, in this case by destruction of vegetation) reduces groundwater recharge, leading to water scarcity and droughts. In addition to this, the growing demand for water for practices such as water-intensive agriculture like food production and crop growing further consumes water resources. Extreme weather consequences such as flooding and heavy rainfall and the rise in sea levels due to ocean warming can contaminate water resources, posing an immense sanitary risk.
Image: Statista
Food scarcity
According to the United Nations Food and Agriculture Organisation, almost half (44%) of the world’s habitable land is used for agriculture. With the overexploitation of these lands and overgrazing (excessive feeding on grassland, performed by animals) due to high demand, as well as a rising risk of extreme weather and poor irrigation (the supply of water to land to help growth) due to climate change, crops and livestock decline. The rise in desertification (the process by which fertile land becomes desert) reduces agricultural land. Similarly, ocean acidification and melting ice reduce marine resources. As Action Against Hunger states, “Climate change is a long-term threat to food security and nutrition. By 2050, the risk of hunger and malnutrition could rise by 20% if we fail to reduce and prevent the adverse effects of climate change.”
Image: Describes an experimental Hunger and Climate Vulnerability Index showing the relative vulnerability of food insecure populations to climate risks at country level, as a tool for better understanding risks to food security presented by climate change.
Research Gate
Endangered species
Climate change and its impacts severely threaten natural habitats and ecosystems all across the globe, on land as much as in the ocean. Extreme weather, wildfires, melting ice, rising temperatures, droughts and diseases present in polluted waters all affect animals’ natural environment, forcing them to relocate and adapt. However, over one million animal and plant species are at risk of extinction as they cannot survive these changes.
A polar bear stands on an ice floe near Manitoba, Canada, in 2012. Polar bears depend on sea ice, which is forming later in the fall and disappearing earlier in the spring.
Photograph by Paul Souders, CORBIS
National Geographic
Livelihoods in danger
In 2024, climate change and air pollution is considered as the greatest environmental risk to health by the World Health Organisation (WHO) . Climate change impacts health, with 99% of the world’s population living in places where the WHO air quality guidelines levels are not met, an increased risk of disease due to rising sea levels and floods, increased hunger and poor nutrition and pressures on mental health. Additionally, each year millions of people are forced to leave their homes because of extreme weather conditions. These include desertification, droughts, floods, hurricanes, cyclones, typhoons, rising sea levels and wildfires. The action of being forced to move is called displacement. In the first half of 2019 alone, 7 million people were displaced by weather events, leaving many vulnerable to poverty.
Image: Johannes Eisele AFP/Getty Images Mix of outdoor and indoor air pollution.
World Health Organisation
