What is Climate Change?

Climate Science Series


By now you have probably heard the terms climate change and global warming thrown around and heard from people who are adamant they are happening and those who are adamant that they aren’t. However, what do these terms really mean? How do we know if they are happening or not? In these journals, we are going to explain all the jargon surrounding this topic and hopefully make the subject much clearer. We’ll also let you know what you can do to fight climate change because every individual’s contribution can make a difference.

Global Warming

The term global warming refers simply to the warming of the Earth over the past century. Since the early 20th century the average temperature of the Earth’s surface and atmosphere has increased. This temperature is calculated by measuring the temperature across the entire globe during the year so seasonal changes and differences between local climates do not affect the results.

The results show unequivocally that the Earth is heating up. Although it may not always seem like it. The term global warming makes us picture warmer summers, more sunshine and less harsh winters. However, the effects of a heating planet are not as pleasant as it may seem.

Climate Change

The other term you hear floating around is climate change. This is often used interchangeably with the term global warming but in fact, there are subtle differences between the two.

While global warming refers purely to the heating of the Earth, climate change refers to the many changes in the climate that occur as a result of the heating of the Earth. This can be an increase in rainfall, more frequent extreme weather events, melting polar ice caps and many other impacts on the Earth’s climate.

The term climate on its own refers to the weather patterns of a particular location. For example, the Sahara desert has a very dry and hot climate and the climate of the UK is wet and moderate. Over the past few decades, we have noticed more extreme weather events such as hurricanes, smaller polar ice caps and shifts in the blooming of plants and flowers. These events are all due purely to the increase in Earth’s average temperature.

Graph showing the increase in CO2 levels since the industrial revolution. Credit NASA and Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record

The Greenhouse Effect

Why is the Earth’s temperature rising?  And how do we know that we are responsible for it?

The Earth’s atmosphere is responsible for controlling the temperature of the Earth and at the Earth’s surface. The atmosphere contains many gases which warm up the Earth in a process known as the greenhouse effect. If you have ever been inside a greenhouse you’ll know that inside it is much warmer than outside. This is because the glass is able to allow sunlight to pass into the greenhouse but traps the heat from the sun inside, warming up the plants.

The Earth’s atmosphere acts in a similar way. Light from the sun passes through the atmosphere and the heat generated radiates from the Earth’s surface. The gases in the Earth’s atmosphere trap this heat and reflect it back to Earth, thereby increasing the global temperature. The gases that cause this effect are known as greenhouse gases.

Without this phenomenon, the Earth would be too cold to be habitable. However, the effect is causing dramatic changes in climate that we are noticing today.

Greenhouse Gases

The major contributors to the greenhouse effect are water vapour, carbon dioxide (CO2), methane, nitrous oxide and chlorofluorocarbons (CFCs). Water vapour, CO2 and Methane are naturally present in the atmosphere whereas the presence of nitrous oxide and CFCs in the atmosphere are entirely due to human activity.

The reason that climate scientists believe that human activity is causing climate change is that the quantity of greenhouse gases in the atmosphere has increased over the past few decades. In particular, the proportion of CO2 has increased due to the emission of CO2 from the burning of fossil fuels and to a lesser extent – deforestation.


What we hope this article shows is that climate change is a real and measurable phenomenon that is irrefutable. Over the next few days, we will explain in more detail the evidence for man-made climate change and what can be done to stop it.

Next up: The Effects of Climate Change


  1. Image – Earth from Space – credit NASA; http://www.abc.net.au/science/articles/2014/09/05/4080293.htm
  2. https://climate.nasa.gov
  3. https://www.wwf.org.uk/climate-change-and-global-warming
  4. https://www.nationalgeographic.com/environment/global-warming/global-warming-overview/
  5. https://www.bbc.com/news/science-environment-24021772

Author: Olivia Drayson

Olivia is a Master's student of Space System Engineering at ISAE-SUPAERO in Toulouse, France. She also has a Bachelor's in Physics from the University of Oxford.

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