An Introduction to Understanding Climate Change, its Causes and Effects

Discussions on climate change have been around for a long time. I bet there’s not one person who has never heard of it. But who actually knows what it is? What are the driving forces? The consequences? The precautions? It is a prominent and extremely dangerous topic, and it is absolutely inevitable to talk about it. I hope this article can act as a starting introduction.


First of all, let’s clear up our terminology. The weather is not the equivalent of the climate. When we talk about weather, we mean the effects we can feel (depending on our location). Those can look like rain, sunshine, or cold. For example, in Germany it might be cold and rainy, while it may be hot and sunny in Australia.

The term climate, on the other hand, refers to the usual, average weather of a particular place. When we think of Antarctica, we think of a very cold and uncomfortable climate, and it’s the opposite when we think of Greece. But that does not mean that the weather is always cold and uncomfortable or nice and warm.

„Weather can change in just a few hours. Climate takes hundreds or even millions of years to change.“ – NASA

Climate Change

In conclusion, climate change is a change in the normal weather of one place. This doesn’t have to imply a change to the complete opposite. The weather in a place, let’s say Mexico, where it’s sunny and hot, flips and it’s solemnly cold and cloudy.

Climate change can be a change in the amount of rain a place usually gets in a month, a season, or a year. It can be a change in averages, variability, or extremes.

Driving forces

Weather and climate can change due to different factors. These include natural processes, like volcanic activities or the sun’s radiation, or human influences like changes in land use.

Greenhouse effect

Graphic explanation of the greenhouse effect
Credits: Efbrazil / Wikipedia

I guess we’ve all heard of the greenhouse effect, but who really knows what it’s about? To make it easier, it’s best to paint a visual picture. Some gases that are emitted into the atmosphere act like the glass of a greenhouse. They trap sunlight and heat and at the same time prevent it from getting back into space. They cause a warming of the earth – global warming.

Most of these greenhouse gases do exist naturally, but that doesn’t mean they are harmless. Although they would exist without human intervention, our activity increases the concentration. Higher concentrations equal greater harm. These gases include carbon dioxide, methane, nitrous oxide, and fluorinated gases.

There are many differences between these gases and I’m only going to focus on the general and most outstanding ones. The amount of atmospheric CO2 produced by human activities like the burning of fossil fuels is the largest driver of global warming. Once oil, gas, and coal are burned, they combine with oxygen and form CO2 which then rises into the atmosphere. Compared to pre-industrial levels, the CO2-concentration has risen to 48%.

Although methane is way more powerful, emissions are smaller. Furthermore, it has a shorter atmospheric lifetime, meaning it breaks down faster.


Gases coming from facrtories causing air pollution
Credits: Chris Leboutillier / Unsplash

The effect of aerosols can also be known as global dimming. Air pollution, stemming from fossil fuel burning and economic activity, reduces the amount of light, energy, and warmth from the sun. Aerosols have an indirect impact on the radiation budget of our planet. Some of them act as condensation nuclei of clouds, which leads to them having more and smaller cloud droplets. Those reflect the radiation of sunlight more effectively.

“Oh, so if they reflect sunlight and warmth, wouldn’t they help reduce global warming, since the amount of energy reaching the earth is smaller?” – Very valid question, but the answer is more complicated than you might think. Black carbon falling on snow or ice contributes to global warming. On one side, it leads to an increase of sunlight absorption, and on the other side, it increases the melting of ice and the following rise of the sea level.

Changes in land surface

Graphic visualization of the global tree cover loss up until 2017
Credits: Global Forest Watch

Agriculture and cattle farming are the driving forces for changes in land use. It is not only about the land that is needed as habitat for cattle animals. Even more land is used to plant the food for those animals. The biggest percentage of deforestation for agriculture can be found in rainforests. There is an overall loss of at least one-third of the forest cover that existed before the expansion of agriculture.

Differences in land use don’t only affect greenhouse gases, which then lead to climate change itself, but also lead to different chemical and physical changes. If the type or amount of vegetation in a particular area is changed, it inevitably has an impact on the local weather, sunlight reflection, and evaporation levels. An easy example is darker spots reflecting less light than lighter ones, just like dark forests reflect less light than lighter grasslands.



Climate change, changes in weather and global warming have many different effects. The most outstanding ones are obviously changes of temperatures and temperature extremes, but there are many more some might not even know about. I divided them into three parental categories.

Physical environment

Graphic visualization of global sea level rise
Credits: NASA Satellite / Wikipedia

It is possible for changes to appear gradually and develop over time or very rapidly. Drought, heat waves, wildfires and extreme weather conditions have increasingly appeared since the 1950s. Moreover, sea levels are rising as a consequence of glacial melting and melting of the ice sheets in Antarctica and Greenland. Furthermore, the oceans are warming, which, again, leads to melting of ice sheets and an estimated sea level rise of 2-meters by 2100.

Oceans are also in danger due to acidification because of dissolved CO2 and lower oxygen levels, since oxygen would be more soluble in colder water.

Nature and wildlife

Starving polar bear on a small ice field
Credits: Andreas Weith / Wikipedia

Due to climate change and warming of the oceans, many terrestrial and freshwater species are moving poleward and to higher altitudes. Higher temperatures combined with higher CO2 concentrations result in global greening while, at the same time, the increase in heatwaves and droughts reduce ecosystems. Furthermore, drier climate zones expand, which will lead to abrupt changes in many ecosystems and ultimately result in the extinction of many species.

The acidification of the ocean affects the production of shells and skeletons. Some of you may have heard of the tremendous bleaching of the Great Barrier Reef. And this is happening to most coral reefs worldwide. In addition, phytoplankton are dying. Phytoplankton act as the trees of the oceans and build the basis of the food-chain in the oceans. Even more importantly, they use sunlight, CO2, and water for photosynthesis to produce organic material.


Graphic visualization of the number of undernourished people worldwide
Credits: UN FAO /

The consequences of climate change don’t affect everyone equally. An overall trend of disadvantaged people (e.g., those living in underdeveloped countries) being more vulnerable to the effects is obvious.

Global warming leads to crop failures, which then lead to food shortages and mass hunger, especially in underdeveloped countries. The World Health Organization estimates an additional 250,000 deaths due to heat exposure. Moreover, a dramatic increase in diarrheal disease, malaria, dengue fever, coastal flooding, and the undernutrition of thousands of children. And from the year 2050 onwards, they project over 500,000 more deaths due to reduced food availability.

The evidence of a connection between climate change and livelihoods is undeniable. Global economic inequality is increasing, and the World Bank is projecting that, by 2030, over 120 million people will fall into poverty. Even more striking, all kinds of inequalities, in gender, status, ethnicities, will worsen with the increase of climate change. Extreme weather and climate conditions will lead to environmental migration between and within countries.

International agreements and policies

I guess we can agree on the urgent need for action to combat climate change, and luckily (most) leading politicians do too. But still, there are many different opinions and disagreements on driving forces and there are always people who just don’t seem to ever take responsibility. However, climate change has been a major threat for a long time now and there are many different climate agreements and goals I want to introduce you to.


The UNFCCC (United Nations Framework Convention on Climate Change) was formed in 1994 to preserve the climate system from the dangerous impacts humans can have on it. Nearly all countries are part of this convention and negotiate in yearly conferences. Some of the main goals include the reduction of greenhouse gases to a level to which ecosystems are able to adapt naturally. In this state, neither food production nor economic development are at threat.

Kyoto Protocol

The Kyoto Protocol acts as an extension to the UNFCCC and, other than the UNFCCC, includes legally binding commitments for most developed countries. Developing countries, on the other hand, require developed countries to act as leaders, since they make up most of the greenhouse gas concentration.

Paris Agreement

All countries of the UN introduced the Paris Agreement in 2015, which can be seen as a replacement for the Kyoto Protocol. However, there are no binding emission limits and they proceed to set more ambitious goals with the binding agreement to meet up every five years and evaluate the momentary situation. The main goals focus on the prevention of global warming rising above 1.5 °C (which, by the way, is most likely to happen by 2040 instead of the former date of 2050, according to the latest IPCC report).

Furthermore, the Paris Agreement emphasizes that developing countries need to receive financial support. Since President Biden signed the papers for the United States to reenter the PA, 194 states, the European Union have signed the Agreement.

IPCC reports

Visualization of how human influence has changed the climate and made it hotter
Credit: IPCC, 2021: Summary for Policymakers

I do want to take some time to scratch on the IPCC, since their newest report has been published only a few days ago. “The IPCC (Intergovernmental Panel on Climate Change) is the United Nations body for assessing the science related to climate change.” It consists of 195 governments, that are part of the UN or WMO. Researchers go through thousands of scientific papers every single year to break the information down to a comprehensive level which then is used in international negotiations about climate change.

They extract the most outstanding, scientifically backed-up and important “drivers of climate change, its impacts and future risks, and how adaptation and mitigation can reduce those risks” (IPCC).

They provide the state of knowledge about the human-induced part of climate change. Because the reports are being reviewed by different people in several stages, they do guarantee an objective outlook on the concerning issues.

Most recent report

"Unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions limiting warming to close to 1.5°C or even 2°C will be beyond reach.
Credits: IPCC / Instagram

In their latest report, they emphasized that the climate crisis is “unequivocally” caused by humans. Code red for humanity was declared. It has been eight years since their last assessment report and the 234 scientists reviewed 14,000 papers to publish the 3949 pages report (shorter versions are available as well). Some of the most striking information includes:

  • The past five years have been the hottest on record since 1850.
  • The global surface temperature was 1.09°C higher between 2011-2020 than between 1850-1900.
  • Temperatures are likely to reach 1.5°C above pre-industrial levels by 2040.
  • The recent rate of sea-level rise has nearly tripled compared with 1901-1971.
  • Sources: IPCC. (2021). The Physical Science Basis.; BBC. (2021). IPCC Report.; (2021). Instagram Postings.

António Guterres (UN Secretary-General) stated, “If we combine forces now, we can avert climate catastrophe. But, as today’s report makes clear, there is no time for delay and no room for excuses. I count on government leaders and all stakeholders to ensure COP26 is a success.”

Actions to take

List of top actions to reduce your carbon footprint. live car-free, battery electric car, one less long-haul flight per year, renewable energy, public transport, refurbished, vegan diet, heat pump, improved cooking equipment, renewable-based heating
Credits: Centre for Research into Energy Demand Solutions / BBC 

There are many ways to help prevent climate catastrophe. It isn’t possible to change what has already been done, but there are ways to stop the situation from worsening much further. The term climate change mitigation covers actions that aim to limit global warming and all related consequences. Some of them obviously include the reduction of greenhouse gas emissions. The following are only three dimensions in which change is necessary.

  • Clean energy. The excessive use of coal, oil, and gas contributes 1100 billion tons of additional CO2 to the atmosphere. And many more billions of tons are set free due to the burning of forests (due to deforestation and environmental catastrophes). It is necessary to switch to sustainable green energies like wind and solar power.
  • Agriculture. As mentioned above, agriculture leads to more and more deforestation. But what some might not know, agriculture (just like coal mining) leads to additional emissions of methane gas. The concentration of methane in the atmosphere exploded to 1870 ppb (parts per billion) compared to 715 ppb in pre-industrialization times. Changes in the way agriculture is proceeded as well as dietary changes are desperately needed.
  • Transportation. There are over 1.3 billion cars on this planet, and only 10 million of them are electric. In 2018, 26% of all CO2 emissions in the EU were caused by road traffic, in comparison to only 16% in 1990. There are more alternatives to cars fueled with petrol, for example, electric cars, hydrogen cars, or simply taking your bike, public transportation, or walking whenever possible.

Why it is important to understand climate change

It is hard to describe the state our world is currently in and has been in for a long time now. To find the right words to make the danger stick is even more difficult, which is why I am not even going to try to. I will simply end with the following quotes, which will hopefully help you see the need for action.

“By polluting the oceans, not mitigating CO2 emissions and destroying our biodiversity, we are killing our planet. Let us face it, there is no planet B.” – Emmanuel Macron, President of France

“We are the first generation to feel the effects of climate change and the last generation who can do something about it.” – Barack Obama, Former US President

“Adults keep saying we owe it to the young people, to give them hope, but I don’t want your hope. I don’t want you to be hopeful. I want you to panic. I want you to feel the fear I feel every day. I want you to act. I want you to act as you would in a crisis. I want you to act as if the house is on fire, because it is.” – Greta Thunberg, 17-year-old Swedish Activist

Feature image credits: Marie Rothenberger

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