Global Warming: Causes, Mechanisms and Consequences

This temperature increase affects the global climate and leads, among other things, to extreme weather, rising sea levels, and altered ecosystems. The phenomenon is driven by the greenhouse effect, a natural process that makes the Earth habitable by retaining heat. The problem arises when human activity amplifies this effect, leading to unsustainable warming with enormous consequences.

How Does Global Warming Work?

The Earth's climate is influenced by the balance between incoming and outgoing energy. The sun emits shortwave radiation (visible light) that reaches the Earth's surface and warms it. The Earth then emits this energy in the form of heat. In a world without greenhouse gases, this heat would radiate into space and the planet would be about 33 degrees colder – a climate too cold to sustain life as we know it. But the Earth's atmosphere contains natural greenhouse gases that trap some of this heat and send it back to the Earth's surface. This is called the greenhouse effect and is vital for life on Earth. The problem arises when human emissions of greenhouse gases intensify this effect, causing more heat to remain in the atmosphere and the Earth's temperature to increase abnormally. In brief:

• Solar radiation hits the Earth – Shortwave radiation passes through the atmosphere and warms the Earth's surface.
• The Earth emits heat – The heat radiates out in the form of longwave infrared radiation.
• Greenhouse gases absorb the heat – Some of the heat is trapped by greenhouse gases in the atmosphere.
• The heat is reflected back – The greenhouse gases send some of the heat back to the Earth's surface, making the temperature warmer.

The more greenhouse gases we emit into the world, the more heat is retained, driving global warming and causing the climate to change.

Greenhouse Gases

Different greenhouse gases have different characteristics and contribute to climate change in different ways. They vary in lifespan (how long they remain in the atmosphere) and global warming potential (GWP), which measures how much a gas contributes to warming compared to carbon dioxide (CO₂).

1. Carbon Dioxide (CO₂) – The Main Culprit

Carbon dioxide accounts for the largest share of human-induced warming and has a long lifespan in the atmosphere – up to several hundred years. Since CO₂ is a byproduct of fossil fuel use (coal, oil, gas) and deforestation, human activities have dramatically increased the amount of carbon dioxide since the start of industrialization.

• Sources: Burning of fossil fuels, cement production, deforestation.
• Lifespan: Hundreds of years.
• Global Warming Potential (GWP): 1 (baseline).

2. Methane (CH₄) – A Powerful but Short-Lived Gas

Methane is much more powerful than carbon dioxide in the short term – about 28 times stronger over a hundred-year period. It mainly comes from biological processes such as digestion in livestock and the decomposition of organic material in, for instance, rice paddies or landfills.

• Sources: Livestock, rice paddies, landfills, natural gas extraction.
• Lifespan: About 12 years.
• Global Warming Potential (GWP): 28.

3. Nitrous Oxide (N₂O) – The Hidden Climate Culprit

Nitrous oxide is a less well-known but extremely powerful greenhouse gas, about 265 times stronger than carbon dioxide. It forms naturally in soil but has increased significantly due to the use of nitrogen fertilizers in agriculture.

• Sources: Synthetic fertilizers, waste management, industrial processes.
• Lifespan: About 114 years.
• Global Warming Potential (GWP): 265.

4. Fluorinated Gases (F-Gases) – Man-Made Super Gases

Fluorinated gases are a group of synthetic gases used in cooling systems, foam plastics, and certain industrial processes. They have a very high warming potential – some are thousands of times stronger than CO₂.

• Sources: Refrigerants, electronics production, industrial processes.
• Lifespan: Decades to centuries.
• Global Warming Potential (GWP): 1000–23,000.

Human Impact on the Climate

Natural processes have always influenced the climate, but it is the rapid increase in greenhouse gases due to human activities – anthropogenic emissions – that is causing the ongoing global warming. Since industrialization, the concentration of CO₂ in the atmosphere has risen from about 280 ppm (parts per million) to over 420 ppm, which is the highest level in millions of years. 2024 was the first year that the global temperature was over 1.5 degrees, showing that warming is happening faster than expected.

The Largest Sources of Anthropogenic Emissions:

• Burning of fossil fuels – Power plants, transportation, industry, and heating.
• Deforestation – Forests act as carbon sinks, but when trees are cut down, stored CO₂ is released.
• Agriculture – Livestock produce methane, and the use of synthetic fertilizers leads to nitrous oxide emissions.
• Industrial processes – Cement production, chemical manufacturing, and the use of F-gases.

The consequences of these emissions are already evident and increasingly tangible, and we need to stop burning fossil fuels completely to curb climate change and have a chance of staying at 1.5 degrees.

Effects of Global Warming

The consequences of global warming are already noticeable and are expected to worsen if emissions are not reduced and we do not slow down climate change.

• Extreme weather: Increased heat waves, droughts, heavy rainfall, and storms.
• Rising sea levels: Melting glaciers and polar ice cause sea levels to rise, threatening coastal communities.
• Food and water shortages: Drought and altered precipitation patterns affect agriculture and freshwater availability.
• Ecosystem changes: Species risk extinction as their habitats change.
• Health problems: Air pollution and heat waves increase the risk of illnesses and fatalities.

Climate Justice

“Climate change is happening now and affecting all of us. No country or society is immune,” says UN Secretary-General António Guterres. “And, as always, it is the poor and vulnerable who suffer first and worst.”

Climate justice connects global warming with social, ethnic, and environmental issues that are closely interlinked. Climate justice highlights the disproportionate effects of climate change on low-income communities and BIPOC communities worldwide, which are the people and places that have contributed the least to the problem. Global warming affects every country in the world, but the changing climate does not affect everyone in the same way or at the same time. This is why the fight against climate change cannot be separated from the fight for justice and equality. People in the most vulnerable groups are often also those who have historically and currently been much more exposed to the catastrophic effects of climate change – such as depleted natural resources, water shortages, wildfires, floods, and so on.

What Needs to Be Done?

How can we address the climate crisis in a way that is both fair and effective, without repeating the mistakes that got us here? Achieving climate justice requires acknowledging how different groups have contributed to climate change. It is crucial that everyone helps mitigate the effects of warming, but it is unfair to expect those who have contributed the least to climate change to bear the greatest burden. Another critical aspect of climate justice is the concept of “loss and damage.” This concept recognizes that the most vulnerable communities, which are often the least responsible for climate change, will suffer unavoidable consequences that they cannot adapt to. It is fair that financial support to address these losses comes from the countries most responsible for the climate crisis.

Why Is Climate Justice Necessary?

The principles of climate justice are reflected in the Paris Agreement, highlighting two key concepts: historical responsibility and common but differentiated responsibilities. The former recognizes that not everyone has contributed equally to climate change, while the latter states that although everyone must take action, it should be done in proportion to their contribution to the crisis. This approach underscores the need for a nuanced and equitable response to the global challenge of climate change.

What Can We Do?

Advocating for climate justice is a collective responsibility that each of us can shoulder. It involves amplifying the voices of underrepresented frontline communities by ensuring their perspectives are heard and valued. Another critical aspect is voting conscientiously, focusing on policies that prioritize climate action, highlighting the significant impact individual choices have on driving positive change. Contacting and placing demands on politicians—whether they received your vote or not—to call for meaningful and fair climate action is also crucial. The key in the fight for climate justice is transparency. It is important to question and understand how communities actively work on climate issues, and to scrutinize companies’ sustainability efforts to avoid greenwashing. Furthermore, delving into the concept of “intersectionality” reveals the multifaceted effects of the climate crisis and highlights how different forms of inequality and discrimination are directly related to climate change. Discussing the climate crisis with others, encouraging reflection and dialogue, plays a crucial role in raising awareness in society. Such conversations can shed light on different perspectives and inspire collective action among those who may not have previously engaged. Examining and questioning information is equally important; diversifying sources and considering different viewpoints helps build a comprehensive understanding of the climate crisis, enabling informed discussions and decisions. Through these multifaceted efforts, we can all contribute to a more just and sustainable future.

Summary

Global warming is a consequence of human emissions of greenhouse gases, primarily carbon dioxide from the burning of fossil fuels. The greenhouse effect, which is fundamentally a natural and vital process, is intensified by these emissions, leading to rising temperatures and severe consequences for the planet and its inhabitants. The solution lies in reducing emissions, improving energy use, and adapting society to the changes already underway. The consequences of climate change are multifaceted and serious. Extreme weather events such as droughts, floods, and stronger hurricanes are becoming more frequent, causing damage to infrastructure, loss of human life, and significant impacts on agriculture and water supply. Today, about 21.5 million people are displaced as a result of these changes. By 2050, the UNHCR estimates that up to 1 billion people may become climate refugees. Furthermore, rising sea levels—due to melting glaciers and polar ice, as well as warming ocean water—pose a growing threat to coastal communities and island nations. Biodiversity is also negatively affected, as many species are forced to find new habitats or risk extinction as a result of the changing climate. This can disrupt ecosystem balance and affect important processes such as pollination and water purification.

Sources: https://www.europaportalen.se/2025/01/2024-slar-alla-tidigare-varmerekord-forsta-aret-over-15-grader