Global Warming: Causes, Mechanisms, and Consequences

This rise in temperature impacts the global climate, leading to extreme weather events, rising sea levels, and ecosystem changes. The phenomenon is driven by the greenhouse effect, a natural process that makes Earth habitable by retaining heat. The problem arises when human activities amplify this effect, causing unsustainable warming with severe consequences.

How Does Global Warming Work?

Earth's climate is influenced by the balance between incoming and outgoing energy. The sun emits shortwave radiation (visible light) that reaches and warms Earth's surface. The planet then emits this energy as heat. Without greenhouse gases, this heat would escape into space, and the planet would be approximately 33 degrees Celsius colder—too cold to sustain life as we know it.

However, Earth's atmosphere contains natural greenhouse gases that trap some of this heat and redirect it back to the surface. This process, known as the greenhouse effect, is essential for life on Earth. The issue arises when human-induced greenhouse gas emissions intensify this effect, causing excess heat retention and an abnormal increase in Earth's temperature.

The process in summary:

• Solar radiation reaches Earth – Shortwave radiation passes through the atmosphere and warms the surface.
• Earth emits heat – The surface radiates heat as longwave infrared radiation.
• Greenhouse gases absorb the heat – Some of this heat is captured by greenhouse gases in the atmosphere.
• Heat is reflected back – Greenhouse gases redirect part of the heat back to Earth's surface, raising temperatures.

The more greenhouse gases we release, the more heat is retained, driving global warming and climate change.

Greenhouse Gases

Different greenhouse gases have varying properties and impact the climate in different ways. They differ 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 Primary Culprit

Carbon dioxide accounts for the largest share of human-induced warming and has a long atmospheric lifespan—up to several hundred years. CO₂ is a byproduct of burning fossil fuels (coal, oil, gas) and deforestation, and human activities have dramatically increased its concentration since the Industrial Revolution.

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

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

Methane is significantly more potent than carbon dioxide in the short term—about 28 times stronger over a hundred-year period. It mainly originates from biological processes such as livestock digestion and organic material decomposition in rice paddies or landfills.

• Sources: Livestock, rice cultivation, landfills, fossil gas extraction.
• Lifespan: About 12 years.
• GWP: 28*.
  

*28 times more potent according to IPCC AR5, 27 times more potent according to IPCC AR6.

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

Nitrous oxide is less known but extremely potent, about 265 times stronger than CO₂. It occurs naturally in soils but has increased dramatically due to nitrogen fertilizer use in agriculture.

• Sources: Fertilizers, waste management, industrial processes.
• Lifespan: About 114 years.
• GWP: 265*.

*According to IPCC AR5: 265, according to IPCC AR6: 273.

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

Fluorinated gases are synthetic and used in refrigeration, foam insulation, and certain industrial processes. They have extremely high warming potential—some are thousands of times stronger than CO₂.

• Sources: Refrigerants, electronics manufacturing, industrial processes.
• Lifespan: Decades to centuries.
• GWP: 1,000–23,000.

Human Impact on Climate

Natural processes have always influenced the climate, but the rapid increase in greenhouse gases due to human activities—anthropogenic emissions—is causing the ongoing global warming. Since industrialization, atmospheric CO₂ levels have risen from about 280 ppm (parts per million) to over 420 ppm, the highest in millions of years. In 2024, global temperatures exceeded 1.5 degrees Celsius for the first time, indicating that warming is progressing faster than anticipated.

Major sources of anthropogenic emissions:

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

The consequences of these emissions are already evident and worsening. To slow climate change and have a chance of staying within 1.5 degrees, we must completely halt fossil fuel combustion.

Effects of Global Warming

The consequences of global warming are already visible and are expected to worsen unless emissions are reduced.

• Extreme weather: Increased heatwaves, droughts, heavy rainfall, and storms.
• Rising sea levels: Melting glaciers and polar ice caps contribute to higher sea levels, threatening coastal communities.
• Food and water shortages: Drought and shifting precipitation patterns impact agriculture and freshwater availability.
• Ecosystem changes: Species face extinction as their habitats change.
• Health issues: Air pollution and heatwaves increase the risk of diseases and deaths.

Climate Justice

"Climate change is happening now and affects us all. 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 most."

Climate justice links global warming to social, ethnic, and environmental issues. It highlights how climate change disproportionately affects low-income communities and BIPOC populations, even though they have contributed the least to the problem. While climate change impacts all countries, its effects are not experienced equally or at the same time. This is why the fight against climate change is inseparable from the fight for justice and equity.

What needs to be done?

Addressing the climate crisis fairly and effectively requires acknowledging how different groups have contributed to climate change. While everyone must take action, it is unjust to expect those who contributed the least to bear the heaviest burden.

A crucial aspect of climate justice is the concept of "loss and damage," which recognizes that the most vulnerable communities, often the least responsible for climate change, will face unavoidable consequences they cannot adapt to. It is only fair that financial support for these losses comes from the nations most responsible for the crisis.

What Can We Do?

Advocating for climate justice is a collective responsibility. It involves amplifying the voices of frontline communities, voting for policies that prioritize climate action, and holding politicians accountable. Transparency is key in this fight—questioning corporate sustainability efforts to prevent greenwashing and understanding the intersectionality of climate impacts helps drive informed action. By engaging in discussions, raising awareness, and making informed choices, we can all contribute to a fairer and more sustainable future.