How Does CO₂ Cause Climate Change?

While carbon dioxide (CO₂) is naturally present in the atmosphere and essential for life on Earth, human activities have increased CO₂ concentrations over the past two centuries.  

Carbon Dioxide and Climate Change: Understanding the Connection  

CO₂ is not harmful at low concentrations and is simply a colourless, odourless gas that forms when carbon-containing substances burn or as a a by-product of respiration and certain natural processes, such as volcanic eruptions and decomposition. On the flip side, plants absorb CO₂ during photosynthesis, making it a central component of Earth’s carbon cycle.   

However, the balance of this cycle has been disrupted by human activities.  

Burning fossil fuels, deforestation, and industrial processes have dramatically increased CO₂ emissions, pushing the planet into a state of imbalance. 

So how does this imbalance affect the climate?  

CO₂ traps heat in the atmosphere. When sunlight reaches Earth, some of it is absorbed by the surface and then radiated back as heat. Greenhouse gases, including CO₂, absorb this heat and re-emit it, preventing it from escaping into space. This “greenhouse effect” keeps Earth warm enough to sustain life.   

The problem arises when excessive CO₂ emissions from human activities intensify this effect, trapping more heat and raising global temperatures. This warming drives a range of environmental changes collectively referred to as climate change. 

We are Experiencing Record-Breaking Earth Temperatures

Each year in the past decade has been hotter than the previous one, with 2024 being the first year to average over the 1.5°C above pre-industrial levels, the bar set by the Paris Agreement in 2015 as a critical point in global warming. [1] 

Besides the rise in the Earth’s temperature, another unwelcome record was achieved in 2024. Fossil fuel emissions reached a record level, and the use of fossil fuels continues, unabated. More than 37 billion tonnes were emitted in 2024, which is 8% higher than in 2015, the year the Paris Agreement was established. 

2024 hottest year on record graph

Effects of CO₂ on the Environment

Increased atmospheric CO₂ has far-reaching consequences for the environment and climate change and it manifests in numerous ways: 

Disrupted Weather Patterns and Extreme Weather-Related Events 

Excess CO₂ exacerbates extreme weather events, including more intense hurricanes, prolonged droughts, heatwaves and unpredictable rainfall. 

For example, climate scientists are warning that the circulation of the Atlantic meridional overturning circulation (Amoc) – a system of ocean currents that is a central part in global climate regulation and is part of the Gulf Stream – is being disrupted and could be heading for an imminent tipping point which will have disastrous climate consequences. [2] 

Melting Ice and Rising Sea Levels 

Glaciers and polar ice caps are melting at alarming rates, contributing to rising sea levels and threatening coastal communities. 

Ocean Acidification 

Oceans absorb about a third of CO₂ emissions, altering their chemistry. This acidification threatens marine life, particularly organisms with calcium carbonate shells, such as corals and shellfish. 

Biodiversity Loss 

Many species struggle to adapt to rapid environmental changes, resulting in habitat destruction and extinction risks. 

Shifts in Ecosystems 

Changing temperatures and precipitation patterns force plants and animals to migrate, disrupting ecosystems. 

Climate Mitigation Strategies

Mitigating climate change requires a multi-faceted approach that combines technological innovation, policy reforms, and collective action. 

Renewable Energy Adoption 

Transitioning to solar, wind, and hydroelectric power reduces reliance on fossil fuels. The good news is that renewable energy costs, particularly solar and wind, are falling and are now cheaper than fossil fuels in many regions, offering avenues to reduce emissions affordably. 

Energy Efficiency Improvements 

Enhancing the efficiency of buildings, transport, and appliances lowers energy consumption and emissions. Developments in e-fuels, like sustainable aviation fuels (SAF), and using captured carbon dioxide in construction, such as in concrete, have opened a door to a world of opportunities to remove CO₂ from the air and safely store or re-use it. 

Reforestation and Afforestation 

Planting trees absorbs CO₂ and restores ecosystems. 

Sustainable Agriculture 

Practices like crop rotation, reduced tillage, and improved livestock management can minimise emissions from agriculture. 

Carbon Penalties and  Incentives 

Mechanisms such as tax incentives or cap-and-trade systems motivate businesses to lower emissions. (See: Who is Responsible for Reducing Carbon Emissions to Fight Climate Change?) 

Carbon Capture to Address Climate Change

Carbon capture refers to the process of removing CO₂ from the atmosphere or industrial emissions. This approach is a cornerstone of efforts to limit global warming and achieve net-zero emissions. (See: DAC Technologies) 

Direct Air Capture (DAC) 

DAC (See: What is Direct Air Capture?) uses advanced technology to extract CO₂ directly from the atmosphere. The captured CO₂ can be: 

Carbon Capture and Storage (CCS) 

CCS focuses on capturing CO₂ from large industrial sources before it enters the atmosphere. Once captured, the CO₂ is compressed and transported to storage sites, typically deep underground. 

These technologies enable high-emission industries, like cement and steel production, to reduce their environmental impact while continuing operations. 

Direct Air Capture is pulling ahead when comparing DAC with CCSThe DAC units can be located anywhere, preferably at the location of storage or utilization, which eliminates the need for controversial pipelines running through urban areas. Furthermore, by being located away from built-up areas, DAC can use off-grid renewable energy that does not draw from the local grid. (See: Direct Air Capture vs Point Source) 

Countries and industries aiming for net-zero emissions must balance CO₂ output with removal. Carbon capture technologies are instrumental in this endeavour: 

Industrial Support 

Hard-to-abate sectors like cement, steel, and aviation can rely on DAC to offset emissions as DAC offers a location flexible. (See: Hard to Abate Industries and the Decarbonisation Challenge) 

Negative Emissions 

Technologies like DAC create opportunities for negative emissions by extracting more CO₂ than is emitted. 

Global Collaboration 

Many nations incorporate carbon capture in their climate plans to meet international targets under agreements like the Paris Accord. 

Conclusion

CO₂ emissions are a leading driver of climate change, with severe consequences for ecosystems and human societies. Addressing this challenge requires immediate and sustained efforts, including the widespread adoption of carbon capture technologies. By integrating solutions like DAC with renewable energy and sustainable practices, industries and nations can effectively reduce their carbon footprint and work towards a stable climate for future generations. 

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