What Activities Concerning The Carbon Cycle Are Contributing To Climate Change?

The carbon cycle is the cyclical process by which carbon moves through the Earth’s various systems, including the biosphere, lithosphere, atmosphere, and hydrosphere. It involves processes like photosynthesis, respiration, decomposition, ocean absorption, weathering of rocks, and combustion of fossil fuels. Within the carbon cycle, carbon exists in various forms like carbon dioxide, methane, carbonates, and organic carbon. Climate change refers to long-term shifts in global weather patterns, primarily caused by human activities like burning fossil fuels that release greenhouse gases like carbon dioxide into the atmosphere. As greenhouse gas levels rise, more heat is trapped, causing global temperatures to increase.

Human activities are disrupting natural carbon cycle processes and contributing to climate change. Key carbon cycle processes that are being impacted include:

Fossil Fuel Combustion

Burning of coal, oil and natural gas releases CO2 into the atmosphere. The combustion of fossil fuels like coal, oil and gas emits roughly 35 billion tons of CO2 into the atmosphere per year. This release of carbon into the atmosphere is the primary driver of climate change.

Global CO2 emissions from fossil fuel combustion have increased significantly over the past decades. In 1990, emissions were about 22 billion tons per year globally. By 2019, they had increased to almost 37 billion tons per year, a rise of over 60%. This increase is largely driven by energy demand growth and lack of progress in clean energy transition.

Coal contributes about 46% of CO2 emissions from fossil fuel combustion, oil provides 34%, and natural gas 20%. While developed countries like the US and EU have reduced coal use, it has increased in developing Asian countries. Overall, fossil fuels still make up about 80% of primary energy use globally.

Reducing fossil fuel emissions is critical to mitigate climate change. This requires transitioning to renewable energy sources, improving energy efficiency, electrifying transport and heat, deploying carbon capture and storage, and rethinking energy systems. Significant emissions reductions are needed globally to stabilize the climate.


Deforestation is a significant contributor to climate change through its impact on the carbon cycle. When forests are cleared, either by burning or timber harvesting, large amounts of stored carbon are released into the atmosphere. Trees naturally absorb and store carbon dioxide through photosynthesis. Global forests currently store over 1 trillion tons of carbon. When they are cut down or burned, most of that stored carbon is emitted as carbon dioxide.

The rate of global deforestation remains high, particularly in biodiversity hotspots like the Amazon and Southeast Asia. According to the UN Food and Agriculture Organization, the world lost around 10 million hectares of forest annually between 2015-2020. At this pace, an area of forest the size of the United Kingdom is lost every year. Much of this is due to agricultural expansion, which accounts for over 70% of deforestation globally.

In addition to releasing carbon into the atmosphere, deforestation also reduces the earth’s capacity to absorb future CO2 emissions. Preventing further deforestation and reforesting degraded areas is widely recognized as one of the most effective climate mitigation strategies. Recent research suggests that restoring forests worldwide could remove two thirds of all the emissions that have been pumped into the atmosphere by human activities.


Modern agricultural practices have substantially increased emissions of nitrous oxide (N2O) and methane, which are potent greenhouse gases. The use of synthetic nitrogen fertilizers and increased livestock production are major contributors.

Globally, emissions from crop and livestock production rose nearly 14% between 2000-2010. The FAO estimates agriculture accounts for 10-12% of total global emissions. Nitrous oxide emissions from synthetic fertilizers increased by 35% during this period as fertilizer use has intensified to increase yields. Methane emissions from livestock manure management rose 17% as meat and dairy consumption increased.

Emissions are projected to rise another 30% by 2050 as food production expands to feed a growing population. Strategies such as optimizing fertilizer application, low-emission manure management, and sustainably intensifying yields on existing farmland can help curb agricultural emissions. Widespread adoption of plant-based diets would also substantially reduce methane from livestock.

Cement Production

Making cement releases CO2 from limestone. The process of making cement requires firing calcium carbonate (raw limestone) at very high temperatures, which releases CO2 gas. As the demand for cement has grown substantially in recent decades, so have the CO2 emissions from cement production.

Global cement production has more than quadrupled since 1950. China alone produces over half of the world’s cement. With this massive growth, cement production is now responsible for around 8% of global CO2 emissions from fossil fuel use and industrial processes. If cement production were a country, it would be the world’s third largest emitter!

Most emissions from cement production come from the chemical reactions in the production process itself. But cement manufacturing is also very energy-intensive, requiring very high temperatures. The fuels burned to heat the kilns also release additional CO2. The industry has made some improvements in efficiency, but not enough to offset the huge growth in cement production happening around the world.

Wetlands Destruction

Draining wetlands releases large amounts of stored methane and carbon into the atmosphere. Wetlands are incredibly carbon-rich environments, with soil that can contain several times more carbon than typical terrestrial ecosystems. This carbon has been steadily accumulating for thousands of years as dead plant material inundates the saturated, low oxygen soils. Draining wetlands exposes the soil to oxygen, accelerating decomposition and carbon release.

It is estimated that natural wetlands store over 35% of global soil carbon, despite occupying only 5-8% of land surface. Unfortunately, over 50% of natural wetland area has been lost since 1900 due to drainage for agriculture and development. For example, 87% of natural wetland area in New Zealand has been converted to farmland. The draining and burning of peatland wetlands in Indonesia alone contributes over 3% of annual global fossil fuel emissions.

Preserving remaining wetlands is crucial to prevent further carbon release and climate impact. Restoring drained wetlands could also recapture substantial amounts of carbon, while providing additional ecosystem services like flood control and wildlife habitat.

Waste Management

Landfills are a major contributor to methane emissions due to the anaerobic decomposition of organic waste. Methane is a potent greenhouse gas, with over 25 times the global warming potential of carbon dioxide. Global waste-related methane emissions increased by over 15% from 1990 to 2020. This rise is largely attributed to increasing municipal solid waste generation per person as economies and populations grow. However, some countries have managed to decrease their methane emissions from landfills by capturing the gas and using it for energy production. Overall though, most global methane emissions from landfills remain uncaptured. With municipal solid waste expected to continue rising as more of the global population becomes urbanized and consumption levels increase, waste management represents an important focal point in climate change mitigation efforts. Proper waste sorting, recycling, composting, and methane capture at landfills can help reduce emissions.

Melting Permafrost Releasing Huge Amounts of CO2 and Methane

Permafrost is permanently frozen ground found mostly in the Northern Hemisphere. It contains large amounts of organic carbon accumulated over thousands of years from dead plants, animals, and microbes trapped within the frozen soil.

As global temperatures increase, permafrost is starting to thaw and melt at an alarming rate. When permafrost thaws, the organic material becomes exposed to warmth and oxygen. This causes the material to decay and release massive quantities of carbon dioxide (CO2) and methane into the atmosphere.

thawing permafrost releases large amounts of potent greenhouse gases like co2 and methane
Methane is an extremely potent greenhouse gas, with 25 times the warming impact of CO2 over a 100 year period. The release of methane from thawing permafrost represents a dangerous amplifying feedback loop that will accelerate global warming.

Current estimates indicate there are about 1,500 billion tons of carbon locked away in frozen permafrost soils, which is almost double the amount of carbon currently in the atmosphere. If huge amounts of permafrost thaw, as is happening now, much of this carbon would be released as extra CO2 and methane, causing substantial further warming.

Ocean Acidification

The oceans absorb about 30% of the carbon dioxide produced by human activities. When carbon dioxide dissolves in seawater, it produces carbonic acid. This leads to a phenomenon called ocean acidification, which decreases the pH of seawater and makes it more acidic. Since the beginning of the Industrial Revolution, the average pH of ocean surface waters has dropped from 8.2 to 8.1. This may seem like a small change, but it actually represents a 30% increase in acidity.

This increased acidity harms many marine organisms that build shells and skeletons out of calcium carbonate, like corals, shellfish, and some types of plankton. The more acidic the water, the more difficult it is for these organisms to form their shells and skeletons. Acidification has been linked with decreased growth rates in corals, shell thinning in plankton, and impaired development of larval oysters. Declines or losses of these species would impact larger marine food webs and ecosystems. For example, coral reefs provide important habitats for a diversity of marine life.

If high carbon dioxide emissions continue, scientists project the average ocean pH could fall to 7.8 or lower by the end of the century. This would result in ocean acidity levels not experienced for tens of millions of years. Such fundamental changes to ocean chemistry could lead to profound impacts on marine ecosystems around the world. Reducing carbon dioxide emissions is crucial to limit further ocean acidification and its detrimental effects.


In summary, human activities are significantly disrupting the natural carbon cycle, leading to increased concentrations of carbon dioxide in the atmosphere and exacerbating climate change. Key activities that contribute include the burning of fossil fuels for energy, transportation, electricity and heat; deforestation, particularly in tropical regions; industrial agriculture and livestock production; cement manufacturing; the destruction of carbon-rich wetlands; waste production and disposal; thawing permafrost; and the acidification of the oceans.

The impacts of these carbon cycle interruptions are wide-ranging, from rising global temperatures, shifting precipitation patterns and increased frequency of extreme weather events, to melting glaciers, rising sea levels, warming and acidifying oceans, and overall challenges to ecosystems and biodiversity. Urgent solutions are required to mitigate and adapt to climate change, including rapidly transitioning from fossil fuels to renewable energy sources; switching to sustainable agricultural practices; preserving forests and wetlands; reducing waste and improving recycling; developing climate-friendly infrastructure; and implementing strong climate policies at the city, state, national and international levels. With coordinated global action, we can restore balance to the carbon cycle, reduce greenhouse gas concentrations in the atmosphere, and create climate resilience.

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