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What is Global Warming?

EcologyGlobal Warming

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Ines Gendre

updated Aug 19, 2024

Copywriter specializing in environmental thematics at Greenly

Global warming is a pressing issue with increasingly visible impacts. Recent history has shown us devastating wildfires in California and Canada, catastrophic flooding in Pakistan, and unprecedented heatwaves across Europe. These events are clear indicators of significant environmental disruption.

Contrary to what some skeptics might say, global warming involves more than just rising temperatures. It is a growing threat to all species, especially humans.

👉 This article explores the primary causes of global warming, its effects on the planet, and the urgent need for action.

What is global warming?

Global warming, often referred to as "climate change" is the long-term increase in Earth's average surface temperature due to human activities. This rise in temperature is primarily caused by the increased concentration of greenhouse gases (GHGs) such as carbon dioxide, methane, and nitrous oxide in the atmosphere.

Put simply, these gases trap heat from the sun, preventing it from escaping back into space, which leads to a warming effect. This phenomenon has far-reaching consequences for our planet, affecting weather patterns, sea levels, and ecosystems globally.

What is the greenhouse effect?

To fully understand global warming, it's essential to understand the greenhouse effect, so what does this term mean?

The Earth absorbs energy from the Sun in the form of visible light. While some of this energy warms the surface, the Earth also emits energy back into space as infrared radiation. Greenhouse gases (GHGs) like carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and water vapor (H₂O) in the atmosphere absorb and re-radiate some of this infrared radiation, trapping heat and warming the planet.

The greenhouse effect can be explained through the following steps:

Solar radiation absorption - The Sun emits energy that reaches the Earth's atmosphere. About 30% of this energy is reflected back into space by clouds, atmospheric particles, and reflective surfaces like ice. The remaining 70% is absorbed by the Earth's surface, warming it.
Infrared radiation emission - The warmed Earth emits energy back toward space as infrared radiation.
GHG absorption and re-radiation - Greenhouse gases in the atmosphere absorb some of this infrared radiation and then re-radiate it in all directions, including back toward the Earth's surface. This process effectively traps heat in the atmosphere, preventing it from escaping into space.

Without the greenhouse effect, the Earth's average temperature would be about -18°C, far too cold to sustain life as we know it. Thanks to the natural greenhouse effect, the global average surface temperature is a much warmer +15°C.

However, there's a difference between the naturally occurring greenhouse effect and the anthropogenic greenhouse effect. The anthropogenic greenhouse effect refers to the human-induced greenhouse effect, generated by human activities, such as the burning of fossil fuels, deforestation, and industrial processes.

These activities have significantly increased the concentration of GHGs in the atmosphere, leading to unprecedented concentrations not seen in three million years. This increase directly impacts the global average temperature, which has risen by 1.1°C since the early 20th century, making the 2011-2020 period the warmest on record.

The anthropogenic greenhouse effect is the primary driver of global warming and is resulting in harmful changes in weather patterns, more extreme weather events, melting ice caps, rising sea levels, and disrupted ecosystems.

Year Interval	GHG Concentrations (ppm CO2-equivalent)	Global Temperature Rise (°C)
Pre-industrial	280 (approx.)	Baseline
1870-1920	290-300	~0.2°C
1920-1970	300-320	~0.4°C
1970-2020	320-410	~1.0°C
2020-2070 (projected)	410-500 (projected)	1.5-4.5°C (projected)

What are the main causes of global warming?

Burning fossil fuels

Fossil fuels, including coal, oil, and natural gas, are major contributors to global warming. The combustion of these fuels for energy production and transportation releases significant amounts of carbon dioxide (CO₂) and other greenhouse gases (GHGs) into the atmosphere, enhancing the greenhouse effect and raising global temperatures.

Historical context

The Industrial Revolution, which began in the late 18th century, marked a turning point in fossil fuel consumption. The widespread use of coal-powered steam engines, factories, and later, electricity generation. As industrialization spread, so did the reliance on fossil fuels. By the mid-20th century, oil and natural gas joined coal as primary energy sources, fueling transportation and industrial activities.

Since the pre-industrial era, atmospheric CO₂ levels have increased from about 280 parts per million (ppm) to over 420 ppm as of 2024. This rise correlates closely with the increase in global average temperatures, which have risen by approximately 1.1°C since the late 19th century.

Key sectors contributing to emissions

Energy production - The energy sector is the largest source of global CO₂ emissions. The International Energy Agency (IEA) estimated that over 75% of global carbon emissions stem from the energy sector. Electricity generation from coal, oil, and natural gas releases billions of tons of CO₂ annually.
Transportation - The transportation sector, which includes cars, trucks, airplanes, and ships, is another major source of CO₂ emissions. According to the UN Environment Programme (UNEP), it contributes approximately 25% of global CO₂ emissions from fossil fuel combustion.
Industry - Industrial processes, including the production of cement, steel, and chemicals, also contribute substantially to global GHG emissions. These activities not only burn fossil fuels for energy but also release CO₂ as a byproduct of chemical reactions.

Economic drivers

The rapid economic growth and industrialization in developing countries have led to increased fossil fuel consumption. Countries like China and India, which are experiencing significant economic expansion, have seen corresponding rises in GHG emissions. According to the European Commission's 2023 Report, China alone accounted for about 29.16% of global CO₂ emissions, while India contributed 7.33%.

The Anthropocene Era

The profound impact of human activities, particularly fossil fuel consumption, on the planet's climate has led some scientists to propose a new geological epoch: the Anthropocene. This era emphasizes the dominant influence of humans on the Earth's geology and ecosystems, marked by significant changes in climate patterns, biodiversity loss, and alterations to natural processes.

Deforestation

Deforestation is a significant driver of climate change, contributing to the increased concentration of greenhouse gases (GHGs) in the atmosphere. This process primarily occurs due to agricultural expansion, infrastructure development, mining, and urbanization.

💡 Land use changes, especially deforestation, account for between 12 and 20% of global greenhouse gas emissions.

Causes of deforestation

Agriculture - Clearing forests for cropland and pasture is a leading cause of deforestation. Large-scale agriculture, particularly for crops like soy and palm oil, results in vast forest areas being converted into farmland.
Infrastructure development - Building roads, dams, and other infrastructure projects often requires clearing large forest areas, leading to habitat destruction and increased carbon emissions.
Mining activities - Extractive industries, such as mining for minerals and fossil fuels, lead to significant deforestation and environmental degradation.
Urbanisation - Expanding cities and towns encroach upon forested areas, leading to habitat loss and increased carbon release.

Impact on climate

Forests act as natural carbon sinks, absorbing CO₂ from the atmosphere and storing it in biomass and soil. When forests are cut down or burned, the stored carbon is released back into the atmosphere, exacerbating global warming. According to the Food and Agriculture Organization (FAO), approximately 10 million hectares of forest are lost annually.

The cycle of deforestation and climate change

Deforestation not only contributes to climate change but is also aggravated by it. Increased global temperatures and prolonged droughts make forests more susceptible to wildfires. These fires destroy large forest areas, releasing vast amounts of CO₂ and creating a feedback loop that accelerates global warming.

Deforestation in the Amazon rainforest

The Amazon rainforest, often referred to as the "lungs of the planet," plays a crucial role in regulating the Earth's climate. Covering approximately 5.5 million square kilometers, the Amazon has faced significant deforestation, particularly in recent years.

Under the administration of former President Jair Bolsonaro, deforestation rates soared. Environmental laws were scaled back, and large areas of Indigenous lands were opened to commercial exploitation. As a result, 2021 saw deforestation in the Amazon reach a fifteen-year high. This loss of forest cover not only threatened biodiversity but also diminished the Amazon's capacity as a carbon sink, crucial for absorbing CO₂ and producing oxygen.

However, the election of President Luiz Inácio Lula da Silva in late 2022 marked a turning point. Lula has taken steps to restore environmental protections and has sought international support to safeguard the Amazon. In the first seven months of his administration, there was a 42% reduction in deforestation compared to the same period in 2022. By July 2023, satellite data from Brazil’s National Institute for Space Research (INPE) showed a 66% decline in deforestation rates compared to July 2022, indicating a positive trend.

👉 Despite this progress, vital forests like the Amazon need long-term protection and shouldn't be subject to changing political priorities.

Livestock farming

Livestock farming is another significant contributor to global greenhouse gas emissions, particularly methane (CH₄), which is released during the digestive processes of animals such as cows and sheep. However, methane emissions are not the only concern; the entire livestock farming process generates substantial GHGs.

💡 The FAO estimates that livestock farming is responsible for 11% of global greenhouse gas emissions.

Key sources of emissions in Livestock Farming

Methane emissions - Methane is a potent greenhouse gas with a global warming potential much higher than CO₂. It is primarily produced during the digestive process of animals such as cows.
Deforestation for feed crops - Large areas of forests are cleared to grow feed crops for livestock. Around 80% of the world's agricultural land is used for livestock, either for grazing or growing feed.
Fossil fuel use - Agricultural machinery, transportation, and other equipment used in livestock farming often run on fossil fuels, contributing to CO₂ emissions.
Water usage - Intensive livestock farming requires massive amounts of fresh water for animals and crops, adding to the environmental impact.

👉 The combined effect of these practices results in significant greenhouse gas emissions. This includes not only methane but also nitrous oxide (N₂O) and carbon dioxide (CO₂) from various farming activities.

What are the consequences of global warming?

Global warming has far-reaching consequences, affecting the environment, human health, and the economy. If immediate action is not taken, the rising global temperatures will lead to severe and widespread impacts.

Environmental impact

Heat waves - One of the most tangible effects, heat waves are becoming more frequent and intense, posing severe health risks to populations worldwide. According to the Environmental Protection Agency (EPA), heatwaves have risen from an average of two per year to six per year in the last decade.
Rising sea levels - Melting ice caps and glaciers contribute to rising sea levels, which can inundate coastal regions and displace millions of people. The Intergovernmental Panel on Climate Change (IPCC) estimates that global sea levels could rise by up to 1 meter by 2100 if current trends continue. Additionally, the acidification of oceans threatens marine life and disrupts carbon sinks.
Loss of biodiversity - Rapid climate changes outpace the ability of many species to adapt, leading to a significant loss of biodiversity. The United Nations reports that up to 1 million species are at risk of extinction due to climate change and other human activities. This loss impacts ecosystems and the services they provide, such as pollination and water purification.
Agricultural yields - Changes in temperature and precipitation patterns can reduce agricultural productivity, threatening food security and livelihoods, especially in vulnerable regions. The Food and Agriculture Organization (FAO) notes that crop yields could decline by up to 25% by 2050 due to climate change.
Extreme weather events and natural disasters - Increased frequency and intensity of extreme weather events, including tropical cyclones, floods, droughts, and wildfires, result in significant economic damage and loss of life. The exacerbation of such natural disasters poses direct threats to human settlements and infrastructure, necessitating costly responses and recovery efforts.

Societal impact

The effects of global warming extend beyond the environment, significantly impacting human society. These impacts are interconnected and often exacerbate existing vulnerabilities.

Health risks

Global warming exacerbates health risks, leading to increased heat-related illnesses, respiratory issues due to poor air quality, and the spread of mosquito-borne diseases like malaria and dengue fever. According to the World Health Organization (WHO), climate change is expected to cause approximately 250,000 additional deaths per year between 2030 and 2050.

Economic costs

The economic impact of global warming is substantial. Extreme weather events and natural disasters cause billions of dollars in damage annually, disrupting industries, infrastructure, and livelihoods. The Global Commission on Adaptation estimates that climate change could push over 100 million people into poverty by 2030.

Migration and displacement

Rising sea levels, extreme weather, and degraded living conditions force people to migrate, leading to increased displacement and increasing the likelihood of conflict. According to the European Parliament, in 2022 alone, 36.2 million people were displaced due to natural disasters caused by climate change.

💡 Research by the WHO shows that 3.6 billion people around the world live in regions that are vulnerable to climate change.

Why we must limit global warming to 1.5°C

Limiting global warming to 1.5°C above pre-industrial levels is crucial to mitigating the worst impacts of climate change. This target is not arbitrary but is based on extensive scientific research indicating that exceeding this threshold would result in severe, irreversible damage to ecosystems, human health, and economies worldwide.

Why 1.5°C?

Avoiding extreme weather - Staying below 1.5°C helps reduce the frequency and intensity of extreme weather events, such as heatwaves, floods, and hurricanes.
Protecting ecosystems - Many ecosystems, including coral reefs, are highly sensitive to temperature changes. Keeping the rise to 1.5°C can help preserve biodiversity.
Safeguarding health - Higher temperatures can exacerbate health problems, increase the spread of diseases, and strain healthcare systems.

International legal commitments

Efforts to limit global warming are supported by international legal frameworks and agreements:

Intergovernmental Panel on Climate Change (IPCC): Established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), the IPCC provides scientific assessments on climate change and its impacts.
United Nations Framework Convention on Climate Change (UNFCCC): Initiated in 1992, the UNFCCC has 197 parties committed to combatting climate change. It serves as the foundation for international climate policy.
Kyoto Protocol: Adopted in 1997, this protocol set binding emission reduction targets for developed countries for seven greenhouse gases.
Paris Agreement: Adopted in 2015, this landmark agreement aims to limit global temperature rise to well below 2°C, preferably to 1.5°C. All UNFCCC signatories are committed to enhancing their climate actions.
European Green Deal: Launched in 2019, the EU committed to achieving carbon neutrality by 2050, strengthened by the "Fit for 55" climate package announced in 2021.

Projections beyond 1.5°C

Exceeding the 1.5°C limit would have catastrophic consequences:

At 2°C - Significant increases in heatwaves, droughts, and heavy rainfall. Coral reefs would likely decline by more than 99%. The risk of severe impacts on biodiversity and ecosystems increases dramatically.
At 3°C - Substantial global food supply disruptions due to reduced agricultural productivity. Coastal cities would face frequent and severe flooding. The frequency and intensity of extreme weather events would be significantly higher.
At 4°C and above - Widespread, severe impacts on human health, global economies, and natural systems. Large-scale displacement of people due to rising sea levels and uninhabitable conditions in some regions.

“ Limiting global warming to 1.5°C is essential to avoid the most severe impacts of climate change. International legal commitments and continued global cooperation are critical in achieving this goal. Urgent action is needed to reduce emissions, transition to renewable energy, and enhance climate resilience. ”

How can we prevent further global warming?

Preventing further global warming requires a comprehensive approach, involving systemic changes to our economy, society, and personal habits. The Intergovernmental Panel on Climate Change (IPCC) provides detailed recommendations to achieve carbon neutrality by 2050 and limit global warming.

IPCC recommendations

Phasing out fossil fuels
Transition to renewable energy - Replace fossil fuels with renewable energy sources like solar, wind, and hydropower.
End fossil fuel subsidies - Redirect subsidies to support renewable energy development and deployment.
Enhancing energy efficiency
Improve building standards - Adopt energy-efficient building codes and retrofit existing buildings.
Optimise industrial processes - Implement advanced technologies to reduce energy consumption in industries.
Promote efficient transportation - Encourage public transportation, electric vehicles, and non-motorized transport options.
Increasing funding for environmental protection
Support developing countries - Provide financial and technical assistance to help developing nations mitigate and adapt to climate change.
Invest in sustainable practices - Fund projects that promote sustainable agriculture, forestry, and land use.
Carbon capture and carbon sinks
Deploy carbon capture technologies - Invest in CCUS technologies that capture CO₂ emissions from industrial processes and power plants.
Enhance natural carbon sinks - Protect and restore forests, wetlands, and other ecosystems that naturally absorb CO₂.
Encouraging sustainable consumption and production
Reduce waste - Promote recycling, composting, and reducing single-use plastics.
Support sustainable agriculture - Encourage practices that reduce methane emissions and enhance soil carbon storage.
Promoting climate education and advocacy
Raise awareness - Educate the public about climate change impacts and the importance of sustainable practices.
Engage communities - Foster community-led initiatives to address climate change at the local level.

👉 Addressing global warming requires concerted efforts at all levels of society. By following the IPCC's recommendations, we can make significant strides towards achieving carbon neutrality and ensuring a sustainable future for generations to come.

How Greenly can help your business reduce emissions

Companies are significant contributors to global greenhouse gas emissions, with industrial and commercial activities accounting for a substantial portion of the world's carbon footprint.

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With Greenly’s support, your business can significantly reduce its environmental impact, achieve ESG objectives, and enhance sustainability. Contact us today to embark on your journey towards a greener future.