Human Impact on Climate Change

Types of Greenhouse Gases

The contribution of a gas to the greenhouse effect, or global warming, depends on its heat absorption, its heat re-emission and the amount present in the atmosphere.

The gases that contribute most to Earth's greenhouse effect are:

• Water vapour (H₂O)

• Carbon dioxide (CO₂)

• Nitrous oxide (N₂O)

• Methane (CH₄)

• Ozone (O₃)

Anthropogenic Impact on Climate Change

Since the Industrial Revolution began in the 18th century, anthropogenic activities have caused an increase in atmospheric greenhouse gases – primarily carbon dioxide. This leads to an enhanced greenhouse effect or global warming:

Increased greenhouse gas concentrations

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More heat is absorbed and re-emitted within the atmosphere

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Earth's surface and atmosphere become warmer

Higher temperatures alter Earth's physical systems, causing climate change.

Human Impact on Climate Change: Cause and Effects

We've learned that anthropogenic activities release greenhouse gases, contributing to climate change.

Sources of Greenhouse Gas Emissions

The vast majority of greenhouse gas emissions stem from burning Fossil Fuels. The remainder comes from deforestation, land use change, and cement production.

• Burning Fossil Fuels: Fossil fuels are non-renewable, carbon-rich deposits. When burned, they release energy - but also carbon dioxide and other greenhouse gases. This enhances Earth's natural greenhouse effect, increasing temperatures and causing climate change.

• Deforestation: The act of cutting down trees is known as deforestation. Forests are carbon stores. When they are cut down, the carbon is released as greenhouse gases, which enhances the greenhouse effect.

• Land Use Change: Any anthropogenic modification of the landscape is classed as land use change. Often, land use change concerns agricultural and urban expansion, which emit greenhouse gases and various pollutants, affecting the local and global climate.

• Cement Production: An astonishing 8% of global anthropogenic carbon emissions stem from cement production. Half of these emissions are generated by the chemical process itself – carbon dioxide is produced when calcium carbonate is heated. Other emissions stem from burning fossil fuels to power this production process.

  Over 900g of carbon dioxide is emitted for every kilogram of cement produced.

The majority of greenhouse gas emissions originate from four economic sectors.

• Effects of Greenhouse Gas Emissions

  Humans' high impact on greenhouse gas emissions leads to global warming. This raises the overall temperature worldwide, affecting the Earth's climate system.

  A climate system is a complex system influenced by the sun and other external mechanisms. The five interacting components are the Earth's air, water, land surface, ice, and living organisms.

  The major effects of climate change are:

  • Rainfall changes causing droughts or floods

  • Higher temperatures leading to heatwaves and forest fires

  • Melting sea ice, leading to rising sea levels and changing global currents

  • More extreme storms such as cyclones, hurricanes and typhoons

  • Decrease in biodiversity due to a loss or changes in distribution patterns of species on land and the oceans

  • Vulnerability to poverty as a result of forced displacement and severe weather

  • A global rise in hunger and poor nutrition due to less grassland, ocean acidification and a diminished water supply

  • Increased health risks because of pollution and pressures on mental health etc.

  The Impact of Human Settlements on Climate Change

  Over half of the world's population live in large settlements like towns and cities. These large settlements contribute to climate change. How?

  • Construction: building houses, roads, and infrastructure require energy and cement production.
  • Transport: large urban areas (especially those lacking public transport) experience pollution and carbon emissions from cars.
  • Energy: fossil fuels are burned to produce energy to power homes, schools, businesses, and hospitals.
  • Waste: landfill sites emit pollutants and methane.

  Cities don't just contribute to climate change; they often bear the brunt of its adverse effects. The poorest residents are most at risk of problems like flooding, landslides and extreme weather. They typically live in low-quality housing, lacking adequate infrastructure like storm drains.

  An estimated 880 million people living in cities are vulnerable to the effects of climate change.

  Modelling Climate Change

  Models help scientists understand complicated systems. They are also used to test theories, predict future changes and look for solutions to problems.

  Climate models use data to solve mathematical equations. Supercomputers are used to analyse this data, which includes:

  • The movements of mass and energy in the atmosphere and oceans

  • Global climate patterns

  • Previous weather records

  Circulation patterns move air, water, and heat around the Earth, influencing temperature and rainfall. These patterns are caused by the uneven distribution of solar energy and the movement of the Earth. Weather monitoring stations detect these changes, and data from the monitoring stations are transferred to the supercomputers and used in future climate simulations.

  El Niño is an irregular climate pattern impacting the oceans, currents and weather conditions. It is triggered by an increase in sea surface temperatures off the coast of South America. El Niño is detected using buoys, satellites, and sea level analysis. This data is then transferred to the climate model supercomputers.

Climate Models vs Weather Forecasts

Weather forecasts present a detailed picture of expected weather in the near future.

Climate models indicate regions likely to experience a change in the long term.

Predicting Future Climate Change

Climate science is a complicated field. It's difficult to predict how atmospheric greenhouse gas concentrations can change in the future, so scientists can never be sure about climate change. Many factors can influence the climate, and there are countless uncertainties due to a lack of data.

Despite this, climate models can help scientists make predictions. They alter variables and equations in the climate model to see how the climate will change according to a scenario.

These models show how the decisions and behaviours of today can influence the climate of the future.

Positive Human Impact on Climate Change

It's not all doom and gloom in the future. Understanding how our decisions and behaviours affect the climate has helped the world to make meaningful changes. Some of the positive changes that are happening or current agreements that will have a positive change on climate change are:

• One hundred and ninety-seven countries have signed the Paris Agreement, the first legally binding global climate agreement. Legislation like the Paris Agreement tracks countries' progress and holds them accountable, encouraging them to make important policy changes to reduce greenhouse gas emissions.

• Over 100 countries have pledged carbon neutrality by 2050. Carbon neutrality is also known as net-zero, which means that all greenhouse gas emissions must be balanced with their removal or elimination.

• Electric vehicles are becoming cheaper and more efficient. Many countries have proposed plans to phase out fossil-fuel-powered cars. Phasing out these vehicles limits the emissions of greenhouse gases and other harmful pollutants.

• Millions of people around the world have shifted towards a plant-based diet. Plant-based protein sources emit up to 90% fewer greenhouse gases than meat.

• Renewable energy resources are becoming commonplace. Electricity from these resources is free from greenhouse gas emissions and is derived from natural, sustainable sources that can be replenished faster than consumed.

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