So what is it, exactly?

Global warming is the primary cause of climate change we experience today. Global warming is sometimes interchangeably used for climate change, and it is important to understand the process.

The event of global warming is very similar to the process taking place in your greenhouse/glasshouse. We rely on greenhouses to protect plants from the cold. Greenhouses have been designed to trap solar radiation, so that it warms up, protecting the plants from cold weather. Simply put, Global warming is the same phenomenon on a global scale.

Radiation from the sun powers our climate system. Parts of solar radiation are reflected back to the outer atmosphere, while about half of the solar radiation received by the planet is absorbed by Earth’s surface and warmed by it. The warmed Earth surface then expels heat radiations called infrared radiation. Some infrared radiation escapes Earth’s atmosphere, but most is absorbed and re-emitted by certain gases, such as carbon dioxide (CO2) and methane.

This warms up the Earth’s surface and the lower atmosphere, which is called the greenhouse effect as it follows the same principle as what happens in a greenhouse. These re-emitting heat radiation gases are known as greenhouse gases (GHG).

This process has been happening for billions of years and helped to maintain the average Earth’s temperature at a healthy level of 15°C. Without the greenhouse effect, Earth would be a much colder place and living would be miserable. Scientists have estimated that Earth would be 33°C colder than now without the greenhouse effect (average temperature of -18°C without the greenhouse effect).

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Data visualised and adopted from IPCC

Greenhouse gases

Carbon dioxide (CO2) – result of from burning of fossil fuels – vehicles, boilers, etc and deforestation.

Nitrous oxide (N2O) – emitted by human activities such as nitrogen fertilizer use, fossil fuel burning and industrial processes.

Methane (CH4) – emitted by livestock (enteric fermentation and manure) and the decomposition of food waste.

Fluorinated gases - include Hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF6) stationary refrigeration, air conditioning and heat pump, electrical equipment, semiconductors etc.

These gases have different warming potential, i.e., the ability of a greenhouse gas to trap extra heat in the atmosphere over time relative to carbon dioxide.

What are the big issues, right now?

Since industrialisation, human actions have led to increased levels of greenhouse gases in our atmosphere. For example, CO2 levels have gone up from 280 ppm (parts per million) to over 400 ppm by 2021. Today’s carbon dioxide concentration in the atmosphere is comparable to the levels in 4-5 million years ago.

Please read further here: How human activities contribute to climate change

Because of the increased level of greenhouse gases, the Earth’s surface and lower atmosphere is warming at an extraordinary rate, which is now known as global warming. Latest findings show the Earth’s average temperature has risen from 1.2°C since industrialisation.

Global warming has changed our climate system, the system humans and all other living beings are used to. Sea levels have risen, extreme events have become more common and severe, threatening the health and safety of humans and all other living beings.

Some concerning impacts are:

  1. sea-level rise due to melting of polar glaciers and thermal expansion of water - sea-levels have risen as much as 200mm over the last 100 years and will keep rising at a rate of 3.6mm annually - scientists have already warned that if the West Antarctic glacier (i.e., Thwaites Glacier also dubbed ‘Doomsday Glacier’) collapses, the sea-level could rise by 4-5 metres
  2. increased sea levels have already threatened our coastal communities and coastal environments, as coastal floods are more frequent and severe
  3. increased variability of rainfall - high intense rainfall and prolonged droughts
  4. more heatwaves and prolong droughts leading to crop losses and degraded biodiversity
  5. loss of marine and terrestrial biodiversity and ecosystems
  6. more severe extreme events, cyclones, droughts and floods.

18 January 2023

Diagram of atmospheric concentrations from IPCC

Strategies - what can we do?

OK, climate change is real, but it is not too late. The clock is ticking and we must act fast. There are two ways, we can act.

Climate change mitigation

Reduce greenhouse gas emissions to limit the global warming.

Common strategies for climate change mitigation could be:

  • Adopting renewable energy options such as solar, wind, biomass, hydro and geothermal
  • retrofitting buildings to make them more energy efficient
  • creating cities with more sustainable transport options such as electric vehicle infrastructure, support active transport (walking, cycling etc.)
  • waste reduction, reusing, recycling
  • reducing deforestation and encouraging reforestation. 

Climate change adaptation

Prepare to face the adverse impacts and new opportunities presented by climate change.

Common strategies for climate change adaptation:

  • avoid building in high risk areas
  • sound land use planning and management
  • flood defenses
  • drought resistant crop varieties and good agricultural practices
  • water saving and rainwater harvesting
  • protection of sensitive ecosystems such as sand dunes and coastal vegetation
  • sound building codes and standards
  • managed retreat or relocate to safe locations.