Climate change is a global phenomenon that affects us all. Yet the terminology and discourse can be confusing if you’re not part of the scientific community and unfamiliar with the lingo. For everyday people who want to better understand these important issues, we’ve created a brief introduction to a few key climate change terms.
When discussing climate change, first, we should know what “climate” means. Climate refers to the long-term (30 years or more) patterns of weather in a given area.
What determines climate?
The average temperature, amount of rainfall, snow, and several other aspects of the weather all contribute to an area’s climate. For example, Macao has a subtropical oceanic monsoon climate that sees high temperatures and heavy rainfall.
Climate Change vs Global Warming
These two terms are often used interchangeably, but they are not the same thing. Global warming refers to the prolonged increase in the average temperature caused by greenhouse gas emissions. According to the latest science, the Earth has warmed by 1.1°C since the pre-industrial period (1850-1990). Meanwhile, climate change describes shifts in existing weather patterns due to global warming.
What’s more, the effects of climate change are not limited to warmer weather. Climate change will make extreme weather events (such as droughts, heatwaves and storms) more intense and frequent in some regions. For example, the continued warming of the North Pole and the loss of sea ice may have led to the rare, intense winter storm that hit Texas, a US state that lies in the subtropical zone, in 2021.
Greenhouse Gas Emissions vs Carbon Emissions
You’ve probably heard of carbon emissions – they’re the most commonly known source of global warming. In this context, “carbon” refers to carbon dioxide (CO2), a major greenhouse gas emitted by human activities.
In addition to CO2, other major greenhouse gases (GHGs) include Methane (CH4) and Nitrous Oxide (N2O). Some level of GHG in the atmosphere is necessary: these warming gases insulate the Earth by trapping heat, which makes the planet suitable for life.
But as is often the case, too much of a good thing becomes a bad thing. And right now, the amount of GHGs human activities are emitting tips the planet’s natural balance and destabilises the climate.
Natural Climate Change vs Anthropogenic Climate Change
Much debate has focused on the cause of climate change. Some say climate change is a natural process, because the Earth has had ice ages and extremely hot periods throughout its history. Indeed, some natural processes – such as small changes in the Earth’s orbit, volcanic eruptions, and changes in energy coming from the sun – have influenced climate change.
However, the impact of these natural occurrences is relatively small when compared to that of anthropogenic – meaning, human – activities. Human activities, including the burning of fossil fuels and deforestation, emit GHGs at a scale and speed that was unprecedented before the Industrial Revolution (when humans began burning coal).
This is well-documented in the latest Intergovernmental Panel on Climate Change Assessment Report, which states that “observed increases in well-mixed greenhouse gas concentrations since around 1750 are unequivocally caused by human activities”. So, it’s more precise to describe the climate change we are currently experiencing as a human-caused, or anthropogenic, phenomenon.
Net Zero Carbon vs Carbon Neutrality
Pledges from governments and businesses to achieve “net-zero carbon” emissions or “carbon neutrality” have proliferated in recent years. And though these pledges sound very similar and both focus on carbon emissions, there is a slight difference when it comes to the actions they will take.
“Net zero carbon” emissions focus on reducing carbon emissions of certain activities as much as possible, then removing inevitable emissions from the activities.
For example, to reduce the carbon emissions from traveling, you can opt for a train instead of a plane because the former emits less CO2. But taking a train will still cause some carbon emissions. To take a “net zero carbon” trip, you can purchase credits to compensate for the inevitable emissions. Sometimes there are also “net zero” emissions pledges, which expands the scope to any and all GHG emissions.
“Carbon neutrality” doesn’t necessarily require a company or government to reduce emissions. Instead, they can offset the GHGs they emit by investing in environmental or community projects that reduce GHGs somewhere else in the world, effectively balancing out the emissions. Offsetting can be done through many ways, most commonly by planting trees, restoring forests, and investing in renewable energy.
You can also pay someone else to not emit the same amount of GHGs – a method known as a “cap and trade” system. For example, two companies in the same area are each given an emissions allowance of 10 tons of CO2 per month; emitting more will result in a penalty. Company A usually emits 15 tons but doesn’t want to pay a fine, while Company B has always emitted less than 5 tons. In this scenario, Company A can pay Company B to trade their remaining 5 tons emissions allowance to avoid a fine.
In essence, while “net zero carbon” focuses on reducing emissions and then considers removals, “carbon neutrality” focuses on balancing emissions and removals; in fact, entities that have pledged to become carbon neutral can actually increase their emissions – as long as they can offset it.
Global Warming Potential
Different GHGs have different “warming powers”, which are referred to as their Global Warming Potential (GWP). GWP measures how much heat 1 ton of a specific gas can absorb over a period of time, compared to CO2, which scientists have chosen as the baseline.
Here’s an example: Over 100 years, CO2 has a GWP of 1, while CH4 has a GWP of 28-34 and N2O has a GWP of 265-298. This means that CH4 and N2O are more potent than CO2. The GWP of a gas decreases as time goes on. For instance, in the first 20 years that CH4 is released into the air, it will trap more heat than in the following 80 years.
Carbon Dioxide Equivalents
GHG emissions are sometimes expressed in a unit called “carbon dioxide equivalent” (CO2-e). Essentially, this unit expresses a greenhouse gas’s contribution to global warming, relative to CO2. By converting greenhouse gas emission into a CO2 equivalent, it enables scientists to compare standardised values and calculate their cumulative impact.
To find the carbon dioxide equivalent of a gas, simply multiply its GWP by the gas’s mass in tons. For example, if a company emitted 1 ton of CO2 (which has a GWP of 1) and 1 ton of CH4 (uses a GWP of 28) in the previous year, the total amount of GHG emissions will be expressed as 29 ton CO2-e in a performance report.
Although a range of GWP factors exist for gases other than CO2, only one factor is used for calculating the amount of emissions. This factor is usually designated by reporting standards, such as the Hong Kong Stock Exchange Environmental, Social and Governance Reporting Guide.
Climate change impacts all of us, and we should all be able to understand how it affects us. Unfortunately, climate talk is often filled with scientific terms, which can make it difficult to understand. By boiling them down to basic terms that everyone can comprehend, more people can join the climate change conversation and take action on it.
About Genervision House
Genervision House is a Macao-based platform for knowledge sharing and advocacy, as well as a community that promotes the 17 United Nations Sustainable Development Goals. Genervision House seeks to raise the awareness of the local community on sustainable development, to encourage more Macao locals to participate in the practice and promotion of sustainable development, and jointly contribute to the development of the local community and different regions of the world. Genervision House is also the first member organisation from Macao to join the United Nations SDSN Youth Initiative. Visit the official website to learn more.