Climate Change and Greenhouse Gas Emissions

At Cherwell Collective we spend a lot of time talking about Carbon Cost. It’s a way of keeping track of the climate-change-inducing greenhouse gas emissions that we produce through our consumer choices and activities.  But what about the climate change basics?  Why should consumers track their greenhouse gas emissions and choose products or services with a lower Carbon Cost?  What’s the science about climate change?  We aim to answer those questions here.

Why Worry About Greenhouse Gas Emissions?

Even if it is cloudy where you are, or nighttime, at every given moment one-half of the planet is basking in the full power of the Sun’s rays.  Our atmosphere and our distance from the Sun make this a comfortable planet to live on, compared to scalding hot Venus or frigid Mars.  Still, everything on Earth must be kept in balance to maintain these Goldilocks temperatures.  If some of the Sun’s energy didn’t radiate back out into space, our planet would actually be much hotter than it is today.

Greenhouse gases have unique chemical properties that absorb the Sun’s energy so that it cannot radiate back into space.  Metaphorically, these gases act like panes of greenhouse glass surrounding the planet and raising temperatures. Having some of these gases actually prevents Earth from being too cold.  But since the start of the industrial age about 200 years ago, the quantity of these emissions released into the atmosphere each year has risen over 10 times the pre-industrial level.

The increase of greenhouse gases has already raised global temperatures by 1.0 degrees C and led to more extreme weather events. Meanwhile, temperatures are still rising.  The Intergovernmental Panel on Climate Change (IPCC) warns that we must prevent temperatures from rising beyond 2.0 degrees C above pre-industrial levels, and ideally no more than 1.5 degrees C.  Otherwise, a more catastrophic series of outcomes is likely (e.g. mass extinctions, flooding, desertification, famine). To achieve these goals, we must greatly reduce human-made greenhouse gas emissions.

What are The Greenhouse Gases and How Powerful Are They?

The Carbon in Carbon Cost refers to carbon dioxide, which comprises the largest quantity (76%) of greenhouse gas emissions released into our atmosphere. All animals produce carbon dioxide (CO2) when they burn calories.  You’re making some right now and exhaling it with every breath. But those quantities are small.  Earth’s plant life can handle that small quantity of emissions and turn the CO2 back into oxygen through photosynthesis.

However, most of the CO2 humans have added to the atmosphere comes from burning fossil fuels such as coal, oil, petrol, and natural gas. We produce it when we generate electricity at power plants that use fossil fuels, when we heat our home with a furnace, and when we drive vehicles that use petrol or diesel fuel.  Those quantities of emissions are enormous and too much for the earth’s plant life to handle.

Methane, Nitrous Oxide, and Hydrofluorocarbons

• Methane (CH4) is another greenhouse gas. It gets released from decomposing landfills, in raising certain “red meat” animals like cows and goats, and in producing natural gas. It makes up 16% of all emissions.  However, methane has 28 times the global warming potency as carbon dioxide. Small quantities of methane emissions have a big global warming impact, so it is a growing area of concern. In November 2023, the USA and China agreed to work to reduce methane emissions.
• Nitrous Oxide (N2O) is another greenhouse gas, which is released mainly from fertiliser use and some industrial processes. Though it makes up only 6% of emissions, devastatingly, N2O is 273 times more potent than carbon dioxide in terms of global warming potential.
• Hydrofluorocarbons are a group of chemicals used in certain equipment like older refrigerators.  The chemicals in this group are thousands of times more potent than carbon dioxide. Leakages of even tiny amounts have disastrous effects. Under the Montreal Protocol, most of these chemicals are being phased out of use, though they remain at 2% of emissions today. These emissions might be negligible by 2030 if the Montreal Protocol is followed.

Estimates of greenhouse gas global warming potential (GWP) come from the United Nations Intergovernmental Panel on Climate Change (IPCC ) Sixth Assessment Report (2021).  Estimates of global greenhouse gas proportions come from the United States Environmental Protection Agency (2023).

Science’s Metric for Carbon Cost is Carbon Dioxide Equivalent

It would get awfully confusing for citizens and consumers to keep track of carbon dioxide, methane, nitrous oxide, and hydrofluorocarbon emissions separately. Therefore, scientists convert all categories into one metric called carbon dioxide equivalent (CO2e) when discussing greenhouse gases.

For instance, raising cattle for beef generates a mix of carbon dioxide from the farm equipment, methane from the cow’s digestion, and nitrous oxide from the fertiliser to grow the cow’s feed. Climate scientists add up the emissions from all those sources and then factor in the higher global warming potential of methane and nitrous oxide.  The sum of all these components is the carbon footprint of the beef in carbon dioxide equivalent or CO2e.  In some stores, you may see your meat labelled with this footprint, such as one common estimate of 25kg CO2e for a one-kilogram package of UK beef.

Decreasing Emissions is the Path to Saving the Planet

We all must reduce our emissions as much as possible to prevent catastrophic climate change. This is especially true in nations like the UK, where we drive bigger cars, have bigger homes, and eat richer diets than the global average.  To help people reduce their emissions, we suggest learning more about the Carbon Cost of your daily activities and consumer choices.  That way, you can make more planet-friendly, low-carbon choices.

Read our introduction to Carbon Cost and start doing your part.