Core to the climate crisis we’re facing is human-made emissions and how we need to reduce them. We're now emitting around 36 billion tonnes of carbon dioxide every year, which has already led to over 1˚C of warming.
But one aspect that's not addressed nearly enough is that those amounts always being cited are actually what’s called “carbon equivalent emissions” or C02-e. Carbon isn't the only greenhouse gas out there and (arguably) it's not the worst.
Firstly just a quick recap - greenhouse gases (GHGs) are molecules that exist in our atmosphere. They reflect heat radiating off Earth back to the surface, just like (you guessed it) a greenhouse! Many of these are naturally occurring and vital to keeping our planet at a habitable temperature, however, human activity has emitted excessive amounts that have thrown off natural systems.
Now carbon is the most prevalent of human-emitted GHGs but it’s by no means the only one, with methane, nitrous oxide and “F-gases” the other most prevalent emitters. Each of these has different “warming potential”, which is the molecule’s strength in reflecting back heat. You take the warming potential of each over 100 years compared to carbon and you’ve got C02-e!
All these other non-carbon emissions are part of a group called “short-lived climate pollutants” (or SLCPs) because while they’re extremely potent, their strength degrades rapidly in the atmosphere. For example, methane has a warming potential 28 times stronger than carbon but only a significant atmospheric period of 12 years, compared to carbon's centuries-long lifespan. It’s emitted from various sources, from energy to agriculture to waste.
*By the way, compost is an amazing solution to reducing this particular GHG.
Now, on the surface, this all doesn’t seem to matter that much. Heat is heat, wherever it comes from, right? Actually, a lot of emerging scientific evidence is starting to show this isn’t the case.
While these SLCPs won’t be hanging around for as long as carbon, they cause a lot of damage when they are there and are constantly being replaced.
More importantly, there’s this thing called tipping points. These are phenomena that emerge because of climate change to make it worse, the best example being the Albedo effect. Passing these points could lead to runaway global warming which we definitely don’t want happening.
Because of this many climate scientists and policy-makers believe that by targeting SLCP emissions, we’ll be able to drastically reduce emissions in the short-term, slowing down warming and giving us time to transition to low or no carbon emissions and develop carbon capture solutions.
Arguments against this claim that both gasses are equally important and that focussing on one is simply a scapegoat for major carbon emitters to delay when they need to take action.
As for us? We’re firmly middle-ground on this - we definitely haven’t given enough attention to SLCPs and their immediate potential but that doesn’t mean we don't also need immediate, drastic action on carbon emissions.