A study this week highlighted that our current models of how much greenhouse gasses we can emit and still stay under 2 degrees might be overestimating it by as much as 20%.
The research took a relatively novel approach to modelling greenhouse emissions, by working backwards from the Paris Agreement’s targets, and focussing on potential feedback loops that might impact the world’s wetlands and Permafrost.
This approach allows them to think through how small rises in temperature might lead to increasing methane emissions from the world’s wetlands. This process is one that has been very difficult to understand in the past, but could have a massive impact on the assumptions we have about our global fossil fuel limits.
When we talk wetlands, we’re not talking about everywhere that’s wet. We’re talking about a few amazing places around the world with these incredible, swampy areas that rivers and oceans often wash over but don’t necessarily flood all the time.
Really, they’re only found across about 4% to 6% of the Earth. So finding wetlands on earth is rare but beautiful thing. They cover some of the world’s most amazing coastlines, like the delta’s of West Africa, the Mekong and Irrawaddy. Hopefully you can find one near you on this cool interactive map.
But they also hold a quarter of all the carbon stored in the Earth’s soil.
According to the Smithsonian, that’s thanks to their wetness, slowing down the decomposition process and creating a natural carbon storage.
Wetlands then turn the carbon into methane, as the world’s original micro-breweries. The wet, soggy soils fement, and create a methane-rich layer of peat. The more carbon the wetlands absorb, the more methane they pump out.
As a kid, I used to love playing in the mangroves of the Hawkesbury River in Sydney, Australia. It’s a muddy, dreamland for a kid who wants to get dirty hunting for crabs and crustaceans. It’s a nightmare for parents with clean floors.
The world’s largest wetland is in Brazil. Well it’s so big its also in Bolivia and and Paraguay. It’s 42-million-acre’s big, which is more than 38 million football fields!
In March, all three countries agreed to protect it, which is an awesome win-win for conservation and everyone who lives in the area.
Brazil’s Agricultural Research Corporation even estimated that the benefits of this conservation agreement is worth over $112 billion a year, thanks to all the amazing things that wetlands and mangroves do – like controlling floods, supporting millions of species of fish, birds and animals, and absorbing tonnes of carbon. That’s a big thing for a government department focussed on agriculture to say.
But this latest study shows that it’s not enough to protect wetlands like this from simply being turned into farms. As the world gets warmer, these wetlands will start to naturally release lots of the methane they currently hold tight.
That process would then create a feedback loop – the warmer it gets, the more methane that would be released. The more methane released, the more the world warms. Think of methane as Carbon dioxide on steroids.
Lead author Dr Edward Comyn-Platt, a biogeochemist at the UK Centre for Ecology & Hydrology said: “Greenhouse gas emissions from natural wetlands and permafrost regions are sensitive to climate change, primarily via changes in soil temperature”.
Wetlands already emit a lot of methane. In fact, they’re probably the biggest single source of methane emissions, with estimates that they emit nearly 1/5th of all the emissions around the world.
In 2007, scientists around the world began freaking out because global methane emissions started rising pretty quickly. It took scientists about 5 years to figure out why, but in 2013 and 2014, they began realising that the emissions were probably coming from wetlands releasing more methane.
In this latest study by the Centre for Ecology & Hydrology, they think that this is a trend that will only continue to get worse, and one that’s not yet built into our climate models.
Many models try to stay away from positive feedback loops, because it’s so hard to make a calculated decision about how powerful the feedback loop will be. James Hansen has been writing about feedback loops for a while. Last month, a pretty nightmarish study on Antarctic Ice loss highlighted we might be entering one already.
Dr Edward Comyn-Platt didn’t want to seem too alarmist, but pointed his paper directly at policy makers; “Changes in these emissions will alter the amount of greenhouse gases in the atmosphere and must be considered when estimating the human emissions compatible with the Paris Climate Agreement.”
That’s a pretty reserved way of saying we might be aiming 20% off-course.