Recent assessments indicate that low-emission pathways like SSP1-1.9 are increasingly viewed as unrealistic due to insufficient policy implementation and reliance on unproven carbon removal technologies. While historical emissions have tracked middle-range projections, current trends suggest a higher likelihood of mid-high emission outcomes, making the 1.5°C target achievable only through a significant temporary temperature overshoot. Consequently, decision-makers are urged to prioritize adaptation planning for higher sea-level rise risks rather than assuming low-emission scenarios are fully attainable.
Alright, folks, gather ’round because we’re diving into the world of climate models, specifically the shiny new CMIP-7 ones. Now, before you roll your eyes and think this is going to be a dry, technical slog, let me assure you – it’s not all doom and gloom. In fact, there’s a glimmer of hope in the Low and Medium-Low emission scenarios that might just make you want to raise a glass (of sustainably-sourced organic juice, of course).
So, what’s the scoop? According to the latest buzz from Carbon Brief, the Low scenario is not asking for a Herculean effort. It suggests that global net CO₂ emissions need to drop to about 35-36 GtCO₂/year by 2030, which is only about 13-15% lower than 2023 levels. That’s right – a mere 15%! It’s like asking your teenager to clean their room and only requiring them to shove everything under the bed instead of actually organizing it. Sounds doable, right?
Now, as for the Medium-Low scenario, it’s even more laid-back. This pathway essentially says, “Hey, let’s just keep doing what we’re doing until about 2040 and then gradually start to reduce emissions until we hit net-zero CO₂ around 2100.” The median warming outcome here is about 2.3°C. So, if you’ve been feeling overwhelmed by the climate crisis, take a deep breath. We’re not asking for a complete overhaul of your lifestyle just yet.
But let’s not get too cozy. The Low scenario doesn’t require a drastic reduction in emissions by 2030. It’s more of a gentle nudge towards sustainability rather than a full-on sprint. And the Medium-Low scenario? Well, it’s practically a leisurely stroll in the park. But hey, that’s better than nothing, right?
Now, let’s talk about carbon removal, because what’s a climate model without a little carbon dioxide removal (CDR) drama? Both scenarios expect a hefty amount of CDR, with estimates of about 1,360 GtCO₂ for Low and 1,450 GtCO₂ for Medium-Low from 2024 to 2150. But before you start panicking about how we’re going to accomplish that, remember – a lot of this removal happens after 2100. It’s like saying you’ll clean your room… someday.
The real kicker here is that these large CDR figures serve multiple purposes: they offset residual emissions, push emissions below zero, and—especially after 2100 in the Medium-Low scenario—help reverse some of that pesky warming. It’s like a climate magician pulling a rabbit out of a hat, only the rabbit is made of renewable energy and the hat is a sustainable future.
Speaking of futures, CMIP-7 has shifted its scenarios downwards from previous generations, which were a bit more dramatic, featuring extreme fossil-fuel expansion scenarios predicting close to 5°C of warming. The new High scenario now predicts around 3.3°C, which is a relief, but still not ideal. Instead, we’re left with a more manageable range: 2.9°C if policies remain stagnant, 2.3°C if we kick things into gear around 2040, and the Low scenario aiming for 1.8°C with some modest reductions.
What’s the takeaway from all of this? The Low and Medium-Low pathways don’t require us to perform impossible feats of decarbonization. They simply ask for steady, sustained effort over the coming decades. And with the continued growth of renewable energy, electric vehicles, and general electrification, these scenarios seem not just plausible, but downright achievable.
So, the next time you hear someone sigh about the climate crisis, remind them that while it’s no walk in the park, it’s also not an impossible mountain to climb. With a little bit of effort, some innovation, and perhaps a sprinkle of optimism, we might just make it to a sustainable future. And if all else fails, there’s always carbon removal – because who doesn’t love a good magic trick?
Inspired by: “The Low and Medium-Low emission scenarios for the new CMIP-7 climate models are eminently achievable” (r/climatechange)