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If you could go back in time, what would you change about your life, or the world?

The idea of giving myself some much-needed advice is appealing (don’t cut your own bangs in high school, seriously). But we can think bigger. What about winding the clock back on the emissions that cause climate change? 

By burning fossil fuels, we’ve released greenhouse gases by the gigaton. There’s a lot we can (and need to) do to slow and eventually stop these planet-warming emissions. But carbon removal technology has a different promise: turning the clock back. 

Well, sort of. Carbon removal can’t literally take us back in time. But this time-machine analogy for thinking about carbon removal—specifically when it comes to the scale that will be needed to make a significant dent in our emissions—is a favorite of climate scientist David Ho, who I spoke to for my latest story. So for the newsletter this week, let’s consider what it might take for carbon removal to take us back far enough in time to reverse our mistakes (emissions-related ones, anyway). 

The world is on track to hit a new record for carbon dioxide emissions due to fossil fuels, with the global total expected to reach 36.8 billion metric tons this year, according to the newest edition of the Global Carbon Budget Report.

For the first time this year, the report included another total: how much carbon dioxide was sucked out of the atmosphere by carbon removal technologies. In 2023, carbon removal is expected to total around 10,000 metric tons. 

That’s obviously a lot less, but exactly how much less can be hard to grasp, as Ho points out. “I think humans (myself included) have a hard time with orders of magnitude, like the difference between thousands, millions, and billions,” he told me in an email. 

One solution Ho has come up with is putting things in terms of time. It’s something we intuitively have a handle on, which can make big numbers easier to understand. A thousand seconds is around 17 minutes. A million seconds is about 11 days. A billion seconds is nearly 32 years. 

Since time is a bit easier to grasp, when Ho talks about carbon removal, he often invokes the idea of a time machine. “My goal is to help people appreciate the scale of the problem, and put ‘solutions’ into context,” he says. 

Imagine all carbon removal technology as one big time machine, winding the clock back on emissions. If the world is emitting just under 40 billion metric tons of carbon dioxide in a year, how far back in time could this year’s total carbon removal take us? Right now, the answer is somewhere around 10 seconds. 

We eventually need to reach net-zero emissions if we’re going to avoid the worst effects of climate change. And it’s pretty clear that 10 seconds is a pretty far cry from being enough to zero out a year’s worth of emissions. There are two things we’d need to do for this time machine to be more effective: scale up carbon removal technology, and drastically scale back emissions. 

It’ll take time, and likely a lot of it, to get carbon removal technology to a point where it’s a more effective time machine. There are technical, logistical, and economic challenges to figure out. And early projects, like the Climeworks direct-air-capture plant in Iceland, are still getting their footing.

“It’s going to take many years to make significant progress, so we should start now,” Ho says. And while we figure all that out, it’s a good time to focus on decarbonization, he adds. Slashing our emissions is possible with tools we already have on the table. Doing so will make it a bit more feasible for carbon removal technologies to eventually play a significant role in cleaning up our emissions. 

If you’re curious to learn more, including how big a dent larger projects might make, check out David Ho’s article from earlier this year in Nature. You can also take a look back at some of our recent coverage of carbon removal below. 

Related reading

Carbon removal tech is vacuuming up significantly less than one-millionth of our fossil-fuel emissions. Get all the details in my latest story.

Startup Climeworks has been one of the major actors in putting direct air capture on the map. We put the company on our list of 15 businesses to watch in climate tech this year.

The US Department of Energy is committing big money to carbon removal. Earlier this year, the agency announced over $1 billion in funding for the technology, as my colleague James Temple covered.

Another thing

Around a decade ago, a huge wave of startups working on energy and climate-related technologies failed. This surge and crash in what’s often called cleantech 1.0 holds many lessons for innovators today. 

Now, as interest and funding in climate and energy technology companies again is surging, what should we take away from the previous generation of startups? My colleague David Rotman took a careful look for his latest story. Give it a read!

Keeping up with climate  

The University of California system is basically done with carbon offsets. While paying to balance out your own emissions sounds like a good deal, there are a host of problems with the practice. (MIT Technology Review)

Generating an image using AI can require as much energy as fully charging a smartphone. Smaller models doing other tasks (like generating text) can be significantly less energy intensive. (MIT Technology Review)

COP28 is in full swing. Here’s a quick roundup of a few of the headlines that have caught my eye so far. (If you need a catch-up on what’s happening at the UN climate talks and why fossil fuels are center stage, check out my story from last week here.) 

• The head of the conference has been criticized for his comments about fossil fuels. (Vox)
• Over 20 countries pledged to triple the world’s nuclear energy by 2050. (Canary Media)
• Nations committed over $400 million in funding to help vulnerable nations pay for climate damages. These are the first pledges to the loss and damage fund, created at last year’s talks. (NPR)

A rule change in California slashed the value of rooftop solar panels six months ago. New sales are (predictably) down since the change. (Canary Media)

The Salton Sea is a salt lake in California. It contains a fascinating ecosystem, and apparently a whole lot of lithium. There might be 18 million metric tons of the metal under the main lake, the equivalent of nearly 400 million EV batteries. (LA Times) 

Congress set aside $7.5 billion for EV chargers. But there hasn’t been a single one installed with the money yet. (Politico)