CO2 Roulette - What number would you bet on?

CO2 ppm past and possibly future--and what it means for us

We get a lot of questions about the math of climate change and climate restoration. So join us on a quick tour of CO2 milestones and projections.

All numbers represent CO2 levels in parts per million (ppm)--i.e., how many molecules of CO2 in a million molecules of air.

CO2 ppm by year

• 280 Pre-industrial levels. Optimal for agriculture and ecosystems.

  Lasted for 10,000 years until ~1800

• 300 The highest our ancestors ever experienced for nearly a million years.

  Therefore proven safe. Last seen ~1920

• 350 Said to be theoretically safe. Last seen ~1987.  

• 420 The level 14 million years ago, before hominids evolved. And today.

• 450 The” net-zero by 2050” pathway brings us here.  No experts claim that this will support life as we know it. We prefer climate restoration    

• 600-800 Common projections for 2100 if we achieve net-zero alone, after 2050 

• 300     Projected for 2050 in climate restoration scenario; achieved by amplifying nature’s age-old ways of restoring CO2 levels. 

• 280     Projected for 2100 in the climate restoration scenario.

Why aren’t our climate leaders aiming for safe levels of CO2?

As discussed in previous posts, we’re laboring under an old paradigm—”stabilize emissions,” now framed as “net zero.”  This made sense in the 1980s, before global warming was serious enough to observe. And before we had a trillion tons of excess legacy CO2 in the air.

Today we do have a path to restoring safe CO2 levels by emulating natural processes.

But for society to support that path requires a paradigm shift. It means resetting our climate goal to net zero AND restoring a historically safe climate— under 300 ppm by 2050. 

These graphs tell the story.

1. The long view back: We’re adapted to conditions with CO2 at or below 300 ppm.  NASA.  

This well known image shows the natural variability of CO2 going back 800,000 years—plus its startling rise in this last blink of a geological eye. The deep-time data comes from ice cores: scientists measure the gasses in ancient atmospheres from the air bubbles preserved in the ice.  Recent measurements reflect the Keeling Curve. 

This favorite also shows that Nature drops CO2 down each time it edges up toward 300 (and usually much lower). We now understand how this happens…and can help Nature replicate the process, in fast-forward. That is the basis for climate restoration.

2. CO2 levels from preindustrial to possible futures

Source: NASA and Keeling Curve for historical data. Shannon Fiume and Peter Fiekowsky for projections under a net-zero and a climate-restoration future.

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From today, CO2 continues to rise if we only achieve net zero, the goal of the Paris Agreement, without also implementing robust  CO2-removal solutions. Take a good look at that orange line. Unless we intentionally restore the climate, it would take at least 1,000  years to return to safe levels. 

The IPCC bases its projections on computer models, particularly MAGICC—but has not yet considered a climate-restoration pathway. So I commissioned modeler extraordinaire Shannon Fiume to use MAGICC to take into account full-scale, natural-process solutions for removing 60 Gt/ year of CO2 a year from the ocean.

The results show CO2 decreasing swiftly with climate restoration solutions. CO2 levels descend to 300 in 2050—safe for humanity. Then they fall to pre-industrial—ideal for humanity and the nature of the previous 10,000 years—and stabilize.

Net-zero is not enough.  We want to restore a safe climate for future generations.  

Will you bet on 300 by 2050 and help shift the focus to climate restoration?

Do tell us below.

And please subscribe and share this blog with everyone you know who’s concerned about the climate.

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