“The accumulation of CO2 in the atmosphere is irreversible on human timescales and will affect climate for millennia” -- World Meteorological Organization (WMO)
The primary driver of our planetary climate crisis -- carbon dioxide gas (CO2) -- continues to pile up in our atmosphere at an accelerating rate. And the last two years were record-busting huge. Take a look.
This chart shows the latest data from the United States National Oceanic and Atmospheric Agency (NOAA).
Orange bars indicate the CO2 increase for each of the last 60 years.
For example, that small bar on the far left is 1964. That year CO2 increased by 0.31 parts per million (ppm).
The tall red bar on the far right is 2024. It shows that last year CO2 rose by 3.33 ppm. The only other year close to this extreme was 2023.
In sheer weight, each of the last two years added another 26 billion tonnes of CO2 to the atmosphere. That’s more than three tonnes each year per human. For high emitters like Canadians, it’s closer to ten tonnes per year.
While those are huge numbers, many of you know that humans emit twice that much CO2 each year. Around half of what we emit gets taken out of the atmosphere by the oceans (causing ocean acidification) and by plants. Without these “CO2 sinks” the atmosphere would gain CO2 twice as fast.
But the amount of CO2 removed each year by oceans and plants varies a lot. This is mostly caused by short-term fluctuations in ocean currents. The result is the short-term ups and downs seen on the chart. To smooth out these fluctuations, and better illustrate the underlying trend, NOAA highlights the decade averages. I’ve added ten-year averages to my next chart.
NOAA just published last year’s CO2 increase, and it was huge. @bsaxifrage.bsky.social charts the trajectory - Blue Sky
Stairway to hell and high water
On this version of the chart, the average annual increase in each decade is indicated by black horizontal bars.
For example, six decades ago, CO2 was increasing by an average of 1.11 ppm per year. That’s the leftmost black bar.
As the decades rolled on, the averages marched higher – a human-built stairway to hell and high water.
During the last decade, CO2 rose two and a half times faster than in the 1960s. That’s shown by the highest black bar that stretches from 2013 to 2024. During those ten years, increases averaged 2.64 ppm.
As NOAA points out: “the rate of CO2 growth over the last decade is 100 to 200 times faster than what the Earth experienced during the transition from the last Ice Age. This is a real shock to the atmosphere.” I’ve added a dashed line to the bottom of the chart to show how fast CO2 was rising back then. That tiny rate cooked away a massive ice sheet that was up to two miles thick and covered all of what is now Canada. Global sea levels rose 125 meters.
What the history of the Earth shows is that our climate system is extremely sensitive to CO2. This is why the best science warns us that the climate will grow ever more extreme until we stop dumping CO2 into it. That point is called “net zero”. And it is literally the zero line on the chart. I point it out with a blue arrow. Does it look to you like we are heading in that direction?
Bending the curve
When increases are increasing, it's called acceleration. And when we do that with the primary control knob of the Earth’s climate -- CO2 -- we accelerate our climate system and all of us living inside it away from stability and safety.
You can see the acceleration in my next chart. It shows the amount of CO2 in our atmosphere since 1960.
I was born back in 1960. At that point, atmospheric CO2 levels were around 320 ppm. That’s the start of the solid orange line on the chart.
By 1990 -- at the start of the global climate conference era -- CO2 levels had surged to around 350 ppm.
Today, CO2 has shot above 420 ppm. That’s the end of the solid orange line on the chart.
That orange line keeps bending upwards -- growing steeper and steeper. That’s what happens when annual increases keep increasing.
Another way to visualize how rapidly we are accelerating this CO2 curve upwards is to look at the dotted lines I’ve added to the chart. These show the rate of increase in various decades.
For example, the lower dotted line shows the 1960’s trend extending out to 2050. That’s the path we would be on if humanity had kept emitting CO2 at the 1960’s rate.
Compare that to the orange dotted line at the top. That’s the rate we added CO2 in the last decade. That path will rocket us quickly to 500 ppm and beyond.
Saddling our youth with a heavy burden
For perspective, climate scientist Dr. James Hansen has long warned that "if humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced … to at most 350 ppm, but likely less than that."
I’ve circled 350 ppm on my chart. We’ve sailed far past that safe harbour.
Hansen argues that the longer atmospheric levels remain above 350 ppm the more likely the additional heating will trigger “irreversible catastrophic effects”. Young people today will have to fight their way back to this safe harbour during their lifetimes or battle it out at sea against ever more dangerous conditions.
This burden we are forcing on today’s young people has a physical weight. Currently, it’s around one trillion tonnes of CO2. That’s how much Hansen calculates must be removed from the atmosphere to lower the current 425 ppm back down to 350 ppm.
Every year we increase that burden by tens of billions of tonnes of CO2.
Our current rate of emissions is rocketing us towards 500 ppm within decades. At that point, the burden placed on young people will weigh two trillion tonnes of CO2. Hansen calculates that the cost to remove that much in time – during this century – could easily cost $100 trillion or more. And it’s not even clear that removal at that scale is even feasible.
Hansen has a clear warning about the path we are on: “continued high fossil fuel emissions unarguably sentences young people to either a massive, implausible cleanup or growing deleterious climate impacts or both.”
Hey kids, have you said “thank you” even once?
[Top: BLACK MARBLE: NASA'S GODDARD SPACE FLIGHT CENTER]
