CNN: We're Burning Through the Earth's Carbon Budget

North America, in a world without glaciers (click to enlarge)

by Gaius Publius

While Fast Track and TPP sort themselves out in the Senate — another vote on which could come soon — I want to pass on some climate news from CNN.

As you may know, I believe we have very little time to address the challenge of climate change. Michael Mann puts the most likely date for crossing +2°C global warming in the 2030s, which means it becomes inevitable sooner than that, in the 2020s, just around the corner. We're already at +1°C warming, with another half degree in the pipeline, guaranteed. We've crossed 400 ppm atmospheric CO2 for the first time since before humans walked the earth, and we're increasing net carbon emissions at more than 2 ppm per year, at a rate that's accelerating.

We have to stop now. Period. Or maybe Stop Now™ — because it needs to be a "thing." As in, "How is Stop Now™ not a thing?"

Look at it this way. There's a pot of water on a burning stove and it's scalding hot. Every minute that passes, you turn the heat higher. If you want the water to return to room temperature, it's not enough to walk away. You have to turn off the heat. Today's concentrations of 400 ppm will cause major changes in the climate of the earth to play out over the next century and beyond. It's not enough to stabilize emissions. We have to stop — bring emissions to zero, and soon.

CNN has finally "cottoned" to that — and that's the news:

We're burning through the Earth's carbon budget

Here's a recent headline that sends chills down your spine if you're a climate-news junkie — and makes just about zero sense if you're any other normal person:

"A Global Milestone: CO2 Passes 400 PPM"

Translation: There's now an even more ridiculous amount of carbon dioxide in the atmosphere — 400 parts carbon dioxide (CO2) for every million parts of something else atmospheric. That's warming the planet. And it's our fault since we're burning fossil fuels and clearing forests.

But that's definitely a mouthful.

Mind-numblingly arcane numbers such as "400 ppm" will determine what life looks like in the future of our planet. How many people will be killed by heatwaves? How many species — not just polar bears, but amphibians, proteas and pikas — will go extinct? What percentage of the world's coral reefs will be lost? How many low-lying island nations will have to be abandoned as the seas swallow them up? Which regions will be newly exposed to malaria and other tropical diseases?

All of these things will be heavily influenced, if not determined, by these goofy little numbers, including the amount of carbon dioxide that's measured in the atmosphere.

Below, you'll find a brief backgrounder on three numbers, including one "ppm" measure, that are central to the climate change discussion. These numbers aren't widely famous — at least yet. I hope that changes, because these odd numbers should be a rallying cry and a goalpost for ensuring that we act fast enough to blunt climate change.

These numbers will determine what the world looks like for us and future generations.

The least we can do is get to know them.

The three numbers are important. They are:

2 degrees

Any amount of global warming is somewhat dangerous, but 2 degrees Celsius of warming (3.6 degrees Fahrenheit) is when things start to get Earth-changingly bad. Water is expected to become much more scarce. A significant percentage of the world's plants and animals will be at risk for extinction. Coral reefs will be heavily bleached if not gone. Some island nations could be underwater, or saltwater intrusion from rising seas could make them uninhabitable.

One climate change activist told me 2 degrees -- and not crossing it -- is pretty much the only thing the world agrees about when it comes to climate change. The number was first proposed by an economist in the 1970s, and it since has become the subject of near international consensus. World leaders will meet in Paris in December to try to hammer out an international agreement, essentially, on how to keep us below the 2-degree mark.

The number is measured as the temperature increase since the Industrial Revolution began about 150 years ago. We've already helped warm the atmosphere by 0.85 degrees since then. ...

Here the writer is way too conservative. There's a strong argument that "2 degrees" is too much, that where we're headed with our inevitable 1½ degrees is also too much, and the recooling has to start now (something that's entirely possible, by the way, since if we stop putting CO2 into the atmosphere, natural processes will take it back out).

Also, later in this section the author says that the "2 degree" point will hit in the 2050s. That's the ultra-conservative IPCC talking, and they're likely wrong, since every speed predictor so far has been wrong to the slow side.

Still, for CNN, this is a huge start. The other two numbers they want you to note are:

450 ppm

There's more carbon dioxide in the atmosphere now than there has been in millions of years. That's why "400 ppm," the benchmark we crossed last week, made headlines around the world. But there's actually another number, 450 ppm, that is real cause for alarm among scientists and policy experts.

450 parts per million of CO2 in the atmosphere likely would push the world past 2 degrees of warming. And, you'll recall, that's the danger zone. We don't want to be this close.

And:

1,000 gigatonnes

[T]here's one more number you need to know in order to understand how urgent climate change actually is: 1,000 gigatonnes. That's how much carbon we can pump into the atmosphere -- in total -- and still hope to stop short of 2 degrees of warming, according to the world's leading climate science group.

The trouble? We've already burned through more than half of that budget....

A gigatonne (or gigaton, if you use non-metric units; almost the same size) is a billion tons. So 1,000 gigatons is a trillion tons, and you're going to be hearing about "the trillionth" ton as the climate debate reheats, as it soon will.

I'll have a longer explainer on this later, or you can look back at this piece. Your bottom line:

• We're at 400 ppm CO2 now. We'll be at 450 ppm in less than 25 years under "business as usual." That's the outer-limit number that can keep the planet habitable for "civilized" (settled, agricultural) man. We have to stop now.
   
• We're guaranteed the consequences of +1½°C global warming now, most of which we haven't seen yet. When +2°C is inevitable, it will be too late. That will most likely occur in the early 2020s.
   
• We have "some" carbon budget — about 250 gigatons of carbon can still be emitted — says the IPCC, under the guidance of (understandably) conservative scientists, and also governmental overseers who are watching out for the interests of the carbon industry and their profits — think Saudi Arabia, China, India, and yes, the Exxon-controlled U.S. The IPCC arrives at that "budget" by adding up the total carbon already emitted, subtracting that from a thousand tons (1,0000 gigatons), and then taking into account the effect of non-carbon greenhouse gases as well. (I'll go through the numbers at another time. It's not rocket science.)
  
  But the statement "there's some remaining budget" comes with a huge caveat — it assumes that stopping at +2°C is safe, and gives only a 66% chance that the plan will work. Guess how much carbon budget there is, if you want a 90% chance of success?
  
  None.

So the first news: CNN has discovered global warming. That's actually huge, since maybe they'll stop "teaching the phony controversy" by giving screen time to bought-and-paid denier scientists.

The second news: It's still not too late, so long as we stop emissions.

The third news: It really is too late if we don't stop very very soon.

For a hint at how to stop "very very soon," click here. Something to ponder while we wait for TPP voting to resume in the Senate.

GP