Climate

Irreversible But Not Unstoppable: The Ghost Of Climate Change Yet To Come

CREDIT: Wikimedia Commons

Unlike Scrooge, we don’t get a spirit to show us what the future holds if we don’t change our ways.

That’s what we have science for. In recent years, observations have confirmed the key projections climate scientists have been making for decades. But some of the most important impacts have been occurring much faster than scientists expected, including sea level rise. As recently as a decade ago, scientists did not expect that the great ice sheets of Greenland and Antarctica would melt enough this century to contribute much to total sea level rise. Now, observations suggest they will be a primary if not the primary driver of sea level rise.

Recently, we’ve had many of the world’s leading scientists and scientific bodies warning us of what is to come.

Yes, it seems unlikely that we will adopt the aggressive but near-zero-net-cost policies needed to stabilize at 450 ppm atmospheric concentrations of carbon dioxide, and then quickly come back to 350 ppm, thanks in large part to the deniers, along with their political pals and media enablers. But the two biggest carbon polluters (China and U.S.) have struck a game-changing deal that could ultimately avoid some of the worst impacts — if other key countries join in and, then all countries pursue even stronger emissions cuts in the coming decades.

Humanitys choice

Humanity’s choice (via IPCC): Aggressive climate action ASAP (left figure) minimizes future warming. Continued inaction (right figure) results in catastrophic levels of warming, 9°F over much of U.S.

On the other hand, the IPCC made clear in its final synthesis report of the recent scientific literature that whatever changes we do bring to pass will likely be “irreversible on a multi-century to millennial time scale,” harming the lives of billions and billions of people.

The question of whether it’s “too late,” doesn’t have one purely scientific answer. It does seem clear that the most dangerous carbon-cycle feedback — the defrosting permafrost — hasn’t kicked in yet but likely will within two decades, adding 0.4°F – 1.5°F to total global warming by 2100. On the other hand, part of the West Antarctic ice sheet now does appear close to if not past the point of irreversible collapse. That said, the worst case of sea level rise can still be avoided, as can many other of the most serious impacts.

If humanity gets truly serious about emissions reduction — and by serious I mean “World War II serious” in both scale and urgency — we could go to near-zero global emissions in, say, two decades and then quickly go carbon negative. It wouldn’t be easy, far from it in fact. But it would be vastly cheaper and preferable to the alternative. A few years ago, scientists found the “net present value of climate change impacts” to be an astronomical $1240 trillion on our current emissions path, making mitigation to under 450 ppm a must.

Delay is very risky and very, very expensive. As the International Energy Agency has explained, “on planned policies, rising fossil energy use will lead to irreversible and potentially catastrophic climate change.”

“Delaying action is a false economy: for every $1 of investment in cleaner technology that is avoided in the power sector before 2020, an additional $4.30 would need to be spent after 2020 to compensate for the increased emissions.”

Action now will save trillions and trillions of dollars.

Five years ago a NOAA-led paper laid out some alarming predictions for our climate-changed future.

…the climate change that is taking place because of increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop … Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450-600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the “dust bowl” era and inexorable sea level rise.

And we know that large parts of the currently habited and arable land are at risk of turning into Dust Bowls, gravely threatening global food security.

We most certainly do not want to significantly exceed 450 ppm for any length of time, given that Dust-Bowlification isn’t the only impact that is irreversible — see “Science: CO2 levels haven’t been this high for 15 million years, when it was 5° to 10°F warmer and seas were 75 to 120 feet higher.”

That said, RealClimate made a good point with the title of its 2009 post, “Irreversible Does Not Mean Unstoppable”, explaining, “we at RealClimate have been getting a lot of calls from journalists about this paper, and some of them seem to have gone all doomsday on us.”

Indeed, the NOAA-led study was the perfect paper for someone, like say, Lou Dobbs, who went from hard-core doubt/denial to credulous hopelessness in one breath, as he did January 30, 2009 [(h/t ClimateScienceWatch)]:

Let’s assume, for right now, that there is such a thing as climate change, let’s assume it’s manmade. What indication — what evidence do we have, what reason do we have to believe that mankind can do anything significantly to reverse it because a number of people, as you know in the last two weeks, are reported that, that, this is a 1,000-year trend irrespective of what we do.

Yeah, let’s assume, for right now, there is climate change and let’s further assume its manmade, considering the U.S. National Academy of Sciences labels as “settled facts” that “the Earth system is warming and that much of this warming is very likely due to human activities.” Then let’s tell the public the latest research means if there is manmade climate change, the situation is now hopeless — when in fact the latest research makes it all the more urgent to keep total emissions and concentrations as low as possible.

Seriously. This guy had his own hour TV show on a major cable network … albeit one that fired its staff covering science and environment and hired a psychic to cover climate change. (OK, let’s assume, for right now, that I made up that last part — though CNN’s Headline News channel actually asked a psychic to opine on the missing Malaysia Flight 370 earlier this year!)

Ghost of Christmas Future

Scrooge implores the Ghost of Christmas Future, “Why show me this, if I am past all hope?”

CREDIT: Wikimedia Commons

The whole world has become Dickensian (see “A Tale of Two Disasters“), which brings us to another Dickens story relevant to the theme that irreversible does not mean unstoppable.

“Before I draw nearer to that stone to which you point,” said Scrooge, “answer me one question. Are these the shadows of the things that Will be, or are they shadows of things that May be, only?”

Still the Ghost pointed downward to the grave by which it stood.

“Men’s courses will foreshadow certain ends, to which, if persevered in, they must lead,” said Scrooge. “But if the courses be departed from, the ends will change. Say it is thus with what you show me.”

The Spirit was immovable as ever.

Scrooge crept towards it, trembling as he went; and following the finger, read upon the stone of the neglected grave his own name, EBENEEZER SCROOGE.

“Am I that man who lay upon the bed?” he cried, upon his knees.

The finger pointed from the grave to him, and back again.

“No, Spirit! Oh no, no!”

The finger still was there.

“Spirit!” he cried, tight clutching at its robe, “hear me. I am not the man I was. I will not be the man I must have been but for this intercourse. Why show me this, if I am past all hope?”

For the first time the hand appeared to shake.

“Good Spirit,” he pursued, as down upon the ground he fell before it: “Your nature intercedes for me, and pities me. Assure me that I yet may change these shadows you have shown me, by an altered life.”

The kind hand trembled.

Or, as RealClimate put it less poetically:

But you have to remember that the climate changes so far, both observed and committed to, are minor compared with the business-as-usual forecast for the end of the century. It’s further emissions we need to worry about. Climate change is like a ratchet, which we wind up by releasing CO2. Once we turn the crank, there’s no easy turning back to the natural climate. But we can still decide to stop turning the crank, and the sooner the better.

Indeed, we are only committed to under 2°C total warming so far, which may be manageable — especially if we did keep CO2 concentrations from peaking below 450 ppm, the small amount of CO2 we are likely to be able to remove from the atmosphere this century could well take us below the danger zone.

But if we don’t reverse emissions trends far faster than currently envisioned, we will certainly double and probably triple that temperature rise, most likely negating any practical strategy to undo the impacts for hundreds of years:

Such is the climate change yet to come.