Are you confused by various takes on the IPCC 1.5ºC Special report?

Can we avoid going through 1.5ºC?

As Gavin Schmidt says, “… the IPCC used a few circumlocutions to avoid giving a direct answer to this question.”

So Nick Mabey could claim, “The IPCC report shows keeping climate change below 1.5°C is necessary, feasible and beneficial.“ The Guardian said it was, “affordable and feasible” but also mentioned that Bob Ward, from the Grantham Research Institute on Climate Change, called the final document “incredibly conservative”.

In 2017, global warming breached 1℃. If the planet continues to warm at the current rate of 0.2℃ per decade, we will reach 1.5℃ of warming around 2040. The report’s prediction range was between 2030 and 2052.

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Feasibility of Limiting Rise to 1.5 ℃

To judge feasibility, look at an IPCC chart which CNN shared, which shows temperature overshooting 1.5°C rise (gold line), assuming immediate drastic emissions cuts.

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Current national pledges under the Paris Agreement are not enough to remain within a 3℃ temperature limit, let alone 1.5℃. If you look at the long term, climate scientist Dr. Peter Carter estimates just our 2017 total greenhouse gas concentration equivalent locked in a long-term global mean surface temperature of 2.6 C.

Gavin reminds us that feasibility involves six dimensions.

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As Gavin puts it, our choice is between (mere) disaster at 1.5°C rise or catastrophe at 2°C. 

… the world (including us) will be involved in wars, revolutions, mass displacement of millions of people, famines, and epidemics. And that’s the better of the two scenarios.

Given the lack of credible alternatives to an unsustainable status quo, modern governments and most of their voters are sleepwalking into catastrophe.

Andrew Freedman reminds us that, “Current emissions projections show the world is on track to increase emissions through 2030.”

Critical Omission

At Bulletin of the Atomic Scientists, Mario Molina, Veerabhadran Ramanathan, and Durwood J. Zaelke point out an even worse problem.

“... the report, dire as it is, misses a key point: Self-reinforcing feedbacks and tipping points—the wildcards of the climate system—could cause the climate to destabilize even further. The report also fails to discuss the five percent risk that even existing levels of climate pollution, if continued unchecked, could lead to runaway warming—the so-called “fat tail” risk. These omissions may mislead world leaders into thinking they have more time to address the climate crisis, when in fact immediate actions are needed.

Adding 50 percent more warming to reach 1.5 degrees won’t simply increase impacts by the same percentage—bad as that would be. Instead, it risks setting up feedbacks that could fall like dangerous dominos, fundamentally destabilizing the planet.

By largely ignoring such feedbacks, the IPCC report fails to adequately warn leaders about the cluster of six similar climate tipping points that could be crossed between today’s temperature and an increase to 1.5 degreeslet alone nearly another dozen tipping points between 1.5 and 2 deg.... These wildcards could very likely push the climate system beyond human ability to control. [emphasis mine]

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Articles used:

Climate report understates threat

IPCC Special Report on 1.5ºC

On Climate, Our Choice Is Now Catastrophe or Mere Disaster

The good, the bad and the ugly: The IPCC special report on global w...

Planet has only until 2030 to stem catastrophic climate change, exp...

We have 12 years to limit climate change catastrophe, warns UN

The stark reality of the IPCC's 1.5-degree climate report

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Replies to This Discussion

... our choice is between (mere) disaster at 1.5°C rise or catastrophe at 2°C. 

Not unlike how (on a much smaller scale) the prognosis of a heart attack victim is frequently not good, even assuming prompt competent CPR, defibrillation on site (if helpful in that particular case), and quick transport to an emergency room with expert treatment. Yet given that choice between "slim" and "none", we don't hold back on giving people that small chance of having a reasonable life afterwards.

In this 15 minute interview Peter Wadhams explains serious inadequacies of the IPCC 1.5°C Special Report.

He uses the word "daft", in particular for their prediction that 1.5°C rise will only result in an ice free Arctic once every hundred years, and 2°C rise only once every 10 years. I was personally shocked by those low predictions. There were no sea ice researcher names on the report, he said. He says the authors had a mentality of basic complacency instead of a mentality of dire warning, and often ignored data. (Apologies for the faith bit)

The growing number of reports from scientists who have more focused knowledge about consequences of climate change turns the alert alarm clock to very close to midnight if we want a planet fit for our future generations in which to live. 

Thanks, Ruth, for keeping us informed. 

Thanks for paying attention, Joan.

Richard Alley, one of the greatest climate scientists of our time, explains why the IPCC 1.5 Special Report vastly underestimates how much sea level could rise. 

What’s Another Way to Say ‘We’re F-cked’?

In a video chat with Baird College students, Alley says there's some risk that sea levels rise 15 to 20 feet in their lifetimes.

Jeff Goodell explains,

… think about what 15-to-20 feet of sea-level rise in the next 70 or so years looks like. 

It means not just higher storm surges from hurricanes, but the permanent drowning of virtually every major coastal city in the world. Miami, New Orleans, large parts of Boston and New York City and Silicon Valley, not to mention Shanghai, Jakarta, Ho Chi Min City, Lagos, Mumbai — all gone.

… compare Alley’s numbers to the latest report from the Intergovernmental Panel on Climate Change,  …  The report projected that with 2 Celsius of warming, which is the target of the Paris Climate Agreement, the range of sea level rise we might see by the end of the century is between about one and three feet.

… IPCC reports …  rely on published science that is often out of date — or at least, far from the cutting edge. 

Alley simply has a broader understanding of ice dynamics than many scientists ,…  Alley’s analysis includes not only geology and paleoclimatology, but also a big dose of physics and engineering — which is especially helpful when it comes to understanding the possibility of rapid ice sheet collapse. 

If West Antarctica goes, that’s 10 feet of sea-level rise right there. Then if you add in ice loss from Greenland, a little from East Antarctica and other sources, you quickly get to 15 to 20 feet.

See this 1 1/2 minute excerpt of Richard Alley:

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