Worst Case Climate Change Scenario Is Scary, But The Reality Could Be Even Worse

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Any fool can predict the future. That’s easy. Predicting it accurately is hard. A recent comment in the journal Nature by Zeke Hausfather and Glenn Peters criticizes some of the existing climate change models because they present a worst case scenario that basically says life on Earth as we know it will cease to exist within 100 years as average global temperatures increase by 5º Celsius. They say such doomsday scenarios just scare the bejezus out of most people.

Image: Carolyn Fortuna

They fear that by putting such information out there, people and governments will simply throw up their hands and choose to do nothing. If it’s inevitable we are all going to die, why fight it? Just get it over with. Maybe in a few million years, a new race of humanoids will arise and be better stewards of the Earth.

They argue the worst case scenario — often called the “business as usual” case — is based on unrealistic assumptions, one of which is that all the coal remaining in the Earth will be excavated and burned during the next 80 years. That is unlikely. Yet Japan, the country that is beating its breast the loudest about the wonders of a clean hydrogen economy, is making a new commitment to coal. According to The New York Times, it plans to build 22 new coal-fired generating plants.

While China is ramping up renewable energy installations, it is simultaneously offering to build coal facilities for its neighbors in Southeast Asia as well as India and Africa. So while the allure of coal is waning, it is a long way from becoming irrelevant to the world’s energy mix.

Hausfather and Peters argue, “We must all — from physical scientists and climate-impact modelers to communicators and policymakers — stop presenting the worst-case scenario as the most likely one. Overstating the likelihood of extreme climate impacts can make mitigation seem harder than it actually is. This could lead to defeatism, because the problem is perceived as being out of control and unsolvable. Pressingly, it might result in poor planning, whereas a more realistic range of baseline scenarios will strengthen the assessment of climate risk.”

They stress that, “This admission does not make climate action less urgent. The need to limit warming to 1.5 °C, as made clear in the IPCC’s 2018 special report, does not depend on having a 5 °C counterpoint.”

Michael Mann Responds

Michael Mann is known as “the hockey stick guy.” Together with colleagues Raymond S. Bradley and Malcolm K. Hughes, he created the graph in 1998 that showed global average temperatures ratcheting up by alarming amounts since the beginning to the so-called Industrial Revolution, the point when humanity learned to use fossil fuels to power civilization instead of muscles, flowing water, and wind.

That graph made Mann one of the most hated scientists on Earth. Like Copernicus and Galileo, his contribution to science upended conventional wisdom. Until he and his hockey stick came along, the conventional wisdom was that nothing humanity did could possibly affect the Earth and its environment in any significant way. Our planet was simply too vast to be affected by anything people did.

No amount of emissions from smokestacks could possibly affect the atmosphere — if you exclude acid rain and a hole in the ozone layer. No amount of plastic could have a significant impact on the vast oceans — until it did. No amount of fertilizer runoff or fracking fluid injected deep underground could possibly alter the drinkability of groundwater — except they have.

Mann’s revelation was an attack on the foundation of commerce in general. If what he and his colleagues said was true, we would have to dismantle the global economy and replace it with one based on an absence of carbon dioxide and methane emissions. Trillions of dollars in wealth would be lost. And so the wealthy banded together to sic their attack dogs on Mann, like a pack of snarling German Shepherds in a junk yard. He was treated to mountains of abuse. Corporations hired private investigators to find some dirt they could use to discredit him. He received multiple death threats.

Yet all he did to deserve this abuse was compile data from the historical record and use it to plot a graph. For more about the blowback Mann experienced, see the article he wrote for The Guardian in 2012. As it turns out, Copernicus and Galileo were correct, but each paid a terrible price for the truths they revealed.

In a blog post dated January 29, Michael Mann says, “Let me provide some context and caveats about this new (Hausfather and Peters) commentary. First of all, it is just that — a commentary, not a peer-reviewed scientific article. That must be kept in mind by anyone somehow thinking this overthrows conventional scientific thinking. It doesn’t. It’s basically an opinion piece.”

The most recent peer reviewed study, Mann says, was published by Rogelj et al in Nature in 2016. But that study used a simplistic climate model that did not take into account what Mann calls nonlinear factors — changes in climate dynamics that are exponential rather than arithmetic. They are often called feedback loops, in which small changes contribute to and reinforce even more changes.

We have seen a sobering example of the importance of these feedback mechanisms here in Australia where I am currently on sabbatical. In the catastrophic fires that have engulfed the continent (which were exacerbated and amplified by unprecedented heat and drought made possibly by climate change), roughly twice as much carbon escaped into the atmosphere as was produced by all of fossil fuel burning in Australia over the last year.

These sorts of amplifying “carbon cycle” feedback mechanisms (and this is just one example–there are many others including, for example, the potential release of frozen methane in the Arctic with warming) are not accounted for in the simple sorts of projections that Hausfather and others are using here. It is very likely that these feedback mechanisms will add substantially to the warming over the next century.

Combine that with the fact that the most recent (“CMIP6”) IPCC climate models seem to be showing the potential for considerably greater warming than the previous generation (“CMIP5”) of IPCC models, and in my view, it is very difficult to rule out warming in excess of 4C under “business-as-usual” climate policies. Only with very strong mitigation efforts and rapid reduction of carbon emissions can we avoid such a scenario with a high degree of confidence.

Finally, let’s not forget that even a 3C warmer world would be catastrophic. Here in Australia, we’re already seeing the catastrophic impacts of less than half that much planetary warming.

Most of this critical context has been lost in the recent discussion.

There is some good news here. The numbers show that escalating efforts around the world to decarbonize our economy are starting to pay dividends. We’re starting to bend that emissions curve downward. But we need to reduce emissions by a factor of two over the next decade and bring them down to zero in a matter of a few decades if we are to avert catastrophic climate change impacts. We have to get off fossil fuels far more quickly than we’re on track to do under current policies.

This latest commentary doesn’t change that at all.

Worse Than The Worst Case Scenario

While Hausfather and Peters are arguing that the worst case “business as usual” scenario is unlikely to happen, the evidence is starting to emerge that changes in the Earth’s environment are happening faster than climate scientists have predicted. In an article in The New York Times dated December 4, 2019, Petteri Taalas, Secretary General of the World Meteorological Organization, says, “Things are getting worse. It’s more urgent than ever to proceed with mitigation. The only solution is to get rid of fossil fuels in power production, industry and transportation.”

A recent article in Nature points out that melting of Arctic and Antarctic ice caps is happening faster than anyone expected. If all that ice were to melt, sea levels around the world would rise by about 220 feet. That might take centuries, but even a increase of a few feet would inundate the cities where hundreds of millions of people live today.

But sea level rise is not the worst of it. Some scientists estimate there is twice as much carbon sequestered in the frozen tundra of the Arctic than is currently present in the Earth’s atmosphere. If things are bad and getting worse now, just imagine what will happen if the permafrost melts and releases all that stored carbon back into the atmosphere.

Louise Farquharson is a geologist and researcher at the University of Alaska-Fairbanks who studies the effect of climate change on permafrost. She tells the Times, “We see warming across the board, and generally the rate of warming is increasing, but the impact varies significantly.” In her research, she discovered the permafrost in northern Canada had already thawed at depths not expected until 2090 under a model of “moderate” global warming.

As the permafrost melts, more carbon enters the atmosphere leading to more melting leading to more carbon leading to more warming leading to more melting. The result could be far more catastrophic than even the worst case “business as usual” scenario.

A Tale Of Four Sea Captains

Long time readers of Yankee magazine may recall a story many years ago about four former captains of whaling ships sitting on the front porch of the Jared Coffin House on Nantucket. They were reminiscing about their many voyages and how their success hunting whales was due largely to the accuracy of the compasses they took with them on their voyages.

One old salt looked up and said the spire of a local church was due south of where they were sitting. A second disagreed, saying south was directly over the a flag pole in the distance. A third proclaimed the roof of the town hall was the correct landmark. The fourth was of the opinion that a hilltop nearby was the proper reference point.

Without a word, all four got up and went to retrieve their compasses from their homes nearby.  They brought them back to the porch, sighted along them as they did thousands of times during their journeys, then stood as one and took the compasses home for safe keeping. Not a word was spoken, but every one of the captains went to bed that night believing his compass was the only accurate one in the group.

A climate model is like a compass. It’s a guide, a tool, but it is no substitute for the human brain. The longer we spend arguing about whose climate model is more accurate, the sooner we will cease to exist as a species. There is only one solution to the challenge of climate change. Stop extracting and burning fossil fuels. Full stop. Nothing else matters. And the time to begin finding alternatives to fossil fuels is today, not tomorrow. We are in a race against the clock and we are falling dangerously behind.

One thing is for certain. It will take all humanity working together to win the battle. Unfortunately, the movement to demonize “the other” in countries around the world is gaining popularity and makes that cooperation less and less likely. We have the power to leverage our collective intelligence, but will we choose to use it while there is still time? There is no compass or climate model on Earth that can answer that question.

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Steve Hanley

Steve writes about the interface between technology and sustainability from his home in Florida or anywhere else The Force may lead him. He is proud to be "woke" and doesn't really give a damn why the glass broke. He believes passionately in what Socrates said 3000 years ago: "The secret to change is to focus all of your energy not on fighting the old but on building the new."

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