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Bracing Ourselves for the Climate Tipping Point

After Earth’s warmest month in history, climate scientists gather in Geneva to debate whether we’ve already gone too far.

By Eric Holthaus


Activists outside COP21 in Paris last December stressed the importance of keeping warming below 1.5° Celsius. (Photo: Carbon Brief)

On Monday, the National Aeronautics and Space Administration released its updated global temperature data for July, and a stunning record was broken: For as long as we’ve been keeping track (since 1880), and likely since long before, there has never been another month as warm as the one just past. And never is a long time: An extrapolation of recent research shows last month likely marked Earth’s warmest absolute temperatures since human civilization began, thousands of years ago. That’s a pretty big deal.

Depending on how you count, our planet briefly surpassed the 1.5-degree Celsius mark above pre-industrial levels this year, and may have also touched two degrees during a February-to-March global heat wave that coincided with the peak of El Niño. (The Earth’s absolute temperature was much warmer during the month just past, because our planet’s land area is concentrated in the Northern Hemisphere, and land heats more quickly than water during the summer.) These numbers are particularly meaningful, since they are the upper limits the world community agreed to less than a year ago in the landmark Paris Agreement on climate change; and embody the point past which scientists agree “dangerous” impacts will become unavoidable. Sure, humanity has agreed to these temperature goals, but there’s a difference between agreeing to do something and actually doing it. The steady stream of new global temperature records point to the possibility that those goals might no longer be in reach.

The report that emerges from Geneva will lay out exactly what it would take for the world to stay below 1.5 degrees, which otherwise could be locked in by about 2021. Problem is, the report itself won’t be published until 2018.

“Impacts have already occurred that are widespread and consequential,” says Chris Field, a climate scientist at Stanford University and co-chair of the Intergovernmental Panel on Climate Change report focusing on climate impacts. “To a very clear extent, the impacts that have already occurred surpass the threshold of ‘dangerous anthropogenic interference with the climate system.’” That wording — dangerous — is part of a foundational phrase of Article 2 of the United Nations Framework Convention on Climate Change, the governing agreement for global climate negotiations. Some observers hold that “dangerous” climate change was witnessed for perhaps the first time earlier this year during a mass global coral bleaching event. The National Ocean and Atmospheric Administration estimates that more than half a billion people worldwide depend on healthy coral reefs for food and livelihood, and their loss would greatly affect coastal communities as well as the entire balance of the oceanic food chain.

So, what does it mean that we’re now in uncharted territory? And have we already come too far to avoid key planetary tipping points? What hope should we have that we’ll fix this sooner rather than later?

This week, scientists are gathering in Geneva, Switzerland, in an attempt to answer these questions. That we’ve reached a new, increasingly urgent phase of global warming is becoming apparent after a surge of millennial-scale floods, ecosystem collapses, and record-strong cyclones — all within the last year, coinciding with what’s likely to become the warmest year on record. The planet seems at the breaking point, with increasing evidence that we’ve already locked in additional warming that will take us further into uncharted territory — assuming we don’t rapidly change course.

The Geneva gathering is officially a “scoping meeting” for the IPCC’s upcoming special report on the 1.5-degree Celsius target, designed to analyze the scale of what it would take to meet that ambitious mark, and what might be gained and lost by doing so. That figure became a rallying cry of the least-developed countries on the front lines of rapid environmental change at the December global climate negotiations in Paris. (Campaigners even created a hand signal for delegates to show their support for the target during the talks last year.)

“The biggest reason this meeting is happening is not out of a deluded sense that we’re on a likely trajectory toward 1.5 degrees Celsius,” says Katharine Mach, director of science for the IPCC’s group focusing on climate impacts. Rather, she explains, the meeting and the upcoming report are designed to state clearly that “there is dangerous climate change at 1.5 degrees Celsius, and that we’re already seeing impacts.”

The exact wording in the Paris agreement was that the global community would “pursue efforts to limit the temperature increase to 1.5 degrees,” which is considered to be the most ambitious temperature target still technically achievable, though most scientists I spoke with that are attending the Geneva meeting, including Mach and Field, said the most realistic best-case scenario would likely involve overshooting the target. (The sum of all countries’ emissions reductions pledges in Paris, according to one analysis, would limit global warming to between 2.6 degrees and 3.1 degrees Celsius, a significant overshoot.)

The new report being worked on in Geneva will lay out exactly what it would take for the world to stay below 1.5 degrees, which otherwise could be locked in by about 2021. Problem is, the report itself won’t be published until 2018, when about half that time has already elapsed. That’s also the year countries are scheduled for a first formal review of their emissions pledges made in Paris, with the idea that the 1.5-degree report might spur bolder targets.

“An interesting question is the extent to which the scoping team will want to include solar geo-engineering, which is probably the most feasible method of stabilizing at 1.5 degrees Celsius, at least in the short term,” climate scientist Ken Caldeira said by email; Caldeira’s own work has examined the scenarios in which artificially boosting the planet’s reflectiveness in an attempt to cool it down might make sense. Meeting the 1.5-degree target without these controversial methods, Caldeira wrote, is “physically possible but highly unlikely when viewed through a sociopolitical lens.”

“Wholesale transformation is required to avoid warming beyond 1.5 degrees and a wholesale transformation will be required if the globe warms beyond it.”

The planning document for the Geneva meeting uses bold language, which is uncharacteristic of the politically neutral IPCC. On page six, the document warns that a “wholesale transformation is required to avoid warming beyond 1.5 degrees and a wholesale transformation will be required if the globe warms beyond it.” The stakes are that high, and the language makes me think that at least a few of the scientists involved in this effort have not yet given up hope of reaching the goal through more traditional means, even though it might amount to closing all coal-fired power plants worldwide by 2025, and eliminating all petroleum-powered transportation by 2030, or some form of geo-engineering.

Those would be aggressive moves, and we are just not built as a society to transition this quickly. To do so, as climate scientist Claudia Tebaldi at the National Center for Atmospheric Research explained to me, implies necessary trade-offs with other things we care about, like poverty reduction and economic growth. “When it comes to these very big step changes that people are thinking about, I don’t think we can [model them].” In an op-ed in the New Republic on Monday, environmentalist Bill McKibben wrote that, in order to meet our climate goals at this point, we should literally declare a war on warming, and re-tool the global economy as rapidly as we did during World War II. Even then, it might not be possible.

In other words, if maintaining the 1.5-degree limit is technically achievable, that in no way means it is politically achievable, as the past decades of increasing global emissions can attest. Even the successful scenarios that scientists have developed increasingly rely on unproven technologies that involve essentially running the world’s factories in reverse, sucking carbon dioxide out of the atmosphere and burying it underground on unimaginably vast scales only decades from now.

So, what do you say to the world when it’s asked you to do the impossible? If the task seems so hopeless, why write a report at all?

“I think our biggest constraint is that are trapped in a way of linear thinking,” says Susanne Moser, a consulting climate scientist and former IPCC author who helped organize this week’s meeting in Geneva. “When you actually look at history, there have been social tipping points where things all of a sudden changed in a non-linear way.”

Moser says that, while climate scientists and journalists often focus on catastrophic tipping points and steep changes in the climate system, the same could also hold true for solving climate change.

“I think it is absolutely crucial that we somehow connect the urgency of what it means to mitigate [climate change] at the same time that we show so clearly how we cannot afford to overshoot,” Moser says. “The idea that we convey something like it’s too late, to me it’s like: And then what? What do you say after that? We have to constantly question our assumptions in terms of what we think is possible.”

We know our current path will lead to catastrophe — incompatible with the livelihoods of billions of people. These profound changes will happen in our lifetimes. These impacts will happen, and are happening, to us. That scientists are willing to speak in increasingly bold terms about the seemingly impossible situation we’re in may help us to question the fundamental economic model that’s brought us to this point.