The background and facts about that 12-year deadline for averting climate change

Source: By Josh Siegel, Washington Examiner • Posted: Friday, August 16, 2019

A host of Democratic presidential candidates have cited a specific time frame when the world would reach a point of no return on climate change — 12 years.

“Science tells us that how we act or fail to act, in the next 12 years will determine the very livability of our planet,” frontrunner Joe Biden said upon releasing his plan to reach net-zero greenhouse gas emissions by 2050.

Jay InsleeBernie SandersPete Buttigieg, and Beto O’Rourke are among other candidates who have also used the 12-year framing.

“Science tells us that we have 12 years before we reach the horizon of catastrophe when it comes to our climate,” Buttigeg said at last month’s debate.

I asked climate scientists and other experts to interpret what the candidates mean by this rhetoric, and whether they are accurately portraying the urgency of climate change, and the consequences of not acting.

The IPCC report was the instigator: All of them agreed the candidates are referring to conclusions from a report issued by the United Nations Intergovernmental Panel on Climate Change in October of 2018. The report is often credited with generating more attention to climate change and inspiring the rise of the Green New Deal.

The main take-away of that report was that the world must reach net-zero emissions by 2050 in order to limit temperature increases to 1.5 degrees Celsius, the more ambitious target of the Paris agreement. Countries in the Paris deal pledged to hold total global warming to “well below” 2 degrees and agreed to “pursue efforts” to limit warming to 1.5 degrees.

Most previous reports have looked at the implications of the 2 degrees scenario, but this one zeroed in on 1.5 degrees, finding that avoiding this temperature threshold is necessary to avoid the worst consequences of climate change, such as extreme heat, water scarcity, mass deaths of coral reefs, and significant sea level rise.

Here’s where there 12 years comes into play: The report says for the world to have a chance of limiting warming to 1.5 degrees, we would need to cut emissions by about 45% by 2030 (12 years from the report’s release, in 2018).

Drew Shindell, a Duke University climate scientist who worked on the UN report, told me the best way to interpret that finding is to say the world must be reducing emissions substantially beginning now in order to secure a “down payment” by 2030 that puts the world on pace to reach net-zero emissions by 2050.

“The report showed that if we are not on a greatly different path by 2030 than our current trajectory we cannot keep within the 1.5C warming target,” Schindell said. “There’s nothing particularly special about 2030 relative to other years, but we often look at changes decade by decade for simplicity. We are not going to change enormously by 2020, and waiting until 2040 is too late, hence 2030 is a good timescale to talk about.”

Schindell says candidates citing the 12-year figure are making a “reasonable characterization” of what the report said, even if they risk oversimplifying the problem.

“Of course, being a scientist, I’d prefer more detail on what exactly the candidates mean by taking action by 2030, but I think this is a sensible slogan that reflects the spirit of the IPCC report,” he said.

What the 12-years time frame is not: ‘The world will end as we know it’: Diana Liverman, another author of the UN report, told me candidates should be careful in how they use the 12 years framing.

“I don’t have a major problem with the ’12 years to act’ discourse as it is one message from the IPCC report as it conveys the urgency of what we need to do if we want to avoid the more severe impacts of climate change,” said Liverman, who studies environmental issues at the University of Arizona. “What creates fear is when this is linked to ‘or the world will end as we know it’ idea.”

She, and other climate scientists, said it would be more accurate to say that the U.S. — as a leading per-capita contributor to emissions — must begin reducing its share of global emissions starting now in order for the world to cut them at least 45% by 2030.

“I don’t know that the 12 year framing is particularly helpful,” Joseph Majkut, a climate scientist at the center-right Niskanen Center, told me. “It requires specific context to be accurate and has a precision to it that betrays how complicated it will be to manage climate change. It’s enough to say that we have dallied too long and we need to make up for lost time.”

Nat Keohane, vice president for international climate at the Environmental Defense Fund, credits Democratic candidates for using the UN report to generate more attention to climate change.

But he worries about the impact of using rhetoric that could be interpreted as over-dramatizing the problem.

“I do worry that some people look at that report and go from complacency to despair,” Keohane told me. “We go straight from not paying attention to the climate crisis to, ‘oh my god it’s too big to solve.’”