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Why zero is a better climate target than 2 degrees

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One important element of the Paris climate accord has been somewhat overshadowed in all the press coverage. Before the whole thing fades from the news cycle, I want to take a moment to celebrate it.

I'm talking about the shared goal, endorsed by 195 nations, to reduce net global greenhouse gas emissions to zero by the end of the century.

Zero. Zilch. Nada. Let that roll around in your mindgrape for a moment. It has a ring to it.

riding zero
My new favorite stock art ever.
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Zero has oomph

To my mind, zero is a much more compelling and evocative goal than the longer-standing and better-established climate goal of limiting temperature rise to 2 degrees or less.

The 2 degrees target has the advantage of being "science-based," at least insofar as science is capable of putting a hard number on the amount of warming that qualifies as "dangerous." But it is difficult to explain to the uninitiated. It doesn't sound like much extra heat, even when you translate it to Fahrenheit (3.6 degrees). It's not a target you want to achieve, but a threshold you want to avoid, which makes it difficult to talk about aspirationally. Above all, it means almost nothing to the public.

(The goal of atmospheric CO2 at 350 parts per million — where 350.org got its name — has the same problems, and more.)

Zero, on the other hand, is intuitive and easy to explain. It offers a bracing clarity of vision.

It settles the question of what will happen to the fossil fuel industry and investments that rely on fossil fuels. They will go away. It might be soon, it might be later, but the end state is determined. They are slated for extinction.

Unlike the 2 degree target, which relies on complicated scenarios with varying mixes of technologies, zero offers a rugged, simple, and universally applicable heuristic:

Does it emit carbon? If so, then it has to be transformed or eliminated. Easy.

It's a target every activist, advocate, entrepreneur, and investor can rally around, no matter their specific focus. Zero means that as long as there are systems and technologies that emit large amounts of carbon, the job is not done.

Zero is powerful. I think it could catch on.

zero Shutterstock

How in the world did 195 countries agree on a target so stark and galvanizing? The answer is: by loading it up with qualifiers.

Zero, with caveats

The zero-carbon target required months and months of tough, detailed negotiations. Inevitably, the language of the agreement was larded up to reflect everyone's concerns.

Here it is, replete with all its clauses and subclauses:

In order to achieve the long-term temperature goal set out in Article 2, Parties aim to reach global peaking of greenhouse gas emissions as soon as possible, recognizing that peaking will take longer for developing country Parties, and to undertake rapid reductions thereafter in accordance with best available science, so as to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century, on the basis of equity, and in the context of sustainable development and efforts to eradicate poverty.

Each of those 478 clauses was lawyered to death, yielding a thicket of diplomat-ese. So let's break it down.

  1. "In order to achieve the long-term temperature goal set out in Article 2" — this acknowledges that in order to reach the 2 degree target (or, uh, avoid it), global carbon emissions are going to have to zero out, as quickly as possible. Zero serves two.
  2. "Parties aim to reach global peaking of greenhouse gas emissions as soon as possible, recognizing that peaking will take longer for developing country Parties" — this combines two important aspects of international global negotiations that were previously thought to be irreconcilable. First is an admission that time is short, there's not much left of our "carbon budget," and all countries (rich and poor alike) need to be planning for a peak in emissions. Second is an echo of "common but differentiated responsibilities," acknowledging that developing countries like India, Brazil, Vietnam, etc. will need more time to peak than wealthier countries.
  3. "and to undertake rapid reductions thereafter in accordance with best available science" — "best available science" means that targets and goals should be recalibrated as new science comes in.
  4. "so as to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases" — this is the key bit. A global "balance" between greenhouse gas emissions and greenhouse gas sinks (like forests, which absorb carbon dioxide) is another way of saying zero net greenhouse gas emissions; anthropogenic (human-caused) emissions and sinks balance out. That's how zero is phrased in the agreement. It leaves open the possibility, badly needed for any hope of hitting, er, avoiding 2 degrees, of substantial "negative emissions" technologies (like carbon sequestration) later in the century, enough to balance out some remaining emission sources.
  5. "in the second half of this century" — this leaves a wide swath of room between 2050, when climate hawks would like to zero out emissions, and 2100, when oil-producing nations would likely prefer. And of course there's huge dispute over how fast emissions feasibly can be phased out, so this wide latitude avoids committing nations to anything that may turn out to be impracticable.
  6. "on the basis of equity, and in the context of sustainable development and efforts to eradicate poverty" — another acknowledgement that poorer countries need help moving onto a path of clean development that enables them to lift their citizens out of poverty without committing the world to irreversible damages.
people person (Shutterstock)

Zero beats two

All of this amounts to a lot of fuzziness and hedging, which is inevitable when you're getting 195 countries to agree to something. The target isn't legally binding anyway, so its precise contours are less important than the headline: We're headed for carbon zero. It sends a clear signal to investors that each new long-term fossil fuel investment, each new mine, well, pipeline, coal plant, or export terminal, is riskier than the last.

There's still a lot we don't know about the transition to a zero (net) carbon world, to say the least. We don't know exactly how long it will take or how much it will cost. We don't know exactly what variety of energy sources will drive it.

But the unanimous agreement in Paris declares that it is underway, and inevitable. We are heading for zero, slowly pulling the wires out of the ticking time bomb, aiming for a civilization that's built for the long haul. That's a clearer goal, and a more hopeful and inspiring vision of the future, than avoiding 2 degrees.

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