The 1.5-Degree Global-Warming Target Doesn't Matter. Here's What Does.

“If you are driving in completely the wrong direction, arguing about where you'll park if you arrive isn't your highest priority.”

That’s prominent NASA climate scientist Gavin Schmidt’s take on the argument over setting a maximum goal for how much human activity will warm the planet. He’s referring to the target of keeping the rise to 2 degrees Celsius higher than in preindustrial times, which has been the aspiration of United Nations-led climate talks for years.

Schmidt tweeted it last fall (and FiveThirtyEight.com noted it in a recent post), but it’s a particularly applicable now as U.N. talks in Paris to reach a final global climate accord enter their final days.

The talks have featured a high-profile negotiation over whether the goal should remain 2 degrees, or lowered to 1.5 degrees—the target favored by a string of island nations afraid of being swallowed whole by rising seas.

It’s looking increasingly likely that the final deal will have at least a nod to a 1.5-degree ceiling. The latest draft accord circulating in Paris late Thursday calls for “holding the increase in the global average temperature to well below 2°C above preindustrial levels and pursuing efforts to limit the temperature increase to 1.5° C, recognizing that this would significantly reduce risks and impacts of climate change.”

But for Schmidt and some other experts, the question of the warming target is simply not as important as the attention it receives might suggest.

They’re worth listening to, because the forces driving these talks—the governments that either will or won’t take action to address global warming—feel much the same way.

Of course the amount the temperature rises (and all the changes that warming entails) matters. But the goal for that warming has less of an influence on steps nations will actually wind up taking in the years to come to combat global warming. Instead, governments respond to what’s politically, economically, and technologically feasible to do in their own countries to cut climate change.

And as world leaders do that calculus, the global temperature goal, whatever it may be, “typically doesn’t rank in the top 5 things that influence policy,” says Michael Levi, a climate and energy expert with the Council on Foreign Relations. “As a substantive policy matter, this distinction between 1.5 and 2 degrees in the Paris text is overblown,” Levi said.

Take sweeping new EPA regulations to slash carbon emissions from power plants. The EPA officials and bureaucrats crafting those and other rules must weigh a suite of factors, from the possible time frames for adopting replacement to coal, how state-based emissions trading systems might work, and more.

While the Obama administration plays up its domestic regulations in Paris, it’s nonetheless hard to imagine the rule finalized last summer would look any different if there were a 2-degree goal, a 1.5-degree goal, or no explicit goal at all in the U.N. climate talks.

It’s much the same abroad. Levi offers the example of China, where terrible air quality is putting domestic political pressure on the ruling communists to curb pollution from coal plants and factories and cars. “When China cuts emissions because it is trying to eliminate horrible pollution in Beijing, it doesn’t look to see whether the climate target is 2 degrees or 1.5 degrees,” Levi notes.

The dynamic boils down to a tautology worthy of the classic TV show The Wire: Countries are going to do what countries are going to do.

While many conservatives are wary of the U.N. and even cast climate initiatives as a stalking horse for global governance, the reality is quite different. No U.N. climate accord—not even the supposedly binding Kyoto Protocol that covered only developed nations—can force governments to slash carbon pollution beyond what they feel is economically, technologically, and politically viable.

That’s one reason why there’s so much emphasis in climate talks on how much wealthy nations will help speed up use of green energy sources.

So if the global temperature target isn’t binding, do these climate summits matter at all?

Of course they do. A lot. But a number of other aspects of the hoped-for U.N. accord will be far more influential in prodding nations to cut emissions.

The summit and the pact it’s likely to produce can help battle climate change by catalyzing financial flows to help use of green energy spread and curb use of fossil fuels. It will create a structure for revisiting individual nations’ nonbinding emissions pledges—called “intended nationally determined contributions—and for nations to check up on each other’s progress and help to ensure a level of peer pressure for action, among other benefits.

One longtime analyst of global climate negotiations said the temperature goal is of limited importance.

“More important at the Paris climate talks ... are the discussions and debates regarding the scope of participation (now having reached some 180 countries that account for 95 percent of global emissions), the ambition of the individual INDCs, and the transparency with which each country’s performance in achieving its INDC will be monitored, reported, and verified, with the stringency of the INDCs revisited on a regular basis,” said Harvard University economist Robert Stavins.

“At these talks, building a foundation for improvements in emissions reductions (which will be carried out by individual countries through their own domestic policies) is of greater value than spending time debating aspirational goals,” added Stavins, who directs the Harvard Project on Climate Agreements.

And the constellation of events and pledges surrounding these big summits also yield important efforts, such as uber-wealthy investors and philanthropists such as Bill Gates and Mark Zuckerberg rolling out a big new effort to help bring breakthrough energy technologies from the lab into commercialization.

The planetary stakes in the success or failure of these efforts are high, even if the long-term warming target isn’t the thing that’s directly motivating national actions. Two degrees is widely seen as a threshold for avoiding the most dangerous effects of global warming, and one that will require deep cuts in global carbon pollution. But even that level of increase is dangerous compared to holding the rise to 1.5 degrees. As Inside Climate News points out, a recent U.N. report describes what a half-degree less warming could mean for marine species, sea-level rise, and other effects.

But there’s another, well-picked-over set of reasons to question the importance of the 1.5-degree target making it into the final accord in some fashion: Attaining it is probably wishful thinking.

Plenty of ink has already been spilled explaining the practical reasons why that’s true. In short: Pushing global emissions downward steeply enough and fast enough to hit even the 2-degree level will be extraordinarily difficult. It would likely require pollution to peak around 2020 and then decline sharply by mid-century. Nations’ voluntary carbon-cutting pledges to the U.N. talks to date would make progress but still enable temperatures to rise by estimates of 2.7 to 3.5 degrees Celsius. That’s one reason why the accord will include language designed to periodically boost the ambition of national plans.

Schmidt, the NASA scientist, signaled mixed feelings about setting a 1.5-degree target.

“I don't see any problem with people emphasizing that 'dangerous' impacts of climate change start well before 2 degrees Celsius—indeed, they have already started—but it is very hard to see any feasible path to remain below 1.5 degrees Celsius this century. If the reduced limit is being proposed to stress the need for serious efforts to reduce emissions, then fine, but if the proponents think it's practically achievable, then I'd be less confident,” he said.

Peter Ogden, a former State Department climate aide, says the temperature target has a role as a yardstick against which nations’ climate initiatives and financial commitments can be judged.

“Locking a collective target into a Paris agreement such as 2 degrees is important, but it's important not to lose focus also on the individual commitments that a given country is willing to take on for itself alone (national carbon emission reductions, climate finance contributions ) and thus be individually on the hook to deliver,” said Ogden, who is now a senior fellow with the liberal Center for American Progress.