How to hit the most stringent targets, with no loopholes.
What would it take to really tackle climate change? No delays, no gimmicks, no loopholes, no shirking of responsibility — the real thing. What would it look like?
To answer that question, it helps to understand the upper threshold of climate ambition. The target agreed upon by the world’s nations in Paris in 2015 is global warming of “well below” 2 degrees Celsius, with good-faith efforts to hold temperature rise to 1.5 degrees.
Countries are not moving anywhere near fast enough to hit those targets, so we are currently on track for somewhere around 3 degrees. It is generally agreed that hitting 2 degrees would be quite ambitious, while hitting 1.5 would be nothing short of miraculous. Yet the scientists at the Intergovernmental Panel on Climate Change, in their latest report, are pleading with the world to go for it, because at this point, every fraction of a degree of warming matters.
While there is nothing like a real-world plan in place for hitting those targets yet, climate modelers have come up with many scenarios for how we might do so. However, as I wrote recently, most of those scenarios rely heavily on “ negative emissions ” — ways of pulling carbon dioxide out of the atmosphere. If negative emissions technologies can be scaled up later in the century, the reasoning goes, it gives us room to emit more earlier in the century.
And that’s what most current 2- or 1.5-degree scenarios show: Global carbon emissions rise in the short term, then plunge rapidly to become net negative around 2060, with gigatons of carbon subsequently captured and buried over the remainder of the century. The oil giant Shell released a scenario along those lines a few weeks ago.
The primary instrument of negative emissions is expected to be BECCS: bioenergy (burning plants to generate electricity) with carbon capture and sequestration. The idea is that plants absorb carbon as they grow; when we burn them, we can capture and bury that carbon. The result is electricity generated as carbon is removed from the cycle — net-negative carbon electricity.
Most current scenarios bank on a lot of BECCS later in the century to make up for the carbon sins of the near past and near future.
One small complication in all this: There is currently no commercial BECCS industry. Neither the BE nor the CCS part has been demonstrated at any serious scale, much less at the scale necessary. (The land area needed to grow all that biomass for BECCS in these models is estimated to be around one to three times the size of India.)
Maybe we could pull off a massive BECCS industry quickly. But banking on negative emissions later in the century is, at the very least, an enormous, fateful gamble. It bets the lives and welfare of millions of future people on an industry that, for all intents and purposes, doesn’t yet exist.
Plenty of people reasonably conclude that’s a bad idea, but alternatives have been difficult to come by. There hasn’t been much scenario-building around truly ambitious goals: to zero out carbon as fast as possible, to hold temperature rise as close to 1.5 degrees as possible, and, most significantly, to do so while minimizing the need for negative emissions. That is the upper end of what’s possible.
In May, I looked at three publications that help fill that gap:
Here’s how this post (first published in May) is going to go: First, we’ll have a quick look at why targeting 1.5 degrees is so urgent; second, we’ll look at a few things these scenarios have in common, the baseline for serious ambition; third, we’ll look more closely at the third paper, as it offers some interesting alternatives (like, oh, mass vegetarianism) to typical carbon thinking; and finally, I’ll conclude.
Americans can’t make much sense out of Celsius temperatures, and half a degree of temperature doesn’t sound like much regardless. But the difference between 1.5 and 2 degrees of global warming is a very big deal. (Read the IPCC’s new science review here .)
Another recent paper in Nature Climate Change makes the point vividly: Bumping ambition up from 2 to 1.5 degrees would prevent 150 million premature deaths through 2100,90 million through reduced exposure to particulates, 60 million due to reduced ozone.
“More than a million premature deaths would be prevented in many metropolitan areas in Asia and Africa,” the researchers write, “and [more than] 200,000 in individual urban areas on every inhabited continent except Australia.”
That’s not nothing! And of course, the difference between 1.5 and 2 degrees could mean the difference between life and death for low-lying islands .
There’s no time to waste. In fact, there may be, uh, negative time. Limiting temperature rise to 1.5 degrees is possible, even in theory, only if the “carbon budget” for that target is at the high end of current estimates .
Again: 1.5 is only possible if we get started, with boosters on, immediately, and we get lucky. Time is not running out — it’s out.
The three scenarios I mentioned are different in a number of ways. The first two project through 2050, but the Nature Climate Change paper goes out to 2100. They target different things and use different tools. But they share a few big action items — features that any ambitious climate plan will inevitably involve.
1) Radically increase energy efficiency.
Just how much energy will be needed through 2050? That depends on population and economic growth, obviously, but it also depends on the energy intensity of the world’s economies — how much primary energy they require to produce a unit of GDP.
Increasing energy efficiency (which, all else being equal, reduces emissions) is in a race with population and economic growth (which, all else being equal, increases them). To radically decarbonize with minimal negative emissions, efficiency will need to outrun growth. (Notably, Shell’s scenario shows much higher global energy demand in coming decades; growth outruns efficiency.)
IRENA’s scenario reduces global energy-related emissions 90 percent by 2050. Of that 90 percent, 40 comes from energy efficiency.
To do this, IRENA says, the energy intensity of the global economy must fall two-thirds by 2050. Improvements in energy intensity will have to accelerate from an average of 1.8 percent a year from 2010 to 2015 to an average of 2.8 percent a year through 2050.
In the Ecofys scenario, energy efficiency is so amped up that total global energy demand is lower in 2050 than today, despite a much larger population and a global economy three times larger than today’s.
The Nature Climate Change paper summarizes the necessary approach to efficiency this way: “Rapid application of the best available technologies for energy and material efficiency in all relevant sectors in all regions.”
“All relevant sectors in all regions” means electricity, transportation, buildings, and industry, all bumped up to the most efficient available materials and technologies, everywhere in the world, starting immediately. Cool, cool, cool.
2) Radically increase renewable energy.
All the scenarios envision renewables (primarily wind and solar) rapidly coming to dominate electricity. In the IRENA scenario, renewables grow sixfold faster than they are currently, supplying 85 percent of global electricity by 2050.
Ecofys has them supplying 100 percent of global electricity — with that sector completely decarbonized — by 2040, even as global demand for electricity triples.
The Nature Climate Change paper notes that the vision of rapid renewables dominance all these scenarios have in common involves “optimistic assumptions on the integration of variable renewables and on costs of transmission, distribution and storage,” which, yeah.
3) Electrify everything!
Notably, all three scenarios heavily involve electrification of sectors and applications that currently run on fossil fuels. In the IRENA case, electricity rises from 21 percent of total global energy consumption today to 40 percent by 2050.
In the Ecofys scenario, it rises to a whopping 70 percent. In the Nature Climate Change study, it rises to 46 percent (compared to 31 percent in the reference case).
I have made the case for electrification before, and it’s not complicated. We know how to radically increase the supply of zero-carbon electricity; increasing the supply of zero-carbon liquid fuels is much more difficult. So it makes sense to move as much energy use as possible over to electricity, particularly vehicles, home heating and cooling, and lower-temperature industrial applications.
The Ecofys scenario makes it particularly clear: If renewable energy and energy efficiency are to be your primary decarbonization tools (more on that in a second), full decarbonization requires going all out on electrification.
4) And still maybe do a little negative emissions.
Even though the intentions, of the Ecofys and Nature researchers particularly, was to minimize the need for negative emissions, neither was able to completely eliminate it.
“Regardless of the rapid decarbonisation” in the scenario, Ecofys researchers write, “the 1.5°C carbon budget is most likely still exceeded.” The only way to hold at 1.5 is to mop up that excess carbon with negative emissions. Ecofys thinks CCS applications will mostly be confined to industry and the rest can be taken care of by “afforestation, reforestation, and soil carbon sequestration,” i.
