This is a guest post from economist Eban Goodstein, Director of the Bard Center for Environmental Policy. It is partially excerpted from this Grist piece. He and his colleagues at the E3 Network have just released a detailed study on The Economics of 350. The figure compares cumulative emissions for a 350 ppm CO2 trajectory.
Recently, many climate scientists have doubled down on the “safe” level for atmospheric CO2. To avoid global warming catastrophe-collapse of the continental ice-sheets and sea level rise of dozens of feet — prominent voices led by NASA’s James Hansen are now telling us we have to get down to 350 ppm, and quickly.
Game over?
No. Instead, time to adjust our thinking about what is possible.
Several co-authors and I recently completed a report for Economics for Equity and the Environment Network (E3), surveying the economic studies informed by recent science. The report found that quicker action aimed at 350 makes good economic sense. With likely investments of about 1–3% of global GDP, we could rewire the planet with clean energy, rebuild global forests to trap billions of tons of carbon, create jobs, and stabilize the climate. And depending on the price of oil, these investments might actually save us money.
Is 350 Possible?Hansen et al. (here, see Figure 1) described a detailed scenario for reducing greenhouse gas emissions with the goal of reaching 350 ppm CO2 by 2100. It included phasing out coal completely (or achieving 100% carbon capture) by 2030, along with a combination of large-scale reforestation, avoided deforestation and carbon capture and storage to withdraw huge quantities of CO2 from the atmosphere. To reach the 350 target by 2100, the world would have to quickly go beyond reductions to achieve net negative emissions-removing more greenhouse gases from the atmosphere than are emitted each year.
Our report contrasts Hansen’s scenario with a less demanding but still quite ambitious trajectory which does not require the world to achieve negative net emissions. In this scenario, the world reaches 350 ppm CO2 by 2200. Emissions are reduced to 54 percent of 1990 emissions by 2020 and 3 percent by 2050, and then zero out, but do not go negative.
The bottom-line on the technical side: Decarbonizing by 2050 is possible with, roughly, the suite of technologies now available or on the near-term horizon. Very aggressive policy, however, will still be required very soon to drive down the costs of renewables, to redesign cities, reimagine transport and agricultural systems, and insure that all efficiencies are captured. Doing all this gets the world to 350 by 2200. Taking the additional steps to achieve negative emissions (and 350 by 2100) would require the development of large-scale, cost-effective sequestration technologies that go well beyond reforestation.
Economics, 350 and Politics
At least four research groups have modeled global scenarios that lead to 350 ppm CO2. One finds that in a world with unemployed labor and other resources, the stimulus from new climate investments might accelerate economic growth. The other three groups find net annual costs that are generally between 1 percent and 3 percent of world output. These studies are consistent with the Stern Review, the reports by McKinsey, and others, suggesting that achieving 450 ppm would cost around 1% or less of global GDP.
Both of these targets, 350 or 450, become a lot cheaper if oil prices return soon to $150 a barrel. If peak oil drives prices that high in the coming decade, then decarbonizing at a pace to hit 350 could lead to economic gains.
Dropping the global climate target from 450 ppm to 350 ppm of atmospheric CO2 may appear to present an impossible task. In fact, it leaves us with qualitatively the same challenge. Achieving 350 simply requires accelerating a global technology revolution that will yield many benefits- in terms of climate stability, energy security, and economic payback. And estimates of the scale of the investment needed to complete that revolution-and complete it on time-are affordable.
In Europe, the US and China, the politics of 450 ppm are beginning, just beginning, to come into view. Our new study sets the stage for a longer-term discussion. The obstacles to achieving 350 are not technical nor are they economic.
JR: For the science behind 350 ppm, see “Stabilize at 350 ppm or risk ice-free planet, warn NASA, Yale, Sheffield, Versailles, Boston et al.” Since the science is preliminary and it is not not yet politically possible to get to 450 ppm, let alone 350, my basic view, as expressed in that post, is Let’s start working now toward stabilizing below 450 ppm, while climate scientists figure out if in fact we need to ultimately get below 350. Either way, this is what needs to be done technology-wise: “How the world can (and will) stabilize at 350 to 450 ppm: The full global warming solution.” The difference between the two targets is that for 450 ppm, you need to do the 12–14 wedges in four decades. For 350 ppm, you (roughly) need 8 wedges in about two decades plus another 10 wedges over the next three decades (and then have the world go carbon negative as soon as possible after that), which requires a global WWII-style and WWII-scale strategy as discussed here. I would like to get back to 350 ppm by 2100, but I tend to think that 2150 is “more likely.” Either way, the cost of doing so is certainly far cheaper than the cost of failing to do so (see “Intro to climate economics: Why even strong climate action has such a low total cost — one tenth of a penny on the dollar”).
Comparing cumulative emissions for a 350 ppm CO2 trajectory