To keep the global median temperature within this optimal 1.5 degree-Celsius limit, according to this study, change would have to happen across all sectors, not just in the energy sector. Power plants would need to be replaced, but so would gas and diesel-fueled cars, aircraft, ships and industrial plants. Even cows would have to go -- essentially, anything that contributes to global warming.
Smith's study doesn't determine if this would be politically or economically feasible, but it does show dozens of scenarios that demonstrate the impact certain actions could have on the global mean temperature. The study shows time matters. If the world waits until 2030 to begin to eliminate its carbon-intensive infrastructure, the probability that the world can meet this 1.5 degree C goal is below 50%, even if the rate of fossil fuel retirement was accelerated.
"(The study is) motivation to continue aiming for a zero-carbon world not long after the middle of this century," Smith said of the research results. "Limiting temperature rise reduces the risks of irreversible damages." He adds, "the earlier we act, the less expensive the transition will be, and the lower the temperature rise is, the less climate-related damages will cost us."
"The scenarios that we investigate in this study are really at the extreme optimistic end of what could be done without negative emissions or killing off power plants or cars before their time," Smith said. "While the solution we propose is technically possible, it still doesn't look particularly likely. However, I would claim that mapping it out is a good starting point, and consistent with the definition of an infrastructure commitment. It would be interesting to see if, or how, some of these results change with perhaps more real-world assumptions."