Combining policies aimed at removing carbon dioxide from the atmosphere with those aimed at reducing emissions could decrease CO2 concentrations faster than natural processes alone, according to a new paper published in Climatic Change and co-authored by University of Arizona assistant professor of economics Derek Lemoine.
"There are a lot of levers that we can pull to manage atmospheric carbon dioxide concentration in the long term," said Lemoine. "What this paper does is consider the interplay between some of those levers."
Lemoine and his co-authors modeled a mix of factors, including abatement, research and development (R&D), and negative emission policies, on long-term climate goals.
"It's not uncertainty about climate that's driving where we want to go," he said. "We're looking at the cost of the climate target. The best target is going to equalize the benefits and the cost."
"We found a few things that seem intuitive in retrospect," he continued. "One is that the ability to do R&D and find new technologies can lower the cost of attaining the overall target. But that is not a substitute for reduction."
Lemoine said that the reductions should be part of an overall strategy, especially if the target is ambitious. But one of the novel aspects of his paper is that it considers emerging technologies that remove CO2 from the atmosphere. "Economic policies rarely recognize the possibility of negative emission technologies," he said.
Planning to deploy negative emission technologies shifts optimal R&D funding from "carbon-free" technologies into "emission intensity" technologies. Making negative emission strategies available enables an 80 percent reduction in the cost of keeping year 2100 CO2 concentrations near their current level.
"But that doesn't include the possibility of abrupt change in climate," he said. He and his colleagues find that negative emission strategies are less important if the possibility of tipping points rules out using late-century net negative emissions to temporarily overshoot the CO2 constraint earlier in the century.
Another paper Lemoine has in progress examines tipping points in climate change, using magnitude and duration of an emission tax to stimulate adoption of green technology. Both papers build on his interdisciplinary background in energy and resources. In addition to his appointment at the Eller College of Management, Lemoine is affiliated with the UA Institute of the Environment.
Said Lemoine: "Solving issues within the complex systems of climate and the environment mean that you also have to deal with human systems, which is where economics comes in."