Pathways to deep decarbonization: how to limit warming to 2° C

We know the destination but have lacked a reliable road map to get us there—until now. Although the Deep Decarbonization Pathways Project*  doesn't chart any single course, it does show that a low-carbon future is economically within reach.

Tidal power turbine
Tidal power turbines, Scotland.
CREDIT: Burntisland Fabrications (BiFab)

The DDP was developed by teams of scientists, economists, and engineers from the 15 countries that emit 70% of GHGs worldwide. They identified country-specific pathways leading to an 80% reduction in GHGs below 1990 levels by 2050, putting the world on track for hitting the 2°C target. (Download the US Deep Decarbonization report, PDF.)

The required changes would “constitute an ambitious transformation of the energy system.” But with an incremental cost of only 1% of GDP, the U.S. prospect is economically palatable—though still challenging in today's political climate. And we use the word "prospect" advisedly: this is a technical report that does not weigh the social and political obstacles.

The wide range of geographic, economic and political conditions around the world required that the project authors adopt a country-level approach. Though the exact course and speeds of transition differ, they share 3 common "pillars" of deep decarbonization:

  • Energy efficiency and conservation (e.g., more efficient urban and architectural design, re-use of waste heat).
  • Low-carbon electricity (replacement of fossil-fuel generation with renewables).
  • Fuel switching (switching end-use in industry and transportation from carbon-intensive to low-carbon fuels).

Avoiding the free-rider problem is critically important. To achieve the target reductions, the major emitting countries and the majority of developing countries must all commit to the goal. Teams must work across countries “to develop a long-term vision for deep decarbonization and shaping expectations of countries, businesses and investors about future development opportunities.” The sooner these countries adopt strategies of decarbonization, the cheaper will be the transition.

Pathways to Deep Decarbonization in the United States is chock-full of highly informative charts (for an example, see below). Still, tackling its 100 pages is something most of us are not likely to do. But in a mere 5 pages, the Abstract and Executive Summary (pages x–xv) offer an encouraging view of the landscape before us. It’s worth a look.

For a short overview of the U.S. Pathways report, see Dave Roberts excellent article on the Grist website, Yes, the U.S. can reduce emissions 80% by 2050 — in 6 graphs.

No stranded assets. From home water heaters to regional power plants, schedules of technology replacements forecast a manageable transition to a low-carbon world. (from the Executive Summary).

Chart illustrating replacement of technology over next 35 years


* Energy and Environmental Economics, Lawrence Berkeley National Laboratory, & Pacific Northwest National Laboratory. (2014, November 1). Pathways to Deep Decarbonization in the United States. Retrieved December 1, 2014, from