Can economic output (called “gross domestic product” or GDP) and population continue to increase while greenhouse gas emissions fall? This phenomenon is known as “absolute decoupling”—economic growth is “decoupled” or operating separately from emissions growth—and is a difficult goal. Most countries have achieved the more modest goal of “relative decoupling,” in which GHG emissions grow more slowly than GDP or population growth. Global emissions likely peaked in 2019, but will need to fall by a consistent 6 percent per year (or more) until 2050 to successfully limit warming to just 2° Celsius. (Limiting warming to 1.5°C would require 10 percent emission reductions per year.) The United States’ emissions peaked in 2007; since then, annual emissions have been lower even as GDP grew (absolute decoupling). But the United States still sees occasional increases in emissions from one year to the next even if total emissions has stayed below 2007 levels.
To offset the nation’s own historical contribution to atmospheric greenhouse gas levels, the United States needs to accelerate the annual pace of emissions reductions and to make time for lower and middle-income countries to invest in steep reductions of their own.
Investments in reducing global energy use are a critical part of making both global and U.S. emissions reductions happen. Energy efficiency improvements reduce the amount of energy required to do the same activity (energy efficiency is not the same as energy conservation, which involves cutting back on activities or consumption). Energy efficiency improvements permit economic growth to continue while energy use and emissions decline. Between 1980 and 2014, U.S. GDP grew by 149 percent, while energy usage only grew by 26 percent. Data from the U.S. Energy Information Administration show that U.S. energy consumed per dollar of GDP fell consistently over the past two decades and projections suggest that it will likely continue to fall.
Globally, GDP rose 84% from 2000 – 2017, while energy usage only rose 38 percent; 40 percent of the energy saved came from using less fossil fuels for power generation while the rest came from reductions in energy requirements for final uses. The energy savings from reduced coal and gas use both equaled 10 percent of 2017 global demand for coal and gas respectively.
Further energy efficiency improvements could build on this global relative decoupling of energy use and GDP. As shown in this figure from a paper in the Journal of Energy and Environmental Science, energy efficiency (top left in light grey) reduces energy demand, meaning less new renewable generation is needed to produce 100 percent of electric demand. As energy consumption declines, fossil fuel generation will retire.
A joint-study by the Center for American Progress and the Political Economy Research Institute argued that it is possible to lower U.S. energy consumption to 30 percent of 2010 levels in 20 years, all while continuing economic and population growth. Similarly, the American Council for an Energy Efficiency Economy estimated in 2015 that large and cost effective energy efficiency improvements could reduce energy usage by 40-60 percent relative to current forecasts. The United States also has a higher energy use per dollar of GDP than most European countries, which suggests additional room for improvement using existing technologies. Policies to implement these reductions are an important part of any serious climate strategy.
