Study: Rate of CO2 Emissions Accelerating, Carbon Intensity in Global Economy Increasing

21 May 2007

Fossil-fuel CO2 emissions for nine regions. Data source is EIA. Click to enlarge.

An open-access paper published this week in the Proceedings of the National Academy of Sciences shows that worldwide CO₂ emissions increased between 2000 and 2004 at a rate that is nearly three times the rate of increase of the 1990s. The rate increased from 1.1% per year during the 1990s to 3.1% per year in the early 2000s.

The study found that the accelerating growth rate is largely due to the increasing energy intensity of economic activity (the energy required to produce a unit of gross domestic product) and the carbon intensity of the energy system (the amount of carbon per unit of energy), coupled with increases in population and in per-capita gross domestic product.

In the unfolding reality since 2000, the average global carbon intensity of energy has actually deteriorated (increased) and no region is showing signs of decarbonizing its energy supply. The emissions growth rate since 2000 was greater than for the most fossil-fuel intensive of the Intergovernmental Panel on Climate Change emissions scenarios developed in the late 1990s.

—Dr. Pep Canadell, Co-author of the paper and Executive Director of the Global Carbon Project

The research showed that the increases in energy and carbon intensities constitute a reversal of a long-term trend toward greater energy efficiency and reduced carbon intensities.

Despite the scientific consensus that carbon emissions are affecting the world’s climate, we are not seeing evidence of progress in managing those emissions in either the developed or developing countries. In many parts of the world, we are going backwards.

—Co-author Chris Field, Director of the Carnegie Institution’s Department of Global Ecology

The acceleration of carbon emissions is greatest in the exploding economies of developing regions, particularly China, where the increases mainly reflect increasing per capita gross domestic product. The study divided the world into the USA, the European Union, Japan, the nations of the former Soviet Union, China, India, and three regions covering the rest of the world.

Between 2000 and 2004 the developing countries accounted for a large majority of the growth in emissions, even though they contribute only about 40% of total emissions. In 2004, 73% of the growth in global emissions came from the developing and least developed economies, comprising 80% of the world’s population. That same year the developed areas (including the Former Soviet Union), contributed about 60% to the total emissions. These countries account for 77% of the cumulative emissions since the start of the industrial revolution.

Between 1980 and 2004, total emissions in the developed areas (USA, Europe, Japan, and other smaller economies) increased as a result of fast growth in per-capita gross domestic product, coupled with relatively slight increases in population. This growth was partially offset by decreases in the amount of energy needed to make each unit of product.

The world’s developing regions are the places where emissions are growing fastest in relative terms. However, this only means that developing regions are catching up: they are still a long way behind the developed regions in terms of total emissions. The developed regions, representing just 20% of the world’s population, account for nearly 60% of current emissions and 80% of cumulative CO₂ emissions since the beginning of the Industrial Revolution. These cumulative emissions are the leading cause of current climate change.

—Lead Author Mike Raupach, CSIRO and the Global Carbon Project

The study emphasizes that the growth in emissions can be caused by a variety of factors and that managing emissions in a growing economy requires progress in both the energy intensity of the economic system and the carbon intensity of the energy system.

Solving the first part of the puzzle requires shifting more of the economy toward activities like service industries and information technology, where emissions can be lower, and emphasizing energy efficiency. Solving the second requires deploying new sources of non-emitting energy like wind, solar, and nuclear power.

—Chris Field

Factors in the Kaya identity for all nine regions. The heavy black line (F) is the expression of CO2 emission flux. Click to enlarge.

The study used the Kaya identity—an expression of CO₂ emission flux from fossil fuel combustion and industrial processes factoring in global population, world GDP, global primary energy consumption, per-capita world GDP, the energy intensity of world GDP, and the carbon intensity of energy—with annual time-series data on national emissions, population, energy consumption, and gross domestic product (GDP).

Resources:

• “Global and regional drivers of accelerating CO₂ emissions”; Michael R. Raupach, Gregg Marland, Philippe Ciais, Corinne Le Quéré, Josep G. Canadell, Gernot Klepper, Christopher B. Field; Proceedings of the National Academy of Sciences, May 2007. [Although the embargo on this paper has lifted, public access to the paper may be delayed briefly.]