Powered by Climate Lab

Climate Lab is a collaborative information platform on climate change. Click here to edit this page.

<< Back to Wiki Index

Background

 The “stabilization wedges” concept is a simple tool for conveying the emissions cuts that can be made to avoid dramatic climate change.   Two futures are considered - allowing emissions to double versus keeping emissions at current levels for the next 50 years (Figure 1). The emissions-doubling path (black dotted line) falls in the middle of the field of most estimates of future carbon emissions. The climb approximately extends the climb for the past 50 years, during which the world’s economy grew much faster than its carbon emissions. Emissions could be higher or lower in 50 years, but this path is a reasonable reference scenario.

Figure 1. The doubling and flat emissions scenarios of the Stabilization Wedges concept

Source: http://cmi.princeton.edu/images/wedg...s_Figure1_8.jp. Author: Carbon Mitigation Initiative, Princeton Universit. Permission: Carbon Mitigation Initiative, Princeton University.

The emissions-doubling path is predicted to lead to significant global warming by the end of this century. This warming is expected be accompanied by decreased crop yields, increased threats to human health, and more frequent extreme weather events. The planet could also face rising sea-level from melting of the West Antarctic Ice Sheet and Greenland glaciers and destabilization of the ocean’s thermohaline circulation that helps redistribute the planet’s heat and warm Western Europe. 

In contrast, we can prevent a doubling of CO2 if we can keep emissions flat for the next 50 years, then work to reduce emissions in the second half of the century (Figure 2, orange line). This path is predicted to keep atmospheric carbon under 1200 billion tons (which corresponds to about 570 parts per million (ppm)), allowing us to skirt the worst predicted consequences of climate change.

Keeping emissions flat will require cutting projected carbon output by about 8 billion tons per year by 2055, keeping a total of ~200 billion tons of carbon from entering the atmosphere (see yellow triangle in Figure 2). This carbon savings is what we call the “stabilization triangle.”
The conventional wisdom has been that only revolutionary new technologies like nuclear fusion could enable such large emissions cuts. There is no reason, however, why one tool should have to solve the whole problem. CMI set out to quantify the impact that could be made by a portfolio of existing technologies deployed on a massive scale.

Figure 2. The eight wedges of the Stabilization Triangle

Source: http://cmi.princeton.edu/images/wedg..._Figure2_8.jpg. Author: Carbon Mitigation Initiative, Princeton University. Permission: Carbon Mitigation Initiative, Princeton University.

To make the problem more tractable, we divided the stabilization triangle into eight “wedges.” (Figure 2) A wedge represents a carbon-cutting strategy that has the potential to grow from zero today to avoiding 1 billion tons of carbon emissions per year by 2055, or one-eighth of the stabilization triangle. The wedges can represent ways of either making energy with no or reduced carbon emissions (like nuclear or wind-produced electricity), or storing carbon dioxide to prevent it from building up as rapidly in the atmosphere (either through underground storage or biostorage).
Keeping emissions flat will require the world’s societies to “fill in” the eight wedges of the stabilization triangle. In CMI’s analysis, at least 15 strategies are available now that, with scaling up, could each take care of at least one wedge of emissions reduction. No one strategy can take care of the whole triangle -- new strategies will be needed to address both fuel and electricity needs, and some wedge strategies compete with others to replace emissions from the same source -- but there is already a more than adequate portfolio of tools available to control carbon emissions for the next 50 years.