“… the total is 0.00476°C (0.0086°F) of global warming avoided by the California cap-and-trade program for reducing greenhouse gas emissions out to the year 2050. Such numbers strain the limits of detectability within our current observing systems, not to mention environmental significance.”
With the California Air Resource Board’s (CARB) recent announcement that they have finalized their greenhouse gas cap and trade regulations, California becomes the first state to have, according to the CARB’s chairperson Mary Nichols, “done something important” on the issue of climate change.
Ms. Nichols couldn’t be further from the truth. While CARB may have done “something important” for many things in California (not all of which may prove positive), climate change isn’t one of them.
If the emissions targets under the CARB cap and trade program as it is scheduled to the year 2020 are met, the total amount of global temperature rise that would be avoided amounts to 0.00015°C (or for those who prefer English units, 0.00027°F). You read that right, one and a half ten-thousandths of a degree Celsius.
If CARB’s cap-and-trade program continues to be the primary mechanism by which to enforce the 80%-below-1990-emissions-by-2050 target legislated under California’s Global Warming Solutions Act of 2006 (aka, Assembly Bill 32, or AB 32), then assuming a business-as-usual (BAU) baseline, the amount of global warming avoided amounts to 0.00476°C (0.0086°F)—a bit less than five thousandths of a degree Celsius (just under one one-hundredths of a degree Fahrenhiet).
This all amounts to a lot of “nothing” for doing “something.”
By the Numbers
Let’s review how I come up with such an inconsequential climate effect from what, by anyone’s reckoning, will require a very consequential amount of effort.
Basically you need to have two pieces of information: 1) the cumulative greenhouse gas emissions savings that the cap and trade program is projected to produce, and 2) how emissions savings translates to reducing global temperatures.
A handy derivation of the latter quantity can be found in some work I published over at the web site World Climate Report a few years ago in an article titled “What You Can(’t) Do About Global Warming”. In that article, I combine observations of global temperature change with observations of changes in the concentration of atmospheric carbon dioxide concentration to determine that it takes ~1,767,250 million metric ton of anthropogenic CO2-equivalent (mmtCO2eq) emissions to raise the global average temperature 1.0°C. The elegance of this calculation is that since I derive it strictly from observations, it inherently incorporates all phenomena which influence it (that is, it is insensitive to debates as to the exact value of the climate sensitivity, or other uncertainties in our understanding).
And assuming that things keep working into the future as they have in the past, this number—1,767,250 mmtCO2eq to produce 1°C—is reasonably applicable for assessing the climate impact of proposed emissions savings (there is room to quibble about this assumption, but it is quite reasonable, at least for the time scale of the next several decades). As such, it is a useful number to have handy.
In fact, I would suggest that all policymakers (even those would-be ones) write it down and tape it to their computer monitors. Then after dreaming up ideas as to how to reduce greenhouse gas emissions, they can divide their proposed emissions reductions (in units of mmtCO2-eq) by 1,767,250 to get the influence on global temperature (in degrees C). My guess is that they would be shocked at what they find (and then proceed anyway without drawing attention to the (climate) ineffectiveness of their ideas).
As to the cumulative emissions reductions from the CARB cap and trade program, I derive a few numbers from the details of the program contained at various places on the CARB website. The “cap” of the cap and trade program is defined starting in the year 2013 and continuing to the year 2020. During the first two years, only electricity suppliers and large industries emitting more than 25,000 mmtCO2eq/yr are included in the program, then starting in 2015, fuel suppliers come under the regulations.
By then, 85% of California greenhouse gas emissions (in terms of CO2 equivalents) fall under the cap and trade regulations. Cumulatively, the program will reduce greenhouse gas emissions by an estimated 267 mmtCO2eq from the CARB business-as-usual emissions baseline projections for California from 2013 to 2020.
After that, the cap and trade targets are not set, however, as cap and trade is the centerpiece of the strategy to meet the goals of AB32, I can assume that it will be used to continue to screw down California’s emissions out to the year 2050. There have been a few attempts at developing a BAU scenario for California greenhouse gas emission out to the year 2050, and the generally they project that California, without regulations, would be producing somewhere in the neighborhood of 850mmt CO2eq/yr up from today’s levels of about 470 mmtCO2eq. So, linearly reducing the emissions from this baseline down to a total of 80% below the 1990 emissions level (or 85.4 mmtCO2eq) yields a cumulative (from 2021-2050) greenhouse gas emissions reduction of 8,150 mmtCO2eq.
With these numbers in hand, we can now calculate the amount of global temperature rise that would be avoided had these emissions actually occurred. To do so, we divide the cumulative emissions savings by 1,767,250 mmtCO2eq/°C.
For the scheduled part of the cap and trade program (from 2013 out to 2020), we get 267 mmtCO2eq divided by 1,767,250 mmtCO2eq/°C equals 0.00015°C of avoided warming. Assuming the program continues through 2050 (and the BAU emissions scenario as a baseline), we get an additional 8,150 mmtCO2eq divided by 1,767,250 mmtCO2eq/°C which equals 0.00461°C of avoided warming. Adding the two together, the total is 0.00476°C (0.0086°F) of global warming avoided by the California cap-and-trade program for reducing greenhouse gas emissions out to the year 2050.
Such numbers strain the limits of detectability within our current observing systems, not to mention environmental significance.
It is not that the cap and trade program, if successful, would not result in large emissions savings from California, it is just that relative to current global greenhouse gas emissions (not to mention the projected large emissions increases from developing nations like China and India) any greenhouse gases emissions from California (whether reduced or not) are a non-issue.
A First Step?
Now, some folks will contend that the efforts of California are only meant to show the rest of the country the way forward, and California should be praised as leaders into a clean energy future. In fact, the editors of the New York Times, are such folk. After lauding California for its cap and trade program, the Times ultimately concludes:
By themselves, local measures are never going to solve the climate change problem. That requires a global response, and the battle will never be fully joined without the United States. At the very least, California provides proof that bold action on a large scale is still possible even though Washington remains sadly gridlocked.
It’ll be interesting to see how the “bold” action goes over if “bold” results don’t follow.
As I have shown above, no matter how long we wait, the rest of America (and the the rest of the world), will never be able to see any bold impacts to the climate from California’s cap and trade system. Therefore, I imagine that the real focus will be on whether or not California is able to take its greenhouse gas emissions in one direction and its economy in the other. If they are able to pull that off, they indeed will be have made a bold achievement.
At this point in time, their chance at success is debatable.