The Climate Impact of Shell Alaska

I recently gave a long interview to NPR's Marketplace regarding Shell's prospects in the Alaskan Arctic.  Quick take: If Shell's exploration efforts are successful, the company's program for the Alaskan Outer Continental Shelf (OCS) would represent the largest, most ambitious, and most important infrastructure project in North America through 2030.

This project has been criticized on grounds of environmental risk and climate impact.  In this article, we take a look at just how much CO2 the project would contribute and its impact on global temperatures.

My analysis of Shell's program suggests that, were Shell fully successful in realizing its ambitions in the Alaskan OCS, the company would produce approximately 650,000 barrels of crude oil per day for some 34 years, starting in the late 2020s and lasting through 2060 or so.

This volume seems quite large, but it is in fact only 0.7% of the anticipated oil supply during the forecast period.  Further, oil itself represents only 38% of anthropogenic CO2 emissions, with coal and natural gas contributing the balance.  Thus, the Alaskan OCS would contribute only 0.2% of all anthropogenic CO2 during its lifetime.

How would this change global temperatures? 

The UN's Intergovernmental Panel on Climate Change's fifth assessment report (AR5) estimates that global temperatures would increase by 1.5 - 4.5 deg C for a doubling of CO2 in the atmosphere. Others believe sensitivity is lower, and indeed, the IPCC reduced the lower sensitivity limit precisely because climate models had over-forecast temperature rise since 1990. But let's use 3 deg C, which represents the midline of the IPCC assessment.  This implies that global temperatures would increase by 3 deg C for a doubling of atmospheric CO2.

Today, atmospheric CO2 stands at 400 parts per million (ppm).  In other words, CO2 is a trace gas in the atmosphere.  A doubling of CO2 to 800 ppm would increase temperatures by 3 deg C according to the IPCC's midline estimate.  Thus, an increase of 400 ppm would equate to a 3 deg rise in temperature.

CO2 is currently rising at the pace of 2 ppm / year.  If Shell Alaska were contributing 0.2% of this amount (as calculated above), then oil from the OCS would be increasing atmospheric CO2 by 5 parts per billion per year, or 0.17 ppm cumulatively over the 34 year life of the project.  This represents 0.04% of the amount needed to double CO2 and raise temperatures 3 deg.  Put another way, oil from the OCS would raise the temperature, assuming IPCC climate sensitivities, by 0.001 deg C by 2060.

Shell estimates that there are some $2 trillion of recoverable hydrocarbons in the Alaskan OCS (probably a good bit less at current prices). 

So how should we think about the climate impact of Shell's plans for the Alaskan Outer Continental Shelf?  Does it make sense to forgo $2 trillion of hydrocarbons to prevent a temperature rise of one one-thousandth of a degree in 2060?

To my mind, this is not a difficult decision.