Public Comment

Suggestions re communicating climate science

Thomas Lord
Thursday October 17, 2019 - 10:08:00 PM

To: Flight Free USA

CC: Berkeley Daily Planet

I noted with interest your op-ed in Berkeleyside ("Please don't fly in 2020: From Sweden to Berkeley, the 'flight shaming' movement takes off", October 14, 2019). Thanks for trying to raise awareness of the climate emergency and to encourage meaningful action.

I noticed in your Berkeleyside op-ed and on your web site that you significantly understate the urgency and scope of the emergency. In two cases you misrepresent the scientific consensus, at least as expressed in the "IPCC Special Report on Global Warming of 1.5°C" (aka "IPCC SR15").

In the op-ed: "At the same time, climate scientists are warning that we have less than 10 years to make a significant reduction in our carbon emissions in order to avoid catastrophic climate change." 

The scientific consensus is that we have 0 years, not 10, to make significant reductions in net global GHG emissions. You might find helpful here figure 2.5 on page 113 of IPCC SR15. The graphs show various pathways by which emissions reductions might stay low enough that we experience only (or only temporarily exceed) 1.5°C warming. In every scenario save one, rapid emissions reductions (far in excess of voluntarily not flying) must happen immediately and then again, year over year, for a long time. Of the scenarios, only the LED scenario ("low energy demand") relies only on proved technology - and that scenario requires emissions to drop like a stone NOW, not in 10 years. The sole exception, scenario S5, allows us to continue to use lots of fossil fuel, but it relies on technologically removing carbon from the atmosphere much, much faster and in greater total amounts than we have any real idea how to do: 

A danger of campaigns such as yours can be illustrated this way: If I believe what you say (as opposed to what the science says) then over the next 6 years we could make plans and get ready, then in years 7-10 make sharp reductions. Yet on this path, in 6 years we will have exhausted the carbon budget for 1.5°C and almost half that for 2°C (and those are rosy projections, it looks like!).

For information about carbon budgets, see the table on page 108 of SR15, which is also in chapter 2. Be sure to subtract the earth climate systems feedback from the budgets (column 4). The 67% confidence budget for 1.5°C as of January 1, 2018 was thus 320GtCO₂. Emissions in recent years, including emissions related to land use changes, have been around 40Gt. So the budget on January 1, 2020 (again, a rosy estimate) is around 240Gt. We are on track to exhaust that budget in 6 years or less. 

You can begin to see the real urgency and scope of the problem. The existential predicament for our civilization is not at the level of choosing to fly a bit less. It is at the level of dropping emissions in the US by double-digit percentages in 2020 and again each year for years to come. It is not about minor changes in lifestyle. It is about questions like how we will cope shutting off natural gas to Berkeley homes, preventing most work commutes long before public transit can compensate, coping with the resulting economic catastrophe, and rapidly adjusting to low-carbon life starting at once, not in 6 or 10 years.

On the Flight Free USA web site: The carbon budget link to 

On the web site you "explain" carbon budgets as personal carbon budgets when, as you can see above, it is the global budget that matters. Worse, you suggest that the goal is a small but positive personal carbon budget when, in every scenario, emissions (global and per capita) must become net negative. A positive personal carbon budget would make carbon capture and sequestration that much more difficult. The whole presentation is confused insofar as there is no definitive personal carbon budget in any of the relevant climate science. (The footnotes on this page don't provide enough information to figure out what confused your group.)

I hope you'll work to improve your communications significantly, around these points. The future of today's young adults and children very much depends on it, as does human civilization itself.