To Acton Selectmen, Dec 2016: Part 1, climate change

Thanks for having us back to help start your conversation about natural gas use in Acton. There are a lot of health and safety reasons for reducing the use of natural gas, but tonight we want to focus on another reason: Climate Change.

A quick refresher: the temperature of Earth’s atmosphere is the result of many forces, including the effects shown in this diagram. When the energy coming into our atmosphere matches the energy going out, Earth’s energy is in balance. What comes in is largely visible light. What radiates away from Earth is mostly heat in the form of infrared waves. When we add additional infrared-blocking gases — greenhouse gases — to the atmosphere, more energy gets trapped, and things heat up. This is why methane, the main ingredient of natural gas, is such a problem.

Here’s an infrared photo of the gas leak at Porter Ranch in California last year. The black cloud is methane, which is opaque, and thus, blocks infrared heat waves from escaping our atmosphere. That’s why it’s such a problematic global warming gas. The International Panel on Climate Change rates methane as having more than 80 times the global warming impact of carbon dioxide over a 20-year period.

Methane leaks into the air during every stage of natural gas processing, from the original drilling to its delivery under the streets of Acton. How much methane leaks? We don’t know. This diagram shows recent EPA estimates, along with the mostly higher estimates of other independent studies. At many of these estimated leak levels, natural gas used for home heating has an even larger global warming impact than coal or oil.

Climate change is a complex process, with many contributing and interacting factors. This chart shows only a few of these factors, but it’s already too complex to go into all the details tonight. I just want to highlight two of the many types of causal loops.


In blue, we’re highlighting one “negative” or “control” feedback loop. The loop shows the way that increasing CO2 increases the growth of some forests, which causes more CO2 to be absorbed from the atmosphere, which then causes lowered CO2. This acts to keep climate change under control.


In red, we’re highlighting one “positive” or “reinforcing” loop. This loop shows increasing temperatures causing more sea ice to melt, which increases the extent of open water, which reduces the reflection of energy back into space, which causes the water and air to heat up even more. This acts to reinforce climate change.


It’s been very difficult for scientists to predict when the positive feedback loops will start to dominate over the negative feedback loops. When that happens, there can be a rapid increase in global warming. We may have entered such a period recently.

One of the positive feedbacks seems recently to have entered a scary new phase, in which both Arctic and Antarctic ice extent are shrinking at the same time. That’s especially strange for the Arctic; with winter coming on in the northern hemisphere, normally the extent of sea ice would be growing quickly rather than shrinking.

Here’s more evidence of a possible shift to a period of rapid change. After a slower rate of rise in average temperatures over the last few decades, each of the last 12 months has seen higher average global temperatures than ever before in the era of modern record-keeping. The red line on top shows those temps. Record-breaking high temperatures are now happening more than 20 times as often as record-breaking low temperatures. And the harmful effects are real.

High temps in Pakistan in 2015 caused more than 1,200 deaths. This photo shows a worker creating new mass graves in anticipation of the next round of heat waves. We’ve hit the era of anticipatory mass graves.

We need to do what we can to stop the use of fossil fuels, the main source of human-caused greenhouse gas emissions. How much do we need to do, and by when?

Because of the difficulties in predicting the details of how climate will actually change, different kinds of targets have been set out in scientific papers and in our laws and treaties. Achieving any of these targets would involve large-scale changes starting now. We don’t know precisely how much we need to do, but we know that the scale of the effort will need to be very large, so we all need to do what we can as soon as we can.


So, what can we do here in Acton?

Here’s the rough carbon footprint for Acton, circa 2010, taken from the Acton 2020 Plan. What we can do locally is to shrink each of these slices as quickly as possible. To do that we must head toward a fossil fuel–free, clean energy economy. Any investment in new fossil fuel/natural gas infrastructure locks us into using it for decades to come. And continued creation of fossil fuel infrastructure, even at a small, local scale, thwarts our Town and 2020 goals.


A simple carbon action plan would involve the same general steps for every pie slice.

This is our handy carbon-reduction plan. First, we need to reduce energy use. In the case of residential heating and cooling, one way is through air sealing and insulation, which are heavily subsidized by MassSave and available to all homeowners.

The next step is to move away from fossil fuel use. This is accomplished by first switching to systems that use electricity, and then working to source as much of the electricity supply as possible from renewables. And we must do this as quickly as possible.

(On to Part 2, mostly about Heat Pumps)

One response to “To Acton Selectmen, Dec 2016: Part 1, climate change

  1. Pingback: To Acton Selectmen, Dec 2016. Part 2: Heat Pumps | Green Acton

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