It’s a spooky time of year, but I can’t help but be distracted by the climate change issue, even as costumes and candy take center stage. It’s that there’s something about the theatrics involved that remind me what’s at stake regarding the climate change issue.
Some background - I love Halloween and was pleasantly surprised at our first Halloween in our neighborhood when about six score ghosts and goblins, witches, princesses, and supermen descended on our house cackling ‘trick or treat.’ So it’s fun to prepare the house, dress in costume, and set the stage with pumpkins and all sorts of ghoulish decorations.
Something that always gets kids excited is the low billowing smoky fog that descends along the sidewalk from the dry ice we hide in bushes by the door. Oh dear does that get them in the bewitched mood!
And of course for the scientist and professor in me, it’s great fun hearing the young ones trying to figure it all out and answering their questions.
No, it’s not from a machine. It’s not a ghost. No, the house isn’t really haunted. Yes, it looks like regular ice but don’t touch!
And long about 9am, when the smallest are already home in bed, the teenage goblins come a callin’. Then we get into the serious questioning.
Why does it keep so low to the ground [the very question reminds me of T.S. Elliot and the fog that “seeing that it was a soft October night, Curled once about the house, and fell asleep.”]. Well, I just have to explain the molecular weight of CO2 compared to the nitrogen and oxygen molecules in the air. Which goes a long way to putting them to sleep. Or I could just say, well it’s heavier than air so it gathers in the lowest places. It will even make pools in hollows if you watch closely.
But it’s usually the more timid schoolchild that asks ‘will it hurt me?’ Oh, that one really tears at my heart. Does she mean directly, and now? Or is she asking me about a couple of decades from now as we continue to add more and more to the atmosphere?
I could give the answer OSHA gives … only if it exceeds 5000 ppm. In that case it’s a ‘simple asphyxiant’ that affects the lungs, skin, and central nervous system with symptoms like headaches, dizziness, restlessness, paresthesis; dyspnea; sweating; malaise; increased heart rate, elevated blood pressure, pulse pressure; coma; asphyxia; convulsions. None of these are particularly appealing. Let’s not go there.
Why do we so frequently hear that CO2 is necessary for life and can’t harm you? Well, 5000 ppm is pretty high and only occurs when you have a concentrated source of CO2, either an industrial source or a natural one (a tragic example occurred at Lake Nyasa in Cameroon and killed several thousand people in 2009).
But we don’t have to worry about that. Do we?
Recently, as part of a monitoring system designed to help the city track major sources of CO2, the city of San Francisco installed sensors for CO2 on school rooftops. The program has only been running for a few months but some data are now available. You might be surprised to learn that the highest recorded value is 1166 ppm.
Remember, globally averaged CO2 levels have been rising rapidly but still only reach about 390 ppm. How does it get to so large a value?
Well, if you are near a concentrated continuous source the gas will not have dispersed by the time it wafts past your school (or home, or workplace). There’s an interesting study (Project Vulcan) done by Kevin Gurney and his colleagues at Arizona State University that shows the many large sources of CO2 in the US and how the gas is concentrated far above those average values over a large region surrounding the source.
|Los Angeles' visible effects of a CO2 dome|
So I think about her question, ‘will it hurt me?’ If the concentration of CO2 in cities already reaches levels above 1100 ppm now, when the average is 390 ppm, what might it reach if the global average CO2 level continues to rise, as it has been rising at about 2% per year, and reaches the global average 1000 ppm as assumed in the Intergovernmental Panel on Climate Change scenario A1FI?
How about the long-term effects of elevated levels of CO2 on children, or the old, or sick, or pregnant women? Do we know what those may be? Do we know what we’re in for? For example, the ‘acid-base imbalance’ noted by government scientists, what will that do to my bone density?
So I can only look into her questioning face, the little princess before me, and hope we don’t get there. I hope she has a Happy Halloween. I hope we all give her treats, not dirty tricks, in this scary new world she faces with a strange and chilling fog swirling around us.