Among large-scale problems, global warming is by far the largest.
Many have wondered if there is a way we ordinary people — and our children — can “get our heads around” the warming mechanism itself, so to speak, to better understand how global warming happens. To that end, we are offering in today’s edition a “thought experiment” designed to give children, especially, a “greenhouse” experience — “up close and personal.”
How big is the global warming problem? The burning of coal and oil worldwide now puts an estimated 37 billion tons of carbon dioxide per year into the atmosphere.
In the U.S. alone, there are over 1,000 power plants that burn coal or oil. Yet in 2006, China surpassed the United States to become an even bigger emitter of carbon dioxide. No other country even approaches the U.S. and China as producers of carbon dioxide.
The challenge for the world right now is to keep the earth’s surface temperature within 2 degrees Celsius (3.6 degrees Fahrenheit) of its level at the start of the industrial revolution. A temperature much higher — either sooner or later — will produce intolerable atmospheric turbulence, scientists agree.
Where are we on that goal so far? No one has done a thing yet to slow global warming — and the earth’s surface is already 0.74 degrees C (1.33 degrees F) above its level 150 years ago.
How quickly can the biggest polluters act? On Monday, June 2, the U.S. announced a proposal that would require the 50 states (excepting Vermont, which has no coal or oil burning power plants) to cut carbon dioxide emissions starting in 2017. And China has announced it will act to put an “absolute cap” on greenhouse emissions.
In order to get our heads around how global warming happens, we offer this thought experiment. (We haven’t heard of anyone who has actually done this, which is the reason we have labeled this small drama a “thought experiment.”)
The “bedroom warming” experiment
On Saturday night, with everyone ready for bed, the whole family — mother, father, the three children (two girls,11 and 9, and their brother, 5) — stretched out on their parents’ bed with pillows under their heads.
They had no sheets or blankets to pull over themselves, however, because the idea was to feel the warmth in their bodies escape into the open air of the bedroom.
“How do you feel warmth escaping from your body?” the father asks rhetorically. “You feel cooler,” he says.
“Now tell me,” he says. “Can you feel the heat leaving your body?” The children dutifully said they could.
“Good,” their father said. “It feels wonderful to cool down.”
Persuaded, everyone agreed it did indeed feel wonderful to cool down.
“What is happening,” their father explained, “is that the warmth in our bodies is flowing out of us, into the open air of the bedroom, in the form of infrared radiation.
“Infrared radiation is flowing out of us,” their father said.
“You can’t see infrared radiation, because it’s invisible to the eye. But you can tell it’s leaving, because you feel cooler.
Believing it was so — for, of course, it was so — the children agreed they couldn’t see the infrared radiation, but they could tell it was leaving.
“Now we’ll fill the room with a greenhouse gas —”
“What I’m going to do now,” the father said, “is turn on the humidifier that I brought up from downstairs. We want to fill the room with water vapour."
As the room — already quite warm — became a bit damper, the father explained what was going to happen next.
“Water vapor,” he said, “is a greenhouse gas. The water molecules in the water vapor absorb any warmth that arrives if it arrives in the form of infrared radiation.
“A greenhouse gas is any gas that absorbs infrared radiation. Water vapor is a greenhouse gas, so is carbon dioxide, so is methane, just to give some examples.
“That means the warmth from our bodies when we lie down again will no longer go up all the way up to the ceiling, and out of the room. It will go, instead, into the water vapor all around us, and it will stay there instead of leaving the room.
“The water vapor will get warmer and warmer — and as the water vapor begins to warm up, it will radiate our own heat back at us, even while we are lying here trying to cool off.
“That is what is known as the greenhouse effect. You’re trying to get cooler — but the air around you keeps getting warmer and warmer, as though you were in a glass greenhouse, which stays warm to keep plants warm.”
And that’s what global warming is — “the greenhouse effect”
“Now, then,” the father said after the bedroom got warmer, and then warmer still, “we can say that what is happening to us in this bedroom is the same thing that happens outdoors now that we have global warming with us all the time.
“That is,” he continued, “the sun shines all day on the earth. The earth’s surface tries to get rid of its extra warmth just like we’re doing, by radiating infrared energy into the atmosphere. But now, in the year 2014, that isn’t working. It isn’t cooling the earth off any more, like it used to.
“If you went back before the industrial revolution,” the father added, “there was always a small amount of greenhouse gas in the atmosphere that kept the earth from cooling off too much. A little greenhouse gas has always been a good thing. It keeps the earth’s surface pleasantly warm.
“But then, 150 years ago, people in what are now the ‘industrial countries’ began burning coal to separate iron ore, and shape the iron into products to sell. When electricity became common in the 1880s and '90s, electric power plants began burning coal to generate electricity.
“In 1917, Alexander Graham Bell commented that the excessive burning of fossil fuels would have ‘a sort of greenhouse effect…. and the net result,’ he said, ‘is the greenhouse becomes a sort of hot-house.’ And now Bell’s prediction has come true. The whole earth is becoming a hot-house.
“Outdoors, it isn’t water vapor, like here in the bedroom — rather, the carbon dioxide we are putting in the atmosphere is absorbing the infrared radiation the earth is giving off.
“And now heat from the carbon dioxide is beaming down on the earth, keeping the earth and the air we breathe and live in too warm. And that’s how global warming happens.”