C’est Chaud

Joseph Fourier, a giant of mathematics and physics, first described the concept in his book ‘Théorie analytique de la chaleur‘—Analytical Theory of Heat.

Fourier, who was a contemporary of Napoleon, published his book in 1822, just over two centuries ago, and opened the door to meteorology, oceanography, earth sciences, environmental sciences…

The sun is our primary source of heat, and without it no life could exist on our planet. However, if the earth’s temperature depended only on the sun, our planet would have a temperature around thirty-two degrees Fahrenheit, or zero centigrade. Mars, for instance, has a surface temperature of -85 ^oF—permafrost.

Temperature on the surface of the planets in our solar system. Earth is the only one where water can exist in a liquid state and a carbon-based biosphere can survive (diagram from NASA).

Uncle Joseph concluded that our atmosphere was responsible for retaining heat and making this place livable—in other words, he discovered the greenhouse effect.

Although carbon emissions—associated with carbon dioxide—are what you hear about on the news, water is the most important greenhouse gas; the evaporation of water and the formation of clouds, and the atmospheric gases, together constitute our atmosphere.

When I was growing up, I wondered why there was snow on the mountains, but rivers and forests down below. Surely, the temperature increased as you went up, as you got closer to the sun? The fact there is snow on the mountaintops, i.e. closer to the sun, was enough for me to understand something else was going on. But what?

Fourier’s greenhouse—that’s what.

Like our own bodies, the atmosphere is a finely balanced, constantly changing system—it works like a pendulum: the more you swing it out, the quicker it comes back—in biology, that’s called homeostasis, from the Greek words ‘same’ and steady’.

The two gases that mainly make up the atmosphere, nitrogen (78%) and oxygen (21%), are not greenhouse gases—these are in the 0.1% of ‘other gases’: in order of importance, water vapor (clouds), carbon dioxide, methane, nitrous oxide, and ozone—four of these contain oxygen, and one contains nitrogen.

So the earth’s heat budget depends on a small part of the atmosphere—if the air we breathe was largely made up of greenhouse gases, we would all suffocate, which would quickly resolve climate change.

The origin of the big five gases—there’s a sixth called chlorofluorocarbon, or CFC, but since it also destroys the ozone layer, it gets weird—is diverse: water vapor is universal, the excess CO₂ comes mainly from fossil fuels, methane from cattle farts, and nitrous oxide from fertilizers.

• When you have a diversity of causes, it’s difficult to apportion blame and settle on solutions.
• When a problem is global and the change is not immediately obvious on the street, people will not change their ways.
• When the contributions required are unequal, particularly in light of history—European and North American deforestation, or industrial development in the West—governments will not agree.

Finally, the signal to noise ratio of climate change is very low. This allows politicians, industry, and deniers to have a field day by confusing weather and climate.

Climate is what you expect, weather is what you get.

The India Road, Atmos Fear, Clear Eyes, and Folk Tales For Future Dreamers. QR links for smartphones