by James Morris
William Happer, a retired Princeton University physicist and Deputy Assistant for Emerging Technologies on the National Security Council, recently stated that carbon dioxide is beneficial to humanity and therefore should not be regulated in any way. In biology, however, the idea that things are “good” or “bad” is simply a lot of hot air.
Let’s take Happer’s example of carbon dioxide. Is it beneficial or harmful? The answer is – it depends.
There are many ways in which carbon dioxide is certainly beneficial. Plants (and algae and bacteria) take in carbon dioxide and water to produce sugar, producing oxygen as a by-product. Humans and many other organisms use this oxygen to break down carbohydrates, producing carbon dioxide and allowing the carbon cycle to keep turning.
Carbon dioxide is also a greenhouse gas, trapping the sun’s heat and warming the planet. Without greenhouse gases, the Earth would be much colder than it is now and life as we know it would not be possible.
But that’s only half of the story. Just because something like carbon dioxide is beneficial doesn’t mean that more of it is more beneficial. Carbon dioxide traps heat in the atmosphere, so more carbon dioxide will inevitably trap more heat, further warming the planet, melting polar ice caps and glaciers, raising the sea level, and providing more energy for wind and storms.
More carbon dioxide in the oceans makes it more acidic, leading to bleaching of corals and making it more difficult for some marine organisms to build their shells.
The same could be said of oxygen. We breathe in oxygen, and need it to live. In fact, the rule of 3’s for survival says that we can’t survive more than 3 minutes without oxygen.
Our atmosphere contains about 21% oxygen. So, if breathing this amount of oxygen is life-sustaining, shouldn’t breathing more oxygen be even better? The answer is no. In fact, breathing pure (100%) oxygen will kill you.
Even atmospheric oxygen is toxic to some organisms, like certain anaerobic bacteria that can’t live in the presence of oxygen. In fact, during the first half of the history of the Earth, the atmosphere did not contain oxygen and life evolved in its absence. Then, when a group of bacteria evolved the ability to produce oxygen as a by-product of photosynthesis, oxygen accumulated in the atmosphere for the first time. Because organisms were not adapted to oxygen, many went extinct in what scientists call an oxygen catastrophe.
So, is oxygen good or bad, beneficial or harmful? The question is nonsensical because it depends on when, where, and how much.
Water, the elixir of life, is similar. Let’s return to the rule of 3’s: we can’t survive more than 3 days without water. We are, in fact, mostly water. But water, like carbon dioxide and oxygen, is not an unalloyed good. Of course, we can’t breathe under water. And water intoxication (or water poisoning) occurs when you take in too much water, a life-threatening condition.
Medicines themselves provide yet another example. We take medicines when we are sick to make us better. But the amount of a medication is critical, as medicines are essentially poisons in small doses. Similarly, certain metals, like iron, zinc, and manganese, carry out essential functions for life, but only in very small amounts.
Life is a delicate balance, whether we consider the water, sugar, and salt in our bodies, our temperature and energy levels, circulating hormones, or even our neuronal circuits. For example, we keep our body temperature right around 98.6˚F in spite of the changing temperature around us. And we maintain our sodium level around 140 mEq/L and our blood glucose level around 90 mg/dL in spite of what and when we eat.
Walter Cannon, a 20th-century American physiologist, coined the term “homeostasis” to describe this balance. What he meant is that even though the outside world is constantly changing – hot or cold, dry or wet, calm or windy – the environment within a cell or organism is remarkably constant. And, these steady conditions are actively maintained, requiring constant and subtle adjustments to keep the internal environment compatible with life.
In fact, the ability to maintain homeostasis is one of the hallmarks of life.
Happer’s statement about carbon dioxide shows breathtaking ignorance (pun intended) or is deliberately misleading (given his ties to the fossil fuel industry). The story of Goldilocks and the Three Bears gets what Happer misses – just as porridge can be too hot, too cold, or just right, the same goes for us and our planet.
© James Morris and Science Whys, 2019