While scientists are still trying to wrap their heads around (and furiously debating) the question of how exactly life on Earth began, they and we do know about the ingenious plot Mother Nature hatched to ensure that it went on. The first order of the day, was, of course, a reliable, steady source of energy to power up life with.
Ah, there was the sun, just 93 million miles away, glowing generously and steadily and providing all the energy ever needed. But this energy, emitted in the form of photons (light), needed to be harnessed. So up she came with the idea of evolving a molecule – a rather large one – that could do just that: chlorophyll, which was a soothing green colour (because it reflected only green light) and which could be found in cyanobacteria (one of the pioneering photosynthesisers), green algae and green plants. Cyanobacteria, formerly known as blue-green algae, and a minute bacteria, were first off the blocks, photosynthesizing so efficiently that it produced so much oxygen that the era was called the “great oxidation event”.
Eventually, oxygen levels stabilised, as much of the cyanobacteria died, but not before multi-cellular life evolved. After this, there was no looking back. It’s thought the first “animals” to emerge were sponges, some 800 million years ago, able to tolerate the now low oxygen levels in the oceans, and then first land plants about 470 million years ago, after which life forms went pretty berserk.
To provide sustenance and therefore energy for life, this miracle chlorophyll molecule absorbed carbon dioxide from the atmosphere and sucked up water and water vapour. Using the energy from the photons, chlorophyll split the water into hydrogen and oxygen atoms. It then used the hydrogen in combination with the carbon dioxide to manufacture sugars and carbohydrates, which powered life and enabled growth. The oxygen it kindly released back into the atmosphere – this was necessary to burn those sugars and carbs to produce the energy other living creatures need to walk and run and sing and dance, to be alive, to grow and to make more of ourselves! And brilliantly, every living breathing creature (and now, alas, too many nonbreathing ones, like cars!) emitted the carbon dioxide so vitally needed by plants to live and grow. Which indeed they did, and became the source of our own sustenance, our fuel and food: fruit and vegetables, seeds, tubers and roots. Mammals, reptiles, amphibians, fish, insects – every living creature dined out on these to fuel their own bodies. Hardcore carnivores simply dined out deliciously on other animals which had become plump and juicy on a plant diet. So, in essence, we are all solar-powered.
Alas, we still can’t manufacture our own food, so are dependent essentially on plants and the animals that eat those plants (and often each other). Can you imagine the number of Nobel Prizes a scientist would have deserved had they thought of an ideal way for humans to produce their own food? Okay, so Big Boss Mama Nature got there first, but we can and should use the principle and philosophy behind it – that what goes around comes around, that nothing goes to waste – in the way we live today. Because that is the only way that things can work out in the end.
We all know that leaves are the storehouses of chlorophyll and leaves grow on trees and bushes, which is why it’s so important to have forests and green areas. In reality, around 50 per cent of the oxygen in the atmosphere is emitted by tiny plankton and other plants floating in the sea. But a good amount of this is used up by marine life and the decomposition that follows when these creatures die. But it’s not all hunky-dory for green plants: their leaves have pores called stomata through which they release oxygen and absorb carbon dioxide. But they also lose water vapour through these same pores. In dry places, this can be a problem for the plant, because it needs as much water as it can get. In humid, cool places, you may have noticed beads of moisture beautifully rimming a leaf (on days when there’s no dew) in the morning; this is excess water that the leaf is getting rid of.
Ah, I can hear the wheels in your brain whirr and see the gleam in your eye as you prepare to pounce! If there is more carbon dioxide in the air, won’t that help plant life – and therefore us – to thrive? The plants will grow bigger and lusher, vegetarians and herbivores will have more to eat and get plumper and juicier, as will carnivores (and our burgers). Best of all, there’ll be more oxygen to go around for everyone! So, theoretically, wouldn’t cars and other carbon dioxide emitters actually help rather than hinder this process?
Well, for a start we are hacking down vast swathes of forest every second, reducing their capacity to produce oxygen. Also, we must remember that plants only work the day shift: at night, in the absence of light, they just breathe out carbon dioxide like all the rest of us, which is why we are told not to keep green plants in our bedrooms at night. So, if there’s too much carbon dioxide around, we will all suffocate. The classic candle-in-a-jar experiment will reveal this: the candle needs oxygen to burn and once the oxygen is used up, pfft, the flame goes out! Yes, that’s not likely to happen to you (unless you’re locked in a car with the windows rolled up) because there’s relatively little carbon dioxide in the atmosphere (compared to other gases). But carbon dioxide in collusion with water vapor and other greenhouse gases like ozone and methane acts like a kind of tea cosy over our potpourri planet, trapping and reflecting the heat generated and causing all sorts of problems in those areas of the planet that try to keep temperatures as steady as they can, such as ice caps and oceans.
And with our millions of jets, cars, trains, massive power plants and factories producing everything from silicon chips to bulldozers by the million, all emitting carbon dioxide and other noxious gases in the process, we are physically heating up the planet too: for instance, as much as 60 per cent of the energy produced by an internal combustion engine dissipates as heat, only 30 per cent being used for actual propulsion. Every time anything is burnt it produces carbon dioxide and often other even more dreadful gases like carbon monoxide, nitrous oxides and methane. Most significantly, we get the fuel to burn in our factories and power our luxury cars and aircraft carriers from the fossilised remnants of plants that died millions of years ago, and were buried and compressed under considerable pressure, taking the carbon they contained with them. In three words: coal, gas and oil. We burn that coal, gas and oil and set that carbon-free in the form of carbon dioxide.
Excerpted with permission from Our Potpourri Planet, Ranjit Lal, illustrated by Anushua Sinha, HarperCollins India.
