The human population has more than doubled in the past 50 years, so has the mass of our planet and everything on it increased?
John Rieuwerts, Yelverton, Devon, UK
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The extra mass of a doubled human population has come from the soil, oceans and atmosphere, so the overall mass of the Earth system hasn鈥檛 changed.
I find it humbling to know that the countless atoms that make up 鈥渕e鈥� were previously scattered across the world and have even been part of people who lived in past centuries.
As such, each of us is a temporary collection of elements borrowed from the largely finite mass of the Earth system and will ultimately be recycled back into it. Ashes to ashes.
Greg Harris, Abu Dhabi, United Arab Emirates
While the human population has doubled in the past 50 years, that life and almost all that sustains it is produced from matter already within Earth鈥檚 gravity well, making no net change to Earth鈥檚 mass. The exception to this is that Earth gains between 30,000 and 100,00 tonnes of space dust every year, some of which is integrated into our biosystems.
鈥淓ach of us is a temporary collection of elements borrowed from the Earth system and will ultimately be recycled back into it鈥�
The planet is estimated to lose close to 100,000 tonnes per year of atmospheric hydrogen and helium, however, creating a net loss of up to 70,000 tonnes a year.
That loss is almost inconsequentially small relative to the total mass of the planet, and has nothing to do with increases in human population size.
Chris Warman, Hinderwell, North Yorkshire, UK
If the mass of Earth鈥檚 human population increases, that mass is derived from whatever is being consumed by those people.
What should be of concern is that, if we continue our present exploitative behaviour, we are gaining mass at the expense of other 鈥渇orms most beautiful and most wonderful鈥� that so delighted Charles Darwin.
It isn鈥檛 too fanciful to imagine that for so many more people, there will be an equivalent loss of elephants and orangutans, and for every extra plantation of oil palm trees, there will be fewer hectares of rainforest.
Earth may not actually gain in weight, but it will be labouring under an additional burden.
Mike Follows, Sutton Coldfield, West Midlands, UK
Humans are increasing Earth鈥檚 mass indirectly. I calculate that human activity makes our planet 150 tonnes heavier per year via an enhanced greenhouse effect. This is because the greenhouse gases we emit have the same effect as increasing the sun鈥檚 brightness by just over 0.8 watts per square metre, and, according to Einstein鈥檚 famous equation E = mc2, more energy in the system means greater mass.
Hillary Shaw, Newport, Shropshire, UK
The total mass of humanity, even with almost 8 billion of us, is minuscule compared with the masses of other organisms on the planet.
The collective mass of carbon in our bodies is , compared with 12 Gt in fungi, 70 Gt in bacteria and 450 Gt in plant life.
Chris Daniel, Colwyn Bay, Conwy, UK
The human population has been able to double only because food for us to eat can be produced in sufficient quantities, often at the expense of other creatures whose habitat we encroach on. Even so, people are a tiny fraction of the total mass of Earth. Seven billion people are , which is less than 5 脳 10-14 per cent of that of the whole planet.
Patrick Forsyth, Maldon, Essex, UK
There are far too many of us and we are adversely affecting the environment through depletion of resources, climate change and extinctions.
Wait a minute鈥� sorry, I misread the question as 鈥渕ess鈥�.
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