Ask HN: Simple Solution to Earth's Rising Temperature | Hacker News Reader

Ask HN: Simple Solution to Earth's Rising Temperature

2 pointsdougSF7011 comments

I am not a climate scientist by any stretch. However given that all life on the planet is a direct result of the Sun and the energy we receive from it, it would make sense if that less of the sun's energy was used to grow things (which must use up a lot of energy as chemical bonds are being formed) then there must be more energy used to just make atoms vibrate. So if we grew more things AND / OR used really inefficient Solar panels OR used the sun's energy to melt vast quantities of eutectic salts then we could reduce the rate of temperature change on the planet by putting more of the sun's energy to state change / energy capture. Just a thought.

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Sadly it's not that simple.

Trees alone do not absorb much CO2 past the lifetime of the tree. In the vast majority of the world they die, decompose, and release a lot it again. To store this carbon (and energy) long term the material needs to be buried. Mangrove forests are excellent at this because anything that dies is quickly covered by sand into an anoxic environment where it can't be broken down by bacteria that create CO2. Over a few thousand years the sand layers really pile up. Over a million or so it'll turn to sandstone and coal/oil/methane). Hopefully a shale develops overtop or that methane is just gonna escape straight into the atmosphere anyways.

Melting eutectic salt isnt much more useful. Once you have molten salt, now what? Bury it? It will equilibrate with the ground. You might as well have just let the ground absorb the energy and saved the trouble of making panels.

Fun fact: Not all life on earth is a direct result of the sun's radiation! Sulphate reducing bacteria are regularly found in ocean floor vents and deep in caves, completely independent of solar events.

I was ignoring the insulating effect of CO2 and focussing on the heat system. What I am getting at is we need to find low temperature way of locking up the Sun's energy. Such that when it is stored it has removed energy from the Earth ecosystem and then when it is released it is at ambient, or below ambient temperature.

The thinking behind eutectic salts is about melting something that takes a lot of energy and can be done by the sun's rays. These molten salts could then create steam to drive a steam turbine and produce electricity that can be stored.

Once energy from the sun penetrates the atmosphere most of that energy is here to stay, so nothing that you do with it after it gets here will help the overall problem.

Yes but it is how it stays that is the problem. If the energy because locked in cell walls because it helped a tree grow then it isn't available to heat up things.

> how it stays that is the problem.

Absolutely correct. But the wavelengths of light used by photosynthesis is mostly green light, and well over 95% of light is reflected from plants. So most of the solar energy, especially the infrared and near infrared stay around in the atmosphere and heat it up. I suspect that the biggest effect of increased mass of living plant material is the decrease of CO2 that would follow, but I have no quantitive figures.

So trees use some energy and remove insulation (CO2). I wonder how much of the energy is reflected back by plants. More energy is in the blue end of the spectrum, if plants are absorbing bluer light then perhaps 80% of energy is reflected?

Instead of trying to stop the climate changes (which is probably impossible), we should focus on adapting to what will inevitably become the new normals.

That too, but if half the planet planted a tree per month that would be 42 billion trees to remove sun's energy.

That isn't anywhere near enough. The World Economic Forum estimates that something closer to a trillion trees are required.

And not just planted, but cared for to make sure that they don't just die and release the carbon back. It's also easier said than done: most of the world's population lives in cities, and don't have access to land on which to plant trees.

Even so, it's not really solving all of the problems. It's like turning on the taps faster rather than patching the hole in the bucket. There are all kinds of follow-on effects from putting so much carbon into the atmosphere that won't be solved simply by removing it in another place -- even if you could meet that extremely high goal. Fossil fuels pollute other things besides CO2, and CO2 is absorbed by the oceans that make them more acidic.

Planting more trees is a worthwhile start, but it won't mean anything if we don't also find ways to dramatically reduce the amount of fossil fuels we turn into atmospheric carbon.

I am thinking from an energy perspective. Energy used to grow an animal or a plant is energy not used to warm the planet.

Perhaps we should design a system that builds a carbon structures using the sun's energy. Rather than Solar Electricity we have Solar Carbon.

https://www.scientificamerican.com/article/splitting-carbon-...

Energy isn't the issue. The issue is heat. The amount of the energy budget is vast, and we can't substantially affect it by capturing more energy and then using it to build things. The problem is that we have a global-scale heat retention failure, and nothing humans do is going to overcome that.

It's entropy. You won't beat the second law.

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