[acsinuk (OP)]

Just noticed this old topic that I have not followed up on.
Well, global warming which is caused by population explosion; particularly in Sahara and desert regions is now causing huge problems with millions of displaced people now living in refugee camps even whole cities like Cox bazaar and Gaza.
If we look at the statistics on the worldometer site
   
https://www.worldometers.info/world-population/population-by-country/ 

we can see that the fertility rate column shows which countries are responsible and have more than 2 children per family.
The UN world health organisation WHO needs to address this problem head on at it receives over $6 billion annually but instead of providing free contraceptives and vasectomies to these third world countries it is just supplying free drugs and food which just makes the situation worse as it wrecks their agricultural economies and self sufficiency with the result being the creation of refugee cities like Gaza.

[Bored chemist]

global warming which is caused by population explosion;

No, not really.

[Bored chemist]

the result being the creation of refugee cities like Gaza.

How did you rule out the actions of the government of Israel in the creation of refugees in Gaza?

[alancalverd]

If anything, the blame lies with the British government in the 1917 Balfour Declaration. Or possibly every parasite in history who invented or promoted a religion and/or suggested it was an excuse for politics and hatred.

[alancalverd]

However, back to the subject.

Climate change during the last 50,000 years has for the most part favored the top land predator, homo sapiens, with rapidly increasing temperatures pushing back the ice sheets and allowing agriculture to dominate over hunting as the primary food source.

Problem is that as the temperate and fertile belt continues to move towards the poles so the area of cultivable land will decrease and conditions for the very large human population of the tropics will become increasingly intolerable.

So the longterm effect of the current warming phase  will be a humanitarian disaster. For the next 500 years or so the temperature will continue to rise and the tropics will become uninhabitable or at least unable to sustain their current human population, and thereafter our descendants can expect to see a gradual return of the ice ages over the following 100,000 years, with the population  of the temperate and polar latitudes being unable to feed themselves at present densities.

The sawtooth nature of the temperature/time curve is such that we are currently experiencing the most acute and obvious changes of climate but fortunately we have enough historic data to be fairly confident  in making a longterm prediction and doing something to mitigate the consequences for our species and all those that we prey on.

Acsin has spotted an inevitable association between population density and climate-determined misery, but has muddled cause and effect.

[acsinuk (OP)]

Both cause and effect just show that an expanding population leads to much more CO2 being emitted not only by us but the animals we eat and the energy we use to build houses, roads, water mains, sewers to service the expansion.
If a country has a fertility rate that exceeds 4 it must double its houses every 20 years which is economically almost impossible to sustain.  Failure to keep up will lead to homelessness, shanty towns and huge public discontent with people blaming the government of failure or favouritism .
This will lead to ethnic groups competing for land and water rights which if armed groups emerge  as we are seeing in the Sahara and middle east is disastrous.
Thousands of people are displaced and move into refugee camps with no future which is tragic but is the result of too many children.  A disaster which surely the UN must solve and quickly.

[alancalverd]

CO2 is irrelevant to climate change, as the historic record shows. It is an effect, not a cause. But it is a measure of the rate of consumption of fuel of all kinds, and the balance between plant and animal populations.

Given that fossil fuels are a limited resource and the plant/animal balance has been so distorted by human activity, the forthcoming human disaster has certainly been accelerated by humans. 

[Bored chemist]

CO2 is irrelevant to climate change

Got evidence?

As I have said before, your claim sounds like someone saying "I know that it's warmer, and I know we put an extra blanket on the bed, but I refuse to believe that these two facts are related."

If anything, the blame lies with the British government in the 1917 Balfour Declaration.

I think you will find they are all dead.
Is there anyone whose current actions are affecting the outcome?

[alancalverd]

And if we put another blanket on top of that, it won't have as much effect. But never mind the physics - there is money to be made.

As for Balfour, I rather think that whatever religious perverts want to eradicate the  State of Israel and make women cover their faces in the Name of the Absurd Hypothesis, are contributing to man-made problem rather than help solve it.

[Bored chemist]

it won't have as much effect.

"not as much" is not zero.

[alancalverd]

At the current level of spectral saturation, even a doubling would be insignificant. But fossil fuels will in any case disappear over then next 200 - 500 years and if the human population and its taste for farmed meat are not controlled, the agricultural disaster will occur regardless of climate.

The climate  cycle itself is of academic interest. If CO2 drives temperature, the unanswered (and usually unasked) question is why there has been a consistent 100,000 year CO2 cycle, characterised by rapid rises and slow declines with quite rigid upper and lower limits, and no correlation with e.g. volcanic ash deposits.

[Bored chemist]

At the current level of spectral saturation, even a doubling would be insignificant. But fossil fuels will in any case disappear over then next 200 - 500 years and if the human population and its taste for farmed meat are not controlled, the agricultural disaster will occur regardless of climate.

The climate  cycle itself is of academic interest. If CO2 drives temperature, the unanswered (and usually unasked) question is why there has been a consistent 100,000 year CO2 cycle, characterised by rapid rises and slow declines with quite rigid upper and lower limits, and no correlation with e.g. volcanic ash deposits.

It has been explained to you that the saturation of  the spectrum is irrelevant.
Just to pick a number, let's say that there's some wavelength where the 1% absorption path of a photon is 1 km.
And there's roughly 100 km between us and space (Yes, I know it gets less dense, but you can allow for that. The idea still works).

After rising up (on average) 1km a photon has a 1% chance of being absorbed.
But it could be re-radiated and there's a roughly 50% chance it will be sent back down again.
Also, the excited state could lose energy by transfer to another atom or molecule (not necessarily CO2)
And that warms the atmosphere "near" the earth in addition to simple conduction or convection.
The same thing happens in the next 1km layer and the one after and so on.
So, for a photon at that wavelength to escape it needs to pass through (simplistically) 100 layers

But if you increase the CO2 concentration by 33% or so you reduce the chance of the photon getting through the air.
In effect, you make the "1% absorption layer" thinner.
So there are now 33 more "layers" for it to get through.
So the energy on its way out gets coupled to the  air 33 more times and that makes it harder for any given "bit" of thermal energy to escape.

That happens at any and every wavelength where there's significant absorption of IR.

If the IR is strongly absorbed, then the layers are thinner. But raising the CO2 concentration by a third still increases the number of interactions by a third.

As
https://history.aip.org/climate/simple.htm#L_0141
puts it "What happens to infrared radiation emitted by the Earth's surface? As it moves up layer by layer through the atmosphere, some is stopped in each layer. (To be specific: a molecule of carbon dioxide, water vapor or some other greenhouse gas absorbs a bit of energy from the radiation. The molecule may radiate the energy back out again in a random direction. Or it may transfer the energy into velocity in collisions with other air molecules, so that the layer of air where it sits gets warmer.) The layer of air radiates some of the energy it has absorbed back toward the ground, and some upwards to higher layers. As you go higher, the atmosphere gets thinner and colder. Eventually the energy reaches a layer so thin that radiation can escape into space.   
What happens if we add more carbon dioxide? In the layers so high and thin that much of the heat radiation from lower down slips through, adding more greenhouse gas means the layer will absorb more of the rays. So the place from which part of the heat energy finally leaves the Earth will shift to higher layers. Those are thinner and colder layers, so they do not radiate heat as efficiently.(11a*) The planet as a whole is now taking in more energy than it radiates (which is in fact our current situation). As the upper levels radiate some of the excess downwards, all the lower levels down to the surface warm up. The imbalance must continue until the upper levels get warmer and radiate out more energy. As in Tyndall's analogy of a dam on a river, the barrier thrown across the outgoing radiation forces the level of temperature everywhere beneath it to rise until there is enough radiation pushing out to balance what the Sun sends in.   
While that may sound fairly simple once it is explained, the process is not obvious if you have started by thinking of the atmosphere from below as a single slab. The correct way of thinking eluded nearly all scientists for more than a century after Fourier. Physicists learned only gradually how to describe the greenhouse effect. To do so, they had to make detailed calculations of a variety of processes in each layer of the atmosphere, such as convection (the transfer of heat by rising columns of air). (For more on absorption of infrared by gas molecules)"

So, we should never hear from you again about saturated trransitions.

[acsinuk (OP)]

Yes, the ice record does seem to go in 100,000 year cycles but has never been as high as 415.  See records graph
https://johnenglander.net/chart-of-420000-year-history-temperature-co2-sea-level/

This probably means that the ratio of vegetation to animal/mammals has never been so unbalanced before.
The planet needs to balance CO2 in atmosphere to O2 because too much oxygen would increase the fire risk of incinerating everything.  The planet can balance too much vegetation by icing over the northern and southern polar tundra areas so plants cannot live  and emit oxygen.  However, too many humans/animals will need more food to grow so planet will increase the area vegetation can live in by global warming caused by extra CO2 in the atmosphere.
So global warming is caused by increased CO2 in atmosphere due to a super abundance of people and animals which requires UN acknowledgement and then action,  by encouraging family sizes not exceed 2 children with free aid to achieve this objective using some of its $50 billion funding.
  CliveS

[Bored chemist]

This probably means that the ratio of vegetation to animal/mammals has never been so unbalanced before.

No, it means we burned a lot of fossil fuels.
We know this because we have the tax records which prove it.

So global warming is caused by increased CO2 in atmosphere due to a super abundance of people and animals

Not really. If we could magically replace our current and historical use of fossil fuels by solar or nuclear power then the oil/ oil would be in the ground, and the carbon wouldn't be in the air. And that would annul the greenhouse effect.

There are clearly problems with having too many people- and we need to address them.

But the greenhouse effect is not a direct, inevitable, outcome of a given size of human population.

[alancalverd]

If we could magically replace our current and historical use of fossil fuels by solar or nuclear power then the oil/ oil would be in the ground, and the carbon wouldn't be in the air. And that would annul the greenhouse effect.

But the oil was in the ground 100,000, 200,000, 300,000 and 400,000 years ago, and still the global mean temperature oscillated through a range of 10 - 12 degrees, with [CO2] lagging the temperature graph. So removing the CO2 from fossil fuels isn't going to "annul" the greenhouse effect.

[Petrochemicals]

I seem to remember that the co2 levels are within the margin of error for historic highs. Also as co2 peaks, temperature comes down in a crash, so that may be what happens.

[alancalverd]

No, temperature rises rapidly (as it is doing now) over a couple of thousand years, then falls slowly over about 100,000 years. Civilisation evolved from the last ice age exactly on schedule.

[acsinuk (OP)]

Well, only human people can light fires and burn fuel to keep warm, cook, burn lime for cement, drive cars, tractors and cranes etc.  so the more people the more CO2 in the air.
Any remains from civilization 100,000 years would be buried only within 1 metre of surface but there are none to suggest a previous civilization.
We know from archaeology that the remains of the past are buried down 1 metre for every million years. The grand canyon is 2 kilometres deep so bottom is 2 billion years old.  The first living organism appeared at the seaside 600 million years ago and is at 600 metre depth.
Human population increase is causing climate change and UN must find a way of saving the planet before we run out of fuel

[alancalverd]

The historical record over the last 450,000 years shows that humans played no part in four  previous climate changes of exactly the sort that is happening now, with similar rises in temperature and CO2 concentration over a period of about 5,000 years followed by a slow asymptotic decline over then next 100,000 years.

It is therefore unlikely that humans are a significant cause now, but almost certain that humans will suffer from the effect.

[Bored chemist]

The historical record over the last 450,000 years shows

It shows no time when CO2 levels rose as fast as they are doing today.
This is the first time this has happened.
It may well be the last.
It is not helpful to pretend "we survived it last time".
Ther was no "last time".