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Comment by leobg | Hacker News Reader

When you look at the chart, it's odd that the temperature rise started only in the 1980s. Or at least what you can see in the chart. People have been burning wood and coal for centuries. The industrial revolution happened in the 19th century. There were railroads and airplanes. And big industry in the 1950s and 60s. So it's what we are seeing there. Just the delayed reaction toall of that? Or is there something especially grave that happened immediately before the 1980s?

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World population was 2 billion in 1930, 3 billion in 1960, and 4.5 billion in 1980. Today the world population is a bit under 8 billion. The Earth could easily support many more than 8 billion people with the right technology install base, I don't want to give the impression that population is an issue in itself, it isn't. However, with the predominant technologies being oil-based transportation, coal-based power, and carbon intensive agriculture throughout that period and continuing today, the size of our economy (enabled by the size of our population) is capable of a much greater degree of warming through GHG emissions than we were in the 1960s, let alone the 1800s.

This is such a terrible situation. We need depopulation but every country's economy seems to be based on infinite growth and can't deal with an aging population.

I'm scared the best case scenario will end up being "the world gets so hot it kills enough people to stop getting hotter." I don't know a lot about climate change but I don't thing the Earth will simply reset when enough people die, considering the melting ice caps won't just unmelt because of that.

We don't need depopulation. We just need to stop eating cows, riding cars and planes so much, and buying everything from across the world.

(and dozens if not millions other things, neither of which is harder than depopulation)

While this ist part of what we need to do, you are forgetting the industry sector, as the first and biggest polution source, that provides living standard to us, and that needs to be regulated the most for the biggest effect.

That's exactly right. We are taking carbon that was sequestered under ground over a period of hundreds of millions of years and releasing it back into the atmosphere in just a few hundred years. That genie will not go quietly back into the bottle.

Although there are ways to bring it back under the earth: Burry trees deeply underground. Which is of no economic value, but that might be a way, if we dig deep enough and do it on big scales.

In terms of population reduction we're actually handling that by ourselves, as the absolute number of births peaked somewhere in 2014-2017 and started declining since.

Overall most of the population growth now is younger, larger generations replacing older ones, with the demographic pyramid looking like a sausage being filled with meat.

World population will peak by 2086 at ~10.4bln.

That's still too many. Sure, it'll probably level, but why not get in front of that and find a good balance today instead of assuming it'll all just sort itself out magically?

It is sorting itself out "magically". If anything, we don't know what to do with ageing populations.

The previous estimate put the population in 2100 at 11bln and growing, but then China had its census, which revealed a very different demographic situation than anticipated and the pandemic happened, upending those projections.

Recently also India went below replacement fertility rate - that now makes the two most populous nations having crossed that threshold - also way ahead of previous projections.

Estimates of populations of African countries are most likely overstated, just like fertility rates.

That's only a prediction, an extrapolation by the UN I believe. Many things can change until then and we don't know anything for sure. Even if it peaks by 2086, the population mass until then, with our current way of living, will have devastated the planet.

Yes, I'm using UN numbers, as they have the best track record.

Looking at past projections the population was typically slightly below the estimated figure, so the most likely scenario is that this will be the case here as well.

In any case I don't think that devastation will come to pass, as China's emissions pretty much plateaued already and India's are looking like they did as well. The west has been in decline in that regard for years now.

It's going to get worse - that's a given - but with the recent estimates giving a more precise number for emissions connected with land use change, global CO2 emissions might have plateaued, or even peaked a few years ago already.

I think that would depend a lot on whether depopulation led to rapid restoration of our lost wetlands and I am going to assume no one is making models of that because the wetlands issue gets so little attention generally.

> We need depopulation but every country's economy seems to be based on infinite growth and can't deal with an aging population.

There is no way of organising an economy that will allow it to support having the demographic of net producers significantly outnumbered by the demographic of net consumers. This is an economic problem, but only in the sense that if you want people to have access to good and service then you need people willing and able to produce those goods and services is economic problem. If you have a demographic collapse, then you don’t have that any more, no matter what system of economic management you’re using.

The idea that we need depopulation is also about as intellectually and scientifically valid as the voluntary extinction movement is, yet somehow a lot more people seem to think it has some credibility.

That doesn't seem to make sense because we're talking about how many people produce and consume things, not the rate of which they produce and consume things.

We just need the working age populace to produce more than everyone can consume. Automation was supposed to achieve that. In fact, I think it has already achieved that long ago?

I'll reword it in a depressing, pragmatic way. We can already produce enough to satisfy the NEEDS of the entire population. So if you only need X jobs to produce for everyone, but extra people are getting born because nobody can just set a limit to how many people are born, then what do these extra people do in their lives? What is going to be their job?

If they produced things, it would be a waste of resources, because the needs of the entire world are already satisfied. But that's exactly what they do. Do we really need fancy clothes, and fancy houses, and fancy food, and TV shows and music? Do we need art? We don't really "need" them, but we already produce enough that we can afford to have people whose jobs is just making these things. But by this logic we don't really need computers either, you can't eat them, so I guess I'm superfluous as well.

I guess the point is, how many of these "superfluous" things we should produce? If population goes down, some jobs won't get as many workers as before. I can't really say "artists are unnecessary, we should just get rid of the entire profession and replace it with Dall-E because it's more productive." In fact, I'm not sure there is any job we can just get rid off to state "we will birth no more people to do that job. It will have 0 workers assigned to it."

And this is of course just speaking theoretically, assuming you could control births and professions with precision, which we can not in practice. People are going to get born and they will do jobs that aren't as productive as other jobs and there is nothing we can do about it. But to say we can't produce enough doesn't make sense if we can't even define how much is "enough."

> If they produced things, it would be a waste of resources, because the needs of the entire world are already satisfied. But that's exactly what they do. Do we really need fancy clothes, and fancy houses, and fancy food, and TV shows and music? Do we need art?

The majority of society’s basic needs have been catered for since ancient Mesopotamia. The only significant innovation we’ve had since then is modern medicine. In regards to needs, everything else since then has just been fine tuning and improving access.

The majority of human development since that period has primarily been delivering for wants. The basic premise of your argument here is “how about you do without _everything_ that you want”.

This also ignores the fact that no, we cannot make “enough” of only the needs, and just remove all of the wants, because they have the same supply chain. You might argue that I don’t need the spark plugs in my car, but a farmer would certainly need the spark plugs in their tractor.

Depopulation is the last thing we need. We are carbon based life forms. We can just sequester carbon in human bodies.

We do not need "depopulation, as I specifically noted in my comment there is no issue with our population numbers being significantly higher than they are, let alone at our current levels. The issue is the kinds of technology that we are using and policies that we have, oil-based transportation, cow-based agriculture and to a lesser extent meat-based agriculture, food waste, coal-based energy generation, etc. We need to decarbonise the grid and transportation (we already know how to do this, it is only a matter of doing it), significantly reduce GHG emissions in agriculture through selecting different crops and livestock as well as increasing efficiency (this will need large scale public buy-in, so it needs to be led by the government), and put serious R&D into decarbonising heavy industry like steel and cement production. Once we get that far, we can focus on solving the remaining GHG issues like synthetic fuel for planes + high-speed rail replacements, and carbon capture & sequestration for what we can't solve in a cheaper way. "Depopulation" is an absurd, unrealistic, and unworkable proposal that does not actually solve the central problem and would actively make it worse. Population size is a huge part of what makes us able to achieve significant scientific and technological progress, "depopulation" would actively harm our efforts to restructure our economy and distribute technology as necessary to combat climate change.

Part of the dramatic rise occurring after the 1970s is a direct response to the clean air / pollution legislation that started getting passed in western countries. Pollution seeds the air with potent cloud condensation nuclei, creating a higher average cloud cover, and reflecting more shortwave solar radiation. We've got cleaner healthier air, but less cloudy.

I believe there was also a noticeable effect from the pollution decrease when global shipping dropped during covid, you had less cloud cover from ship trails, and more solar radiation reaching the surface.

https://www.nature.com/articles/s41586-022-05122-0

2022 Nature article on the phenomena.

Not surprisingly, deliberately polluting it again is a proposed method of reducing global warming. https://en.wikipedia.org/wiki/Stratospheric_aerosol_injectio...

This mitigation strategy is so obvious I'm surprised that this isn't implemented already.

Yeah, I mean, wasn't the worst year to be alive some year after a volcano eruption? So, let’s geo engineer this against global warming and hope our calculations pan out…

There are many counteracting natural processes on Earth that keep the climate relatively stable in all directions. For instance, oceans can just absorb quite a large amount of CO2, thus preventing a greenhouse gas effect from occurring in the atmosphere. Polar icecaps also melt and that absorbs a huge amount of energy, stabilizing the temperature.

Eventually, many of these processes become depleted and global average temperature starts to rise.

Finally someone that has it right -_-'

The chart is relative to the 20th century average, so even though values before 1980 are less than 0, it doesn’t mean warming hadn’t started. It is just that around 1980 we got clearly above the average of the 20th century.

Imagine this wasn’t deviation from average, but absolute values and ignore the blue/red colors. Then notice the trend — it is getting warmer through all the 20th century. I think, I can easily see a trend line already from 1910.

That's just the point that it crosses the average temp for the 20th century and crosses over to being above that average. It's climbing before that too.

The number of people burning wood and oil has increased during that time, the total volume of CO2 released by human activity has steadily increased since the industrial revolution.

If you look at the charts again you'll see the temp. has been rising more and more in response since the industrial revolution.

As a peer comment noted, you can ignore the 0 degree line, the article uses two different epoch markers, these are just arbitary convention.

Eyeballing the graph, it looks to me like the increase begins around 1910.

The red portion of the graph starts later because of the arbitrary temperature they decided to use as the 0 point.

I think that’s because that’s when we started having weather satellites that could take consistent measurements.

I really find it hard to believe you can compare temperature measurements “globally” before 1950s with any sort of consistency or accuracy. Today’s infrared thermometers for fevers have a 2F accuracy. You’re telling me that you can calculate temperatures from around the world pre-1950s and trust that it’s consistent and accurate?

Capacities of your specific chinese broken thermometer doesn't tell much about how scientists measured temperatures decades ago, does it.

And 2F spread ain't right, doctors use rather precise instruments that need some experience to be used correctly though, we have one at home too for kids since wife is a doctor (not a pediatrician but its manageable).

> You’re telling me that you can calculate temperatures from around the world pre-1950s and trust that it’s consistent and accurate?

Consistent and within an envelope of accuracy, sure.

Today we can even compare high resolution, many measurement point global tempreture distributions against what would be projected if we only had the same stations from the 1850s - 1950s.

Recall that pre GPS navigation was highly reliant on accurate time pieces which were highly reliant on accurate tempreture, humidity, air pressure readings. From the 1850s onward there are highly reliable records from scientific grade instruments at trading ports about the globe.

>I really find it hard to believe you can compare temperature measurements “globally” before 1950s with any sort of consistency

You're right to be skeptical and we can't. There isn't even a single "global temperature" today. There is, for example, a global surface temperature measured by satellites and ground stations, except where there is cloud cover and no ground stations. It is extrapolated in such places based on mathematical models. Also a satellite passes only so often across certain area (or takes low resolutions photos if at geostationary orbit) so data is further extrapolated in time. And that is only the surface. What about the depths of the oceans and the thickness of the atmosphere? Is this what is meant when they make claims like "hottest 12 months" on record? If yes, it tells you nothing about true "global temperature".

"Global temperature" today is a mathematical construct, a model based on limited sensor data. A LOT is extrapolated in that model. How exactly you do that affects the results you get.

We don't have consistent measurements across the thickness of the atmosphere and depth of the oceans. There are sporadic measurements, like satellite measurement of cloud cover temperature and knowing how high this cloud cover is, but what's going on below and above? It's all filled in by "the models". Models people wrote to behave how they expect they should behave.

> Models people wrote to behave how they expect they should behave.

Based on the laws of thermodynamics, the heat equations, understanding of heat flow, yes.

> Today’s infrared thermometers for fevers have a 2F accuracy. You’re telling me that you can calculate temperatures from around the world pre-1950s and trust that it’s consistent and accurate?

Yes. Believe it or not, the average of multiple calibrated measurements is more accurate than some random off the shelf consumer electronics. My laptop display has a delta E of about 20 out of the box. If someone calibrates it they could bring it down to 5, most likely. I have no trouble believing an actually decent panel can achieve less than 3.

I can probably finagle a way of measuring haemoglobin with my kitchen equipment and some reagents I order off eBay. I might even get one sig fig out of that. That doesn't mean the literal bottom shelf crap I use is going to be the absolute limit of possible precision.

I mean, what kind of argument even is that? "I can't make similar measurements using the equipment I have at home, therefore climate scientists must have either no idea what error bars are or are lying"?

Cities have grown and many temperature measuring stations report higher temperatures as a result. As buildings trap heat as well as concrete.

I see an upward line starting from the 1920's onward if you focus on the general trend.

We tripled our oil use between 50 and 80, and there is some inertia

My first guess is that Mao Tse Tung basically kept China in a pre-industrial communist fever dream until he died and the reformers, like Deng Xiaopeng, took over in the late 70s. Then China, a nation of 1 billion people, did a speed-run on the last 300 years of Western industrial history in about 30 years. At the same time the US underwent a mass de-regulation and neo-Globalization was off to the races.

edit - good example, Toyota. Right around the 70s/80s they became a massive multinational exporter. This is enabled by pax Americana and neo-liberal free trade policies which, for example, allowed Toyota to import to the US in large numbers and also build factories inside the US itself, multiply by several other companies in several other countries, massive growth. Before this time global trade was far more limited.

https://www.toyota-global.com/company/history_of_toyota/75ye...

If we take the stock market as an analogy for energy (and hence pollution) there is just a massive explosion starting around 1980. people forget that the stock market used to be kind of boring and went down alot. https://www.macrotrends.net/1319/dow-jones-100-year-historic...

edit - another good one. The US trade balance. I.e. the rise of the foreign nations who had "interesting" currency policies and manufacturing exports designed for the US, in order to get USD so they could participate in globalism, buy oil (sold mostly in USD), and modernize. https://en.wikipedia.org/wiki/Globalization#/media/File:U.S....

Also GDP of the Asian Tigers https://en.wikipedia.org/wiki/Four_Asian_Tigers

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