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Comment by Madmallard | Hacker News Reader

Is the major issue here that 3 degrees Celsius is like an average so all the hot tropics places just become uninhabitable whereas temperature rises are more moderated in higher latitudes?

Also how much faster and higher will that number go with all the data centers? Can't imagine it not just getting worse.

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One major issue is the extreme difficulty of being precise about tipping points.

Eg: Have you seen a train derail? A couple of degrees of tilt - nothing .. and then .. whoops.

The global climate has been 'stable' about mean values for the bulk of human written history and development of urban civilisations. The planet now hosts 7 billion+ people, largely urban, and feed by a century of stable agriculture patterns write large.

The disruption of that will have a major impact across the human population of the planet.

The tipping points, when they come, are related to the significant loss of polar ice, and the beginning of positive feedback of atmospheric insulation factors other than CO2.

Melting ice, the transformation from near zero degree ice to near zero degree water, takes up a large amount of the energy from the sun trapped by increasing insulation. The energy used to melt X tonnes of ice, if no ice can be melted, will instead raise the temperature of X tonnes of water by some 66 degrees C (or there abouts - worth looking it up exactly).

Increased land and sea surface temperatures releases methane from peat bogs and tundras, and increases the water vapour content of the lower atmosphere.

Both of these things increase the insulation factor of the atmosphere to a greater degree than CO2.

We hit 8 billion in 2022 btw.

I think the problem is much worse than people imagine as well. Of those around 5.5 to 6 billion people live in "developed world" conditions (sanitation, water & electricity to the home). Over the next 20 years that's expected to grow to by another 1.5 billion (the previous 20 years was around the same). That alone is going to be a huge demand in energy, for construction and ongoing day to day energy usage.

On the other hand global energy demand has a very close correlation with the number of people living in developed world conditions - so after this point the growth in energy demand should start to level off.

Let's hope China continues to push renewables, and their investment in developing countries favours that instead of fossil fuels.

Yet Europeans will continue to hamstring their economic activity to lower their footprint which is really not doing anything in the grand scheme of things vs. China/India and what Africa will produce if/when they modernize.

Yeah lets continue releasing carbon while telling the rest of the world they're not allowed to.

Well whatever you guys have been doing hasn't worked for a damn and only hampered EU's ability to actually project power and make changes.

But there have been way higher atmospheric carbon dioxide levels historically, and those have largely coincided with plant and animal life climaxing. See the Jurassic.

> But there have been way higher atmospheric carbon dioxide levels historically

Historically? In written human history?

If we're talking the state of the planet throughout the past 4 billion odd years of existence, it once had no breathable atmosphere and had a stretch with a largely molten surface, and got smacked up hard when the moon was spun off.

None of these things are relevant to the planets near future as a direct result of human induced changes of the past century and a half.

I believe those followed global extinction events thanks to large scale volcanic activity over long enough time frames to change the climate. Life did adapt, the life that survived. I'm not sure we want to run that experiment on human civilization.

"History" is generally used to mean when humans were around writing stuff down. And no, CO2 levels have never been this high during the entire history of human civilization, and likely the entire existence of Homo sapiens

It’s sort of all over the place but it’s mostly the other way round. The poles might see like +5-8c. It’s also the overall temperature. Today’s high temperature where I am is 33 and the low is 25. 33 isn’t super unusual, maybe a dozen days a year. 25 as a low though is crazy high even on days historically above 30. It all averages out to +whatever.

For temps by latitude/region this source seems ok on a quick search https://scied.ucar.edu/interactive/compare-climates-regional...

// The poles might see like +5-8c.

Poland continues to experience significant cold related deaths and any warning might be welcomed.

Among _many_ other things, 3 degrees Celsius globally means more evaporation over oceans, which makes the air denser.

Denser air carries more momentum, which means more frequent (and more severe) hurricanes.

Greenpeace literature in the 1980s predicted hurricanes from Global Warming.

And here we are.

Greenpeace is responsible for a lot of that warming.

May I ask how you came to that conclusion?

If you don't build nuclear plants, you'll get your base load generation from fossil fuels. Greenpeace has always strongly opposed nuclear power.

In itself, that doesn't mean they're wrong. But right or wrong, it's unquestionable that they have been successful at antinuclear activism. As a result, their activism has the net effect of promoting carbon pollution, and by no small measure.

As well as radiological pollution, for that matter: https://pubmed.ncbi.nlm.nih.gov/14169712/

> more evaporation over oceans, which makes the air denser

More humid air is less dense than less humid air at the same temperature and otherwise same composition. H2O has a molar mass of 18, vs ~29 for dry air.

As I understand it just means there's a lot more energy in the atmosphere. Like imagine the amount of energy it takes to increase water temperature in a pot by 3° and scale it up to the planet. All that energy makes everything bigger, badder, and less predictable. Longer, dryer droughts; bigger, longer winter storms, etc.

There's a lot of bad things that happen at 3C.

The first is that 3C represents a lot more energy in the atmosphere. That translates to more water evaporating from the oceans creating bigger more violent storms (think more frequent flash floods).

It changes the ocean currents which can be really bad. Right now Europe is warm for it's latitude because of a weakening current from the equator to the UK brings a lot of heat. If that completely collapses, Europe can enter an ICE age.

The rising temperature also ends up weakening the vortex of the north pole which mostly keeps the arctic temperatures sealed up north. As that vortex weakens, spills of crazy blizzards can hit unusual places pretty hard. The winter storm in 2021 is an example of that happening.

Then of course there's the potential melting of the ice caps which will release a lot of methane into the atmosphere (speeding up warming). That will ultimately cause sea levels to rise which won't be great for the state of Florida.

Mass migration, crop instability, more frequent and more extreme weather. It's just a combo of bad things that all come together at once.

The most extreme warming happens at the poles, doesn't it? Plus increases in volatility on top of a rising baseline, so more extreme heat wave peaks even in temperate climates that don't change as much on average.

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