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.

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fy20 7 hours ago | parent | next [-]

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.

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MaxHoppersGhost 7 hours ago | parent [-]

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.

	▲	Hikikomori 42 minutes ago \| parent [-]
		Yeah lets continue releasing carbon while telling the rest of the world they're not allowed to.

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hcurtiss 7 hours ago | parent | prev [-]

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.

	▲	defrost 6 hours ago \| parent \| next [-]
		> 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.
	▲	peterashford 6 hours ago \| parent \| prev \| next [-]
		"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
	▲	goatlover 6 hours ago \| parent \| prev [-]
		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.