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Comment by flavius29663 | Hacker News Reader

> - whether the earth is warming or not

The Earth is warming, but how much of it is caused by humans is under debate. The Earth is still coming out of an ice age, so it would be warming even without humans.

Also, the more important question is: how much will it accelerate based on our emissions? If there are no positive feedback loops, it would only warm up 1C maximum, no matter how much more CO2 we will emit. But because of the positive feedback loops (warmer earth -> more water evaporating -> more warming), this warming can trigger a 4-5C further warming. The feedback loops are just theoretical(you can't measure them empirically) and the quality of the estimations is based on our understanding and modelling of the climate.

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https://xkcd.com/1732/

We've had in the last 100 years a temperature swing that usually takes a thousand years or more. We've already seen greater than +1C of temperature increase compared to before widespread use of fossil fuels.

Is that caused by humans? Sure that's up for debate, in the same way whether tobacco causes cancer is. People are willing to be wrong when being wrong gives them money/status/utility.

> We've had in the last 100 years a temperature swing that usually takes a thousand years or more.

A cute xkcd is not a time machine. You rely here on indirect measurements of tree ring measurements or ocean sediments. You can't verify if there were any other factors at play over the millennia, and I seriously doubt that these methods can even be theoretically +/- 0.5 degree C accurate. You may believe that, but you can't verify unless you travel into the past. Besides, 1000 years are NOTHING on the scale we are looking at. If you live anywhere north of the 40th degree, the place you now sit was probably covered by an ice sheet without a living thing in sight, only 10000 years ago. And a 100000 years ago. There is no way that you can divide that timescale into thousands and measure every one of them with a high enough precision to compare it with the present. The bold claims of climate science have lost any scientific humility.

> You may believe that, but you can't verify unless you travel into the past.

Do you believe in the method of radiocarbon dating? What about dinosaurs?

What about them, and how was your debate class? Can you measure the time of day an organism died with radiocarbon dating? This rhethorical question is meant as a hint. Did you know how they calibrated radiocarbon at first? They used wine bottles from french cellars, because they have a year printed on them. That's scientific verification, because believe doesn't do it.

> If there are no positive feedback loops, it would only warm up 1C maximum, no matter how much more CO2 we will emit.

GHG emissions are still increasing. If we assume that temperature increase is only linear in the amount of atmospheric GHGs, that means temperature will continue to increase, not remain flat.

Little known fact (I am still amazed how people don't know the mechanics of global warming...): CO2 effect in the atmosphere is logarithmic, increasing with concentration. That is because CO2 can only block one band of light, so at one point, you're approaching asymptotic effect. That's why we keep talking about "doubling of CO2", because it's a logarithmic function....

But yes, the temperature will increase slightly because of CO2 emissions. That triggers more warming due to feedback effects though, and those are hard to quantify, and more scary.

To be fair, the cause of the warming wasn't given as an example of indisputable fact.

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