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Comment by tomohawk | Hacker News Reader

Only going back to 1850 is exactly the kind of thing someone would do if they wanted to cherry pick their data to suit a case. You have to go back much further. It is known that at that time we were coming out of a period of much cooler temperatures. See for example the year without a summer (1816).

There are periods of human history where it was warmer than it is now. For example, during the Viking expansion, and during the Roman expansion. Then things cooled off - for example the Viking and Roman contraction.

If you go to L'Anse aux Meadows in Newfoundland, you can see the remains of the only known Viking settlement in the new world. The buildings were made with logs from trees that do not exist there today because it is cooler now and does not support the tree growth required.

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The truth is that the past doesn't matter. If the current warm up is aggravated [0] by human activity, and pretty much everyone agrees it is, we should do something about it. Saying "it was warmer/colder before" makes it sound as it is a non issue. And tbh even if, and that's a big "if", pollution isn't directly linked to climate change everything reducing the air/water/food poising we're inflicting to ourselves is good.

[0] I'm not even saying 'caused' because at that point it doesn't change anything

As far as I understand there is a very big difference between reducing carbon emissions and reducing air/water/food pollution/contamination.

Carbon isn't everything; ozone, NOx, particles (pm2.5, pm10), heavy metals, oils, &c.

https://static.skepticalscience.com/images/Temperature_Patte... vs https://static.skepticalscience.com/images/Temp_Pattern_1999...

source: https://skepticalscience.com/greenland-used-to-be-green.htm

You can go to L'Anse aux Meadows and see the ruins with your own eyes. You can then look around the area and look at the trees.

Could you explain how this relates to the argument here? I understand that there has been a lot of discussion about how much can grow that far north and how that has changed over time but it doesn’t seem a conclusive discussion at all.

It is ridiculous to say that in other times it was warmer. Nowadays we have many resources to measure, compare and identify the cause of the temperature rise and so far the best correlation is the increase of CO2 in the atmosphere. You're saying "Average temperature increases, it's not because of this theory, it's something else that no one knows." Denialists need to come up with a better theory instead of saying "natural causes not understood."

To be fair, the longer one goes back in time the less data there is and I would hazard a guess that prior to 1600 there is no direct data at all.

We do have history though Check out the Roman Climatic Optimum, for example.

The point I was trying to make is that history is not direct data and thus not anywhere near as reliable.

This is not to say that direct data from 2 centuries back is necessarily reliable but it's a step in the right direction

See for example the year without a summer (1816).

As far as cherry-picking goes to suit a case, this also sounds like a pristine example. Even worse then what you are countering, since it is only one single year.

There are periods of human history where it was warmer than it is now.

Well, yes, but what does that prove?

The buildings were made with logs from trees that do not exist there today because it is cooler now

You make this sound as evidence of something, but what? That the people shipped trees there from somewhere else? That those trees grew there but now are extinct due to some disease or bug?

Don't get me wrong, I'm open to whatever evidence provided, but if you're going to go against something at least come up with quality arguments. None of what you wrote supports a solid case against the anomalies presented.

I'm guessing it's some variation of "we know of climate change in the past that was not caused by humans, therefore no climate change is caused by humans".

For the record, we do know of at least one instance of positive climate change in the past caused by humans. Genghis Khan famously went on a huge murderous rampage (some estimate that he directly and indirectly caused the death of ~10% of the world population), causing massive forest regrowth in previously populated areas, which in turn scrubbed CO2 out of the atmosphere.

https://carnegiescience.edu/news/war-plague-no-match-defores...

Thanks, first time I hear about this. Interesting!

Regardless of his counter-example, I think the chosen time period is too short to mean anything significant. I'm not saying global warming isn't a concern, but that graphs like these are not useful in reference to global warming. I mean imagine if in a decade global temperatures drop for a decade, are we going to assume global warming isn't an issue anymore?

> <...> thing someone would do if they wanted to cherry pick their data to suit a case. <...> See for example the year without a summer (1816).

_comes and cherry picks a single year to "prove" something_

> There are periods of human history where it was warmer than it is now.

Yes, but you are talking about geologic time scale and extremely gradual changes compared to what we see now, which is just dozens of years.

I recommend to watch this: https://www.youtube.com/watch?v=Yze1YAz_LYM

What data would convince you that anthropogenic climate change was real?

What is your own estimate of probability that anthropogenic climate change is real? That is, anthropogenic factors are the most significant contributor to climate change and mitigating them will allow to significantly affect the rate of climate change (to the point where it would make a significant difference to humans).

Thank you for wording that. This should be the first question in any climate change discussion.

High. In terms of what effect complete mitigation would have, I don’t know. However I figure that it costs me little to change my habits to things that are positive whether or not they cause climate change.

What lack of data would convince you that apocalyptic ACC concerns were largely overblown, or at least unjustified? Because that's what you're dealing with here - a remarkable lack of quality, unadulterated data. Most people don't have a clue about this, though; they just trust what they're being told.

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