What would be worse: Asteroid or Global warming?

[kehvan]

@Simon_Bradshaw

Risk is often defined as a factor of two quantities: likelihood, and seriousness of consequences. The highest risks are those that are both likely to happen and very damaging in their consequences.

Considering that in no time in Earth’s history, according to the geologic record, has warming been identified as the reason for mass extinctions, but cooling as well as asteroid strikes have been shown to lead to mass extinctions, the seriousness and likelihood weighs far greater in favor of the next glaciation cycle or an asteroid strike being the cause for a serious climatic event that leads to mass deaths; not warming.

@Simon_Bradshaw

An asteroid strike is a low-probabilty, serious-conseqences event. Estimates suggest that Earth experiences megaton-yield impacts (well, that includes airbursts) several times a century, and about a year ago Chelyabinsk had a very near miss.

This is something you simply cannot know, because we’ve only begun to take a serious account of near Earth asteroids. We’re finding new asteroid all the time, and we’ve barely begun to scratch the surface of what we know on this front. Slate, certainly not a bastion of global warming denial, just ran such an article yesterday, which was the impetus for this conversation. If that’s not proof of our continued ignorance about the risk of asteroids, I don’t know what is.

@Simon_Bradshaw

There is at least a medium probability that there will be climate change with serious consequences in the next few decades. (If you don’t believe there is at least a significant possibility of this, you are beholden to a dogmatic position that neither I nor anyone can argue you out of, because, to be frank, you weren’t argued into it - you hold it as a matter of faith.)

Actually, sir, it’s you who is doing what you’re accusing me of. Unlike you, I haven’t deemed the sum total of effects of warming to be negative, where as you have, even though you nor anyone else can actually say for sure if that sum total will be positive or negative. Categorically declaring those effects to be summarily negative isn’t science, it’s fortunetelling.

@Simon_Bradshaw

As such there is a very significant risk from climate change, and it is a much more concrete risk than the risk from asteroid impact.

I can prove great risk of an asteroid strike via the geologic record. Can you do the same for “global warming”?

Someone below attempted to retort this by stating…

@AcerPlatanoides

By the same geologic record I can tell you the climate was not hospitable for the current diversity of life the last time carbon dioxide and other ‘greenhouse gas’ concentrations were elevated to the concentrations we are projected to achieve.

That’s pure sophistry, as the Azolla Event demonstrates.

@Simon_Bradshaw

It amazes me that some people can competently discuss the risk of asteroid impact and at the same time dismiss climate modelling. To do this requires that you pick and choose which parts of physics you believe and/or when you believe them, and that is not the behaviour of an objectively rational person.

I’m going to assume your knowledge of physics is more limited than you imply, because if it were more extensive, you’d realize that the one field of science where “global warming” has its least tenacious hold, it has been amongst physicist.