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Comment by DigitalSea | Hacker News Reader

This scares me. I know it's only the surface that thawed, but what happens when more than the surface melts next time around? How long can people keep denying the Earth is warming before lower-level coastal regions start to flood?

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Mission accomplished.

The article also states that this happens every 150 years or so and did so 150 years ago. Like winter comes every 12 months. Now it would be wonderful to understand the mechanism, we've only been watching via satellite for 30 years, so in another 150 years we'll have captured a full cycle on satellite and we will know a lot more. It would have been a much more reasonable article to say:

"For the first time NASA has captured a once in 150 year event on satellite images. ..." but you still might click the link but you wouldn't feel threatened.

Ice cores from Summit show that melting events of this type occur about once every 150 years on average

It's not a 150 year cycle, it's a random event with a low probability. AKA 0.66% per year ~ 10 events per 1500 years but 3 of them could have fallen within 10 years of each other.

You've reading way to much into the "150 year cycle".

Core samples aren't accurate to the day so we really don't know if this exact event is what's happened in the past. What it really sounds like is that we know there are similar melting events that happen every century and a half or so. But unlike Winter coming every 12 months we have little idea why these events might occur or whether that's all there is and we can pack it in for another 120+ years.

So I get downvoted for saying that this kind of thing scares me. I clicked the link and read the article, if you read the article correctly yourself then you would realise that this isn't an event that happens precisely every 150 years. There's nothing stopping this event happening again next year... Ever heard the weather experts say something along the lines of, "This is a 75 year weather event" or "100 year weather event" it just means the odds of it happening again are slim, not impossible but slim.

The HN community has really deteriorated as of late. People down voting comments for no warranted reason, this site is starting to become Digg...

It seems to me that there really are very few people who actually deny the earth is warming. There may be a very vocal minority in your circles but I don't see it in my travels. The only real question is how much of the warming is caused by humans and how much is part of a natural cycle. You did read the article right? This is part of a cycle. Perhaps there is some human influence on this cycle but how would the researchers know? Maybe in another 150 years when the ice sheet has already reformed and then begun to melt again repeating the cycle? Level heads are needed; not panic and politics.

There's nothing in the article about a cycle. That it happens on average every 150 years is a statistical statement, not a scientific one.

So, it happens on average every 150 years and that isn't a cycle in your book. That's fine for someone like yourself but for me I feel that we then need to redefine things like solar cycles and seasons which only happen on average as well. All in all, what the article describes sounds like a cycle to me.

The seasons happen for a known, cyclical reason. If it turns out that there's a first cause behind the ice melt, then it would be proper to refer to it as a cycle.

Many coastal cities do flood, right now, but this is mainly due to more people living on the coast in areas with lax engineering codes. Panic probably won't come until building sea walls any higher becomes too expensive in areas where sea walls and other tide restricters are required. I'd wait until a few man-made islands go under water to be sure.

Based on the Greenland ice shelts melting, calculations show you're pretty good for another 28,000 years.

That doesn't take into account any change in the ocean temperature from the melted ice, and any cold changes that might create.

The current historical rate of sea level rise is about 2-3mm per century. So if you're in a coast city there's probably a couple of centuries to go. Given the rate at which man-made islands can be created (or existing land masses extended) if necessary (Dubai, Hong Kong, Manhattan) I'd say there are much bigger problems to worry about.

What's really interesting about the whole things is how the ice flow depends on temperature - ice can be in several states which will react differently under pressure. Warmer ice will flow faster, thus more ice will flow onto the sea an melt, and the ice sheet on the land will get thinner if it gets warmer.

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