Europe Is Warmer Than Canada Because of the Gulf Stream, Right? Not So Fast | Hacker News Reader

Europe Is Warmer Than Canada Because of the Gulf Stream, Right? Not So Fast

blogs.smithsonianmag.com

27 pointsgeorgecmu17 comments

In climate modeling studies where the Gulf Stream was artificially swept out of existence, the temperature differences between eastern Canada and western Europe persisted.

Okay, so the Gulf Stream does not play any role. But then, in the very next sentence:

So what’s really going on? According to Riser and Lozier, the cause of the temperature difference is likely a complex interaction between the surface ocean, the Gulf Stream, massive upper atmospheric currents and differences in pressure on either side of the Atlantic.

So the Gulf Stream does get in the equation. One of these two sentences is incorrect.

Maybe, in the model, the differences persisted but decreased (or increased?).

Also, perhaps the model isn't given as much scientific weight as the author of the article indicated. (It's been something I have wondered about... given how hard it is for us to predict the weather, how can we possibly find long-term climate models useful?)

Climate models can be useful, especially when you use them to predict events that have already happened (e.g you have the data to either show the model is correctly forecasting the past event, or you have the data to show the model has gone awry.) Theoretically, if your model can predict past events correctly, you can then apply it to present and future events and get reasonable results. Theoretically...

PS. Weather forecasting is pretty accurate these days. I'd take bets on 7 day forecasts from the NWS.

Source: Meteorology degree.

The model forecasting past events doesn't really tell you much about the accuracy of the model, even theoretically. It could be overfitting for example.

Within 10 degrees F for 10 consecutive hours and precipitation to 1/4" in Boston for even money.

I noticed that too – that and the fact that "likely a complex interaction" sounds like an expertise-preserving way of saying "we don't know". Plus the article makes it sound like they tested the gulf stream theory by experimenting on their models, which would yield results about the models, not the reality to which the models refer.

Maybe the differences persisted because they were built into the model using a mechanism other than the Gulf Stream? Maybe the model was based on some other assumption that implicitly produces the differences?

Models seem very easy to do poorly. They seem basically impossible to do well. The question, "how would temperature differences between North America and Europe change if the Gulf Stream ceased?" is not of a scientific nature.

>>Models seem very easy to do poorly. They seem basically impossible to do well.

Yes, insufficient understanding of the phenomena will often produce bad results. It doesn't matter whether the explanation is a model or hypothesis. Rigorous analysis and verification is required.

>>The question, "how would temperature differences between North America and Europe change if the Gulf Stream ceased?" is not of a scientific nature.

Thats equivalent to stating that the effect the gulf stream has on temperature differences between North America and Europe is impossible to discover scientifically.

There is no contradiction between those sentences. The Gulf Stream contributes to those differences, but is not the only cause.

Incidentally the basic explanation is obvious if you know something about climate. The powerful upper air current in question is certainly the jet stream, which at that latitude blows from west to east, and carries weather patterns with it. (The source of the jet stream is a Hadley cell.) The result is that Labrador gets weather off of land, while Europe gets weather off of the ocean. If you look at pictures from space, oceans are darker than land, and therefore absorb heat better. (This is doubly true in winter!) Thus the surface of the ocean tends to be warmer on average than land. (As well, water holds heat better, and so tends to fluctuate less. This leads to milder winters and summers.)

The moral? The fact that someone doesn't try to explain something doesn't mean that they don't understand it.

This is a blog post summarizing an article that condensed several scientific papers into a summary for popular consumption. It isn't clear in post but the sentences are referring to different competing models. The actual article suggests that the latest model where the gulf stream does play a role(but not the only one) is the correct one.

Where does this leave us in understanding public policy related to climate issues? Do we have enough understanding of climate influences to know which influences may need policy interventions in the current haphazard pattern of global human behavior?

What I read from that is that the stories we tell ourselves about why climate happens tend to be massively oversimplified and miss major things.

I read absolutely nothing to cause me to trust detailed computer models more or less.

My belief about computer models is that they are crap for detail, but still indicative enough at the level we're trying to use them for to be indicative. If you want to learn more, and to dig in yourself, http://www.azimuthproject.org/azimuth/show/HomePage is a useful starting place.

It has been posited in the press and in movies, that a warmer earth would melt the poles which would reduce salinity and then 'stop' the flow of the Gulf Stream current. That would plunge Europe into an ice age. Deeper analysis casts doubt on both sides of this proposition, either a) that the gulf stream current would stop, and b) if it did, that it would cause an ice age in Europe.

Living in California we've had about three major theories about the impact of the pacific current applied and then found wanting on California weather. There is an effect, but the extent that the weather is affected is not easy to predict.

This 2006 article from American Scientist went into this issue in great detail:

https://www.americanscientist.org/issues/pub/2006/4/the-sour...

It is by no means clear that this is the accepted view of the mainstream of climate scientists - the linked papers seem to be the work of a couple of groups banging the drum against the Gulf Stream. I'd wait a while before accepting this as the new orthodoxy.

> Take a gander at this map, and you’ll see the red line marking the 50th parallel, a line of equal latitude that runs a full circle around the Earth. Every point on this line is the same distance from the equator, and the same from the frozen pole.

There are 360 degrees in a circle, not 400. 360/8 = 45. Of course, there's some slight variation because the earth isn't an exact sphere, but it doesn't add up to 5 degrees.

I'm going to read on, but that's really a very disappointing start.

Of course, the alternative explanation is that what they meant was that each of these points has the same distance to the pole and the same distance to the equator as every other point, but the wording doesn't seem to indicate that, and if that was the intent it was a badly written sentence.

It's ambiguously worded, but I don't read that to imply that he thinks every point on the 50th parallel is equidistant from the pole and the equator. Break the clauses into separate sentences and you'll see what I mean:

Every point on this line is the same distance from the equator. Every point on this line is the same distance from the frozen pole.

These are both true sentences, they just don't refer to the same distance.

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