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Ocean Currents Explain Why Northern Hemisphere Is Soggier
vinces99 writes "A quick glance at a world precipitation map shows that most tropical rain falls in the Northern Hemisphere. The Palmyra Atoll, at 6 degrees north, gets 175 inches of rain a year, while an equal distance on the opposite side of the equator gets only 45 inches. Scientists long believed that this was a quirk of the Earth's geometry – that the ocean basins tilting diagonally while the planet spins pushed tropical rain bands north of the equator. But a new University of Washington study shows that the pattern arises from ocean currents originating from the poles, thousands of miles away. The findings, published (paywalled) Oct. 20 in Nature Geoscience, explain a fundamental feature of the planet's climate, and show that icy waters affect seasonal rains that are crucial for growing crops in such places as Africa's Sahel region and southern India."
Yes, very nice straw-man, but the real concern here is that if the sub-surface ocean currents cause rainfall in the northern hemisphere, climate change is bad news for northern-hemisphere populations. We've seen noticeable drop-offs and changes in those currents correlated quite strongly(and explained quite thoroughly by thermodynamic principals) with increasing ocean temperatures.
Isn't most of the land in the Northern Hemisphere? When clouds are forced to go upward to pass over a land mass, they are more inclined to drop their rain load. Isn't that basically how it all works?
I come here for the love
Northern hemisphere is on top, southern hemisphere is underneath, rain falls downwards. TBH it's a miracle that rain falls in the southern hemisphere at all. I think they use magnets.
A given quantity of ocean is as soggy as any other equivalent quantity of ocean, and there's more of that ocean in the southern half of this planet. Hence the southern hemisphere is more soggy, QED.
Do not look into laser with remaining eye.
Yes, very nice straw-man, but the real concern here is that if the sub-surface ocean currents cause rainfall in the northern hemisphere, climate change is bad news for northern-hemisphere populations. We've seen noticeable drop-offs and changes in those currents correlated quite strongly(and explained quite thoroughly by thermodynamic principals) with increasing ocean temperatures.
Not really. Not only do the currents correlate with thermodynamics, they are caused by it.
You can worry all you want about the gulf stream stopping or changing direction but thermodynamics tells us that if it does a new stream will have to warm up the northern hemisphere.
There aren't many places for such a stream, the question is really if it will flow west from Africa and along the east coast of America before a part of it splits back or if it will change direction and flow directly north from Africa with a part of it split of to go down along the east coast of America.
The latter will lead to a slightly warmer Spain and slightly cooler Florida. UK and everything north will be mostly unchanged.
bad news for northern-hemisphere populations
Pfft. As if anyone lives north of the Equator.
All the cool people do.
Get it? Get it?
Dark Reflection
From what I remember of my climatology course, rainfall is tightly tied to the oceanic currents. In the northern hemisphere there are a lot of things going on. We have more land mass, resulting in more "circles" of currents. The axis of the earth impacts insolation and global wind patterns, which create areas of evaporation and condensation at particular lattitudes on the earth. These currents change with the elevation of land mass, but by and large hard rock doesn't hold heat nearly as well as water, so you get a (sometimes drastic) temperature difference and condensation above land, which of course results in various wind patterns and rainfall. What is also interesting is look at the deserts of the northern hemisphere, notice how they are all at the same latitude?
This stuff has been known for years, I'm not sure how this is really "news".
Actually, the real concern here is that we are still building and refining atmospheric and oceanographic models. Models that some people have already tried to use to initiate political and economic changes.
Good science, just too early to use for anything important.
Have gnu, will travel.
We're still refining models of planetary motion.
And plate tectonics.
The models are never 'done,' but we can use what we think we know to get stuff done.
You're looking for quotes? See my journal.
Actually, the real concern here is that we are still building and refining atmospheric and oceanographic models. Models that some people have already tried to use to initiate political and economic changes.
There are of course flaws in the climate models, just as there are flaws in our models of gravity, subatomic physics, etc,etc,etc - we are imperfect beings and it is the nature of scientific knowledge to evolve as our understanding expands. Those models are still far and away the best guides we have to predicting the future though, and their accuracy and reliability far exceeds the economic and sociological models that are currently driving most of the world's political process.
The point is that all the science for the last many decades has agreed with ever-increasing certainty and detail that we will be facing major human-caused climate problems in the next century, though the exact manner in which those problems will unfold is still being understood. And the longer we put off dealing with those problems the more drastic and expensive the eventual solutions will have to be. Had we headed the scientists in the '60s and started mitigating oil usage, or at least dedicated some noteworthy resources to developing alternative energy sources, then we would now have only a moderate challenge in front of us. Instead fusion research funds have been continuously dwarfed by fossil fuel subsidies (as just one example), solar is only just starting to become economically viable, and we are likely already past the point where it will be possible to maintain the global climate in a state similar to the last several thousand years.
If we wait another 50 years for the climate models to have all the details hammered out we'll be far too late to even start building the infrastructure we'll need to weather the transition and adapt to the new reality. As one example, several years ago an extremely high-resolution regional climate-change simulation was done for California, using the most well accepted global-scale climate change predictions as the input. Even using the most conservative numbers for global climate change, their model predicts the near-total elimination of mountain snow-pack in California by mid-century, and probably considerably sooner. That translates into *much* worse winter flooding and summer droughts, which will be devastating to both agricultural and population centers unless there have been a lot of dams built by then, and to get them built properly in time we need to start planning them now.
Now obviously we can just keep on with life as usual and hope for the best - after all that's what our species has done for the last 100,000 years, but three things are different this time:
1) We can see it coming, so we have the opportunity to start adapting preemptively at a much lower cost.
2) We are the forcing factor - had we reacted sooner we could have prevented the drastic changes from coming at all (or at least delayed it by a few hundred or thousand years), as it is we may still be able to moderate the changes.
3) There's seven-plus billion of us on the planet, and we're already over-utilizing the available ecological resources, and global climate change will drastically reduce those resources, at least for a few centuries until a new equilibrium is reached. The resulting famine and wars will dwarf anything our species has ever seen. If nuclear or bioweapons see much usage (as they may with most nations on Earth struggling for survival) then we may be lucky to survive this change even as well as we did the last ice age, when the global human population was reduced to only a couple thousand people.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
I wouldn't like to trust our climate models. The problem is, we've got to. Saying "Assume things will stay the same." is also a climate model, after all. And the evidence so far seems to show it's wrong...though not usually drastically wrong in the short term. But changes are cumulative, so when you project further out, you get larger amounts of uncertainty.
OTOH, even a primitive climate model says that the climate between, say, 1930 and 1980 was unusually stable and favorable (unless you lived in a place where it wasn't favorable, of course). That means NO MATTER WHAT you should expect an increase in unseasonable storms and droughts. That's even without thinking about global warming. So currently I don't believe that global warming has had as many effects as people are crediting. But changes are cumulative, so one shouldn't expect that to continue to be true (except, of course, in every short term).
I think we've pushed this "anyone can grow up to be president" thing too far.