Okay. I have a question about warming.

[conuly]

All these predictions!

I understand why the sea level rising, say, 100 feet is horrible. I understand why less rain in various parts of the world is horrible. Changing weather? These things are concrete to me.

But then I keep reading that predictions say the world could warm one degree, three degrees, five degrees in the next century, and... I stop.

I grasp that these increases in temperature are what ultimately causes the rising sea level, the droughts. I get it.

But I don't get how what seems to be such a small increase in temperature can really be such a big deal. Three degrees? I doubt I even *feel* three degrees either way, even if we *are* using Celsius. Five? I'd barely register it. So how does it make such a big impact on the entire Earth? That, I don't understand.

Comments

[twistor.livejournal.com]

Five degrees Celsius is nine degrees Fahrenheit. It's just about the global average temperature difference between an interglacial (which we're in right now) and full-on glaciation.

Imagine a summer heat wave in New York City reaching temperatures of 101 deg.F for 10 days in a row -- that would be extremely unpleasant. Now imagine a summer heat wave reaching 110 deg.F for 10 days in a row. That's not something we would "barely register." For a lot of people, it would be fatal. In fact a less severe version (a preview, if you will) hit Europe in 2003, and caused the death of 35,000 people.

Imagine the Himalayan glaciers melt away. That's not something Americans generally think of as important, or directly relevant to our quality of life. But the disappearance of the Himalayan glaciers would dry up the great rivers of Asia. That would threaten the water supply for about two billion people. Again, this is not just unpleasant, it's lethal.

If you've been to the American desert southwest you know that the land is very beautiful, but poorly suited to growing things like wheat, corn, and soybeans. Now imagine that the American MIDwest -- in many ways the "breadbasket of the world" -- turns into a similar desert. From Nebraska to Pennsylvania, wheat is replaced by cactus. Once again, it passes unpleasant and goes directly to lethal.

"Five degrees" doesn't sound like much. But that's the *average* -- many areas will experience considerably more, and most of those areas are places full to the brim with people who depend for life on things like food and water. And five degrees really is the global average difference between interglacial and full glacial conditions. "Full glacial" means the city of Chicago is covered by ice three miles thick.

[conuly]

Okay. I think I follow.

[peaseblossom03.livejournal.com]

conuly, meet Mr. Peaseblossom. Mr. Peaseblossom, conuly.

[peebs1701.livejournal.com]

A shorter response than twistor, those changes are changes in the average temperature of the earth. If the average temperature goes up by say 3 degrees, there may only be half a degree difference at the equator, but ten degrees change at the poles, and that means a lot of ice will melt, permafrost will thaw, etc. etc.

[conuly]

That makes even more sense. Got it.

And what happens at the poles affects what happens elsewhere, even if their temperatures don't go up as much, or even go down, yeah?

[peebs1701.livejournal.com]

Exactly.

[peebs1701.livejournal.com]

Also, now that I'm thinking more clearly, it makes a difference how big of a temperature difference there is between the poles and the equator. The fact that the poles are so much colder than the equator is what drives most of our ocean and air circulation. With a smaller temperature differential the water and air might move in vastly different ways which would drastically change the weather patterns all over the world. For example, right now Western Europe is much warmer than it should be at that latitude because of the heat the Atlantic currents bring up from the equator. That could easily change with different ocean movement.

[noodles-morgyn.livejournal.com]

Like others have said, it's not the temperature change itself, it's the side effects.

I think of it being like a disease: if you have, say, a cold, it's not having the virus in your body that's the problem, it's what your body does to get rid of it - the runny nose, coughing, etc... At least, that's how I understand it; I'm no doctor! (Incidentally, I'm wondering what would happen if your body didn't try to get rid of bugs, and thus didn't have any symptoms of disease... I assume it would be bad somehow, or else it wouldn't try, but why? Anyone want to explain...?)

[siderea]

I don't know for certain. I'm making this up. But I think it's something like this:

Think about how much heat it takes to raise a pot of water one degree. Now how much heat would it take to raise one degree a pot of water twice as large? Twice as much.

How much heat would it take to raise the seven oceans of the Earth one degree?

Now do the same mental exercise with air, and consider the entire atmosphere of Earth.

Now, all that heat is loose in the system. Heat in the system drives all sorts of things. For instance, how fast water evaporates is a function of both how warm the water is and how warm the air is. When everything gets a degree warmer, water evaporates a smidge more. It's only a smidge... but it's a smidge multiplied across millions upon millions of square miles of ocean surface.

And that's the force multiplier: the water cycle.

[velvetchamber.livejournal.com]

To heat one gram of water at 20°C about 1°C takes 4.2 Joules. Heating most other components of the atmosphere does take less energy, but considering how much air there is in the atmosphere, a temperature increase of only one degree centigrade amounts to a lot of energy.

[sporks5000.livejournal.com]

I think that part of it involves understanding that given the entire surface of the earth over the course of an entire year, the average change in temperature is zero. For every place where it gets colder during one part of the year, there's somewhere else compensating by getting warmer. Given that, one degree is monumental, and five degrees it terrifying.

[twistor.livejournal.com]

Five degrees Celsius is nine degrees Fahrenheit. It's just about the global average temperature difference between an interglacial (which we're in right now) and full-on glaciation.

Imagine a summer heat wave in New York City reaching temperatures of 101 deg.F for 10 days in a row -- that would be extremely unpleasant. Now imagine a summer heat wave reaching 110 deg.F for 10 days in a row. That's not something we would "barely register." For a lot of people, it would be fatal. In fact a less severe version (a preview, if you will) hit Europe in 2003, and caused the death of 35,000 people.

Imagine the Himalayan glaciers melt away. That's not something Americans generally think of as important, or directly relevant to our quality of life. But the disappearance of the Himalayan glaciers would dry up the great rivers of Asia. That would threaten the water supply for about two billion people. Again, this is not just unpleasant, it's lethal.

If you've been to the American desert southwest you know that the land is very beautiful, but poorly suited to growing things like wheat, corn, and soybeans. Now imagine that the American MIDwest -- in many ways the "breadbasket of the world" -- turns into a similar desert. From Nebraska to Pennsylvania, wheat is replaced by cactus. Once again, it passes unpleasant and goes directly to lethal.

"Five degrees" doesn't sound like much. But that's the *average* -- many areas will experience considerably more, and most of those areas are places full to the brim with people who depend for life on things like food and water. And five degrees really is the global average difference between interglacial and full glacial conditions. "Full glacial" means the city of Chicago is covered by ice three miles thick.

[conuly]

Okay. I think I follow.

[peaseblossom03.livejournal.com]

conuly, meet Mr. Peaseblossom. Mr. Peaseblossom, conuly.

[peebs1701.livejournal.com]

A shorter response than twistor, those changes are changes in the average temperature of the earth. If the average temperature goes up by say 3 degrees, there may only be half a degree difference at the equator, but ten degrees change at the poles, and that means a lot of ice will melt, permafrost will thaw, etc. etc.

[conuly]

That makes even more sense. Got it.

And what happens at the poles affects what happens elsewhere, even if their temperatures don't go up as much, or even go down, yeah?

[peebs1701.livejournal.com]

Exactly.

[peebs1701.livejournal.com]

Also, now that I'm thinking more clearly, it makes a difference how big of a temperature difference there is between the poles and the equator. The fact that the poles are so much colder than the equator is what drives most of our ocean and air circulation. With a smaller temperature differential the water and air might move in vastly different ways which would drastically change the weather patterns all over the world. For example, right now Western Europe is much warmer than it should be at that latitude because of the heat the Atlantic currents bring up from the equator. That could easily change with different ocean movement.

[noodles-morgyn.livejournal.com]

Like others have said, it's not the temperature change itself, it's the side effects.

I think of it being like a disease: if you have, say, a cold, it's not having the virus in your body that's the problem, it's what your body does to get rid of it - the runny nose, coughing, etc... At least, that's how I understand it; I'm no doctor! (Incidentally, I'm wondering what would happen if your body didn't try to get rid of bugs, and thus didn't have any symptoms of disease... I assume it would be bad somehow, or else it wouldn't try, but why? Anyone want to explain...?)

[siderea]

I don't know for certain. I'm making this up. But I think it's something like this:

Think about how much heat it takes to raise a pot of water one degree. Now how much heat would it take to raise one degree a pot of water twice as large? Twice as much.

How much heat would it take to raise the seven oceans of the Earth one degree?

Now do the same mental exercise with air, and consider the entire atmosphere of Earth.

Now, all that heat is loose in the system. Heat in the system drives all sorts of things. For instance, how fast water evaporates is a function of both how warm the water is and how warm the air is. When everything gets a degree warmer, water evaporates a smidge more. It's only a smidge... but it's a smidge multiplied across millions upon millions of square miles of ocean surface.

And that's the force multiplier: the water cycle.

[velvetchamber.livejournal.com]

To heat one gram of water at 20°C about 1°C takes 4.2 Joules. Heating most other components of the atmosphere does take less energy, but considering how much air there is in the atmosphere, a temperature increase of only one degree centigrade amounts to a lot of energy.

[sporks5000.livejournal.com]

I think that part of it involves understanding that given the entire surface of the earth over the course of an entire year, the average change in temperature is zero. For every place where it gets colder during one part of the year, there's somewhere else compensating by getting warmer. Given that, one degree is monumental, and five degrees it terrifying.