Global warming will end life on earth (but don't panic, you've got 3.5bn years left!)

Being in this ‘Goldilocks’ zone has allowed oceans to develop in temperatures neither too hot to boil the water away, or too cold to freeze it into permanent ice.
The problem is, however, that stars become hotter over time, ensuring that the habitable period cannot last.
As the stars emit more heat, any surface water on nearby planets dries up and without water nothing can survive.

Source:

I was just reading the article and I don't understand how they end up with their prediction.

For example:
The Star Arcturus shines about 15 times brighter then the Sun, and it's mass is about 130 times that of the Sun. The temperature however is lower then the temperature of the Sun.

Modern understanding of Arcturus

Today, astronomers know Arcturus packs a lot of punch despite it being only about 1.5 times the mass of the sun. To the naked eye, according to Jim Kaler, a professor emeritus at the University of Illinois. Arcturus appears to shine about 113 times more brightly than the sun.

Arcturus, however, has a lower temperature than the sun, which means that a lot of its energy is radiated as heat. Once this is accounted for, Arcturus actually releases 215 times more than the sun's radiation.

Source:

How do they predict the increase in temperature ?

Arcturus is said to be near the end of its lifespan, but is colder then the Sun. The fusion of heavier elements could explain why more heat gets radiated, but what makes it shine so bright then ?

The Sun isn't nearly as bright, and it's still fusing hydrogen atoms, what could explain the higher temperature of the Sun.
However, if fusing higher elements causes less heat and more light, radiating out, like Arcturus shows.
How can it radiate more heat and shine more brightly, when the star itself is colder ?

Arcturus is also slightly larger then the Sun is, so I would expect it to runs out of hydrogen faster then the Sun would.
How can they predict anything about the Sun's temperature, when we are only able to observe and measure any data for only a brief moment of the entire lifespan of our Sun, and any other Star for that matter ?

Also:

The Earth is protected by a magnetic field, which prevents our atmosphere getting blown of the planet, by solar wind etc.
So even if the Sun radiates more heat, and water starts to vaporize, it won't simply vanish. When night falls and temperatures plummet way below freezing, everything without an atmosphere gets cold.

The atmosphere is what creates a stable environment. When the Sun gets hotter, the Earth will hold more heat, but if our atmosphere is filled with water vapor, most of the heat won't even reach the surface, as the cloud cover would reflect it back into space. Everything below won't be receiving much heat, and at night the atmosphere gets to cool down.

The Sun will also lose a lot of mass during its lifetime, as it gets blown into space. That could result in larger orbits of the planets, as gravity is a little less.

Anyway... I just don't get it. An explanation is more the welcome.

What's the point of making these predictions, when it's pretty obvious, our knowledge about it is limited.

As I understand it, we've only got about 1bn years.

If we haven't found a way of bailing to Mars by then, it's goodnight vienna.

The sun will shrink in size but will burn brighter and hotter (about 40% hotter, hot enough to boil away the oceans).

From one day to the next there is change taking place.

Global Warming? It doesn't exist. The term is totally misleading. It was a term that has no basis today and no true data to back it up. Not only that, how many years would we have to document the data to come to a more true conclusion?

One scientist screams ice age while another screams global warming. Now NASA's John Holdren is screaming no to global warming but saying "Global Climate Disruption".

It should be called.... "Climate change" as climate change does exist and has and will until the Earth transforms/ends.

Our weather/climate comes from Space Weather and as we travel through the Solar System we will continue to experience changes. Change is inevitable and is the ONLY constant. This is the reason why natives moved their entire communities to higher or lower ground. It is what it is.

Predictions come and go and most of the time the one making the prediction comes back to say, "OOPS! The data is wrong."

reply to post by CJCrawley


From what I understand, is that the Sun will eventually increase in size and become a red giant.
Before its light go out.

reply to post by MamaJ


Thank you for your reply, but what does it have to do with the Sun a few billion years in the future ?

Sinter Klaas
reply to post by CJCrawley

 

From what I understand, is that the Sun will eventually increase in size and become a red giant.
Before its light go out.

The operative word there being "eventually".

In the very first phase of our sun's dying process, the sun becomes smaller, brighter, hotter....millions of years before it becomes a red giant.

We've got 1bn years.

It's an immense period of time, and I'm quite confident the human race will have relocated to Mars by then.

Mars will be much warmer than now, warm enough to sustain life.

Eventually we'll have to leave Mars as well, but not for a few million years.

reply to post by Sinter Klaas


The term you are using in your title and post "Global Warming".

Their Sun's prediction is just that... a prediction... but if something happens to it before it "burns" up is anyone's guess/prediction.

Sorry, maybe I am missing the totality of the OP. lol It's possible.

reply to post by CJCrawley


So the Sun gets hotter and smaller first ? Are you able to link me to a source where I read that ?

I don't think Mars will ever get hot enough to sustain life again. It lacks a magnetic field, which causes the atmosphere getting blown out into space, by solar winds etc...
The atmosphere will never get dense enough, for it to absorb enough heat. There aren't any oceans either.
The oceans on Earth play a key role, they absorb the heat from the Sun and slowly distribute the heat back into the atmosphere.

Without a magnetic field, the surface is also bombarded by radioactive particles, that destroys life as we know it.

It isn't really the best place to settle so to say.

reply to post by Sinter Klaas


It rather seems to me, that if we have anywhere even remotely close to three point five billion years, we ought to use our time constructively, to maximise our chances of getting off this rock before the sky turns to fire, and our planet melts and breaks apart like a chocolate orange in a charcoal oven. Many have said that we have less time than this before, and if this information is even close to solid, then this represents a bit of a stay of execution.

For a start, some of the more Eco-mentalist reports that have been issued since green matters came to the fire gave us less than two hundred years before it all hits the fan, and although such claims are patently based on about as much science as your run of the mill episode of the Teletubbies, this new scenario gives us some serious lead time.

This species ought to use this extra time as wisely as possible.

reply to post by Sinter Klaas


Actually, you were more correct about the time; it will be around 3bn years not 1bn (as I incorrectly said) that the earth will become unsustainably hot.

www.youtube.com...

I'm sorry, I don't know how to upload videos, but if you watch this from 8:39, he says the sun will get smaller, brighter, and hotter. Also that the sun will become a red giant in about 5bn years.

As for Mars not being an ideal alternative....it's our only chance.

Sinter Klaas
reply to post by CJCrawley

 

From what I understand, is that the Sun will eventually increase in size and become a red giant.
Before its light go out.

And will consume the inner planets.

Life will be long gone before then.

What we should be looking more closely at is the near future. There will be major changes in earth's climate over the next decade.

Not much point in thinking about 500,000,000 years from now, if we can't survive the next thousand years.

ausername

Sinter Klaas
reply to post by CJCrawley

 

From what I understand, is that the Sun will eventually increase in size and become a red giant.
Before its light go out.

What we should be looking more closely at is the near future. There will be major changes in earth's climate over the next decade.

Is that a prediction or what?
There is a menu of course, Climate Change is the caf'e, on the menu is cooling down,
Heating up,
Baked Alaska.
My Sun is doing the cooking BTW.

reply to post by smurfy


A prediction, yes an absolute certainty in my opinion....

Has nothing to do with either man-made greenhouse emissions or solar output.

More to do with cyclical solar system orbital dynamics, and cyclical galactic dynamics.

Too complex for here and now, too far off topic as well.

ausername

Sinter Klaas
reply to post by CJCrawley

 

From what I understand, is that the Sun will eventually increase in size and become a red giant.
Before its light go out.

And will consume the inner planets.

Life will be long gone before then.

What we should be looking more closely at is the near future. There will be major changes in earth's climate over the next decade.

Not much point in thinking about 500,000,000 years from now, if we can't survive the next thousand years.

Exactly where my mind went when I read the thread. Too much uncertainty in the near future much less a billion plus years.

We really have no idea what will happen tomorrow with our Sun. It's anyone's guess/prediction.

CJCrawley
reply to post by Sinter Klaas

 

Actually, you were more correct about the time; it will be around 3bn years not 1bn (as I incorrectly said) that the earth will become unsustainably hot.

Depends on the source I suppose but you were not incorrect to say 1 billion years according to some sources, such as NatGeo:

news.nationalgeographic.com...

Will Earth's Ocean Boil Away?
Yes—a billion years from now, as the sun gets brighter. But could we make it happen sooner through climate change?

Sinter Klaas
Arcturus is also slightly larger then the Sun is, so I would expect it to runs out of hydrogen faster then the Sun would.
How can they predict anything about the Sun's temperature, when we are only able to observe and measure any data for only a brief moment of the entire lifespan of our Sun, and any other Star for that matter ?

It's like if you went into a school and saw children at various stages of development. You notice that the younger kids have rounder faces and the older kids have more slender faces. So without seeing the younger kid grow up, you can predict based on all the older kids you see that the younger kid's face will get skinnier and less round as he grows up, statistically.

We do something similar with observations of stars in various stages of their life cycles. We see them in various stages from birth to death even though we can't watch the whole cycle for a single star.

Also our models of nuclear fusion are pretty well developed, so we can make general predictions, but they could be off a bit. The Natgeo source says the oceans could boil away in 1 billion years, or even less, and the OP source says 1.75 to 3.5 billion. Since the OP source is not very good I'd lean more toward the Natgeo estimate but still it could be .8 billion to 1.5 billion depending on a lot of variables.

Also you asked a lot about temperature, but your source didn't really talk much about temperature...it's not a very good measure. Energy output, and absorption is a better measure, and things like albedo. (for example if everyone had a white roof, we could slow down global warming due to the albedo change).