Firefly5494
Okay - so I'll start off by saying that this question is for research, and any information you may have, whether it be a book to look into, and article to read, a person to try and contact, or just your personal opinion would be VERY helpful.

Well... what WOULD happen if all plants died? If something changed and you woke up the next day and EVERY single plant on Earth was dead... I know that plants produce oxygen for humans and animals, but does it produce the ONLY means of oxygen?? How long would it take before breathable air was gone? A day? A month? A year? Would everyone end up suffocating?

~~~~~~OR~~~~~~

I also know that high outputs of carbon dioxide is the "cause" for "global warming". Would this sudden burst of the gas, unable to be filtered by plants, cause a faster destructive and catastrophic climate change? How quickly would things change with such a newely and unexpected carbon dioxide output? Would that end up destroying us before oxygen ran out???

Steveo
According to my estimations and a few facts from wikipedia:
The average person at rest uses 18-2.4g of oxygen per minute, so using the higher number that works out to
3.456kg/day per person and
2.0736*10^13kg per day for the whole world (using 6 billion people).

Compare this to the weight of the atmosphere (5.15*10^18kg) which is 21% oxygen, which gives a mass of the oxygen available in the atmosphere to be
1.0815*10^18kg. Thats 5 orders of magnitude difference, and we would have over 100 years before we ran out of oxygen in the atmosphere, assuming that oxygen would be transported all through the atmosphere well.

This conclusion makes sense, since humans inhabit only a fraction of all of the land available on earth, and that is less than 50% of the surface of the earth. You wouldn't expect the oxygen to run out very quickly.

I think our biggest problem would be a lack of food very very fast.
SteveA2
Actually carbon dioxide helps plants grow and produce oxygen, so if there's a worry about all plants on Earth dying , then carbon dioxide would help counter this.

The life cycle relies upon carbon as one of the primary components of organic life. Plants take carbon dioxide from the atmosphere (as well as carbon from chemicals in the ground) and use the carbon as an element to grow. They release the "dioxide" component as oxygen, which animals inhale and recombine with carbon. So it's the cycle of splitting carbon dioxide, via. plants, into carbon and oxygen and then recombining these to release the energy "stored" by plants in this manner that "powers" life on Earth.

Carbon dioxide levels have dropped over time one Earth, though oil extraction has had a small influence on recycling some of it, and just like many environmentalists encouraging not tossing organic materials in a landfill, it's similar extracting organic material that has been "disposed" by nature over the years (for example, the Mt. St. Helens eruption buried a large quantity of organic material or forests and life underground.)

With regards to how long oxygen levels would remains at levels sustainable for life without it, I don't know, but I'd assume it would be years before oxygen reserves in the atmosphere dropped sufficiently to cause major problems for life on Earth.
Zarkov
QUOTE
what WOULD happen if all plants died?

If by "plants" you are referring to land plants
then if they all died, basically nothing would happen..except the atmosphere would become thick with particulate matter

now if you are referring to "all plants", including marine "plants"
then all animal life would also die, and you are an animal.

The oxygen for this world is mainly produced by marine algae et al.

How long would it take for YOU to suffocate.... oh about a week !

Don't knock plants... they are keeping you alive as well as cleaning the air.

But you don't have to worry, your doom is soon at hand.... freeze.... plants and you

pathetic earthlings.

Steveo
QUOTE
How long would it take for YOU to suffocate.... oh about a week !

How did you arrive at one week?
Firefly5494
QUOTE (Steveo+Sep 4 2008, 04:29 PM)
I think our biggest problem would be a lack of food very very fast.

That's a very good point Steveo So with oxygen not being the immediate problem, food would be the main issue... So animals would not have any food to survive and thus we would not have any plant grown food OR animals to consume. Are there any other edible options? Anything that could sustain people or would it more or less be the end of the line? How long do you think that we could extend the existing food before it all ran out?
philip347
op asked,.Okay - so I'll start off by saying that this question is for research, and any information you may have, whether it be a book to look into, and article to read, a person to try and contact, or just your personal opinion would be VERY helpful.\\\

The biolustre of the planet would be much less.

If your with the the powers that be and are planning some sort of dfisaster, which would do this, I don't recommend it.

There was a scientific article published not long ago, about water having a sort of memory.

If you were to euthanize all plants, the effect would be much the same as taking a live newborn infant and placing it on the sidewalk to watch it die.

Earth or the hidden gaia factor might realize this and a new surface to Earth, might remain elusive?
Zarkov
QUOTE
How did you arrive at one week?

maybe an exaggeration but

bacterial fermentation of dead matter would quickly consume any available oxygen... and reduce it below say 10%..... game over

if drought and fire then maybe very quickly

if floods, O2 depletion could be very rapid

which ever way... it would be rapid
kjw
QUOTE
Steveo Posted: Today at 3:08 AM How did you arrive at one week?
http://www.random.org/calendar-dates/
Steveo
kjw, I think you are right!
TheDoc
QUOTE (Firefly5494+Sep 5 2008, 10:23 PM)
That's a very good point Steveo So with oxygen not being the immediate problem...

Actually, oxygen would be an immediate problem.

Think about it. We give them carbon dioxide, and in return they give us oxygen. If that extra source of oxygen - the plants - disappears, CO2 would build up pretty quickly, especially in the big cities and metro areas, where there are cars, buses and the like that add to the output of CO2.

I think that if every plant died, simply being able to breath would become a problem fairly quickly.
kjw
QUOTE
Steveo Posted: Today at 1:37 PM kjw, I think you are right!
i think you are too
buttershug
QUOTE (TheDoc+Sep 8 2008, 03:57 AM)
Actually, oxygen would be an immediate problem.

Think about it. We give them carbon dioxide, and in return they give us oxygen. If that extra source of oxygen - the plants - disappears, CO2 would build up pretty quickly, especially in the big cities and metro areas, where there are cars, buses and the like that add to the output of CO2.

I think that if every plant died, simply being able to breath would become a problem fairly quickly.

If you are trapped in an enclosed space with no fresh air.
You won't die from a lack of oxygen. You will be dead from the build up of carbon dioxide before you use up all the oxygen.

Has anyone seen the old movie The Last Woman on Earth?
It's a corny old sci fi movie where some scuba divers come up to the surface to find everyone dead.
PhysOrg scientific forums are totally dedicated to science, physics, and technology. Besides topical forums such as nanotechnology, quantum physics, silicon and III-V technology, applied physics, materials, space and others, you can also join our news and publications discussions. We also provide an off-topic forum category. If you need specific help on a scientific problem or have a question related to physics or technology, visit the PhysOrg Forums. Here you’ll find experts from various fields online every day.