Does planting more trees lead to Global Warming?

Question

My common knowledge is that plants emit CO2 at night (in the absence of light, since no photosynthesis occurs). If this be true then it means the more the plants the more CO2 is emitted.

Answer 1

Your conclusion is true, but your facts are incomplete. I hope you and others get trough this quite long answer.

Plant respiration accurs at all times. Most living cells (plants included) need oxigen for their life processes. The thing with plants and some bacteria, is that they have a second process, photosynthesis, that actually does the reverse thing: use the Carbon from CO2 and hydrogen from water (H2O) to produce simple sugars and in the process liberate some Oxigen. Six molecules of CO2 and 6 molecules of water will combine in the presence of energy to form one molecule of a simple sugar (glucose) that will join others to form chains of either starch or cellulose (depending on how they link together). A molecule of glucose will have 6 carbons (C), 12 Hidrogens (H) and 6 Oxigens (O), but if you count the elements involved in the reaction you will notice that you have exactly the amount of H and C that you need, but you have extra O. You have 6 O's coming from the water which are actually the ones that go on to be part of the glucose (it has been tested with radioisotopes) but each CO2 has 2 O's, so in 6 CO2's, you have 12 extra O's. These 12 are the extra product of photosynthesis.

I apologize for the somewhat technical explanation. I will now address some of the comments you have been receiving:

1) Plants absorb more CO2 than they produce: Partial Truth.

For a plant hat is actively growing, photosynthesic activity will be such that it will produce more O than it will consume by respiration, so the net effect will be positive. A mature tree, on the other hand will even both processes out and will become carbon-neutral. (It will produce roughly the same amount of Oxigen that it consumes) If temperatures are too high, though, the plant will slow photosynthesis in order to avoing burning itself, so it has been determined that in Britain, some forests are now producing LESS O than they produce. This they attributed to an increase of 3 degrees in average temperatures in the last 100 years, so their theory is that global warming will cause our friends the trees to become our competitor... scary.

2) Trees darken the Earth's surface causing more global warming: Myth

A darker atmosphere produces colder temperatures, not warmer. This fact can be confirmed by anyone who has stood under the shade of a big tree. Temperatures under and around trees are lower than under artificial shade because trees evaporate water and act as radiators. Air that passes through the canopy of a forest can cool down several degrees. The largest drop in temperature comes from banana trees, because of their huge leaves.

The idea that darkening the Earth warms it probably comes from the cloud cover. Our atmosphere with its cloud cover allows light to get in, but keeps infrared radiation, which includes heat, from escaping. The more CO2 and other gases (known for this very reason as greenhouse gases) are in the atmosphere, the more efficient the atmosphere becomes at trapping heat.

3) While there is no sun the plant just stands still waiting for the light: Total myth.

While you might say that plants always stand still. Plants do have the respiration process at all times.

4) Plants do photosintesis during the day and respiration during the night: Partial Truth

Photosynthesis, because it's light dependant can't occur at night, but respiration occurs at all times as I said already. The misundertsnding occurs because in the past photosynthesuis was called the "Light Cycle" while Respiration was called the "Dark Cycle". This did not mean that the Respiration cycle happenned in the dark, but that it was not light-dependant. More appropriate names would be Light-Dependant Cycle and Light-Independent Cycle.

5) Averaged during the whole day (which is what counts) plants absorb CO2: Partial Truth

Only actively growing plants and bacteria. Mature plants and heat stressed plants do not.

6) Technically we are in a CO2 deficit (if you look at it over millenia): Unable to determine

Hard to ascertain the levels of CO2 over millenia, and even if we have reliable data, to know how friendly the planet was when it had more CO2 or other gases. I don't know.

7) Trees produce Oxigen through transpiration: False

Not a myth, just an error. Transpiration is the evaporation of water (sweat). Photosynthesis produces oxigen.

8) Plants (including trees) actually absorb CO2 even more efficiently when the sun is not out: Not True

The article cited is misunderstood, This is a good one. The truth is that even when photosynthesis depends on light for its energy, when there is too much energy present, the process can't be performed safely for the plant. Allow me to explain in as simple terms as I can. The way plants absorb solar energy is by photoreactive pigments called chlorophyls. There are two types of clorophyls in plants, known as A and B. Type A absorbs solar energy and transforms it to chemical energy. Type B absorbs chemical energy from type A. The cell itself can't take chemical energy from clorophyl A, but takes it from type B. When the plant is doing this, sometimes energy is being absorbed by type A faster than the plant can use it. Having too much energy would fry the cells, so there are other pigments, called carotenoids, that take on that energy an dissipate (get rid of) it on the form of heat. In order for the plant to stay cool during this, it evaporates water from the leaves, effectively using them as a radiator to keep itself cool. (This evapotranspiration also works to make water come up the plant and bring nutrients from the soil up to the leaves, but this is a different story)

In the tropics, from 10:00 am to 2:00 pm, when the available sunlight (and also the heat) is at its maximum level. Most plants slow or even stop photosynthesis. If they did not do that, they would burn. They also close the pores on their leaves (called stomata) to avoid water loss. So, contrary to us, humans, plants stop sweating when it gets really really hot.

What the article is saying is that if the sunlight is not as strong, as in a hazy day, photosynthesis can be more effective, because it will be more continuous. (no interruption around noon) The article does not say that photosynthesis can occur at night, becuse it does not, unless you have your plant under artificial light.

9) Plants store CO2, but they all eventually die. And when they die they began to rot and return the CO2 back into the system: Truth, but...

A plant that is alive, even if it's carbon-neutral (mature) is holding carbon away from the atmosphere. The more carbon is in biomass (living organisms) the less can be free as CO2. Normally, in nature, when a plant dies, another one (or more) takes its place. It is a good thing to replace a mature plant for one or more growing ones because they fix more carbon. The problem is that when you deforest, you reduce the biomass and release more CO2 that will not be captured back.


I apologize for the size of this reply. I am a both a Plant Scientist and an armchair environmentalist, and could not resist the urge. Luckily for all of you, this is not a personal conversation, because I could speak for hours...

Hope this helps a little.

Answer 2

Plants use more CO2 than it produces. Thats how it grows. During the day, it converts Co2 into plant matter. We are technically in a CO2 defecit (If you look at our CO2 over millinia.) I've seen charts, on CO2 level and there is little change. These date may be bias though, since the source tries to dispel the greenhouse affect. It is known that the plants are growing faster because we are making more CO2 available. The question is if the plants are absorbing enough CO2. The other question is, does these plants permanently solve the excess CO2. Most of the increase growth in plant matter is made in food production. If we eat the food, most of the Carbon stored in the plant is transformed back into co2. Also if we cut down the tree and burn it, the carbon is mostly returned into the atmosphere. If we bury it, some of the plant matterial will decay and return into the atmosphere as well, but some will stay underground. I think it helps, but the question is how much. Even if you burn the tree, some of the carbon would stay out of the atmospere. My oceanagraphy teacher told me the best way to remove CO2 is to encourage coral growth. coral produces calcium carbonate. This would eventually turn into beach sand, which is obvious won't burn.

Answer 3

It's tricky.

Averaged over the whole day (which is what counts) plants absorb CO2.

But trees can darken the Earth's surface causing more warming. It may be that the answer is that trees do a good job of absorbing natural CO2, but can't cope with man dumping CO2 into the atmosphere. This graph would seem to suggest that.

http://scrippsco2.ucsd.edu/graphics_gallery/mauna_loa_record/mlo_record.html

The little squiggles are nature doing its' thing. CO2 falls a bit during summer when plants are active, and rises during the winter. The huge increase is us, burning fossil fuels.

Answer 4

Plants including trees take in the air, destroy the toxins and then release Clean Air /CO2..Clean Air will not harm the enviroment nor cause Global Warming but is much needed for our and the planet earth's good health. one of the contributors to Global Warming is the destruction of Tropical Rain Forests and Great swaths of forest,trees by acid rain-the bad stuff that we send into the air and comes back down as acid rain. Trees are also essential for rain/storms and lightning also cleans the air along with the rain. Trees also keep the earth healthy for will stop erosion of the land-why when great expanses of trees are cut then there is nothing to hold the earth-winds ,storms dry up the layers of soil and in time there'll be a desert for with the trees gone there will gradually be no rain.We are also encouraged to have plants in our homes esp those like ferns or ivy etc fo they clean the toxins out of the air in our homes naturally. Trees in our yards give us shade,majestic beauty and homes for the little creatures. Trees are most definitely a GOOd Thing!

Answer 5

Plants store CO2, but they all eventually die. And when they die they began to rot and return the CO2 back into the system.

Here's an interesting little fact, every acre of woodland that is turned into farmland via "slash & burn" returns the same carbon as 400 SUVs driving 15,000 miles a year. About 3 million acres a year undergo this process in Brazil alone..

Answer 6

Since nothing in this world is perfect, it is sad to say that plants are not perfect either. But at least, it provides us shade and produce food via photosynthesis. As far as I'm concerned, plants are the only solution to solve Global Warming. Unless you have other ideas to stop Global Warming for good...

Answer 7

This is educated but outdated science you're speaking of. Plants (including trees) actually absorb CO2 even more efficiently when the sun is not out. Plants take in carbon dioxide during photosynthesis in the day, and release it during respiration at night. But they don't necessarily photosynthesize and respire at the same rates.

Check out this article:

http://www.gsfc.nasa.gov/topstory/20011210co2absorb.html

Answer 8

No dude! You got a wrong information. Plants absorb them and pruduces oxygen. Water and Carbon Dioxide needs light from the sun to make starch and cellulose. While there is no sun, the plants just stay still waiting for the light. Oxygen is exhaled when photosynthesis occurs.

Answer 9

The problem with global warming is that humans are upsetting the natural balance of gasses being emitted into the atmosphere. The plants have been here for millions of years and are part of the natural cycle. We are interrupting that cycle and that is what is causing the problems. Plants also take in CO2.

Answer 10

plants consume more co2 than they emit. verdict? Yes, to a certain degree they do lessen the effects of the greenhouse effect.