<p>The difference is that a carbon sink <strong>accumulates</strong> carbon, whereas a carbon reservoir <strong>has accumulated</strong> carbon.</p>

<p>That is to say:</p>

<p>A carbon sink is an ongoing process which is increasing the amount of carbon stored in it.</p>

<p>Whereas although a carbon reservoir might exchange individual carbon-based molecules with other parts of the carbon cycle, as much will go out as goes in, keeping the amount of carbon in the reservoir broadly constant.</p>

<p>Both of these contrast with things such as coal seams and natural gas &amp; crude oil reservoirs that humans have tapped as sources of fuel; and leakages of methane from the ground: these <em>were</em> carbon reservoirs until the amount of carbon in them began depleting (e.g. through mining, well-drilling, or - in the case of methane clathrate leakages - ice melt), at which point they became carbon sources.</p>

CC BY-SA 3.0
2015-06-21T12:37:19.153Z
Would if be fair to say that coal seams & crude oil deposits are carbon reservoirs, whereas, an active peat bog is a carbon sink?
Fred
CC BY-SA 3.0
2015-06-23T08:06:28.010Z
@Fred updated to cover coal, oil & gas deposits
410 gone
CC BY-SA 3.0
2015-06-23T21:12:30.337Z
Those last two paras aren't quite right.  The phrase "carbon reservoir" doesn't imply anything about the change (or lack of it) with time, just that it's an identifiable part of the system that has some carbon in it.  Reservoirs that are net sinks or sources over some period are still reservoirs.
Deditos
CC BY-SA 3.0
2015-06-21T12:11:50.630Z
2015-06-23T08:06:00.853Z
2015-06-23T08:06:00.853Z
410 gone
<p>A carbon reservoir is measured by the amount of carbon it contains, for example kilograms of carbon [kg C]. A carbon source or sink is measured by the amount that comes out or into the reservoir from the rest of the system per unit of time, for example kilograms per day [kg C/day]. A coal or oil deposit can be either a reservoir or source, as carbon flows out (it's a source as product is extracted) the size of the reservoir decreases.</p>

<p>Because carbon (or any element) is a conserved quantity, if your peat bog is growing larger, then it may be a <em>net sink</em> for carbon.  But if is losing carbon to the atmosphere (say as methane or if it is a burning peat bog) as deposition of organic material continues, the reservoir may not be growing and the bog could be a <em>net source</em> of carbon to the rest of the system. (I really don't know how real peat deposits behave.)</p>

<p>In mathematical transport-models, you can specify sources and sinks without specifying a reservoir, but in actual systems there has to be reservoirs to provide or take-up whatever element is being transported.  </p>

CC BY-SA 3.0
2015-06-23T01:04:42.870Z
2015-06-23T04:32:49.150Z
2015-06-23T04:32:49.150Z
Mark Rovetta
<p>According to the United Nations Framework Convention to Combat Climate Change (UNFCCC)</p>
<ul>
<li><p>“Reservoir” means a component or components of the climate system where a
greenhouse gas or a precursor of a greenhouse gas is stored.</p>
</li>
<li><p>“Sink” means any process, activity or mechanism which removes a greenhouse gas, an aerosol or a precursor of a greenhouse gas from the atmosphere.</p>
</li>
</ul>

CC BY-SA 4.0
2024-02-05T16:48:17.553Z
2024-02-05T16:48:17.553Z
user30447
<p>Both carbon sinks and carbon reservoirs store carbon and accumulate them but the only difference is in their flexibility and stability to release carbon back to the atmosphere.</p>

<p>In simple terms, carbon sink (like iceberg) takes longer time to release carbon because it takes longer time to melt. On the other hand, in your example, the mature forests can release carbon relatively quicker because they are in their last stage of their life cycle and hence they are carbon reservoirs. </p>

CC BY-SA 4.0
2019-11-08T08:18:57.713Z
2019-11-08T08:18:57.713Z
Albert
<p>I am trying to figure out the difference between a carbon sink and a carbon reservoir.</p>

<p>The definition for a carbon sink from Wikipedia is </p>

<blockquote>
  <p>carbon sink is a natural or artificial reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period. </p>
</blockquote>

<p>And the definition for carbon reservoir is </p>

<blockquote>
  <p>Carbon-storing natural feature (such as a forest or the land mass) that exchanges carbon with other reservoirs.</p>
</blockquote>

<p>My textbook says that mature forests are carbon reservoirs but they are not carbon sinks. So what is the difference between a carbon sink and a carbon reservoir on earth?</p>

<carbon-cycle><carbon><biogeochemistry><forest><atmospheric-chemistry>
What is the difference between a carbon sink and a carbon reservoir?
Betty
# What is the difference between a carbon sink and a carbon reservoir?

(Asked by: username_0 on 2015-06-21)

I am trying to figure out the difference between a carbon sink and a carbon reservoir.

The definition for a carbon sink from Wikipedia is

> carbon sink is a natural or artificial reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period.

And the definition for carbon reservoir is

> Carbon-storing natural feature (such as a forest or the land mass) that exchanges carbon with other reservoirs.

My textbook says that mature forests are carbon reservoirs but they are not carbon sinks. So what is the difference between a carbon sink and a carbon reservoir on earth?

**Tags:** carbon-cycle, carbon, biogeochemistry, forest, atmospheric-chemistry


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## 4 answers

### Answer by username_1 on 2015-06-21. Score: 7

The difference is that a carbon sink **accumulates** carbon, whereas a carbon reservoir **has accumulated** carbon.

That is to say:

A carbon sink is an ongoing process which is increasing the amount of carbon stored in it.

Whereas although a carbon reservoir might exchange individual carbon-based molecules with other parts of the carbon cycle, as much will go out as goes in, keeping the amount of carbon in the reservoir broadly constant.

Both of these contrast with things such as coal seams and natural gas & crude oil reservoirs that humans have tapped as sources of fuel; and leakages of methane from the ground: these *were* carbon reservoirs until the amount of carbon in them began depleting (e.g. through mining, well-drilling, or - in the case of methane clathrate leakages - ice melt), at which point they became carbon sources.

> **Comments:**
> **username_2**: Would if be fair to say that coal seams & crude oil deposits are carbon reservoirs, whereas, an active peat bog is a carbon sink?  
> **username_1**: @username_2 updated to cover coal, oil & gas deposits  
> **username_3**: Those last two paras aren't quite right.  The phrase "carbon reservoir" doesn't imply anything about the change (or lack of it) with time, just that it's an identifiable part of the system that has some carbon in it.  Reservoirs that are net sinks or sources over some period are still reservoirs.  

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### Answer by username_4 on 2015-06-23. Score: 4

A carbon reservoir is measured by the amount of carbon it contains, for example kilograms of carbon [kg C]. A carbon source or sink is measured by the amount that comes out or into the reservoir from the rest of the system per unit of time, for example kilograms per day [kg C/day]. A coal or oil deposit can be either a reservoir or source, as carbon flows out (it's a source as product is extracted) the size of the reservoir decreases.

Because carbon (or any element) is a conserved quantity, if your peat bog is growing larger, then it may be a *net sink* for carbon. But if is losing carbon to the atmosphere (say as methane or if it is a burning peat bog) as deposition of organic material continues, the reservoir may not be growing and the bog could be a *net source* of carbon to the rest of the system. (I really don't know how real peat deposits behave.)

In mathematical transport-models, you can specify sources and sinks without specifying a reservoir, but in actual systems there has to be reservoirs to provide or take-up whatever element is being transported.


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### Answer by username_5 on 2024-02-05. Score: 1

According to the United Nations Framework Convention to Combat Climate Change (UNFCCC)

* “Reservoir” means a component or components of the climate system where a
  greenhouse gas or a precursor of a greenhouse gas is stored.
* “Sink” means any process, activity or mechanism which removes a greenhouse gas, an aerosol or a precursor of a greenhouse gas from the atmosphere.


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### Answer by username_6 on 2019-11-08. Score: 0

Both carbon sinks and carbon reservoirs store carbon and accumulate them but the only difference is in their flexibility and stability to release carbon back to the atmosphere.

In simple terms, carbon sink (like iceberg) takes longer time to release carbon because it takes longer time to melt. On the other hand, in your example, the mature forests can release carbon relatively quicker because they are in their last stage of their life cycle and hence they are carbon reservoirs.


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