<blockquote>
<p>Is there really a relationship between pressure drop and sea level rise?</p>
</blockquote>
<p>The author of the card was writing about storms at sea. By way of analogy, think of what happens when a person with a significant other flops onto a waterbed. Suppose the significant other, who weighs half as much as the flopper, is already in bed. The significant other may get a bit of a lift from the flop. Another analogy: Think of how you start siphoning gasoline from a gas tank: You reduce the pressure in the siphon. It is the low compressibility of a liquid that makes those responses possible.</p>
<p>When there is a storm at sea, it is the waves that are responsible for the bulk of the storm surge. Reduced atmospheric pressure plays a lesser role, but that role does exist. A cyclone whose central pressure is 50 mb less than surrounding areas can cause a huge storm surge. Most of that is wind driven, but about half a meter is pressure driven.</p>

CC BY-SA 4.0
2022-08-25T08:11:34.020Z
Thanks. I've dug a little and found that it's called the "inverted (or inverse) barometer effect". Could you please add some kind of scientific reference to your answer? I'd be glad to accept it then.
Jean-Marie Prival
CC BY-SA 4.0
2022-08-23T12:16:36.490Z
2022-08-23T12:16:36.490Z
David Hammen
<p><a href="https://climatefresk.org/" rel="nofollow noreferrer">Climate Fresk</a> is a NGO which publishes a card game aimed at educating people about climate change. Card 33 (page 16 of <a href="https://climatefresk.org/wp-content/uploads/2022/06/Climate-Fresk-EN-US-Adults-V8.1_PRINT.pdf" rel="nofollow noreferrer">this pdf file</a>) reads (emphasis mine):</p>
<blockquote>
<p>Cyclones and atmospheric waves bring wind, waves and low pressure
conditions. <em>A 1 hectopascal pressure drop causes a 0.4 inches sea
level rise.</em> Therefore cyclones can cause marine submersions (or
coastal flooding), amplified by the sea level rise already caused by
sea level rise.</p>
</blockquote>
<p>Is there really a relationship between pressure drop and sea level rise? And if so, which relationship and what is the mechanism behind it? I find it hard to believe, because <a href="https://en.wikipedia.org/wiki/Properties_of_water#Compressibility" rel="nofollow noreferrer">water has a very low compressibility</a>, so I don't see how a drop, even big, in atmospheric pressure, could cause such a rise in sea level. The Climate Fresk project claims that all its facts come from the IPCC reports, but I don't know where to start digging...</p>
<p><sub>(PS: I'm not questioning the need to educate people about climate change, nor the integrity of the Climate Fresk project; I just want to get the facts straight.)</sub></p>

CC BY-SA 4.0
2022-08-23T12:01:19.940Z
Interesting mix of units: hectopascals and inches. Most places say that a 1 mb drop in pressure causes a 1 cm sea level rise, which is the same thing.
David Hammen
<climate-change><sea-level><tropical-cyclone><barometric-pressure><flooding>
Is there a relationship between pressure drop and sea level rise?
Jean-Marie Prival
# Is there a relationship between pressure drop and sea level rise?

(Asked by: username_0 on 2022-08-23)

[Climate Fresk](https://climatefresk.org/) is a NGO which publishes a card game aimed at educating people about climate change. Card 33 (page 16 of [this pdf file](https://climatefresk.org/wp-content/uploads/2022/06/Climate-Fresk-EN-US-Adults-V8.1_PRINT.pdf)) reads (emphasis mine):

> Cyclones and atmospheric waves bring wind, waves and low pressure
> conditions. *A 1 hectopascal pressure drop causes a 0.4 inches sea
> level rise.* Therefore cyclones can cause marine submersions (or
> coastal flooding), amplified by the sea level rise already caused by
> sea level rise.

Is there really a relationship between pressure drop and sea level rise? And if so, which relationship and what is the mechanism behind it? I find it hard to believe, because [water has a very low compressibility](https://en.wikipedia.org/wiki/Properties_of_water#Compressibility), so I don't see how a drop, even big, in atmospheric pressure, could cause such a rise in sea level. The Climate Fresk project claims that all its facts come from the IPCC reports, but I don't know where to start digging...

(PS: I'm not questioning the need to educate people about climate change, nor the integrity of the Climate Fresk project; I just want to get the facts straight.)

**Tags:** climate-change, sea-level, tropical-cyclone, barometric-pressure, flooding

> **Comments:**
> **username_1**: Interesting mix of units: hectopascals and inches. Most places say that a 1 mb drop in pressure causes a 1 cm sea level rise, which is the same thing.  

---

## 1 answers

### Answer by username_1 on 2022-08-23. Score: 3

> Is there really a relationship between pressure drop and sea level rise?

The author of the card was writing about storms at sea. By way of analogy, think of what happens when a person with a significant other flops onto a waterbed. Suppose the significant other, who weighs half as much as the flopper, is already in bed. The significant other may get a bit of a lift from the flop. Another analogy: Think of how you start siphoning gasoline from a gas tank: You reduce the pressure in the siphon. It is the low compressibility of a liquid that makes those responses possible.

When there is a storm at sea, it is the waves that are responsible for the bulk of the storm surge. Reduced atmospheric pressure plays a lesser role, but that role does exist. A cyclone whose central pressure is 50 mb less than surrounding areas can cause a huge storm surge. Most of that is wind driven, but about half a meter is pressure driven.

> **Comments:**
> **username_0**: Thanks. I've dug a little and found that it's called the "inverted (or inverse) barometer effect". Could you please add some kind of scientific reference to your answer? I'd be glad to accept it then.  

---

