Question

Calculate the amount of CO2 (in kg) dissolved in the top 10 meters of the oceans (assume uniformity). If melting glaciers add 1 meter to the ocean level, how much additional CO2 (in kg) will this water hold? [Liquid ocean surface area = 361.9 Million km^2, average ocean temp 17 C]

Answer 1

Of the Earth’s surface, the oceans occupy 361.9 million square kilometers (or 361.9 x 10⁶ km²).

Suppose one cubic kilometer of water (or one gigatonne of water) is spread evenly over the entire 361 million square kilometers, then the thickness of the new layer of water formed will be,

1 km³ / 361.9 x 10⁶ km² = 2.76 x 10^-6 meters = 2.76 microns.

This in terms of gigatonnes is,

(1 km³/Gt) / 361.9 x 10⁶ km² = 2.76 x 10^-6 meters = 2.76 microns / Gt

So, according to this, 1 km³ of water (or one gigatonne of water) will add less than 3 millionths of a meter to the oceans.

The number of gigatonnes of water that should be added to the oceans for raising the sea level by 1 meter is given by:

1m / (2.76 microns / Gt) = 1 m / (2.76 x 10^-6 m / Gt) = 362318.84 Gt

Likewise, 362318.84 km³ of water will raise the oceans 1 m.

Likewise, 3623188.4 km³ of water will raise the oceans 10 m.

1 Gt = 10⁹ tonnes (where 1 tonne = 1000 kg).

3623188.4 Gt = 3623188.4 * 10⁹ tonnes

And 1 tonne = 1000 kg

So, 3623188.4 * 10⁹ tonnes =3623188.4*10¹² kg