# Why is the creation of water from the combustion of hydrocarbons not listed as a cause for rising sea levels?

https://iopscience.iop.org/article/10.1088/1748-9326/aa8390

According to this paper, water is created by burning hydrocarbon fuels. It seems like a major thing to exclude from "reasons the sea levels are increasing".

From the paper:

The annual global formation of water from combustion of hydrocarbon fuels from 2005–2015 amounted to an average of $$1.2 \times 10^{13} kg⋅yr^{-1}$$, as shown in figure 1. By comparison, the atmosphere is estimated to hold on average approximately $$1.3 \times 10^{16}$$ kg of water, while the global rates of irrigation-induced and natural evaporation are on the orders of $$10^{15}$$ and $$10^{17} kg⋅yr^{-1}$$, respectively.

I understand from the figures, the amount of water introduced into the atmosphere is small compared to irrigation and natural evaporation, but that is only dealing with water that is already there. This paper details that we are essentially pulling hydrogen out of the earth, combining it with atmosphere oxygen and creating water.

Water vapor is already listed as a GHG, so maybe it is just being swept along with that term?

I have to be making a connection that doesn't exist, right? Otherwise it would be noticed by someone / anyone else.

Make me understand why I am wrong to think that the creation of water by burning hydrocarbon fuels is adding to the amount of water in the oceans.

Thank you,

• the weight of the hydrocarbons burned is the same as the water and waste products so the net result is zero,you simply get more water and less hydrocarbons so nothing is added or removed from the system. – trond hansen Jul 30 at 10:09
• There is an assumption that the amount of water in the system is nearly constant. It is known that it is not exactly constant. That it is not exactly constant is irrelevant. – David Hammen Jul 31 at 7:53
• 100% accuracy is unachievable, in any science. – David Hammen Jul 31 at 11:15
• Re Would it not be sound to understand the total amount of water? Not really. There's an apocryphal story about a scientist who was so intent on studying bugs that only lived on the north side of a certain species of trees suddenly emerge from the trees that he missed that the forest was on fire. Don't be this guy. – David Hammen Jul 31 at 11:26
• It is worth considering water can easily be removed , plant life converts water into sugar, and many biological process destroy water. You would need to compare the contribution to the larger water cycle. – John Jul 31 at 14:31

1.2 x 10^13 kg equals 12,000,000,000,000 l water. One liter equals 0.001 m³, while one km³ equals one billion (1 x 10^9) m³. So we're supposedly adding 12 km³ water to the atmosphere per year.

According to wikipedia the total oceanic surface is about 361,900,000 km². If we spread the added amount of water over all the oceans, we end up with a sea level rise of 0,03316 mm per year. The german wikipedia page on sea level rise claims - based on the 5th chapter of the Fourth Assessment Report by the IPCC from 2007 - that the annual sea level rise between 1993 and 2003 due to thermal expansion was about 1,6 ± 0,50 mm.

Since we didn't take into account sinking surface above oceanic hydrocarbon sources or the increased atmospheric capacity for water vapour due to heating, which both are connected to the effect you are interested in, I'd estimate there is an existing, but almost negligible contribution to sea level rise. Other effects contribute way more - and all of them will likely peter out, once we reduce fossil fuel consumption significantly.

• You're off by a factor of ten somehow. Your value should be 0.03316 mm, or 33.16 μm. In other words, completely negligible. – David Hammen Jul 30 at 15:30
• @EricRamljak -- The amount of water created by burning hydrocarbons is at over four orders of magnitude small than the amount of water that passes annually through the water cycle. If doubt that scientists know the numbers to three degrees of precision. This means that the quantity you are concerned with is over an order of magnitude smaller than the uncertainty. Those are the kinds of quantities one ignores. – David Hammen Jul 30 at 23:10
• Note well: The "1,6 ± 0,50 mm" quoted in this answer is due to thermal expansion of the oceans. Water added to the oceans via melting ice adds about the same amount to sea level rise. The net sea level rise has less uncertainty than does the contribution of each contributor because the net sea level rise is somewhat directly observable while the individual contributions are more indirect. Nonetheless, the uncertainty in the net sea level rise is orders of magnitude greater than 33 μm/year. – David Hammen Jul 31 at 8:01
• Which means that that 33 μm/year can more or less be ignored. – David Hammen Jul 31 at 8:02
• @EricRamljak David didn't provide any answer, he just corrected mine. We proofed to you, that while there is an inflow of additional water, the total amount is insignificantly small. And yes, this "production" of water can be considered for future life cycle analyses - of fuel production - but not for analyses of the whole water cycle/sea level rise. Maybe you should point out more clearly what question you want to have answered. – Erik Aug 1 at 11:34

The current popular view is that the total quantity of water on the planet is a constant value. This appears to be an assumption. There has not been enough study and information published on this subject to prove or disprove that burning hydrocarbons fuels can contribute to rising sea levels.

Thank you to those who have provided comments and an answer. This has been a good learning experience.

Water Cycle

The Role of Anthropogenic Water Vapor in Earth's Climate provides a review of the positions taken by various organization concerned with climate about the role of water vapor in the Earth's climate system. I encourage you to review / read this yourself.

Some key items from that review to consider:

"the burning of one gallon of gasoline produces 3,914.6 grams of water. This is equal to 8.6 pounds of water, which has a volume of 1.033 gallons"

"There was about 22 trillion cubic feet of natural gas burned in the United States in 2006...so the water vapor proburninduced (sic) in a year from burning natural gas is 263.4 billion gallons of water. This is per year; per day the figure is 722.4 million gallons."