Does global warming inhibit transport of moisture?

Question

This northern summer, 2021, there were wildfires in Southern Europe and floods in Germany nearly at same time, also, floods and wildfires in different parts of Turkey, and floods in Far East of Russia and wildfires in Siberia.

Also, there was dry weather in the places where the wildfires were. So, it looks like that moisture was not transported to where it should be transported, by winds, and it rained where it should not normally have rained.

I never saw anybody state that these things are connected this way, (except myself, I think I said this hypothesis 1-2 times). Probably, they do not say that because it is not known. In that case, I hope this question waits answers in future.

Has anybody checked whether this idea is true?

How can it be true?

Answer 1

Increased air temperature tends to increase the rate of moisture transfer, firstly because at a given relative humidity and pressure warmer air has a higher absolute humidity and is carrying more water. Secondly warmer air causes more evaporation off the water and land.

There are however a couple of issues that are becoming increasing apparent,

1. Climate change is (through mechanisms we are yet to fully understand) increasing total rainfall in many areas while decreasing the number of rainfall events they experience. So now when it rains it pours and we see a lot of flooding in areas where the usual pattern was for a lot of lighter rain throughout the year. Between those floods events we see much drier conditions, to the point of drought and forest fires where they had not previously been common.

2. There has also been an increase in wet season rainfall in a number of fire dependent ecosystems making fuel more abundant during the traditional fire season which is becoming both longer and hotter.

Answer 2

Warmer air holds more moisture. That means when and where conditions for rainfall reliably occur the likelihood of higher than historic average levels of rainfall is increased because of global warming.

It also means that where such conditions are uncommon rainfall is reduced, because warmer air requires more water vapor to reach saturation and that condition is harder to reach.

The regions mentioned with the question, that are affected by reduced rainfall tend to historically have periods of low rainfall, often related to ocean circulation based phenomena like El Nino Southern Oscillation, Indian Dipole, Atlantic Nino and others that change the distribution of warm and cool surface water, which in turn impacts wind patterns and the amount of water vapor they take up. In combination with warming they can enhance or inhibit evaporation and consequently rainfall.

It does seem likely that global warming is changing those wind patterns as well as their intensity, with consequences for rainfall, in addition to the impacts of the raised capacity to hold water vapor and the raised water vapor threshold for precipitation.

Answer 3

If true, this would be an example of a teleconnection affected by climate change. However the explanation of extreme drought and extreme precipitation, both as results of global warming, is generally considered to have the "opposite direction": higher temperatures lead to increased evaporation rates and to clouds which store more water before they finally produce rainfall. Hence: on the one hand drought at certain locations, and on the other, larger amounts of water and thus increased precipitation over locations where it is expected to rain. That is, it is thought that global warming tends to intensify the water cycle, not dampen it.

However, global warming also leads to stronger and more persistent heat waves at certain locations, which means that indeed storms are being "stuck" over other locations for longer times instead of spreading out over larger areas.

Then, in order to answer whether a wildfire and a storm/flood are inter-related by one or (most likely) both of the above consequences of global warming, studying those concrete events and their causes is needed. This is probably already underway for the summer 2021 events.

Answer 4

No, in fact moisture rates increase. Because more warmth means more oceanic evaporation. Increasing humidity. Even local climates that are tyipcally dry accumulate more moisture. Africa during the Holocene had lakes the Size of US states, the Sahara was an alluvial plain with grasses and wetlands.

research on Australia Holocene wetness data. https://australian.museum/learn/australia-over-time/evolving-landscape/the-holocene-epoch/

Answer 5

I have several hypotheses.

Nature is involved in the formation of rain. How Mushrooms Make It Rain - YouTube. How Trees Control the Weather. Nature may purposely release particles to form clouds. Water molecules in the atmosphere cannot form a rain droplet without a bigger particle of other type. Human activity may damage the natural system.

1. There are particles produced by humans in the atmosphere like smoke, dust, microplastics. They may cause water molecules to form rain too early.

2. Water in the atmosphere is a greenhouse gas. The global mean (average) temperature is rising because of greenhouse gases released by humans. Nature (global ecosystem) may purposely remove water from the atmosphere (by releasing particles) in order to reduce temperature.

3. Plants grown by humans may not have the correct program in them to release particles on time to support good rain schedule. Plants grown naturally keep local DNA, humans often grow plants from seeds taken from comparatively far away. Also, naturally grown plants may educate each others via signals.