4 ms·
TLDR: Global warming causes a weakened jet stream, which results in less movement of weather patterns. Less movement makes a normal event 'extreme' by turn rai
by baldeagle 10y ago
TLDR: Global warming causes a weakened jet stream, which results in less movement of weather patterns. Less movement makes a normal event 'extreme' by turn rains into floods and droughts. Still highly contested.
Personally, I think it might just be confirmation bias, as the definition of 'flood' changes a lot due to urban landscape and population density.
- mabbo 10y ago> urban landscape and population density. Interestingly, flooding is made worse by low density housing, like suburbs. Forests, meadows, wetlands, they all act like sponges. They soak up recent rainfall and release it slowly, or just keep it. Cut that down, replace it with suburbia- concrete roads, short-grass lawns, nothing that holds much water for long but instead does it's best to get it into a drain and then a river system immediately. Instead of a continuous flow that varies mildly, it's all or nothing. Bone dry, or biblical. Most cities have realized these problems now, but have decades of poorly-thought-out development already in place.
- maxerickson 10y agoGrass is generally treated as a permeable surface.
- mabbo 10y agoAfter it permeates, then what? The water still has to go somewhere, and usually it's into nearby ditches (and then streams, and then rivers). As well, with any larger rainfall the local water table below the grass will fill up quickly- now the water is running on the surface. Permeation is definitely good, but having more stops before it gets there is important to prevent floods. (To be clear, I'm not expert on this at all. But I did marry one, and you sort of absorb a lot just from conversations over dinner).
- maxerickson 10y agoThe point is that it is more similar to a meadow than to a parking lot.
- pixl97 10y agoGrass, as in lawns are a little bit different than wild fields. Most people design good drainage into their lawns so water doesn't pool and flows off quickly. Drainage is key to permeability, the longer water stays on soil, the more time it has to absorb into the soil. If it flows of quickly it will never reach full saturation.
- specialist 10y agoLegally (land use code), but not in practice. Oh, maybe your mean "grasslands" and I'm talking about lawns. The conservationist I worked for refer to lawns as urban deserts.
- maxerickson 10y agoThe conservationist I worked for refer to lawns as urban deserts. Because of the water retention characteristics? Or for more reasons than that?
- specialist 10y agoMost people don't aerate or thatch their yards. Mature lawns are like dense mats. Water doesn't soak thru. Other species can't compete.
- kpil 10y agoI agree. Population density, building near shorelines, and a short collective memory probably clouds our analysis. I also think that tinkering with models and drawing conclusions about the real world is extra sensitive to confirmation bias...
- LoSboccacc 10y agos/causes/correlates with/ they have no idea how the mechanism work, no model actually predicted it until it was discovered and added as a factor to the models themselves etc. etc.
- dhimes 10y agoIt makes me think of the red spot on Jupiter. I remember a few years back a hurricane parked itself off of the Eastern US coast and stayed there for a couple of days. It was really weird, but it made me wonder then if there was some sort of stable solution to the equations of meteorology.