this post was submitted on 03 Mar 2024
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Climate - truthful information about climate, related activism and politics.

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Discussion of climate, how it is changing, activism around that, the politics, and the energy systems change we need in order to stabilize things.

As a starting point, the burning of fossil fuels, and to a lesser extent deforestation and release of methane are responsible for the warming in recent decades: Graph of temperature as observed with significant warming, and simulated without added greenhouse gases and other anthropogentic changes, which shows no significant warming

How much each change to the atmosphere has warmed the world: IPCC AR6 Figure 2 - Thee bar charts: first chart: how much each gas has warmed the world.  About 1C of total warming.  Second chart:  about 1.5C of total warming from well-mixed greenhouse gases, offset by 0.4C of cooling from aerosols and negligible influence from changes to solar output, volcanoes, and internal variability.  Third chart: about 1.25C of warming from CO2, 0.5C from methane, and a bunch more in small quantities from other gases.  About 0.5C of cooling with large error bars from SO2.

Recommended actions to cut greenhouse gas emissions in the near future:

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[–] [email protected] 13 points 8 months ago (4 children)

Wdym? The faster a car moves (or anything, not just a car) the less efficient it's gonna be, because it has to fight against more and more wind resistance.

[–] [email protected] 3 points 8 months ago

Wdym? The faster a car moves (or anything, not just a car) the less efficient it's gonna be, because it has to fight against more and more wind resistance.

That isn't entirely true. At lower speeds there may be other inefficiencies that are worse than wind resistance (since wind resistance becomes negligible at low speeds).

It will depend on the vehicle, but for example, small gasoline cars are more efficient at ~70 km/h than at lower speeds. Electric vehicles will likely be more efficient at lower speeds (~40 km/h) than gas vehicles, due to (lack of) gearing but there will still be low speeds where they are less efficient than higher speeds.

https://www.researchgate.net/figure/ehicle-energy-economy-at-different-speeds_fig1_326822085

[–] [email protected] 6 points 8 months ago

The measure of productivity of transportation is distance traveled, not speed (unless this were some time race). Comparing kw/speed tells you nothing about the kWh used to make the same trip as alternative modes of transportation.

[–] [email protected] 4 points 8 months ago

In theory I agree, in practice other stuff, as the need for heating/cooling, really muddled the theory and puts the sweet spot speed way up. And if we turn the Aircon off, 150 is a really high number.

[–] [email protected] 41 points 8 months ago* (last edited 8 months ago) (2 children)

They're saying that at highway speeds the cars energy usage would be off the chart, or if they scaled the chart to that usage, everything else would be too small to discern the differences.

You guys are in agreement.

[–] [email protected] 13 points 8 months ago

Aaah, I get it now, thanks!