this post was submitted on 11 Dec 2025
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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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California's cap and trade gets a new name [Cap & Invest] and a new mission beyond cutting carbon pollution (calmatters.org)
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[โ€“] andrewrgross@slrpnk.net 1 points 2 days ago

Alright, I just wasted a bunch of time I should've been working looking into this, and here is the HSRA's most recent report on the subject: https://hsr.ca.gov/wp-content/uploads/2024/09/Sustainability-Report-2024-FINAL-A11Y-20240916.pdf

From the relevant section, pg 58:

With high-speed rail, the annual GHG emissions reductions are projected to be 0.6 to 3 million MTCO2e. based on 2024 Business Plan ridership models. This reduction is equivalent to the annual carbon emissions associated with the energy use of between 77,000 and 372,000 homes โ€“ more than the housing stock of San Jose. The cumulative reductions in well-to-wheels emissions over the first 50 years of operations are projected to be between 29 million and 142 million MTCO2e.

I wish they'd provided a percent reduction in vehicle emissions, but according to another source (https://ww2.arb.ca.gov/ghg-inventory-data), in 2023, transportation emissions in California were 137 million metric tons of CO2. The average of the range comes out to around 1.3% of that range.

That's interesting. I wonder what fraction of transit emissions are from passenger travel across the state, vs commercial hauling and inner city traffic. I still think this is an obviously necessary step, but I'm curious what other actions are needed to take care of the other 99% of transit emissions. Perhaps urban public transit and bike infrastructure.