[zosima]

We had a ~10C increase in temperature from 20000 YA - 13000 YA or so and then a yoyo jump back down ca. 6C and up again in a 1000 years, during the younger dryas.

While the 19th-21th century increase of 1-1.2C or so is a bit faster, it's not a magnitude faster.

Humans have definitely changed nature everywhere, and is probably responsible for many species dying. But blaming that on the climate change doesn't really make sense. Deforestation is much more likely to be the cause.

[myshpa]

I'm not blaming it on the climate change. I'm blaming overshoot.

Mainly our agriculture (deforestation, biodiversity loss, pollution), misuse of fossil fuels and the structures of our societal and financial systems.

[zosima]

But deforestation and the following biodiversity loss is a completely different problem than reducing CO2. And in general, very few things that will reduce CO2 is going to help against deforestation (and contrary to popular opinion, even large scale reforestation will probably not affect CO2 very much either).

[myshpa]

> very few things that will reduce CO2 is going to help against deforestation

Reform of agriculture might be it. Agriculture is also the leading driver of deforestation (50% of pastures were forested in the past).

> large scale reforestation will probably not affect CO2 very much either

But it could, it's probably the best tool in our arsenal. And it would not only affect CO2, but many of our other problems too (droughts, biodiversity, warming ...).

https://journals.plos.org/climate/article?id=10.1371/journal...

Rapid global phaseout of animal agriculture has the potential to stabilize greenhouse gas levels for 30 years and offset 68 percent of CO2 emissions this century

https://www.nature.com/articles/s41893-020-00603-4

Agricultural land use, particularly for animal feed, poses the biggest obstacle to ecosystem restoration and carbon sequestration, hindering climate efforts. The potential for carbon sequestration is vast, with enough capacity to meet the entire 1.5°C carbon budget.

https://www.theguardian.com/environment/2023/jul/04/improvin...

Improving soil could keep world within 1.5C heating target, research suggests. Better farming techniques across the world could lead to storage of 31 gigatonnes of carbon dioxide a year, data shows

https://phys.org/news/2023-04-climate-crisis-biodiversity-ap...

The climate crisis and biodiversity crisis can't be approached separately, says study

https://news.mongabay.com/2023/06/to-meet-u-n-climate-biodiv...

To meet U.N. climate, biodiversity goals, 79% of plant cover must be saved, study

https://ourworldindata.org/drivers-of-deforestation

Every year the world loses around 5 million hectares of forest. 95% of this occurs in the tropics. At least three-quarters of this is driven by agriculture – clearing forests to grow crops (upto 80% for animal feed), and raise livestock

https://ourworldindata.org/land-use-diets

If the world adopted a plant-based diet we would reduce global agricultural land use from 4 to 1 billion hectares (and free up an area the size of Africa).

[bryanlarsen]

> If the world adopted a plant-based diet we would reduce global agricultural land use from 4 to 1 billion hectares (and free up an area the size of Africa).

No we wouldn't. Everybody gets cause and effect backwards on this one. They see that we're using essentially all of our arable land for food production and draw the conclusion that's how much is needed to produce the amount of food we currently produce.

But it's actually the other way around. We use all the land available because that's the cheapest way to produce the amount of food we need. If we had more land, we'd use it and food would be cheaper. If we had less land we'd produce the same amount of food, but it would be more expensive.

For an extreme example, we could probably feed 8 trillion people on the same amount of land by covering all of our arable land with greenhouses.

[myshpa]

Moving towards a plant-based diet would mean needing less land as we wouldn't be raising as many animals for meat. The greenhouse idea is cool, but it'd be very resource intensive.

So, while we can definitely get creative with land use, we also need to consider the costs and environmental impacts.

[bryanlarsen]

No, it means that farmers will stop dumping so much fertilizer, herbicides and pesticides on their land chasing high yields. It means 30 bushel per acre crops instead of 100 bushel per acre crops. It means cheaper food. All good things, but land usage won't change significantly.