Ancient farmers spared us from glaciers but changed Earth's climate: study

And the whole ebook thing is quite frankly off-putting. There is a ton of hive mind/group think in this field which I find very off putting as well... I was at a Native Plant nursery and asked if they had any apple trees. Now as a computer programmer, permaculture is a hobby to me, I don't have the time to study it full time. But if I'm interested in something, I do read as much as I can about the subject. I had just read "Beyond the War on Invasive Species: A Permaculture Approach to Ecosystem Restoration" [0] which explores who defines native plants (pesticide industry) and why (to sell more pesticides).

So rather than having a friendly dialog, my request was met with a snarky and dismissive "Apple trees aren't native." I replied, "Define native." knowing this is actually a quite controversial subject.

But honestly permaculture is like any other field. There are some people who identify with their tightly held beliefs and don't question them. It bugs me but it doesn't take away from some of the great things are doing in this field. I've found that the best thing to do is to focus on people not topics.

For example, if someone asks me to learn Javascript. I tell them to focus on people like Eric Elliot, Douglass Crockford, Dan Abramov, etc. You will learn more doing guided learning from what they think is important than some random blog post on arrow functions. In the permaculture world, I recommend reading as much as you can from these people:

- Bill Mollison

- Elliot Coleman

- Mark Shepard

These people are great, and reading from them will produce more of a knowledge than any course. (Still recommend doing a course to meet other people interested in this stuff)... but some of the best recommended reading to me from permies wasn't about permaculture at all:

- Thinking in Systems by Donella Meadows - It is dry but well worth it. Permaculture in a way is systems thinking applied to environment. Understanding the underlying science is the difference between knowing Javascript programming and just knowing one Javascript Framework.

- Hard Rain by Tim Egan - Beautiful anthropological history of the PNW.

- https://www.nytimes.com/2016/08/08/opinion/against-sustainab...

- https://grist.org/article/doe-reprint/

- https://e360.yale.edu/features/environmental_failure_a_case_...

- https://monthlyreview.org/2002/09/01/capitalism-and-ecology/

I've found that people willing to dive into the science and areas that influence permaculture is the difference between someone who actually cares and someone who is an instagram farmer. And speaking of which, beware of biodynamics, it's a total pseudoscience [2] that people are starting to conflate that with permaculture. Biodynamic farmers will often tell you stuff like "oh it's like organic farming" or "You can do both permaculture and biodynamics". Maybe. But to me, new age mysticism isn't going to fix the environmental problems we have.

At the end of the day, the best way to learn permaculture is to get your hands dirty and start caring for plants. Even if you live in a city apartment with hardly any sun, treat it as a environment and find plants like peace lily's and devil's ivy that will grow just fine.

[0] https://www.chelseagreen.com/product/beyond-the-war-on-invas...

[1] https://en.wikipedia.org/wiki/Malus

[2] https://en.wikipedia.org/wiki/Biodynamic_agriculture#Effecti...

We're currently increasing CO2 in the atmosphere by 2 ppm CO2/yr or 350 times faster.

So he's not claiming that pre-modern agriculture had a huge impact on CO2 levels, but that those CO2 levels do have rather large climate impact over time. He does this by comparisons with prior ice age due to similarities in the precession of the Earth. The paper is about MIS19 which is 18 interglacials ago, which provides a good analog in the orbital properties, and which there is CO2 data for in ice cores.

That can then be correlated with the paleoclimate record showing glacial inception happening ~10,000 years after the maximum in MIS19. Using the actual paleoclimate data from MIS19 to control a GCM for MIS1 they run the GCM forwards from the glacial maximum and find that the mean global temperature falls by 1.2K and that the high Arctic cools by 5-6K with 3K falls in temperature over most of the Arctic and Siberia.

That paints a consistent picture where by right before the pre-industrial revolution the Earth should have been cooler and continental shield glaciers should have started forming across Northern Canada and Siberia. And this matches the paleoclimate record of MIS19.

If this seems counter intuitive at all, then your calibration of how much human impact is necessary to produce global climate changes (particularly over thousands of years) is likely off.

That also means that the argument that climate change will be beneficial is correct in a way, but pre-industrial humans already made that impact. We're well beyond the climate impact that would produce a consistent, beneficial boost to global temperature and are blasting the furnace.