Humans, Fire and Evolution of the Biosphere


My original hypotheses on this blog, were derived from an inspection of various graphs about the evolution of the climate over the last 65 Myrs, and I based my conclusions on this and knowledge I had about geology and human evolution.

I came to the conclusion that AGW was both an integral component of the earth system and a desirable outcome. I have appended some references below, with links. Link 3 is a discussion of human evolution in Africa, and the contention that human evolution was driven by climate (ice ages). Link 4 is a new in-depth paper with new correlations to changes in climate specifically transitions between wet and dry climates.

These are not new contentions, although the second paper has a detailed set of evidence based correlations. I do not intend to discuss either of these papers in any more depth but urge the reader to check them.

The information in the links 1 & 2 contain new information to me which I believe supports my previous ideas. In paper 1 the authors show that arriving waves of colonisation in new lands transform the vegetation from temperate forest to grassland, and discuss the implication of anthropogenic habitat change by the use of fire. This article contains numerous references to papers on fire ecology. One of the interesting ideas is that grassland habitats are then maintained by ecological processes

‘recurrent landscape firing can cause ecological systems to rapidly switch from one state to another and that ecological feedbacks provide strong resistance to a return to the predisturbance state’

Paper 2 is only available as an abstract but indicates that alteration of the biosphere by human use of fire could have started as long ago as 300 kyrs in Africa, followed by a large increase in fire ignition frequency coupled with population growth after 70 kyrs.

I believe that:

Because of our intelligence and use of tools, including fire we have mastered our own environment, and as an outcome of our deforestation of the earth and our use of fire we have added CO2 to the atmosphere. As the temperature warmed up at the start of the last interglacial, the growth of human populations across all continents, altered the biosphere, and these contributions tipped the balance.

The younger dryas was a cold period at the start of the Holocene, my contention is that this should have been the start of the next glacial, which would then have lasted about 100,000 yrs.

It’s possible that the longer than usual interglacial 100,000 yrs previously may have been caused by a similar human intervention, but the neanderthals didn’t make the next steps to farming and industry, so this attempt failed.

It appears that human adaption into every available niche and our attempts to keep warm and use the environment serendipitously saved the planet by eliminating the ice ages. If you don’t believe me look up snowball earth and see what could have happened

http://www.pnas.org/content/107/50/21234.full.pdf+html

Paradise burnt:

How colonizing humans transform landscapes with fire

http://www.pnas.org/content/early/2011/12/13/1118648109.abstract

Evolution of human-driven fire regimes in Africa 

http://anthro.palomar.edu/homo/homo_3.htm

Climate change and Human Evolution

Many animal species were driven to extinction by the advancing and retreating ice ages.  Humanity survived primarily by becoming more intelligent and adaptable.

http://www.pnas.org/content/108/51/20422.full?sid=f732f2d6-9aeb-4a7a-95db-e25460f99274

Nonlinear detection of paleoclimate-variability transitions possibly related to human evolution

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About madmikedavies

Retired Communications Engineer, living in Portugal. Interests are Cosmology, Earth Sciences, Organic farming, Climatology, Football, Golf, Birdwatching, and Dogs
This entry was posted in Climate change, evolution and tagged , , , , . Bookmark the permalink.

5 Responses to Humans, Fire and Evolution of the Biosphere

  1. Very good! It took me 3-4 years of extra study to come to these (basically) same conclusions. Thanks for sharing. I will be reading more…. ~SA p.s. Do you know of the Cycle of Fire books by Stephen J. Pyne; and of course 1491 (by Ch. Mann)?

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    • Sam,
      I started off my journey, by assuming that the global temperature record could be read like a calibration graph, and wrote my first paper Modelling the Earth as a Thermal Amplifier. This lead me to the belief that evolution of humanity was both in response to climate change and necessary for control of the climate. Human intelligence and our use of fire to terraform the earth was the missing ingredient which made AGW the dominant componenent of the climate over 10,000 years ago.«Catastrophic climate change» made the earth more productive and stopped what would have been the next glacially induced mass extinction. For better or worse humans now control the climate, and have also restored low climate sensitivity, so going forward climate changes will be less extreme. High climate sensitivity is only evident at glacial/interglacial/glacial boundaries

      Mike

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  4. Pingback: Humans, Fire and Evolution of the Biosphere | Madmike Davies Climate Blog

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