Although there is evidence that we can measure anthropogenic effects from pre-industrial times, we see the greatest anthropogenic effects from the beginning of the industrial revolution. It is human activity that is now pushing the planet to the sixth mass extinction:
- Atmospheric C02 has increased due to the burning of fossil fuels from 120 ppm before the industrial revolution to 400 ppm today.
- The amount of nitrogen and phosphorous in our soils has doubled due to agricultural products – an event unprecedented in 2.5 billion years.
- The age of nuclear experimentation during the 1950’s and 60’s has left an indelible mark of toxic radio isotopes on the world and facilitated what we today call carbon dating.
- In this graph taken from the IPCC’s fourth report (2007) we can see that in the last 2000 years concentrations of CO2, CH4, and N2O – three important long-lived greenhouse gases – have increased substantially since about 1750. This largely due to the increase in human activity from the beginning of the industrial revolution (1800).
- The current increases in these gases is largely due to a competition between emissions and sinks. However even as emissions increase we continue to destroy the essential sinks that counteract these. Of critical importance are the wildfires in the Amazon. These fires that are principally caused by illegal land grabs for agricultural expansion, and has affected one fifth of the Amazon – the world’s largest carbon sink.
- 20% of the amazon in now a net carbon emitter.
With these significant increases in anthropogenic factors we also see a huge reduction in species diversity:
- 1 million animal and plant species are now threatened with extinction, many within decades, more than ever before in human history.
According to this study:
- Humans make up just 0.01 percent of the biomass on Earth, but have managed to wipe out 83 percent of all wild mammals and cut the plant biomass in half during our time on this planet.
- When you look at mammals specifically, humans make up 36 percent of all the mammals on the planet, with just 4 percent being wild animals. This means that humans and their livestock make up 96% of mammalian biomass.
- Today, the biomass of humans and the biomass of livestock far surpass that of wild mammals.
- This is also true for wild and domesticated birds, for which the biomass of domesticated poultry is about threefold higher than that of wild birds. In fact, humans and livestock outweigh all vertebrates combined, with the exception of fish.
Let’s say that again. The biomass of humans and the biomass of livestock far surpass that of wild mammals. Most of this mass is the mass of animals that we slaughter for food:
- It is estimated that 72 billion land animals are slaughtered every year, that is 10 times the human population of this planet.
- Furthermore, although meat uses 77% of agricultural land (40 million square kilometers) it only makes up 18% of the global calorie supply.
- We also find a strong correlation showing that the greater the GDP per capita, the higher meat consumption.
Finally, as we can see here, there is a direct correlation between species extinction and human population growth:
Since the industrial revolution, and then at exponential rates since the 1960’s, we have destroyed species in favor of unrestricted growth.