The document discusses using dead pandas and honey bees as units to measure CO2 emissions, noting that 81 tonnes of CO2 is equivalent to 1 dead panda and 1g of CO2 is equal to 100 dead bees. It notes extinction rates of 140,000 species per year during the Holocene and estimates the number of pandas and honey bees that would equal those extinction levels. The main hypothesis is that human-caused CO2 emissions are directly responsible for mass extinction events and are an indicator of humanity's environmental impact. Specific CO2 emission figures like 34 billion tonnes per year are also included to provide context.