In the last 100 years, how has man significantly increased the level of #CO_2#?
1 Answer
Population, average lifespan, resource use, transport, etc.
Explanation:
Population was less than 2 billion in 1916 (http://www.scottmanning.com/content/year-by-year-world-population-estimates/)
There were wars, there were catastrophic events, diseases etc. Average lifespan of one average man was lower (compared to the today's).
Resources were not used excessively. There were 3.6 million cars in the USA in 1916 (http://www.scientificamerican.com/article/automobiles-the-reliable-motor-vehicle-1916-slide-show/). Today in the USA, there are more than 260 million cars.
The energy was not a big problem a century ago, but today we use a lot of energy for everything.
All these activities increased CO2 level in the atmosphere (from 302 ppm in 1916 to over 390 ppm (nowadays).
