Free Astronomy Magazine January-February 2022

35 JANUARY-FEBRUARY 2022 ASTRO PUBLISHING T he modern record of atmospheric carbon dioxide levels began with observations recorded at Mauna Loa Observatory in Hawaii. This graph shows the station’s monthly average carbon dioxide measurements since 1960 in parts per million (ppm). The seasonal cycle of highs and lows (small peaks and valleys) is driven by summertime growth and winter decay of Northern Hemisphere vege- tation. The long-term trend of rising carbon dioxide levels is driven by human activities. NOAA (climate.gov) image, based on data from the NOAA Global Monitoring Lab. electricity produced in a year comes from photovoltaics. It is understand- able that in the short term (decades) it will be impossible to counteract global warming, regardless of the willingness of the various govern- ments to share the provisions of the Intergovernmental Panel on Climate Change. There is also the possibility, currently controversial, that the cli- mate system will continue by inertia to fuel global warming, even if emis- sions were to be eliminated today. It could take centuries before natural balances are restored. However, one thing is certain: global warming has grown and will con- tinue to grow in tandem with the exploitation of our planet’s re- sources, an exploitation that is closely related to population growth. In the year 1700 (just before the be- ginning of the industrial era), there were 600 million human beings. A hundred years later, there were al- ready a billion. In 1960, the year in which global warming began to spike, the world population num- bered 2.5 billion. Now (end of 2021), one step away from our “point of no return,” we have exceeded 7.9 billion. In 2050, we will most likely reach 10 billion. By considering that we already consume the resources of 1.7 Earths in a year, how many billions of individuals must human- ity reach before cannibalism be- comes inevitable? T he graph shows the growing number of people living on our planet over the past 12,000 years. A frightening increase: the world population today is nearly two thousand times larger than it was 12 millennia ago, when it amounted to about 4 million people, half of the current population of London. !