The Case for Man-Made Climate Change

Have you ever walked up to your car on a pleasant afternoon and once inside realized it was a blast furnace?  You start to overheat and do not want to touch your hot steering wheel; this is greenhouse warming.  The brilliant sunshine through the windows warms everything in your car as it sat in the parking lot.  Once warmed, the steering wheel, seats-everything-start emitting heat (infrared radiation – IR).  Most of the heat (IR) gets reflected off the windows back into the car, starting the heat trapping effect, causing the temperature to soar.  This same effect applies to planet Earth, but instead of windows, gasses such as carbon dioxide, natural gas, refrigerants used in air conditioners and water vapor (clouds) reflect the heat (IR) back to Earth causing temperatures to rise.

The surface (land and sea) temperature of the Earth is constantly being monitored.  This average temperature over the 20th century (1901-2000) was 57 degrees F.  Since 1980, the average yearly temperature has consistently exceeded the 20th century average, with the 2020 average temperature being 58.8 degrees F, or 1.8 degrees F (1 degree C) higher.  This warming correlates with the increase in the level of carbon dioxide in the atmosphere.  The level was ~280 ppm (parts per million) during the Industrial Revolution (approx. 1750-1850) and in 2020 the level has risen to 413 ppm (a 1.5x increase), the highest on planet Earth for at least ~800,000 years (Homo Sapiens came on the scene 250,000 to 300,000 years ago).  To recap, the Earth’s 2020 average temperature has risen 1.8 degrees F above the 20th century average and the level of carbon dioxide has increased 1.5 times since the Industrial Revolution.  Like the windows of the car, the increased level of carbon dioxide is trapping heat causing the temperatures to rise.

How do we know that the increased level of carbon dioxide is leading to the temperature increase?  First, John Tyndall, 150 years ago, showed in lab experiments that certain gasses, like carbon dioxide, do absorb and then reradiate (reflect) heat (IR), acting as a car window on a sunny day.  Second, satellite measurements of temperature from 1979 to 2018 in the upper troposphere (the atmospheric layer closest to Earth where the carbon dioxide resides) show an increase between 1.1 and 1.4 degrees F compared to the lower stratosphere (the atmospheric layer directly above the troposphere), which show a decrease in temperature of 1.8 to 5.4 degrees F.  It’s become increasingly warmer below the atmospheric region which contains the carbon dioxide and increasingly cooler just above this region, directly indicating the greenhouse effect produced by carbon dioxide.  Last is the molecular nature of carbon dioxide itself.  The carbon in carbon dioxide takes different forms called isotopes (carbon 12 and carbon 13).  The lighter carbon dioxide, carbon 12, is readily taken in by plant life on Earth, called biocarbon (captured by nature and stored in organic life).  The heavier form, carbon 13, comes mainly from the Earth’s interior and volcanic activity.  Analysis done on the carbon dioxide in the atmosphere indicates that the heavier carbon dioxide (carbon 13) has been decreasing over the past thirty years, whereas the lighter form of carbon dioxide (carbon 12) has been increasing (now 413 ppm).  This is direct evidence that the increasing carbon dioxide causing global warming is coming from plant-based material (the burning of fossil fuels). 

In conclusion, it has been shown that carbon dioxide absorbs and then reradiates (reflects) heat (IR) acting as a greenhouse gas in laboratory settings.  It has also been shown that in the Earth’s atmosphere, the temperature below which the carbon dioxide resides has been increasing and above which has been getting cooler, directly providing evidence of the greenhouse effect.  Last, it has been demonstrated that the carbon in the carbon dioxide in the atmosphere comes primarily from organic (plant based) material, namely the burning of fossil fuels.  Fossil fuels are only used by us humans; thus, the inescapable conclusion is that global warming, climate change, is man-made (anthropogenic).  In a hot car, we instinctively roll down the windows to provide cooling (remove the greenhouse trapping glass). However, the solution for the Earth is to remove the greenhouse gasses, e.g., carbon dioxide, by drastically reducing the burning of the fossil fuels.