Global Warming
Michael H. Fox
Why We Need Nuclear Power
The Environmental Case
"Some day the earth will weep, she will beg for her life, she
will cry with tears of blood.  You will make a choice, if you will
help her or let her die, and when she dies, you too will die."
John Hollow Horn, Oglala Lakota, 1932
The International Panel on Climate Change (IPCC) has issued a series
of reports beginning in 1990, with the latest appearing in 2013/2014.  
These panels present consensus scientific reports of thousands of
climate scientists and also consensus summary reports by scientists
and government officials.  While there is a small, vocal minority of
scientific skeptics, these scientific reports show without a doubt that
humans are affecting the climate of earth.  This is generally called global
warming but a better term is global climate change, since the climate
becomes more extreme, with hotter spells but also colder spells.  Tom
Friedman coined the term "global weirding" and it is perhaps the best way
to think about the changing climate.

The climate has always changed and skeptics suggest that humans have
no influence.  While it is certainly true that the climate has always gone
through warming and cooling phases, many scientists think we are
impacting the earth sufficiently to cause a new geologic era called the
anthropocene.  The primary reason is the dramatic increase in
greenhouse gases, especially carbon dioxide, methane and nitrous
oxide, that we have been producing over the last 100 years or so.  
IPCC 2007 Fig. TS-1.  Gas trapped in Antarctic ice sheets analyzed from ice cores.  
Shaded areas are interglacial periods.  Green is nitrous oxide, red is carbon dioxide
and blue is methane.  The black line is a proxy for temperature.  
Greenhouse gases GHGs) warm the earth by absorbing heat (infrared
radiation) emitted by the earth.  The more GHGs, the more the earth will
warm.  Previous periods of global warming shown above were caused by
periodic changes in the earth's orbit around the sun (the Milankovitch
cycle), not primarily by GHGs.  The recent increase in GHGs is
unprecedented in the 650,000 year record  shown above.

Carbon dioxide is the most important contributor to anthropogenic global
climate change because it is the most abundant, though methane and
nitrous oxide are more efficient at absorbing heat.  Since the industrial
revolution in the mid-1800s, humans have been pumping out increasingly
large amounts of CO2.