Since 1750 industrial activity has unearthed and burned approximately 500 billion tons of fossil fuels. The addition of this carbon, mostly in the form of carbon dioxide, into the atmosphere has caused the average global temperature to increase 0.8 degree Celsius (1.5 degrees Fahrenheit). Scientists are now projecting a global temperature rise of 4 degrees Celsius (about 7 degrees Fahrenheit) by 2100.
To most people, this seems a rather small increase in temperature to fuss over. We experience far larger increases and decreases in temperature every season and in some places, every day. A recent uptick in drought, floods, intense storms, wild fires, heatwaves, and blizzards, however, is blasting away the skepticism people once had and forcing the public to accept that climate change is not the future, it is the present.
Hurricane Sandy brutally shook the American people awake to the effects of climate change. These massively destructive storms are predicted to increase in frequency (once-a-century events could become once-a-decade or once-every-three-years) if greenhouse gas emissions continue at the current pace. Imagine having New York city blasted every three years with category 4 or 5 hurricanes.
In addition to intense rainfall from storms, a warmer planet produces more heat waves, which can cause wildfires, heat-related deaths, and drought. The US experienced the worst drought conditions in 50 years in 2012, an expansion of the 2011 record-breaking drought, with more than 2,000 counties designated disaster areas, and 80% of the US (not including Alaska and Hawaii) in abnormally dry conditions. Farmland was particularly affected, with half of the 2012 crops harvested in poor or very poor condition. Decreased food production will lead to increased food prices, globally, hitting low-income and poor families the worst.