The Blue Hills Meteorological Observatory in Milton, one of the oldest weather stations in the United States, has been collecting weather data since 1884. At that location, the average annual temperature has risen about 3 degrees Fahrenheit (F) in the past hundred years.
Carbon dioxide and other greenhouse gases in the atmosphere, including those from the burning of fossil fuels and other human activities, act like a blanket to warm up the Earth. The Sun's rays of visible light easily come in; but the infrared radiation that the Earth emits has a harder time getting out as the concentration of greenhouse gases increases. As a consequence, the atmosphere, on average, heats up, though actual changes vary by location. In Massachusetts, the average annual temperature has risen about 1 degree F in the past hundred years.
Another human-related phenomenon that is affecting the temperature in the Blue Hills and Boston is the urban heat-island effect.
Graph courtesy of Blue Hill Observatory and Science Center, East Milton, MA. http://www.bluehill.org/
