Bits and pieces 10: Global Warming in Pictures
Science is about using observation and reason to understand the physical world. Some people are suspicious of computer models and theories; so here is some of the the basic data in pictures and graphs.
Ice Ages: In the past, the Earth’s temperature has varied from the Ice Ages to the much warmer temperatures of the interglacial periods. Ice core data gives a good picture of what has happened to the Earth’s temperature in the last half million years, as shown by the blue line. The changing temperatures are attributed to the Milankovitch cycles, small variations in the Earth’s orbit that cause the Earth to receive different amounts of sunlight. The Earth becomes slowly warmer during the periods where the solar energy increases. As the Earth begins to be warmed by sunlight, CO2 becomes less soluble in the ocean and the CO2 concentration in the atmosphere increases, which further amplifies the warming since CO2 is a greenhouse gas. The CO2 did not rise above 300 ppm in any of the the warmer interglacial periods but it is now 398 ppm and rising.
CO2: Man is now putting about 30 billion tons of carbon dioxide into the air each year. About half of it dissolves in the ocean, making them 20% more acidic, and the rest increases the concentration in the air.
Temperature: CO2 is one of the greenhouse gases that warm the Earth, and NASA’s graph shows how its increase is changing the Earth’s temperature:
The Sun: The current global warming is often wrongly attributed to an increase in intensity of the sun. The sunspot activity does not show up above the noise in the temperature record above – and the solar irradiance increased slightly until 1960 and has declined slightly since then.
Arctic Ice: Many of the changes in the Earth are subtle but this NASA picture clearly shows how the Earth is changing:
Arctic ice: The next two graphs show quantitatively how both the extent and the volume of the Arctic ice is changing.
Antarctica: Research by Steig and by O’Donnell show that Antarctica is warming. The warmer oceans result in more snowfall which increases the inland glacier mass, but the erosion of ice by the warmer oceans is causing an overall loss of ice mass.
Greenland: The Greenland ice sheets are also beginning to decline.
Ocean Level Rise: The melting ice sheets, melting glaciers, and thermal expansion are causing the oceans to rise by about 3 mm per year which, though it seems small, amounts to an increase in ocean volume of 1190 cubic kilometers/yr.
Severe Weather: Warmer temperatures increase both the rate of evaporation and the energy and moisture in the air. This has doubled the incidence of severe weather, floods, droughts, and wildfires.
Economic Costs: Large insurance companies such as Suisse Re now consider global warming a risk factor as there has been a fivefold increase in billion-dollar weather events in the last 30 years.
Droughts: The Palmer Drought Index below includes most of the continental areas used for food production. Zero represents average rainfall and -4 represents extreme drought. Since 1980, drought conditions have grown worse worldwide, and no one disputes the effect of droughts on food production.
Note : This was posted on 08/31/2011 and updated on 04/03/2012,08/11/2012, and o2/12/2013.
(c) 2011 J.C. Moore
Tags: Acidic Oceans, Antarctica ice, Billion-dollar weather events, Climate Change, CO2, droughts, extreme temperature probabilities., global Warming, Greenhouse Effect, ice-ages, james-hansen, Keeling Curve, Munich Re, NASA's temperature graph, Ocean level rise, Palmer Drought Index, polar ice melting, Solar irradiance, Sun, sunspot activity