Science is about using observation and reason to understand the physical world. Some people are suspicious of computer models and theories; so here is the basic data about global warming 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.
As you can see in the graph, the red line shows how intricately the CO2 concentrations and temperatures are related. The CO2 concentration drops to about 180 ppm during the glacial periods and rises to about 290 ppm during the warmer interglacial periods. As the far right of the graph shows, we are now in an interglacial period that began about 6000 years ago. The Milankovitch Cycles predict that Earth should slowly cool for the next 20,000 years, but it is warming instead. Please note that the concentration of CO2 did not rise above 300 ppm in any previous warmer periods but on the far right side of the graph, the red line indicating the CO2 concentration is now approaching 380 ppm. http://www.daviesand.com/Choices/Precautionary_Planning/New_Data/IceCores1.gif
Current CO2 Levels: In the past, the warming oceans released the CO2 as a natural process. However, man is now putting about 30 billion tons of carbon dioxide into the air each year. Much of it stays there and the Keeling curve below shows how CO2 is building up in air. What might that mean for man? In 2011, the CO2 concentration reached 387 ppm, far higher than it has been for perhaps 15 million years.
This article explains what the Earth may have been like then: ”The last time carbon dioxide levels were apparently as high as they are today — global temperatures were 5 to 10 degrees Fahrenheit higher , the sea level was approximately 75 to 120 feet higher, there was no permanent sea ice cap in the Arctic, and very little ice on Antarctica and Greenland.”
Earth’s Temperature: Carbon dioxide is one of the greenhouse gases that warm the Earth. NASA’s graph below shows how its increase is changing the Earth’s temperature. Though the Earth’s mean temperature varies widely from year to year, the graph on the right is a moving average that allows you to see the trend in the temperature much easier.
The effect of particulates, which cool the Earth, can be seen around 1991 when Mount Pinaturbo exploded. The flat place in the graph from about 1940 to 1970 is attributed to particulates generated by World War II, atmospheric atomic bomb testing, and postwar industrialization – before particulate emissions were regulated. Clearly, the Earth is getting warmer.
Record Temperatures: Nine of the 10 hottest years on record occurred in the last decade. The other record-breaking year was 1998. the chart gives the record temperatures for 50 years and the inset for the last last 160 years.
This has led to extreme heat waves in areas such as Moscow.
Effect on the Weather: According to NOAA, global warming is affecting the El Niño and La Niña ocean currents cycles which affect the weather patterns in North America. The cycles are occurring at higher temperatures and are becoming more unpredictable . Changes in ocean currents may be a major tipping point in climate change.
Effect on the Earth: Scientist tell us that the increasing CO2 concentration is leading to a warmer Earth, more extreme weather, melting glaciers and polar ice, crop failure, droughts, and wildfires. We have certainly experienced many of those things recently, which should make us think about what effect our activities are having on the Earth. Many of the changes in the Earth are subtle, but here are two of NASA’s pictures that clearly show how the Earth is changing. Between 1979 and 2010, about 30% of the Arctic ice has disappeared.
This has greatly affected the way of life of the native Inuit who live and hunt on the Polar ice. While they may adapt, their way of life and culture which sustained them for centuries will be destroyed. The Polar bears, uniquely adapted to live in on the Polar ice, have been put on the threatened species list because their habitat is clearly declining. As their habitat disappears, so will be the Polar bear. It is something man should think about – as our habitat is deteriorating, also.
Note: This was posted on 09/01/2011 and updated on 03/06/2013 to include data that was not presented in this more comprehensive collection of pictures and graphs of global warming data.
(c) 2011/ 2013 J.C. Moore