Global Warming in Pictures
Published 04th September 2011 - 0 comments - 1786 views -
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 and the Milankovitch Cycles predict that Earth should slowly cool for the next 20,000 years - but it is warming instead. The red line on the far right side of the graph shows that the concentration of CO2 is now approaching 390 ppm, far higher than 300 ppm observed in any previous warm periods.
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. In 2011, the CO2 concentration reached 387 ppm, far higher than it has been for perhaps 2 million years.
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.
Effect on the Earth: Scientist tell us that th 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 shows how the Earth is changing. Between 1979 and 2003, 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.
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