Evidence of Global Warming*

by

J. Ernest "Sunny" Breeding, Jr., PhD Geophysics

Examples in Polar regions

There are many examples of global warming in all parts of the Earth. But none are more clear than those found at the higher latitudes. The polar regions are the first to show the effects of climate change.

Fig. 2.1. Muir Glacier in Alaska. Picture on the left was taken in August 1941 and the one on the right in August 2004. (NSIDC of NOAA) See References for the sources of figures.

A good example of the retreat of a glacier is seen in Fig. 2.1. The picture on the left of Muir Glacier was taken by William O. Field on 13 August 1941 and the picture of the same area was taken again by Bruce F. Molnia on 31 August 2004. The glacier is found in a park west of Juneau, Alaska. In the 63 year period the glacier retreated by more than 7 miles (12 kilometers) and its thickness decreased by 875 yards (800 meters) according to Molnia of the United States Geological Survey (USGS).

Fig. 2.2. Glacier decline. (USGCRP)			Fig. 2.3. Length variation of glacier tongues. (IPCC)

The total loss in glacier ice since 1960 is shown in Fig. 2.2. The amount is huge. To comprehend the amount think of a room with a floor that is a mile (1.6 kilometers) on each side and that the height from the floor to the ceiling is also one mile. The volume of that room would be one cubic mile. Since 1960 we have lost about 2,250 rooms that size of glacier ice. Fig. 2.3 displays the loss in the length of glacier tongues since 1700. The important thing to note is that the result is nearly the same for the Atlantic, Alps, Southern Hemisphere, Asia, and Northwest America. This is a world wide phenomena. Note that the values are zero for 1950 since the data for all years were compared to the 1950 values.

Fig. 2.4. Loss in Arctic sea ice. (USGCRP)

The loss in Arctic sea ice is quite dramatic as seen by comparing the pictures taken in 1979 and 2007, which are presented in Fig. 2.4. The amount of sea ice that has been lost by 2010 was not expected to happen until about 2040. That is alarming, and shows the climate is changing faster than expected. A fascinating look at some of the ongoing research in the Polar Regions is described in a video by Dr. Robin E. Bell and other scientists at the Lamont-Doherty Earth Observatory of Columbia University.

Fig. 2.5. Rise in sea level. (IPCC)			Fig. 2.6. Thawing permafrost. (livescience.com)

With the melt water of glaciers and ice sheets draining into the oceans the mean sea level has risen. In Fig. 2.5, which shows data from several different investigators, it is seen that the mean sea level has risen by about 8 inches (200 millimeters) since 1870. Considering that about 70% of the globe is covered by the oceans, that is a lot of melt water. A disturbing fact is that sea level is now rising at the rate of 1.2 inches per decade (3 centimeters per decade). This is twice the rate during the twentieth century (Hansen, 2009.) If our planet ice continues to melt at an ever increasing rate or breaks up into more and more icebergs, which is likely, the future of coastal cities and other costal developments are in doubt unless the trend can be reversed.

The picture of the railroad tracks in Fig. 2.6 was taken in the northern Tibetan Plateau. The tracks became useless because of thawing permafrost; what was once a solid footing is not anymore. In Alaska there are homes and other buildings that are now collapsing because the permafrost is thawing. The ground had been solid for so many years, many thousands, that no one expected the permafrost to thaw.

Fig. 2.7. Penguins. (USGCRP)			Fig. 2.8. Drought and famine. (USGCRP)

Creatures and plants of the Earth are severely affected by climate change because they require a narrow range of environmental conditions to survive. Penguins are pictured in Fig. 2.7. The Adelie Penguins near the Antarctic Peninsula are suffering because of the rapid increase in warming and the subsequent loss of sea ice. Because of the loss of sea ice the Krill they eat is less available to them. The loss of sea ice in the Arctic Ocean has created a similar problem for polar bears, which use the sea ice to hunt for seals. Some species of seals are also in danger. Due to the longer and longer summers the ice-free time has lengthened, which is not good for polar bears, penguins, and some other animals. The loss of sea ice also means less protection of the coasts from storm waves, leading to erosion of land.

Examples in Temperate and Tropical regions

Temperate and tropical regions also show evidence of global warming. Fig 2.8 is a picture where there is drought and famine. One of the most discussed places for this is the Sahel desert in Africa, south of the Sahara Desert. The Southwest in the United States has also experienced drought. In both cases global warming is thought to be a factor. It is also necessary to take into account the Southern Oscillation (El Nino and La Nina), which has had a major impact on climate in many parts of the world for many years.

Fig. 2.9. Phoenix is hotter. (USGCRP)			Fig. 2.10. Dead trees. (USGCRP)

Many places are experiencing more hours of hotter temperatures than in the past. In Phoenix the average number of hours per summer day that the temperature exceeds 100 degrees Fahrenheit (37.7 degrees Centigrade) has doubled in the past 50 years. Fig. 2.10 is an example of dead trees. This can result due to drought. But increasingly some trees are being killed by bark beetles. These insects cannot survive a cold winter. But with the milder winters the bark beetles are surviving in greater number and are destroying some of the whitebark pine trees in Yellowstone National Park. The same thing is happening to the white spruce forests in parts of Alaska. The mild winters are also affecting the harvesting of maple syrup in New England. The problem is fewer nights with below freezing temperatures. The proper environment for harvesting maple syrup is moving north into Canada. With shorter winters the growing season for many crops has been increasing in length. Vineyards are now possible where they were not before. These are all examples of climate change.

Fig. 2.11. Butterfly. (USGCRP)			Fig. 2.12. Coral. (USGCRP)

Butterflies, birds, amphibians, and reptiles are other examples of creatures that must adjust to a changing climate. A butterfly is pictured in Fig. 2.11. In Europe the Apollo butterfly has been slowly moving to higher elevations in the mountains to find the temperature range it needs. In the Monteverde Cloud Forest of Costa Rica, one of my favorite places, the orange-billed nightingale thrush has moved to higher elevations as the temperature has warmed. Some animals and plants are moving to higher latitudes to find the environmental conditions that they need and have been accustomed to. The rate of movement has increased in recent years as the Earth has been warming at a faster rate (Hansen, 2009.) Once these critters and plants are no longer able to find the environmental conditions they need they will have to adapt to a warmer world or they will join the many species that are now extinct.

The oceans also have clear evidence of global warming. Coral reefs, seen in Fig. 2.12, are very fragile ecosystems. They can be damaged and even killed by very warm temperatures. In the process they change color to light yellow or white, which is called coral bleaching.

There are many more examples of climate change from all around our planet to numerous to mention here (Burroughs, 2007; Henson, 2008; Hansen, 2009, 2011; and Schmidt and Wolfe, 2009.) But it should be clear from what is presented above that the Earth is warming, and the consequences are not good.

We need data that defines climates of the past to compare with the present. This is accomplished by a rather impressive set of measurements. We look at that next.

Pages

Page 1: Climate Change and Definition
Page 2: Evidence of Global Warming
Page 3: Measurements
Page 4: Ice Ages
Page 5: Causes of Climate Change
Page 6: Predicting the Future
Page 7: How Can We Fix Our Climate?
Page 8: References

*A slide show version of these pages on climate change is available for presentations to groups. See References for more details.

 

 

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