Glaciers, Ice Ages & Oceans

1. Glaciers, Ice Ages & Oceans

2. Glaciers

3. Carstensz Pyramid In 1623, Jan Carstenzoon, was exploring the coast of New Guinea and Australia for the Dutch East India Company At that time, the Dutch controlled a very rich colonial empire, including Indonesia

4. Carstensz Pyramid On an exceptionally clear day, Carstenzoon could see from the ocean that the high, central peak on New Guinea was covered with snow and ice His discovery was ridiculed in Europe, since as everybody knows, snow cannot exist in the Tropics and New Guinea is on the equator

5. Carstensz Pyramid The Carstensz Pyramid is now known to be 16,023 feet (4,884 meters) high, which makes it the highest mountain in the Pacific Oceanic region

6. Carstensz Pyramid And yes, there are glaciers on the peak

7. Carstensz Pyramid The first photograph of the glaciers was taken in 1936 from the air and shows a series of small glaciers along the crest of the mountain By 1972, more than half of the ice had melted The glaciers are expected to be gone in our lifetime

8. Glaciers A glacier is a mass of ice that moves over land under its own weight, through the action of gravity

9. Glaciers Glaciers are divided into two types on the basis of size and occurrence Alpine glaciers are also known as mountain or valley glaciers Continental glaciers are also known as ice caps or ice sheets

10. Alpine Glaciers Alpine glaciers occupy valleys in mountainous terrain, most often at relatively high elevations They are the most common type of glaciers

11. Alpine Glaciers The World Glacier Monitoring Service, in Zurich, Switzerland, maintains a catalog of 67,000 alpine glaciers world-wide

12. Continental Glaciers Continental glaciers commonly occur on plains and relatively flat terrain They are categorized by size Ice caps generally cover less than 50,000 square kilometers Ice sheets are larger and can cover entire continents and reach thicknesses of over a kilometer

13. Antarctic Ice Sheet There are only two continental glacier ice sheets, the Antarctic and Greenland The Antarctic ice sheet covers an area larger than the 48 states and has trapped two-thirds of all the fresh water on Earth as ice

14. Ice Caps There are still many ice caps on Earth The Southern Patagonia Ice Cap in South America covers an area of 16,800 square kilometers The Vatnajökull ice cap in Iceland is easily seen in satellite photographs and covers 8,100 square kilometers

15. Where Glaciers Occur “Worldwide distribution of perennial surface ice on land. The map shows the approximate distribution of glaciers, ice caps and the two ice sheets from ESRI’s Digital Chart of the World (DCW), overlaid by the point layer of the World Glacier Inventory (WGI) and the polygons of the Global Land Ice Measurements from Space (GLIMS) databases (status June 2008).”

16. Where Glaciers Occur People tend to only associate glaciers with the extreme cold of polar regions, such as Norway, Alaska or the Antarctic As we have seen, glaciers can occur on mountain tops even in tropical or sub tropical climates Iztaccihuatl Volcano, Mexico

17. Where Glaciers Occur Likewise, glaciers can occur on mountain peaks in desert regions such as the Atlas Mountains in the Sahara Desert in Africa

18. Glacier Formation Glaciers are the product of precipitation Most glaciers start in the mountains as snow patches that survive the summer Slopes facing away from the sun, favor this survival So do gentle slopes, which allow the snow to pile up thickly, rather than being lost to avalanches

19. Glacier Formation As the snow accumulates, the weight of the overlying snow packs itself down into an intermediate form between snow and ice, called firn Finally, it is gradually transformed into a compact solid mass of interlocking ice crystals This conversion of snow into glacial ice can take only a few seasons or thousands of years depending on the climate and amount of snow fall

20. Glacier Movement Once the ice reached a thickness of 20-30 meters, the weight of the ice will cause it to flow under the influence of gravity The flow is always downslope

21. Glacier Movement Since alpine glaciers typically form on mountain slopes, they simply flow downhill However, the ice in continental glaciers flows from the thickest part of the ice cap or sheet out to the thinner edges (the glacier is trying to flatten itself out into a pancake shape)

22. Glacier Movement The ice in a glacier moves as a bendable, but brittle solid Glaciers flow at very slow speeds, typically a few tens of meters per year A glacier will flow down slope until it reaches a place that is warm enough to melt or evaporate the ice faster than it can flow or accumulate Or until it reaches the ocean

23. Calving When a glacier reaches the ocean, it tries to flow out over the water, but the rise and fall of tides causes the ice to break up, creating ice bergs by a process called calving

24. Ice Berg Yes, 90% of the ice in an ice berg is below water

25. North America and Glaciations Glaciers are responsible for much of the topography and near-surface geology of North America The Rocky Mountains and Sierra Nevada show abundant evidence of carving by glaciers

26. North America and Glaciations The Great Lakes occupy basins created by ice sheets The drainage pattern of the Mississippi River was established by carrying runoff from melting glaciers

27. The Snows of Kilimanjaro ... is a book by Ernest Hemingway A white hunter is burning of fever as he lays dying from an infection in the heat of the African plains, while the cool snows of Kilimanjaro are visible in the distance

28. The Snows of Kilimanjaro Kilimanjaro is 19,340 feet (5895 meters) high and dramatically ascends more than 3 miles (5 kilometers) above the plains of Africa

29. The Snows of Kilimanjaro It is a good thing that Hemingway wrote his book 70 years ago It hardly ever snows any more on Kilimanjaro and the glaciers are rapidly melting away

30. The Snows of Kilimanjaro Since 1912, 85% of the ice has disappeared Without new snow, the glaciers are doomed 1912 1996 2006

31. The Snows of Kilimanjaro Scientist now predicted that the glaciers will be gone by 2022 Some predict by 2015

32. Iztaccihuatl and Popocatepetl Only two small glaciers are left on top of Iztaccihuatl Volcano, in Mexico Some snow remains, but the glaciers on Popocatepetl Volcano in Mexico are gone

33. World-Wide Glacial Melting

34. DOUBLEXPOSURE documents one aspect of the warming climate through fine-art photography that brings the viewer into panoramas of glaciers once grand but now receding. The compelling comparisons put into stark view the fact of melting glaciers. DOUBLEXPOSURE has an exhibition of paired photographs and educational panels to be presented at museums and galleries across the United States.

35. Aug 12, 1938 Guyot Glacier, Alaska Jun 12, 2006

36. Aug 12, 1940 Hugh Miller Glacier, Alaska Jun 12, 2005

37. Aug 8, 1938 20 Mile Glacier, Alaska Aug 10, 2007

38. Ice Ages

39. Ice Ages An ice age is a period of long-term reduction in the temperature of Earth's climate, resulting in an expansion of the continental ice sheets, polar ice sheets and mountain glaciers There have been at least four major ice ages in the Earth's past and they typically last from tens to hundreds of millions of years The earliest hypothesized ice age is believed to have occurred around 2.9 billion years ago

40. Snowball Earth? Probably the most severe ice age, occurred between 710 to 630 million years ago and may have produced a “Snowball Earth” in which permanent sea ice extended to or very near the equator

41. Slushball Earth? While the presence of glaciers is not disputed, the idea that the entire planet was covered in ice is more contentious, leading some scientists to suggest a "slushball Earth", in which a band of ice-free, or ice-thin, waters remains around the equator

42. Warm Ages Between ice ages, the Earth is known to have had very warm periods “Between 52 and 57 million years ago, the Earth was relatively warm. Tropical conditions actually extended all the way into the mid-latitudes (around northern Spain or the central United States for example), polar regions experienced temperate climates, and the difference in temperature between the equator and pole was much smaller than it is today. Indeed it was so warm that trees grew in both the Arctic and Antarctic, and alligators lived in Ellesmere Island [Canada] at 78 degrees North.” - PBS Nova

43. Ice Ages The present ice age began 33 to 35 million years ago with the growth of ice caps in Antarctica It intensified starting around 3 million years ago with the spread of ice sheets across the Northern Hemisphere During those 3 million years, the world experienced cycles of glaciations with ice sheets advancing and retreating on 40,000 to 100,000 year time scales

44. Ice Ages The Wisconsin Glaciation was the most recent It lasted from 100,000 to 10,000 years ago and covered much, but not all of North America

45. What Causes An Ice Age? We now know that changes in the Earth's orbit around the Sun and changes in the tilt of the Earth’s axis cause ice ages Changes in the composition of the Earth’s atmosphere (such as green house gases and dust) also play a major roll

46. What Causes An Ice Age? Russian scientists have drilled to a depth of 3.6 kilometers in the Antarctic ice sheet and collected ice cores Information contained in these ice cores provide a history of the Earth’s atmosphere and climate

47. What Causes An Ice Age? These are the variations in temperature, carbon dioxide (CO2) concentration and dust in the atmosphere for the past 400,000 years as measured in the Antarctic ice cores

48. Oceans

49. Oceans and Climates Since the oceans cover 70% of the Earth’s surface, they obviously must have profound affect on both global and regional climates For example, the Gulf Stream not only warms the east coast of the U.S. but also the coast of England and Europe Also, the oceans are a natural “sink” for carbon dioxide, which is used by coral and organisms to create skeletons and shells

50. Oceans and Climates Most of the vigorous circulation of the oceans in confined to the near-surface waters Only the top 100-200 meters are well mixed by waves, currents and wind, and warmed and lighted by the sun The average temperature of this layer is about 15° degrees C (60° F)