Featured Research

from universities, journals, and other organizations

The Woes Of Kilimanjaro: Don't Blame Global Warming

Date:
June 12, 2007
Source:
University of Washington
Summary:
Two scientists writing in a new magazine article say that global warming has nothing to do with the decline of ice atop Mount Kilimanjaro, and using the mountain in northern Tanzania as a "poster child" for climate change is simply inaccurate.

A photograph by Edward Oehler taken in 1912 (top) shows the extent of the icecap atop Mount Kilimanjaro, and a similar photo taken in 2006 by Georg Kaser illustrates the icecap's decline.
Credit: Edward Oehler / Georg Kaser

The "snows" of Africa's Mount Kilimanjaro inspired the title of an iconic American short story, but now its dwindling icecap is being cited as proof for human-induced global warming.

However, two researchers writing in the July-August edition of American Scientist magazine say global warming has nothing to do with the decline of Kilimanjaro's ice, and using the mountain in northern Tanzania as a "poster child" for climate change is simply inaccurate.

"There are dozens, if not hundreds, of photos of midlatitude glaciers you could show where there is absolutely no question that they are declining in response to the warming atmosphere," said climatologist Philip Mote, a University of Washington research scientist.

But in the tropics -- particularly on Kilimanjaro -- processes are at work that are far different from those that have diminished glacial ice in temperate regions closer to the poles, he said.

Mote and Georg Kaser, a glaciologist at the University of Innsbruck in Austria, write in American Scientist that the decline in Kilimanjaro's ice has been going on for more than a century and that most of it occurred before 1953, while evidence of atmospheric warming there before 1970 is inconclusive.

They attribute the ice decline primarily to complex interacting factors, including the vertical shape of the ice's edge, which allows it to shrink but not expand. They also cite decreased snowfall, which reduces ice buildup and determines how much energy the ice absorbs -- because the whiteness of new snow reflects more sunlight, the lack of new snow allows the ice to absorb more of the sun's energy.

Unlike midlatitude glaciers, which are warmed and melted by surrounding air in the summer, the ice loss on Kilimanjaro is driven strictly by solar radiation. Since air near the mountain's ice almost always is well below freezing, there typically is no melting. Instead ice loss is mainly through a process called sublimation, which requires more than eight times as much energy as melting. Sublimation occurs at below-freezing temperatures and converts ice directly to water vapor without going through the liquid phase. Mote likens it to moisture-sapping conditions that cause food to suffer freezer burn.

Fluctuating weather patterns related to the Indian Ocean also could affect the shifting balance between the ice's increase, which might have occurred for decades before the first explorers reached Kilimanjaro's summit in 1889, and the shrinking that has been going on since.

Glaciers in more temperate latitudes have declined sharply as the troposphere around them has warmed (the troposphere is the atmospheric layer from the Earth's surface to about 10 miles in altitude). The best example of a glacier declining because of atmospheric warming might be the South Cascade Glacier in Washington state, perhaps the most-studied glacier in North America. Photographs by government scientists in 1928 and in 2000, along with detailed surveys, showed that the glacier lost half its mass during that time. Similar evidence exists for a number of other glaciers, Mote said.

But in their analysis of already published research, Kaser and Mote say the same factors do not apply to Kilimanjaro's icecap, even though its decline has been cited in forums such as the Academy Award-winning documentary film "An Inconvenient Truth."

"There is no evidence to support that assertion," Mote said. "It's not that it is impossible, but rather the decline is most likely associated with processes dominated by sublimation and with an energy balance dominated by solar radiation, rather than by a warmer troposphere."

The volcano Kibo is the highest point on Kilimanjaro, about 19,340 feet above sea level. A rough survey in 1889 suggested that Kibo's icecap occupied about 12.5 square miles. By 1912, more than two decades before Ernest Hemingway wrote his masterpiece short story "The Snows of Kilimanjaro," it had dwindled to about 7.5 square miles. By 1953 it had shrunk to about 4.3 square miles and by 2003 it was at a little more than 1.5 square miles.

The level of nearby Lake Victoria, the world's largest tropical freshwater lake, also declined in the late 19th century, when the decline of Kibo's icecap began. The lake and the icecap likely suffer from a precipitation decline caused by Indian Ocean variability, which also could also have caused the icecap to vary in size and shape over millennia, Mote said.

"It is certainly possible that the icecap has come and gone many times over hundreds of thousands of years," he said. "But for temperate glaciers there is ample evidence that they are shrinking, in part because of warming from greenhouse gases."


Story Source:

The above story is based on materials provided by University of Washington. Note: Materials may be edited for content and length.


Cite This Page:

University of Washington. "The Woes Of Kilimanjaro: Don't Blame Global Warming." ScienceDaily. ScienceDaily, 12 June 2007. <www.sciencedaily.com/releases/2007/06/070611153942.htm>.
University of Washington. (2007, June 12). The Woes Of Kilimanjaro: Don't Blame Global Warming. ScienceDaily. Retrieved April 23, 2014 from www.sciencedaily.com/releases/2007/06/070611153942.htm
University of Washington. "The Woes Of Kilimanjaro: Don't Blame Global Warming." ScienceDaily. www.sciencedaily.com/releases/2007/06/070611153942.htm (accessed April 23, 2014).

Share This



More Earth & Climate News

Wednesday, April 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

UN Joint Mission Starts Removing Landmines in Cyprus

UN Joint Mission Starts Removing Landmines in Cyprus

AFP (Apr. 23, 2014) — The UN mission in Cyprus (UNFICYP) led a mine clearance demonstration on Wednesday in the UN-controlled buffer zone where demining operations are being conducted near the Cypriot village of Mammari. Duration: 01:00 Video provided by AFP
Powered by NewsLook.com
California Drought Is Good News for Gold Prospectors

California Drought Is Good News for Gold Prospectors

AFP (Apr. 22, 2014) — For months California has suffered from a historic drought. The lack of water is worrying for farmers and ranchers, but for gold diggers it’s a stroke of good fortune. With water levels low, normally inaccessible areas are exposed. Duration: 01:57 Video provided by AFP
Powered by NewsLook.com
Raw: MN Lakes Still Frozen Before Fishing Opener

Raw: MN Lakes Still Frozen Before Fishing Opener

AP (Apr. 22, 2014) — With only three weeks until Minnesota's fishing opener, many are wondering if the ice will be gone. Some of the Northland lakes are still covered by up to three feet of ice, causing concern that just like last year, the lakes won't be ready. (April 22) Video provided by AP
Powered by NewsLook.com
Scientists Warn Of Likely El Niño Event This Year

Scientists Warn Of Likely El Niño Event This Year

Newsy (Apr. 22, 2014) — With Pacific ocean water already showing signs of warming, the NOAA says there's about a 66 percent chance the event will begin before November. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins