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Global Warming May Cause Sea Levels to Rise 34 Centimeters by 2100
January 27, 2006 — By Michael Casey, Associated Press
BANGKOK, Thailand — Global warming will cause sea levels to rise up to 34 centimeters (11 inches) by
the end of the century, causing increased flooding and coastal erosion, according to a new study by
Australian researchers. The study -- published in this month's issue of the journal Geophysical Research
Letters -- said global warming was expected to further heat up the world's oceans and cause glaciers in the
Himalayas and ice sheets in Greenland to melt. The study estimated sea levels would increase between 28
centimeters (11 inches) to 34 centimeters (13 inches) by 2100.
"What we found is that sea levels are rising and increasing with time," said John Church, a co-author of the
study by the Commonwealth Scientific and Industrial Research Organization, the Australian government
main research body. It means there will be increased flooding of low-lying areas when there are storm
surges," he said. "It means increased coastal erosion on sandy beaches. We're going to see increased
flooding on island nations."
Most scientists believe greenhouse gases from human activities like coal-burning power plants cause
global warming by trapping solar heat in the atmosphere. Greenhouse gas emissions should be reduced by
50 percent by 2050, Church said.
"If not, climate change will continue and increase in magnitude," he said. "I think governments around the
world, including Australia, have started the process, but there is a long ways to go and I would argue that
it's urgent.“
Clive Wilkinson, coordinator of the Global Coral Reef Monitoring Network, a nongovernment group that
follows closely developments on rising seas, said the findings were in line with what many scientists have
predicted about global warming. "It fits a pattern that everyone is coming up with," Wilkinson said. "It
means we are in real trouble. If you add another meter (yard) over coral reefs, it won't notice it. But the
rising water would flood any low-lying areas. Coral island like Tuvalu, Maldives and Kiribati will become
uninhabitable."
By examining tidal data, Church said sea levels rose by 19.5 centimeters (7.7 inches) between 1870 and
2004. The increases accelerated with time, averaging 1.7 millimeters (0.07 inches) a year in the 20th
century and 1.8 millimeters in the past 50 years. Church said sea increases were previously estimated
based on climate change models. He said his team's research was the first to document rises based on
extensive historical tidal data, allowing predictions on sea-level increases to be made with greater
precision. Many island nations are already feeling the impact of rising seas. In Vanuatu and Papua New
Guinea in the southwest Pacific, increased sea levels have forced hundreds of islanders to abandon
vulnerable coastal homes for higher ground, according to the United Nations and news reports. The 1997
Kyoto Protocol mandates specific reductions in emissions of carbon dioxide and five other gases by 2012
in 35 industrialized countries that are blamed for causing the warming of earth's atmosphere. The U.S. and
Australia rejected the treaty in part because they feared mandatory cuts would cause economic hardship.
Church said containing greenhouse gas emissions would help stem increases, but added sea levels would
rise nonetheless. "We do have to reduce our emissions but we also have to recognize climate change is
happening, and we have to adapt as well," Church said.
1/R2 law – Demo by Scott Kittelman
Short Question 3
A planet that has the same radius and
albedo as Earth, but is 5 times farther
from the Sun, will receive:
(c) 25 times as much solar energy
(b) 5 times as much solar energy
(c) the same amount of solar energy
(d) 1/5 as much solar energy
(e) 1/25 as much solar energy
Energy balance – incoming radiation
Box Fig. 3.1
Energy balance – outgoing radiation
Elongwave = σTe4 x (surface area)
= σTe4 x 4πRe2
What about albedo? (Demo by Scott Kittelman)
Clouds and ice are bright, reflect radiation (albedo close to 1)
Oceans and trees are dark, absorb radiation (albedo close to 0)
Deserts are relatively bright (somewhere in between, but
closer to 1 than 0)
Think of possible feedbacks if Earth’s temperature changes
Project 1 (approximately 2 pages, double spaced)
Due next Friday (February 3)
As you are traveling around CU and the Boulder
area, observe three examples of ways in which the
natural environment has been changed by human
activities. Discuss how the environment has been
changed and speculate about how the environment
might be different if the changes had not occurred.
σTe4 x 4πRe2 = Se (1-A) x πRe2
Te = [Se (1-A)/(4σ)]1/4
where
Te is called the ‘effective temperature’
Re is radius of Earth
Se is solar flux at Earth
A is albedo (fraction of light reflected back to space)
σ is Stefan-Boltzmann constant
Atmospheric Composition
How molecules interact with infrared light
Fig. 3.12
How absorption of infrared light emitted by the earth varies
with wavelength
Fig. 3.13