Climate
Change and
Coral Reefs
By: Maddie Renner
What is Climate Change?
• Climate change refers to the long term
effects on and patterns of change in
ecological and planetary systems due to
changes in the average surface
temperature of earth.
Some factors that are usually responsible
for climate change:
-variations in the earth’s orbital
characteristics
-atmospheric carbon dioxide variations
-volcanic eruptions
-variations in solar output
• In today’s world, humans are releasing a
growing concentration of harmful
chemicals into the atmosphere that in
turn, are changing the chemistry of the
earth that affect, among other things,
how the atmosphere works.
The Planet’s Energy Budget
• It all begins with the planet’s
energy cycle where solar
waves (of short wavelengths)
radiate toward earth.
• They heat the surface, and
then are re-radiated back out
to space (in longer
wavelengths of energy) to
keep the energy balance of
the planet.
• Stable surface temperatures
occur when the energy
coming in is balanced by the
energy leaving the planet.
• Illustration by Sarah O’Brien
“Heat Trapping” Molecules
(the so called Greenhouse Effect)
• The Greenhouse Effect determines how much
heat radiation can leave the planet
• Some incoming radiation is reflected back into
space blocked by clouds or reflected off the
surface from materials or ground cover that is
white or highly reflective (ice and snow)
• Radiation that penetrates the atmosphere is
absorbed by the oceans, forests, rocks, sand,
soil and other surfaces and converted to “heat”
• Heat, or infrared radiation, has longer
wavelengths and different characteristics from
the short wave radiation that originated from
the sun
• Infrared radiation can be absorbed by certain
gases in the atmosphere which behave as
“heat trapping” molecules. Too many and the
surface of the planet heats up (like the inside of
a greenhouse) since the heat can’t escape to
space.
• These “greenhouse gases” include carbon
dioxide, water vapor, methane, nitrous oxide,
and chlorofluorocarbons.
Illustration by Carolyn Vasko
How Climate Change is
Affecting Our Planet
• Warming our planet by increasing its surface temperature
• Melting polar ice caps which cause sea levels to rise
• Destroying ecosystems throughout the world such as coral reefs
• Depleting populations of certain organisms
Coral Reefs
• They are warm, clear, shallow, and salty ocean habitats that are rich in marine
life.
• Form from accumulated animal and plant skeletons that produce limestone
(well preserved in geologic record), and they are among the most diverse
ecosystems in the world.
• Require specific water temperature range (3-29 degrees Celsius) for optimal
growth.
• Three types: fringing reefs, barrier reefs, and coral atolls. Fringing reefs form
along the coastlines and on the continental shelf in shallow water. Barrier reefs
grow parallel to shorelines and further out, usually separated by a lagoon.
They are called barrier reefs because they form a barrier between the lagoon
and the seas. Finally, coral atolls are the rings of coral that grow on the tops
of old, sunken volcanoes. They begin as fringing reefs just surrounding the
volcano but as it sinks, it grows and sometimes, all that is eventually left is the
reef.
Examples of Coral Reefs
Throughout the World
• Fringing Reefs:
Frankland Island,
Indian Islands, Red
Sea
• Barrier Reefs:
Great Barrier Reef
(Australia)
• Coral Atolls:
Chagos
Archipelagos
How They Are Beneficial To
Humans
• The protect ocean shores from erosion
• Create products for medicines that humans use
• They protect shores from flooding (during natural disasters like
hurricanes)
• Provide popular tourist attractions that many economies depend on
Pictures of Coral Reefs
This is a picture of the locations of coral
reefs around the world.
Next to this is a diagram
of a location that a
fringing reef and coral
atoll might be located (on top
of a volcanic base).
This is a picture of the Great
Barrier Reef in Australia.
How Coral Reefs Are Being
Affected
• Corals Reefs are sensitive to changes to the environment and are
being affected by multiple stresses. Warming ocean temperature
due to climate change is one of many assaults but one, scientists
believe, impacts entire reef systems worldwide and jeopardizes their
ability to withstand the other assaults. The observations are that coral
reef systems are:
- Dying worldwide
- Showing signs of stress and disease
- Bleaching (when coral reefs eject the algae they need
to survive)
- Decreasing in population
What Is Destroying Coral Reefs?
• Human Activities (ship damage, harvesting for the aquarium
business, smothering by soil run off from deforested land which also
carry new pathogens, poisoning by cyanide fishing techniques)
• Global Warming (from fossil fuel use, which increases
concentrations of heat trapping gases which in turn warm the
planet’s ocean and air temperature)
• Water pollution
• Natural Disasters
• Bleaching (the coral’s reaction to stress)
• Increased ultraviolet radiation (from the loss of
protective ozone in the atmosphere due to mad-made chemicals)
Explanation For Destroying
Factors of Coral Reefs
• In addition to climate change effects, coral reefs are dying/being destroyed
because of water pollution, natural disasters (hurricanes), and other human
effects. They are also very prone to disease which can spread throughout the
reef.
• Physical and chemical changes can then occur due to increased sea-surface
temperatures, ultraviolet radiation, and other pollutants in the water.
• Diseases: The most common diseases that are affecting corals right now are
white-band disease, black-band disease, white plague, and yellow-blotch
disease.
• Coral reefs are mostly made of calcium carbonate. When carbon dioxide
dissolves in water, it makes carbonic acid, which causes calcium carbonate
to deteriorate. Therefore, the amount of carbon dioxide has increased,
increasing the amount of reefs being destroyed. This directly ties into climate
change because carbon dioxide is causing that too.
Bleaching
• Another main cause of coral reef death is bleaching. There has been an
increased amount of “bleached” reefs due to increase in water temperature.
• It has been discovered that just an increase of one degree Celsius will cause
the zooxanthellae to leave.
• The zooxanthellae are microscopic plants that color their tissues and provide
them with food from photosynthesis.
• When these tiny plants leave due to stressed reefs, the reefs turn white or
“bleached” and can then die. The Great Barrier Reef offers some of the most
vivid examples of “bleached” reefs. This world renowned reef is one of the
main attractions in Australia but is suffering from climate change.
Severity of Bleaching
• The severity of the bleaching has increased dramatically just from 1997.
Prior to that, monitoring of bleaching activity began in 1979. The chart
below shows how the number of reef provinces with moderate- severe
bleaching has fluctuated over a twenty year period.
Drastic Changes in Health of
Coral Reefs
• The picture below offers a clear A. B.
distinction between a healthy coral
versus one suffering from
bleaching. Certain places in the
world where the coral reefs are
suffering are the African coastal
zones such as Senegal, The
Gambia, Sierra Leone, Nigeria,
Cameroon, Gabon, Angola which
have low lying coast zones already
(susceptible to flooding). Flooding
and other natural disasters could
increase if coral reefs are then
destroyed (help from coastal
erosion). Places like Egypt are also
losing land for agriculture due to
sea-level rising. Specifically, the
Great Barrier Reef which I Figure 5. A. Coral showing normally
mentioned already, is suffering
from bleaching, and has been a pigmented regions and bleached regions to
main attraction in Australia. the upper side more sunlit side of
However, people need to be colony. B. Coral in shallows showing
careful because if we do nothing, it
could be completely destroyed. similar pattern. Photographer: O. Hoegh-
Guldberg.
What We Can Do To Help
• The effect of climate change on coral reefs is a serious and ongoing
problem. Reefs are constantly dying and, eventually, could be completely
extinct. We are the ones causing climate change and if we want our
ecosystems to survive, and thrive, we need to:
-Make sure people are aware of the ongoing problems with reef damage
and global warming
-Limit our greenhouse gas emissions by finding alternatives to fossil fuels
for energy and by using energy as efficiently as possible
-Proactively monitor human behavior which adversely affects our
environment
Resources
Herring, David. “Climate Close –Up: Coral Reefs” NASA Earth Observatory
Accessed: June 3, 2006
http://earthobservatory.nasa.gov/Study/Paleoclimatology_CloseUp/Images/coral_reef.jpg
Australian Institute of Marine Science
Updated: 2005 Accessed: January 8, 2006
www.aims.gov.au/pages/research/reef-monitoring/
George Mason University
Updated: 2004 Accessed: January 3, 2006
www.ceosr.gmu.edu/
National Oceanic and Atmospheric Administration
Updated: December 9,2005 Accessed: December 20, 2005
www.coralreef.noaa.gov/
Resources
National Oceanic and Atmospheric Administration
Updated: November 10, 2005 Accessed: 12/21/05
http://www.coris.noaa.gov/
Enchanted Learning Software
Updated: 2005 Accessed: December 20, 2005
www.enchantedlearning.com/biomes/coralreef/coralreef.shtml
Environmental Protection Agency
Updated: September 1,2005 Accessed: December 20,2005
www.epa.gov/owow/oceans/coral/about.html
Intergovernmental Panel on Climate Change
Updated: Accessed: January 6, 2006
Resources
National Oceanic and Atmospheric Administration
Updated: December 15,2005 Accessed: January 3, 2006
www.ncdc.noaa.gov/paleo/paleo.html
University of Queensland
Updated: 2001 Accessed: December 20,2005
www.reef.edu.org
Hoegh-Guldberg, Ove. The Coral Reef Research Institute- Sydney
Updated: 1999 Accessed: January 4, 2006
http://www.reef.edu.au/OHG/res-pic/HG%20papers/Hoegh-Guldberg%201999.pdf
Jason education Project
Updated:2004 Accessed: December 20, 2005
www.oceanworld.tamu.edu/students/coral/index.html
Quiz Questions
1. What is climate change?
2. What are coral reefs?
3. How are coral reefs being affected by global warming?
4. How are coral reefs beneficial to humans?
5. What is one of the main causes for the death of coral reefs?
6. What can we do to help prevent coral reefs from dying and
global warming in general?