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 • A. B. The picture below offers a clear 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 pigmented regions and bleached regions to from bleaching, and has been a the upper side more sunlit side of main attraction in Australia. However, people need to be colony. B. Coral in shallows showing careful because if we do nothing, it similar pattern. Photographer: O. Hoeghcould be completely destroyed. 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 <http://www.grida.no/climate/ipcc/ > 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?