Transcript power point
CLIMATE CHANGE Describe what climate change is. This line graph shows the change in global temperatures the climate change over the more This over graph shows recent (the 20,000 years. It shows temperature course of 5.5 million years increase and atmospheric carbon dioxide. planet is 4.5 billion years old). The Is there a relationship between the two? information was found taking sediment cores. Years before present CLIMATE CHANGE Give examples of evidence that our climate has changed. Click on the image below to view the changing levels of carbon dioxide in the mid-tropospheric level of our atmosphere between 2002 and 2014 Carbon dioxide (CO2) is an important heat-trapping (greenhouse) gas, which is released through human activities such as deforestation and burning fossil fuels, as well as natural processes such as respiration and volcanic eruptions. The chart above shows CO2levels during the last three glacial cycles, as reconstructed from ice cores. CLIMATE CHANGE Give examples of evidence that our climate has changed. Click on the image to watch a 9minute video that shows the IPCC’s recent collation of evidence of global warming and climate change 1. How has the IPCC collected evidence? Describe these in detail 2. What are main contributors to sea levels rising? 1. How do scientists predict the future of climate change? CLIMATE CHANGE Give examples of evidence that our climate has changed. Long-term changes (over 1000’s of years) Medium-term changes (over 100’s of years) Short-term changes (over last 100-200 years) Ice core analysis Tree ring analysis In polar regions snow falls each year and becomes compacted over time into ice. Which builds up into annual layers. Ice can be drilled and records of temperature and atmospheric gases from thousands of years ago can be collected. Samples can contain ash, dust, gas , air bubbles and radioactive substances that are analysed to build a climatic record. A year-by-year record or ring pattern reflects the climatic conditions in which the tree grew. For example, a wide ring shows it was wet and warm but a narrow ring indicates a cold, dry year Recording changes in biodiversity Glaciers Glaciers are sensitive to climate change and will advance or retreat accordingly. They can be mapped to chart the extent of their growth. Different species of flora and fauna are adapted to specific environments and will move, adapt or die if climate changes. Ice extent Satellite imagery helps to show the annual summer and winter coverage of sea ice. Measuring sea and air temperatures Making a continuous record of sea and air temperatures show the average annual change. CLIMATE CHANGE Give examples of evidence that our climate has changed. Ancient trees can show climatic changes over 5,000 years (a bristlecone pine tree from California's White Mountains, is thought to be almost 5,000 years ) Does the tree core above show: • Dry and cold climate? • Warm and wet climate? CLIMATE CHANGE Give examples of evidence that our climate has changed. Sea level rise Global sea level rose about 17 centimetres (6.7 inches) in the last century. The rate in the last decade, however, is nearly double that of the last century. Shrinking ice sheets The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's Gravity Recovery and Climate Experiment show Greenland lost 150 to 250 cubic kilometers (36 to 60 cubic miles) of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic kilometers (36 cubic miles) of ice between 2002 and 2005. Declining Arctic sea ice Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades. . CLIMATE CHANGE Give examples of evidence that our climate has changed. Global temperature rise Most of this warming has occurred since the 1970s, with the 20 warmest years having occurred since 1981 and with all 10 of the warmest years occurring in the past 12 years. Even though the 2000s witnessed a solar output decline resulting in an unusually deep solar minimum in 2007-2009, surface temperatures continue to increase. Warming oceans The oceans have absorbed much of this increased heat, with the top 700 meters (about 2,300 feet) of ocean showing warming of 0.302 degrees Fahrenheit since 1969. Decreased snow cover Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and that the snow is melting earlier CLIMATE CHANGE Give examples of evidence that our climate has changed. Glacial retreat Glaciers are retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska and Africa. Extreme events The number of record high temperature events in the United States has been increasing, while the number of record low temperature events has been decreasing, since 1950. The U.S. has also witnessed increasing numbers of intense rainfall events. Ocean acidification Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased by about 30 percent. This increase is the result of humans emitting more carbon dioxide into the atmosphere and hence more being absorbed into the oceans. The amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by about 2 billion tons per year.