Global warming

8.6.4 Describe the evidence that links global warming to increased levels of greenhouse gases.

Ice core data
By examining the timing and magnitude of their change during different climatic periods, a link between temperature and greenhouse gases may be established. As snow falls, layers are formed to eventually accumulate into ice. In it's solid form, gases are trapped in air bubbles. Isotopic analysis can be conducted on the air bubbles in an ice core layer to examine the atmospheric concentrations, allowinig the different types of gases that existed in a given time to be estimated. Furthermore, the temperature may be determined by the ice core and sediment cores. Ice cores provide direct climate information, but sediment cores do not. However, sediment cores provide indirect climate information; temperature. Sediment cores may be analyzed to sort out plankton shells that twist in various directions depending on the temperature of the water they grew in. Scientists count the number of shells and analyze them, and in that way they are able to determine the temperature at a certain time.

In the Russian Antarctic base at Vostok, over 420,000 years worth of ice cores are drilled to collect this history since 1957. Additionally, the study of ice cores can allow researchers to determine whether the Earth was going under global warming or cooling, and the change in temperature due to insolation(Earth moving closer or further from sun). The data collected from this research suggest the correlation between greenhouse gases and global warming.

external image iceCoreCO2deepest.jpg

Physics for the IB Diploma: Tim Kirk