來自 Hong Kong
Let me try to explain my project in much more simple words than merely scientific data and wikipedias here.|
The project I am working on right now is about Paleocene-Eocene Thermal Maximum at 55.5 million years ago. It is a global warming in paleogene period that the global average temperature rose up 6-8°C in 200,000 years. The event was discovered by abrupt changed in C12/C13 ratio in the corresponding sedimentary core. The C12/C13 ratio is an indication of organic activity and carbon cycle. Since in organic production such as photosynthesis, life prefer taking up carbon-12 than carbon-13 in atmosphere and it generate a distinctive Carbon-12 and carbon-13 ratio in the earth environment ( in fact our study in UCLA suggesting life begin around 4.1 Gya on earth is based on the carbon-12/carbon-13 ratio stored in a zircon crystal stored in Western Australia). Since the carbon-12/carbon-13 ratio can be affected by increased or decreased organismic production, a sudden drop of the ratio can infer a sudden reduce in organismic activities suggesting an extinction event may occur.
Apart from carbon ratio, the oxygen-18/oxygen-16 ratio is also recorded in the sediment. Since oxygen 16 is lighter than oxygen 18, the water molecule with oxygen 16 is more likely to evaporate in the hydrocycle, as a result the change in oxygen 16 ratio can tell the change in hydrocycle and from the hydrocycle we can estimate the climate and temperature of the time period. Since water with oxygen 16 is easier to evaporate and precipitate, the ice formed in glacier contain more oxygen 16 than oxygen 18. During glaciation advance in the ice age, since more oxygen 16 is stored in the ice in glacier, the oxygen 18 ratio in the ocean in higher. As a result a higher oxygen 18 refer to lower temperature as the oxygen 16 is stored in places like glacier.
my project is basically used the carbon and oxygen isotope ratio to study the temperature variation and carbon cycle at that period and to find out the effect of rapid climate change to evolution and extinction of life in the PETM effect. Since it is a climate model for global warming, the result of the paleoclimatology study can be compared and interpreted with the current climate change and it can be used to find out the solution to prevent further extinction of current species from human-generated climate change. My presentation of this topic also include the application of paleontology to solve current issue and crisis iwe facing now.