Are human beings the one to make the world warm? : An investigation based on paleoclimate study.
It is often said that global warming is led by human activities. After the industrialization, the CO2 level has been rising extraordinarily in a few folds in such a short period of time. As CO2 is a greenhouse gas, it is generally believed that human is the killer of Earth’s climate and the weapon is the CO2 level.
However, is this general believe true? Is CO2 the crucial factor to change global climate? Is global warming really a outcome caused by human beings or the world is juts in an inevitable cycle? I am going to investigate more about this issue based on the study of paleoclimate.
(The proxy data)
Paleoclimate is the climate in the past. In the recorded history, there are too few data for us to investigate the relations among global temperature, global CO2 level, Oxygen isotope level, methane level, etc. In order to have a more broadened and reliable database for us to investigate paleoclimate, we might have to use the proxy data. Proxy data is data that paleoclimatologists gather from natural recorders of climate variability, e.g., tree rings, ice cores, fossil pollen, etc. In this essay, we will mainly use one of the proxy data, Ice core in Vostok, to let us know more about the previously mentioned relations.
The working principle of the proxy data (Ice core) is that the ancient air was trapped by the snow deposited on it and the snow later solidified. The chemical composition of the ancient air trapped may be experimentally recorded and later reveal the ancient climate after correlating their relations. Vostok is chosen to be a good position of reliable proxy data probably because of its low temperature throughout its past years. Snow is keeping on depositing on the land and helps the formation of ice core. A place without snow deposition will be quite difficult to do so in the same way.
Unfortunately, just having the chemical and physical compositions of the ancient air didn’t really help. The data is kind of messy and unsystematic. Then, the only thing we are going to do is to correlate the relations between the composition and some parameter such as global temperature. This is probably the main focus and also the most difficult thing concerned.
After knowing their relations, we can simply incorporate the relations into today’s observation and data. And then we might finally find out if human being is really the one who makes the world warm by considering if CO2 is the crucial factor for the occurrence of global warming.
In the Vostok proxy data, scientists have worked out the dust level, CO2 level and CH4 level in ancient years, up to 160000 years ago.
For CO2 and CH4, they are both greenhouse gases, we are firstly interested in finding which one is more related to the study of ancient global climate, i.e. Temperature. In order to investigate it, one has to work out the ancient temperature trend first and relate them with CO2 and CH4 concentration.
In fact, the temperature is related to the delta-deuterium and it might be worked out by the following equation:
Temperature(deg-C) = -55.5 +(§D +440)/6
Then, we estimate the degree of correlation between CO2 and Temperature, CH4 and Temperature. By comparing their R2 value, it is observed that CO2 has a higher degree of significant correlation with temperature. Up till now, one might suggest that CO2 may be a crucial factor which affect global climate.
After knowing that CO2 is more related to the global temperature, we should be interested in whether CO2 leads to temperature change or vice versa. It could be achieved by investigating the time relation between the changes of temperature and CO2 level in the past. If there is a significant time lag in between one of those, we might we be certainly at the edge of getting know which one is the cause of the other. Of course we will need...