From the mid 1800s to the year 2000, scientists believe that the temperature of the earth’s surface has increased by around 0.6 Celsius, which is the highest level in recorded history. If the climate continues to change at the same pace, researchers warn that ice sheets of Greenland and Antarctic could start to melt and therefore raise the ocean levels leading to coastal flooding. Thus, researchers have worked tirelessly to find explanations to the growing problem of ‘global warming’, and understanding past climates by analyzing lake and bog sediments is one method of ‘learning from the past’.
Natural records of climate change
In the past, in search of climate related records, scientists looked towards glacial ice and ocean sediments as they hold vast amount of climate related proxies as against any other natural record. However, from recent times, scientists have recognize the importance of peat bog sediments and lake sediments as reservoirs of climate related proxies relating to millions of years of climate change.
Using bog sediments for understanding past climates
Peat is composed of organic matter left behind when herbs and other plants die and rot in shallow, acidic water. They can accumulate over many years in marshes and swamps if humans have not disrupted its natural evolution. The plant debris which forms peat bogs accumulate in layers and scientists are able to extract core samples from these bogs allowing them to analyze its contents which can give clues related to the temperatures, warm or wet weather, rainfall, colder or drier conditions and other similar information pertaining to a particular period of time. Although scientists believed that peat bogs may not be useful to understand climatic conditions at a distant site other than the location of the peat bog, from recent times, this notion have receded to a certain extent. The reason being that, peat bogs also harbor pollens that had been carried by the wind from distant places. Thus, analysis of pollens not only tells the story related to a particular area, but the climate story behind a region vaster than what was previously thought. At the same time, the ability to recognize the type of fossilized pollens in a peat bog has further expanded the descriptive ability of a peat bog in relation to past climates.
Using lake sediments to understand past climates
Similar to peat bogs, lake sediments have also gained the interest of the scientists who are seeking information related to past climates. According to them, lake sediments can preserve much more details pertaining to past climates because of its undisturbed nature. In general, the core samples of lake sediments can indicate the probable water temperatures during a certain period of time and therefore infer the probable atmospheric temperature during the same period. At the same time, the pollen grains that are preserved in lake sediments can also give valuable clues as to the climatic conditions that were in existence during that time.
Thus, it is apparent that lake and bog sediments are valuable sources of past climate information and further exploration of these entities might shed light to a more accurate description of the earth’s climate change that has been taking place for millions of years.