What can we learn about climate change by studying the climate of the past?
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Predicting the weather is a complex science. Predictions become less accurate as the range of the forecast increases. So how have scientists managed to learn what the climate was millions of years ago? And why is this important today? Scientists convened at the Smithsonian National Museum of Natural History. They got together last spring. They pieced together what the climate was like throughout Earth’s history going back millions of years. Their findings help explain paleoclimate. And they also provide useful models. These models help them understand and predict present and future climate change.
Scientists have a wide array of models and proxies. These are at their disposal to study ancient climates. For example, models can be used to simulate the weather millions of years ago. The late Jurassic was 150 million years ago. Paleoclimate models may use changes in solar constant and continental configuration. They also may use the amount of carbon dioxide. This can provide a kind of weather forecast for dinosaurs. These can be averaged to approximate the climate of the time.
The archeologist studies artifacts. Paleoclimatologists study different types of environmental evidence. They reconstruct previous climates. Fossilized plankton contain evidence of the environment in which their shells were formed. The chemical composition of the shells alters according to temperature. In this way, ocean temperatures are imprinted in the fossil records. It can be read using chemical analysis.
Skeletonized marine invertebrates include clams and snails. They also include coral. They also reflect the environment in which they develop. Approximates of the temperatures in which they grew can be recovered. This data can revealed by analyzing their chemistry. Growth rings are like the rings of a tree. They show development over a number of years. There may be variances in the chemical composition between consecutive rings. These illustrate seasonal variation. Thus, we can get a picture of how hot the summer was and how cold the winter was millions of years ago.
The scientists and climate modellers convened in the spring of 2018. They combined their research. They created a graph. It showed how climate and temperature changed throughout Earth’s history.
But how does looking back millions of years help us predict future climate? For one, these studies provide evidence of how different climatic factors come together. And it shows their various consequences. For example, scientists study the fluctuations of carbon dioxide over time to understand the effects of carbon dioxide on climate and sea levels.
The Devonian era was 400 million years ago. In that era, carbon dioxide levels were approximately four times what they are today. Carbon dioxide levels similar to those observed today were last seen 3 million years ago – a time when there was no ice on Greenland. What happened the last time carbon dioxide levels were as high as scientists predict they might be by the end of the century? There was no ice in Antarctica. This would produce a 60 m difference in ocean levels (approximately 197 ft.). Paleobiologists provided a model reconstructing historical climate change.
It helps us understand different environmental processes and predict the effects of future climate change.
Funding for the Earth’s Temperature Curve Symposium, on which this article is based, was provided by Roland and Deborah Sauermann.