Continental drifts, glaciations, and a period of dynamic changes -.an insight into a transition that caused a global turnover.

Why do we study the Miocene climate – an insight into the significance of Miocene climate

23 million years ago the Earth witnessed a global warmth relative to the present time. The planet resembled what it is today with a little change. With prolonged glaciations and continental drifts, the period reflected a large turnover in flora and fauna. Changing tectonic patterns altered several geographic factors across the globe. It’s quite interesting to know that not only do the present-day carbon dioxide levels match up the range reconstructed for the Miocene, but the ones projected for the future also fall in this range. Apart from this, the reconstruction of the Miocene period reflects several parameters that have a hand in the prediction of future climatic changes. Standing on the verge of climatic changes with several goals like net-zero, India today strives to attain sustainable development. Today, we are breathing in polluted air and are surrounded by pollution-related diseases. It is therefore very important to have a sneak peek into the history of climatic changes that occurred across the globe in the past years. And Miocene climate having a resemblance with the present times is of great significance to chalk out plans for sustainable development in the near future.

The phases of the Miocene period-

The Miocene period is broadly classified into three categories – the early Miocene, the mid-Miocene, and the late Miocene.

The Early Miocene changes- how did it begin?

Early to mid-Miocene changes include an overall rise in global temperature. It is said that the East Antarctica Ice glaciers had collapsed and owing to the tectonic organizations the low latitudes had their seaways closed which affected the climate in several ways.

However, it has been reconstructed that the middle Miocene saw global geography that resembled the present time.

Early Miocene climatic transition can thus be interpreted as the globe turning into a warm house

The Mid- Miocene changes- the transition

world maps depicting the boundary conditions for MMCT through colors

In the mid- Miocene, there was another transition of climate. The climate became comparatively cooler. It has been found that the middle Miocene was marked by a two-degree cooling of deep ocean temperatures. There was a rapid expansion of Antarctic ice sheets owing to the circulation changes in the deep ocean. Scientists call it the middle Miocene climatic transition(MMCT). Atmospheric carbon dioxide levels post MMCT was 380-420ppm.

The Late Miocene changes – towards the end

world maps comparing changes in the early and late Miocene phases

Post MMCT period is thus categorized under the late Miocene. The period was reconstructed as the time of global drying and cooling. Marked by large ecosystem changes, the period saw a dynamic change. It is said that the plants that used the C-4 synthetic pathway increased rapidly, hence causing an expansion of C-4 grasslands. There were changes in plant lineages and the landscapes across the subtropics changed drastically.

What could have caused such dynamic changes? Human activities?

The cause of these changes has been attributed to the dynamic changes of the carbon cycle which must have led to a transition in the transport of heat and moisture. It has been found that there was a change in the carbon isotopic ratio of oceans. Was it human activity or not is still a moot point.

Relevance of the Miocene climate to present times – why does it matter?

Assessing climate sensitivity is a heated debate today. We need to keep a check on climate change and the Miocene climate is a possible tool to do so. It provides a deep insight into the climatic variations and is an important aspect of global climate which cannot be neglected in any case. Today when we are heading to net zero, it is necessary to know what carbon emissions could do to the environment. We need to know how the environment reacts to carbon changes. Thus, the Miocene is a quintessential part of global climate change and its study.

Pooja kumari Sha

06/01/22