Somewhere there is flood, somewhere there is drought… Beware of the turmoil of the weather, more challenges are coming ahead, understand from the experts

We often find history in stories of war and peace. It is the power of history to connect us to the present. Climate history tells us how many layers the Earth has. It includes everything from the beginning of the biosphere to biodiversity. History keeps an eye on how we are disturbing nature’s balance. Climate events have doubled from 1999 to 2019. Between 1850 and 2022, we have burned fossil fuels, destroyed forests and polluted ecosystems, emitting billions of tons of greenhouse gases. Climate history is also warning us and can help us prepare for current challenges:

If the earth gets hotter it will not be tolerated

Dagomar DeGroot is an Associate Professor of History at Georgetown University in the US. In this exclusive interview with Srijana Mitra Das, he/she talks about climate change and its impact on the earth.

What is your research about?

I am an environmental historian. I work to understand past climate change, collaborate with scientists and experts to understand how climate change affected populations in different places, why some people lost the battle for survival and some won, and why some even managed to thrive. My job is to explore this and make sure that this information informs climate policy.

What sources do you use to find out this history?

To understand climate change, I turn to scientists. There are aspects of the natural world that record the effects of past climate change. For example, tree rings tell us how old a tree is. Depending on the climate, the pieces of these rings can be thicker or thinner. You can use their width to figure out how the climate changed during the tree’s lifetime. Ice sheets, like tree rings, accumulate gradually, layer by layer. In some places, ice melts in the summer, forming layers. The different isotopes in these layers can tell us the temperature of the entire planet. The heavier isotopes evaporate as the Earth’s temperature rises and then become part of the ice sheet. Researchers like me also use social archives. This can also be a weather report. In ancient times, educated people also kept weather diaries. Officers on ships recorded changes in wind direction and speed. Many historical books have described in detail the activities affected by weather. Such as the date of harvest, the time of sowing, when the cherry blossoms and when the battle field blossomed? etc. All these give indications about the weather. Archaeological remains give us information about material culture. While oral history tells about the climate verbally. If we combine all these different sources, we can find out how and how much our planet has changed.

When was it proven that humans are affecting climate processes?

Humans have been changing the environment for thousands of years. They’ve been changing landscapes, killing off large species of animals and developing agriculture. Some of the biggest changes came in the Western Hemisphere in the 15th century, when European colonists began killing millions of indigenous peoples. This left ancient farming and forest systems unable to survive long enough for tropical forests to grow back and remove carbon dioxide from the atmosphere. Industry led to the use of coal, oil and fossil fuels, which caused massive pollution. This releases carbon dioxide, methane and other greenhouse gases. The amount of greenhouse gases released into the atmosphere in the last 150 years exceeds the weight of all life on Earth and everything we have ever built. In the 1890s, Swedish chemical expert Svante Arrhenius wrote about how the growth of industry led to the release of warming gases into the atmosphere, raising the Earth’s temperature. In the 1930s, British engineer Guy Calendar discovered that the Earth was warming due to carbon dioxide.

Can climate history make people ‘smarter’ today?

The world could warm by about 3 degrees Celsius by the end of this century. That is extremely dangerous. Many of the events that led to the collapse of civilizations, including the Mayan civilization, happened when the climate was not changing so much. There are now 8 billion people on the planet. We must limit warming to 2 degrees Celsius because it is likely that we cannot tolerate it beyond that. We have recently seen heatwaves in India killing people. Climate history can tell a hopeful story, but only if we learn from it.

What is the solution to weather turmoil?

Mahesh Rangarajan is a professor of history and environmental studies at Ashoka University. Here he/she talks about India’s rich climate history and also discusses climate change.

Sometimes it rains, sometimes it’s scorching heat

Recently, some parts of the country have suddenly turned into places of heavy rainfall after a severe heatwave. A few days ago, Delhi, which was scorching with heat, experienced the highest heat in the month of June in 88 years. Then Delhi received such heavy rains that records were broken. The roads of the capital were submerged in rainwater. India has seen changes in the weather before as well, but now sudden changes are being seen more. The reason for this is global warming and increasing heat in the atmosphere.

Monsoon system in India

India is governed by a tropical and monsoonal system. It has distinct wet and dry spells. But now the dry spells have become exceptionally dry and very hot. This is becoming a difficult time for vertebrates. In addition, there is a lot of rainfall in a short period of time. Such periods, which affect human lives and resources, emphasize the importance of understanding climate history. Any subject of the past is seen through the lens of the present. Climate history traces how human civilizations have understood the nature of the biosphere over time, i.e. the blue-green layer in which all living organisms live.

How the agricultural cycle depends on rain

Humanity has depended on climate stability for thousands of years, including the Holocene (the present day began about 11,700 years ago), which is characterized by atmospheric weather and moisture conditions. This stability has made every society prosperous. And African societies feel the monsoon. In the past, this seasonal phenomenon had specific dates. When it increased or decreased, water enriched the earth accordingly. The stability of these dates shaped Indian civilization. Think about how our agricultural cycles are dependent on rain. The presence of water helped create cities. As conditions change, there is a possibility that a largely agricultural country will be in turmoil. Already, sowing and ripening times for crops like wheat are changing. This is due to changes in winter and rainfall. Many areas of India are agro-climatic zones, where different crops are grown. Unless we learn from our climate history, we will remain stuck in cycles of extreme heat and heavy rains. The impact of this can be huge. Heat waves in cities can increase if we do not adopt old ways of building cities. In contrast to concrete and deforestation, earlier we used to plant shade trees in cities. These include neem to peepal, tamarind to jamun. During monsoon, children used to eat the purple fruits of jamun trees and birds and small animals also liked them.

need to learn lessons from history

Learning from history, we must build wisely. There was a time when we had buildings with high ceilings or low-rise buildings with cross pantilation, which were heat-tolerant. But now we live or work in metal and glass towers. They trap heat and need air conditioning to cool them. As we add AC units, we increase urban heat. These intensify heatwaves. So traditional methods of construction were more sensitive to our eco-system.

When Delhi was facing water crisis

It is notable that Delhi was facing a water crisis before the recent rains and floods. To deal with this, we have to save wetlands. That place should not be acquired for building construction. Such places are necessary to absorb rainwater and revive underground water sources. Harini Nagendra and Seema Mundoli’s book ‘Shades of Blue’ analyzes water issues in different Indian cities. From Guwahati to Mumbai and Delhi, everyone has their own stories, yet one thing is seen everywhere. They are all drying up their wetlands, which increases the risk of drought in summer and floods in rain. In Delhi, floods in the last few years have affected those urban areas where earlier drains used to flow and there were old water channels. Construction has taken place here and in many places the channels going towards Yamuna have been closed. Actually, we should leave those places alone.

History is about learning from the past and informing the present. In the 17th century, India and Japan coped better with climate change than Europe. One reason was that the Indian elite valued nature. Before the British came, Indian rulers even gave people interest-free loans to build wells. The current heat and floods both show that Delhi must avoid losing its floodplains.