Asian Monsoon 3: The Asian Monsoon and the Great Rivers of Asia

Summary

Professor Peter Clift from Louisiana State University explores the unique characteristics of Asia's great rivers, their significance to agriculture and civilizations, and their connection to climate change and tectonic activities. He explains how the uplift of the Himalayas and the Tibetan Plateau influenced river courses, particularly the Yangtze's dramatic course change due to the India-Asia collision. The monsoon's impact on river sediment flow and the potential effects of global warming on these waterways are also discussed, highlighting the rivers' critical role in sustaining billions and shaping the continent's history.

Takeaways

• 🌏 The Asian monsoon and its changes over time are linked to the uplift of the Himalayas and the climate of Asia.
• 🏞 Southeast Asia is home to some of the world's largest rivers, which are significant for delivering sediment and nutrients to the ocean and supporting agriculture.
• 🌾 The Mekong delta and the Yangtze River are particularly important for food production, serving as vital sources of water and nutrients for agriculture.
• 💧 The importance of these rivers to human civilizations dates back to the oldest known civilizations, highlighting their critical role in the development of agriculture.
• 🔌 The Three Gorges Dam on the Yangtze River exemplifies the modern significance of these rivers, as it produces more electricity than any other power plant globally.
• 🗺 The close proximity of large rivers in Southeast Asia, particularly around the Tibetan Plateau, is unique and influenced by the region's tectonic activity.
• 🏔 The unusual courses of some rivers, such as the Yangtze's 'first bend,' are indicative of the strong tectonic control on river paths in the area.
• 🌊 The uplift of the Tibetan Plateau, beginning around 50 million years ago due to the India-Asia collision, disrupted the ancient river systems and created the current river patterns.
• 🌧️ The strength of the Asian monsoon has varied over time, affecting the amount of water and sediment carried by the rivers, which in turn has implications for agriculture and the environment.
• ⛰️ The Himalaya glaciers, a significant source of river water, are shrinking due to global warming, posing a threat to water supply in the region.
• 🌍 The script emphasizes the interconnectedness of the great rivers of Asia with the continent's climate, geology, and human civilizations, illustrating their importance across time.

Q & A

Who is the speaker in the video script?

The speaker is Peter Clift, a Professor of Geosciences at Louisiana State University.

What is the main topic of the video script?

The main topic is the great rivers of Asia, their connection to the changing climate and uplift of mountains in Asia.

How many great rivers originate along the margins of the Tibetan plateau according to the script?

There are eight great rivers that originate along the margins of the Tibetan plateau.

What is the significance of these rivers to human civilizations?

These rivers have been crucial for the development of agriculture, which allowed ancient civilizations in China, India, and Pakistan to grow and prosper.

How does the Yangtze River contribute to modern China?

The Yangtze River, through the Three Gorges Dam, produces more electricity than any other power plant on Earth.

What makes the rivers of Southeast Asia unique in terms of their geographical distribution?

Southeast Asia is unique in having several large rivers that flow very close together, particularly in the southeastern corner of the Tibetan plateau.

What is special about the Salween River's drainage basin?

The Salween River has an unusually narrow drainage basin, squeezed between the Irrawaddy and Mekong drainage basins, which are also curiously narrow.

How does the script explain the unusual course of some rivers, such as the Yangtze?

The script suggests that strong tectonic activity in the region, particularly the India-Asia collision, has a significant control on river courses, causing them to change direction abruptly.

What historical event is linked to the uplift of the Tibetan Plateau and the reorganization of river systems?

The uplift of the Tibetan Plateau began around 50 million years ago when India started colliding with the rest of Asia, disrupting the old south-flowing river system.

How has the strength of the Asian monsoon affected the rivers over time?

The strength of the summer monsoon rains has changed over time, affecting the amount of water and sediment carried by these rivers, with periods of weakening and strengthening linked to global climate changes.

What is the potential impact of global warming on the Asian monsoon and the rivers?

Global warming, caused by anthropogenic emissions of CO2, may make the monsoon rains stronger. However, it has also caused Himalaya glaciers to shrink, threatening the river water supply that is crucial for agriculture.

Outlines

00:00

🌏 The Great Rivers of Asia and Their Significance

Professor Peter Clift introduces the Asian rivers' importance to climate, geology, and human civilization. He explains the unique concentration of major rivers in Southeast Asia, their role in providing nutrients and water for agriculture that supports billions, and their historical significance to ancient civilizations. The rivers' close proximity is attributed to the region's intense tectonic activity, with the Yangtze River serving as a case study for how tectonics can redirect a river's course. The script also touches on the impact of the India-Asia collision on river systems and the formation of the Tibetan Plateau.

05:06

🌧️ The Influence of Monsoons on Asian Rivers

This section delves into the relationship between the Asian monsoon and the region's rivers. It discusses how the rivers' sediment load has varied with the strength of the monsoon rains over geological time. The script explains that as Earth's climate cooled, the monsoon weakened, reducing the rivers' sediment transport. Conversely, during warmer periods, the monsoon and river activity intensified. The impact of global climate phenomena like El Niño and La Niña on monsoon strength is highlighted, along with the potential effects of anthropogenic global warming on monsoon rains and the shrinking of Himalayan glaciers, which are crucial for river water supply.

Keywords

💡Asian Monsoon

The Asian Monsoon is a seasonal wind system that affects the climate of the Asian continent, particularly in the south and southeast regions. It is characterized by a rainy season during the summer months due to the southwest winds and a dry season during the winter due to the northeast winds. In the video, the Asian Monsoon is discussed in relation to its impact on the uplift of the Himalayas and its connection to the great rivers of Asia, which are vital for the region's climate and agriculture.

💡Tibetan Plateau

The Tibetan Plateau, often referred to as the 'Roof of the World,' is a vast, high-altitude region in Central Asia. It is the source of many of Asia's major rivers due to its topography. The uplift of the Tibetan Plateau is a significant geological event that has influenced the formation and flow of the rivers discussed in the video, as well as the development of the Asian Monsoon system.

💡Sediment

Sediment refers to solid particles that are transported by and eventually settle out of water, air, or ice. In the context of the video, the rivers of Southeast Asia are noted for delivering a significant amount of sediment into the ocean, which contributes to the fertility of the floodplains and supports agricultural productivity.

💡Floodplains

A floodplain is a flat area of land adjacent to a river that is prone to flooding. In the video, floodplains are highlighted as areas where rivers provide essential nutrients and water, making them crucial for agriculture and food production, particularly for growing rice, which is a staple food for billions of people.

💡Three Gorges Dam

The Three Gorges Dam is the world's largest power station in terms of installed capacity, located on the Yangtze River in China. The video mentions this dam as an example of the significant role rivers play in providing energy and resources to nations, showcasing the human utilization and management of these natural waterways.

💡Tectonic Activity

Tectonic activity refers to the movement of the Earth's crust, which can result in the formation of mountains, earthquakes, and changes in the landscape. The video explains how the tectonic activity in Southeast Asia, particularly the uplift of the Tibetan Plateau and the India-Asia collision, has shaped the courses of the region's rivers and influenced their proximity and unique drainage patterns.

💡India-Asia Collision

The India-Asia Collision is a geological event that began around 50 million years ago when the Indian tectonic plate started moving northwards and collided with the Eurasian plate, leading to the formation of the Himalayas and the Tibetan Plateau. The video discusses how this collision has had a profound effect on the landscape and river systems of Asia.

💡Paleogene

The Paleogene is a geological period that spans from the end of the Cretaceous period to the beginning of the Neogene, approximately 66 to 23 million years ago. The video mentions the Paleogene as the time when the Asian Monsoon first strengthened, affecting the climate and the flow of rivers in the region.

💡El Niño and La Niña

El Niño and La Niña are opposite phases of a climate pattern that involves changes in the ocean temperatures in the equatorial Pacific Ocean, affecting weather patterns globally. In the video, it is explained that the strength of the Asian Monsoon is influenced by these climate phenomena, with the monsoon being weaker during El Niño and stronger during La Niña.

💡Anthropogenic Emissions

Anthropogenic emissions refer to the release of substances into the environment by human activities, particularly greenhouse gases like carbon dioxide (CO2). The video suggests that recent global warming, largely due to anthropogenic emissions, may alter the strength of the monsoon rains and affect the availability of water for rivers, with implications for the region's agriculture and ecosystems.

💡Himalaya Glaciers

The Himalaya Glaciers are ice masses located in the Himalayan mountain range. They are significant sources of freshwater for the rivers that originate in the Himalayas. The video discusses how global warming has led to the shrinking of these glaciers, which could impact the water supply for the rivers and the communities that depend on them.

Highlights

Professor Peter Clift introduces the great rivers of Asia and their connection to climate change and mountain uplift.

Southeast Asia's rivers deliver more sediment to the ocean than any others, supporting billions of people with nutrients and water for agriculture.

Eight major rivers originate from the Tibetan Plateau margins, including the Indus, Ganges, Brahmaputra, Irrawaddy, Salween, Mekong, Yangtze, and Yellow rivers.

The Mekong Delta is known as Vietnam's rice bowl, while the Yangtze River is vital for China's agriculture and energy production.

The Three Gorges Dam on the Yangtze River is the world's largest power plant, demonstrating the rivers' importance to nations.

Southeast Asia's rivers are unique for flowing closely together, unlike other continents where large rivers have broader drainage basins.

The Salween River has an unusually narrow drainage basin, squeezed between the Irrawaddy and Mekong rivers.

The Yangtze River's 'first bend' is an example of how tectonic activity influences river courses in Southeast Asia.

India's collision with Asia 50 million years ago uplifted the Tibetan Plateau, disrupting the ancient river system.

The uplift and monsoon strengthening around 25 million years ago caused the Yangtze River to change direction, forming its current course.

The Asian monsoon has varied in strength over millions of years, affecting the amount of sediment carried by the region's rivers.

Global climate changes, including the ice ages and anthropogenic warming, have impacted the monsoon and river systems.

El Niño and La Niña phenomena influence the strength of the monsoon, with implications for river flow and sediment transport.

Recent global warming has caused Himalayan glaciers to shrink, threatening water supply for rivers and agriculture.

The video concludes by highlighting the importance of understanding the great rivers of Asia for human prosperity and climate adaptation.

Transcripts

Hi, I’m Peter Clift, Professor of  Geosciences at Louisiana State University.  

In earlier videos I talked to  you about the Asian monsoon,  

why it exists, how it has changed through  time and how it is linked to  

uplift of the Himalayas. Today I want to  introduce you to the great rivers of Asia  

and explain how they are tied up with both the changing  climate and uplift of mountains in Asia.  

Why are the rivers of Asia special?

Southeast Asia is home to some of the biggest  

rivers on Earth and these rivers deliver more  sediment into the ocean than any other rivers.  

There are eight great rivers that originate along  the margins of the Tibetan plateau.

these are, from West to East , the Indus, the Ganges, the Brahmaputra, the Irrawaddy, the Salween, the Mekong,  

the Yangtze and the Yellow. On their way to  the sea these and other rivers of SE Asia  

provide nutrients and water to floodplains where  food to feed almost 3 billion people is grown.  

The Mekong delta in particular is  known as the rice bowl of Vietnam.  

The Yangtze River, the longest river in Asia,  plays the same role in China. The importance  

of the rivers to humans dates back to the oldest  civilizations, including those in China and along  

the Indus Valley in India and Pakistan. The  supply of water to these areas was critical  

for developing the agriculture that  allowed these populations to grow.  

These powerful rivers continue to be  important for the nations they flow through.  

This importance is shown spectacularly by the  Three Gorges Dam on the Yangtze River of China.  

The waters behind this dam  produce more electricity  

than any other power plant on Earth.

So, why are the rivers so close together?

Although Asia is not the only place  in the world with large rivers,  

Southeast Asia is unique in having several large  rivers that flow very close together. This is seen  

in the southeastern corner of the Tibetan plateau  where the Salween, Mekong, Red and Yangtze rivers  

flow parallel to each other in deep gorges. The  Salween’s drainage basin is especially unusual.  

This 3300 km long river flows have an unusually  narrow drainage basin, squeezed between the  

Irrawaddy and Mekong drainage basins, which  are also curiously narrow. In addition,  

some rivers have unusual courses such as the  hair-pin like “first bend” of the Yangtze.  

Big rivers on other continents, like  the Mississippi River of North America  

have broad drainage basins  with regular branching patterns  

where tributaries flow towards the sea,  progressively coming together as they do so.  

The Mississippi also flows far from  the other big rivers of North America.  

In contrast, the great rivers of SE Asia have  drainage basins that are remarkably narrow  

because of the strong tectonic activity of this  region. The Yangtze River example provides some  

useful insights into how tectonics can affect  river courses. Upstream, the Yangtze flows out  

of the Tibetan Plateau towards the southeast,  apparently heading to the South China Sea.  

However, in SW China the river changes its  mind and heads off towards the northeast  

finally entering the East China Sea near  Shanghai. This 90° course change suggests  

strong tectonic control on river courses  around the India-Asia collision zone.  

How does this the first bend of the Yangtze  relate to the India-Asia collision?  

Uplift of the Tibetan Plateau began when  India started colliding with the rest of Asia  

about 50 million years ago. Uplift disrupted  the old south-flowing river system,  

splitting the various tributaries into  the independent rivers we see today.  

Early in the collision, what is today the middle  Yangtze River flowed southwest. As the collision  

continued, Tibet rose up, strengthening the monsoon  and its rains, then fed these giant rivers.

Around 25 million years ago as the uplift continued, the  upper Yangtze joined the middle Yangtze and its  

old connection to the South China Sea was lost.  The middle stretches of the river would have  

instantly reversed direction! The Yangtze went  its own way. The leftovers of what would have  

been the Mississippi of South-East Asia became the  Red River, flowing into the Gulf of Tonkin.

Rivers and the monsoon

After the major reorganization of South and  

East Asian river patterns around 25 million years  ago the network has been pretty stable, because  

these rivers are deeply entrenched in their  canyons. The amount of water and sediment carried  

by these rivers has varied over time because the  strength of the summer monsoon rains has changed  

since the monsoon first strengthened in  Paleogene time, that is more than 23 million years ago.  

As Earth’s climate cooled, starting around  15 million years ago, and especially after  

8 million years ago, the rains weakened and  the rivers washed less sediment into the ocean.  

After the northern hemisphere ice age began  about 2.5 million years ago, the Asian monsoon  

and its rains strengthened when the climate  was warmer, and drier as Earth’s climate cooled  

and the glaciers advanced. Monsoon strength is  also linked to other global climate phenomena  

such as El Niño, being weaker during strong El Nino, when the Eastern Pacific  

is warmer than usual and stronger  during La Nina, when it is cooler.  

More recent warming caused by anthropogenic  emissions of CO2 may make the rains stronger.  

Global warming has also caused  Himalaya glaciers to shrink.  

Their spring melting is a significant source of  river water, a supply that is now threatened.

I hope you've enjoyed learning how the great  rivers of Asia and how they come to look the way they do  

How they changed with the changing Asian Monsoon

and how they allow people to live and prosper across this  

great continent. Thanks for watching along with me.

Now keep an eye out for the next video about how Monsoons and people have changed through time.