What La Niña Will do to Earth in 2025
Summary
TLDRThis video explores the El Niño Southern Oscillation (ENSO), a climate pattern affecting global weather. It discusses the recent strong El Niño event and anticipates the upcoming La Niña, explaining their impacts on weather patterns. The script also touches on how climate change may influence future ENSO cycles, emphasizing the need for adaptation and preparation.
Takeaways
- 🌍 Earth's weather and climate are influenced by a variety of factors including its position in the solar system, rotation, atmospheric patterns, and seasonal changes.
- 🌊 El Niño and La Niña are opposite ends of the El Niño Southern Oscillation (ENSO) cycle, which can significantly impact global weather patterns and have historical implications for civilizations.
- 🔍 The end of a strong El Niño event in June 2024 was marked by record-high ocean temperatures, coral bleaching, Amazon rainforest drought, and extreme rainfall in North America.
- ⏱️ ENSO cycles typically take 2 to 7 years to transition from one extreme to the other, with episodes lasting 9 to 12 months, though they can extend for several years.
- 🌡️ ENSO-Neutral periods are characterized by average sea surface temperatures and trade winds, leading to expected weather patterns worldwide.
- 🌀 The Hadley Cell rotation, driven by the Sun, is a global air circulation that, when altered, can relate to El Niño and La Niña events through changes in trade winds.
- 🌟 The Southern Oscillation, documented by Sir Gilbert Thomas Walker, is a shift in air pressure across the equatorial Pacific Ocean, which is part of the larger Walker Circulation.
- 🌊 El Niño is characterized by higher than average Pacific sea surface temperatures and can lead to ecosystem disruptions, such as coral bleaching and changes in fish populations.
- 🌈 La Niña, the cooler phase of ENSO, is marked by stronger trade winds and cooler sea surface temperatures, often intensifying neutral conditions in most areas with some regional exceptions.
- ❓ The impact of climate change on the ENSO cycle is uncertain, but it's likely to amplify the severity of weather events, as recent history shows stronger and more frequent El Niño and La Niña events.
Q & A
What is the El Niño Southern Oscillation (ENSO)?
-The El Niño Southern Oscillation (ENSO) is a climate pattern that involves the periodic warming and cooling of the central to eastern tropical Pacific Ocean. It is a complex system that includes changes in sea surface temperature, atmospheric pressure, and wind patterns, which can have significant impacts on global weather and climate.
How do El Niño and La Niña events affect global weather patterns?
-El Niño and La Niña events can alter worldwide atmospheric patterns, leading to extreme weather conditions. El Niño typically causes droughts in some regions and heavy rainfall in others, while La Niña often intensifies the normal weather patterns, such as colder and wetter winters in certain areas.
What is the difference between El Niño and La Niña events?
-El Niño is characterized by warmer than average sea surface temperatures in the eastern Pacific, leading to a variety of weather disruptions globally. La Niña, on the other hand, is marked by cooler than average sea surface temperatures in the same region, which can intensify typical weather patterns in various parts of the world.
How do the trade winds play a role in the development of El Niño and La Niña?
-The trade winds, which blow from east to west across the Pacific, play a crucial role in the development of El Niño and La Niña. During El Niño, these winds weaken, allowing warm water to accumulate in the eastern Pacific. In contrast, during La Niña, the trade winds are stronger, pushing warm water westward and allowing cooler water to rise to the surface in the east.
What is the impact of El Niño and La Niña on coral reefs?
-El Niño events can lead to increased sea surface temperatures, causing coral bleaching where corals expel the symbiotic algae they rely on, leaving them vulnerable. La Niña's cooler waters can disrupt the balance necessary for coral health, potentially leading to other stressors that affect their survival.
How do El Niño and La Niña affect the Amazon rainforest?
-El Niño events can lead to drought in the Amazon rainforest due to the shift in atmospheric circulation, which reduces rainfall. La Niña, while typically associated with wetter conditions, can also influence the rainforest's climate, although the effects are less predictable and can vary from year to year.
What was the significance of the El Niño event that ended in June 2024?
-The El Niño event that ended in June 2024 was one of the five strongest on record. It caused record-high ocean surface temperatures, heat stress on coral reefs, drought in the Amazon rainforest, and extreme rainfall with dangerous consequences for North America.
How does the ENSO cycle influence the occurrence of hurricanes?
-During El Niño, the development of hurricanes in the Atlantic is typically reduced due to increased wind shear. Conversely, La Niña conditions often lead to a more active hurricane season in the Atlantic, with the potential for more and stronger hurricanes.
What is the potential impact of La Niña on global agriculture?
-La Niña can influence global agriculture by altering rainfall patterns. For instance, it can lead to increased rainfall in Australia and east Asia, which might benefit agriculture in those regions, while other areas, like parts of Africa, might experience drought, negatively affecting crop yields.
How does climate change potentially affect the ENSO cycle?
-While the exact impacts of climate change on the ENSO cycle are not fully understood, it is believed that global warming could lead to more intense and frequent El Niño and La Niña events. This could result in more extreme weather patterns and greater variability in global climate.
Outlines
🌍 El Niño and La Niña: The Power to Change Our World
This paragraph introduces the concept of El Niño and La Niña, which are part of the El Niño Southern Oscillation (ENSO). These phenomena can significantly influence weather patterns and climate, potentially affecting ancient civilizations. The paragraph discusses the end of a strong El Niño event in June 2024, characterized by record-high ocean temperatures, coral reef stress, Amazon rainforest drought, and extreme weather in North America. It also introduces the upcoming La Niña event and sets the stage for a discussion on how these events work and their global impacts.
🔄 Understanding the ENSO Cycle
The second paragraph delves into the science behind the ENSO cycle, explaining the role of Earth's position in the solar system, atmospheric patterns, and seasonal changes. It describes the transition from El Niño to La Niña, which typically occurs every 2 to 7 years and lasts for 9 to 12 months. The concept of 'ENSO-Neutral' periods is introduced, where average conditions prevail. The paragraph also discusses the Hadley Cell rotation, driven by sunlight, and how it relates to El Niño and La Niña through the Coriolis Effect and trade winds. Historical impacts of ENSO on global events, such as the Spanish conquest of the Incan Empire and the French Revolution, are mentioned, highlighting the significance of understanding these phenomena.
🌡️ The Impact of El Niño on Earth's Ecosystems
This paragraph focuses on the effects of El Niño, describing it as the warm phase of the ENSO cycle with higher than average sea surface temperatures. It discusses how El Niño disrupts ecosystems, particularly coral reefs, which suffer from bleaching due to increased water temperatures. The paragraph also addresses the broader ecological consequences, such as the reduction of phytoplankton and the impact on fish populations, which affects coastal communities. El Niño's influence on global weather patterns is highlighted, with examples including droughts in east Asia, flooding in the western United States, and worldwide shipping delays due to low water levels in the Panama Canal.
🌊 La Niña: The Cooler Counterpart
The fourth paragraph discusses La Niña, the cooler phase of the ENSO cycle, characterized by stronger trade winds and cooler sea surface temperatures. It contrasts La Niña with El Niño, explaining that while El Niño often reverses neutral conditions, La Niña is typically a more intense version of neutral conditions. The paragraph outlines the predicted impacts of La Niña, such as colder and wetter winters in northern North America, increased rainfall in east Asia and Australia, and potential drought in eastern Africa. It also touches on the uncertainty of how climate change may affect the ENSO cycle, noting that while ENSO events are becoming stronger and more frequent, their long-term impact remains unclear.
Mindmap
Keywords
💡El Niño
💡La Niña
💡ENSO (El Niño Southern Oscillation)
💡Hadley Cell
💡Coriolis Effect
💡Atmospheric Rivers
💡Coral Bleaching
💡Upwelling
💡Walker Circulation
💡ENSO-Neutral
Highlights
El Niño and La Niña are part of the El Niño Southern Oscillation (ENSO), which can influence weather patterns and climate globally.
ENSO may have played a role in destabilizing ancient civilizations.
One of the five strongest El Niño events on record ended in June 2024, causing various environmental impacts.
La Niña is predicted to begin in late 2024 or early 2025, potentially bringing significant global weather changes.
ENSO-Neutral periods are characterized by average sea surface temperatures and trade winds.
El Niño and La Niña events alter worldwide atmospheric patterns and can lead to extreme weather.
The Coriolis Effect influences the trade winds and is related to the occurrence of El Niño and La Niña events.
ENSO activity has been documented back tens of thousands of years and has historical impacts on global events.
Sir Gilbert Thomas Walker's research in the 1920s led to the understanding of the Southern Oscillation.
El Niño is characterized by higher than average Pacific sea surface temperatures.
El Niño can cause droughts, affect monsoons, and lead to transportation issues and flooding.
La Niña is marked by stronger trade winds and cooler than average Pacific sea surface temperatures.
The U.S. National Oceanic and Atmospheric Administration predicts a high chance of La Niña developing in late 2024.
La Niña can cause colder, wetter winters in North America and increase the likelihood of a more active hurricane season in the Atlantic.
The impact of La Niña on Europe is less clear, but it is expected to bring lower temperatures and varied precipitation.
Global warming may amplify the effects of ENSO, but the exact impact is still uncertain.
The upcoming La Niña is expected to provide more insights into our planet's climate system.
Transcripts
Imagine a force so powerful that it can change weather patterns around
the world and even alter the fate of ancient civilisations.
Earth’s short term weather patterns and long term climate are influenced by a complex collection of
factors, from our place in the solar system and the planet’s rotation, to atmospheric patterns and
seasonal changes. To further complicate things, every few years our planet experiences El Niño and
La Niña events – two opposite ends of a cycle that are part of the El Niño Southern Oscillation,
or ENSO for short. Evidence of the ENSO goes back tens of thousands of years,
and may have even played a role in destabilising some of the world’s great ancient civilisations.
One of the five strongest El Niño events ever recorded has finally
come to an end as of June 2024, after months of record-high ocean surface temperatures,
unprecedented heat stress on coral reefs, drought in the Amazon rainforest,
and extreme rainfall with dangerous consequences for North America.
With La Niña predicted to begin in late 2024 or early 2025, what changes can we expect globally,
and locally? I’m Alex McColgan, and you’re watching Astrum. Join me as we
take a look at our changing planet, the ENSO, and what La Niña will do to Earth.
Our previous video about El Niño explored one side of a global cycle
that typically takes between 2 to 7 years to swing from one extreme to the other. These
El Niño and La Niña episodes usually last 9 to 12 months, but can last for several years. In
this video we will take a closer look at how this cycle works, what neutral periods are,
and what might happen as we head into the opposite extreme of La Niña in the coming months.
When our Earth experiences average conditions,
we call those periods “ENSO-Neutral.” But every few years, fluctuations in wind and
ocean surface temperatures can signal the beginning of an El Niño or La Niña event,
and a departure from Earth’s normal conditions. These events alter worldwide atmospheric patterns
and are known to wreak havoc by contributing to extreme weather and environmental harm.
Imagine we're on the International Space Station orbiting Earth. From here we can see
our planet’s spherical shape, and as you might expect, sunlight affects the Earth’s surface
unevenly. More light and heat reaches Earth at the equator where sunlight strikes most directly,
compared to the poles where sunlight reaches our planet at a low angle.
In the same way that a hot air balloon rises, or hot steam rises over a pot of boiling water,
the same thing happens along the equator.. Direct sunlight warms up the air, and that hot,
moist, low pressure air rises up into the atmosphere. As the warm air gets higher,
it begins to cool off and condense
into clouds – this is why we see an abundance of tropical rainforests close to the equator.
More warm air continues to rise, pushing the cooler air away from the equator and out towards
the north and south, where it will eventually sink back down to the surface. Then, that cool air will
move from higher pressure, along the surface of the Earth, back to lower pressure near the
equator to start the cycle all over again and complete what we call Hadley Cell rotation. But
how does this worldwide circulation of air, driven by the Sun, relate to El Niño and La Niña events?
The surface winds created by these Hadley Cells are deflected towards the equator
due to the Earth’s rotation, a phenomenon we call the Coriolis Effect. It’s this effect
that creates the trade winds on either side of the equator, and it’s changes to these
trade winds that indicate when we will experience El Niño and La Niña events.
Historically, the trade winds have been so reliable that sailors have used them
to navigate the globe for centuries, hence the name, “trade winds.” Chemical signatures of the
ENSO stretch back tens of thousands of years in paleoclimate indicators like coral fossils,
and we have written records of the ENSO as far back as the 1500’s.. El Niño events may have
aided Spain in their conquest of the Incan Empire in the 1500’s, and in the late 1700’s, likely
contributed to crop failures and unrest that sparked the French Revolution. Despite this long
record of ENSO activity and the massive impact it has on worldwide weather and environments,
it wasn’t until the 20th century that we finally started to understand the mechanisms behind it.
The first defining breakthrough came in the 1920s, when a British scientist named Sir Gilbert Thomas
Walker set out to better understand the strength of monsoons in India. In his search for a way to
predict monsoon strength, he ended up documenting the Southern Oscillation,
a repeating shift in air pressure that happens across the equatorial Pacific
Ocean. This oscillation was part of another large-scale air circulation
that had not been documented before, and was later named the Walker Circulation.
Remember how I said that Hadley Cells circulate air north and south? The Walker Circulation is
just like Hadley Cells, except instead of moving air north and south, the Walker Circulation moves
air to the east and west over the equatorial Pacific. And instead of being driven by sunlight,
the Walker Circulation is guided by the easterly trade winds and ocean temperature.
It would be 60 more years before scientists were able to connect these changes in air
pressure over the Pacific with the alternating pattern of warm and cool surface water in the
Pacific. Combined, these make up what we now know as the El Niño Southern
Oscillation – ENSO. El Niño refers to the changes in sea surface temperature,
and the Southern Oscillation refers to the simultaneous changes in air pressure.
Unlike Hadley Cells that reliably move air north and south, the equatorial Walker Circulation is
not consistent and can experience colossal shifts as part of the Southern Oscillation.
Every few years, the surface temperature and trade winds over the Pacific experience fluctuations,
signalling an oncoming shift in the Walker Circulation. In turn,
these shifts, which we refer to as El Niño or La Niña events, can upset the balance of
weather and ecosystems over the entire Earth. So what happens to the Earth during each of these?
During neutral ENSO periods, the sea surface temperature and trade winds are near average
conditions. Trade winds blow across the Pacific Ocean, guiding warm surface waters to travel
west from South America towards Australia and Asia. As that warm surface water moves west,
it makes way for deep, cooler waters to rise up in its place. This ocean
circulation brings nutrient-rich cool water to the surface in a process called upwelling,
where it feeds phytoplankton and in turn supports other parts of the ecosystem like fish.
In neutral periods, weather across the world occurs, more or less,
as expected. This can include normal hurricane development in the Atlantic,
and average monsoon rainfall across southeast Asia. Walker Circulation
drives columns of warm moist air to rise above southern Asia,northern South America,
and middle Africa, so it’s no coincidence that these three regions are where we see
a concentration of vast, lush rainforests. The influence of this equatorial airflow is vast,
so it’s easy to imagine how changes to this system could cause a ripple effect around the world.
The first signs of trouble are when the trade winds begin to weaken and
sea surface temperature rises in the Pacific,
which can indicate an oncoming El Niño event like the one we experienced in 2023 and 2024.
During El Niño, the colossal columns of warm air that rise above our world’s rainforests are
shifted to the east or west.This change disrupts Asia’s monsoon season with prolonged droughts and
water scarcity, and affects the livelihoods of billions of people in east Asia. The last
El Niño also brought nine atmospheric rivers to the western United States that led to major
transportation issues, dangerous landslides, and flooding. You can think of an atmospheric river
like a river of moisture streaming through the air. When these atmospheric rivers reach land,
they release all of that moisture, causing monumental precipitation.
Everywhere on Earth, this shift in Walker Circulation is felt during El Niño. However,
the changes you experience in your local weather conditions may be completely different from the
changes another person sees in their local weather elsewhere on our planet. El Niño typically brings
a reversal of the normal conditions for a given area. This is why places like east
Asia or the Amazon rainforest, which typically get plenty of rain, will experience drought
during an El Niño event, or why usually dry climates like western North America,
will experience tremendous rainfall events. The recent El Niño event was also responsible
for worldwide shipping delays in 2023, as there wasn’t enough water to feed the Panama Canal,
which relies on consistent rainfall to accommodate all of the cargo ships hoping to pass through.
El Niño is described as the warm part of the ENSO cycle because Pacific sea surface temperatures
are higher than average during this time. In addition to changing worldwide weather patterns,
this also negatively affects ecosystems.Take, for example,
coral reefs. They rely on particular sea surface temperatures to survive,
and support some of the most important and biologically diverse life on Earth.
Corals have a symbiotic relationship with algae, but an increase in water temperatures can cause
the coral to expel this algae, leaving it drained of colour and vulnerable. A reef can recover from
this bleaching if conditions improve in time, but their risk of dying is high,
and the last El Niño event was no exception. An unprecedented 99.7 percent of Atlantic tropical
reefs were impacted by bleaching-level heat stress during the 2023 to 2024 El
Niño event, as part of the fourth worldwide mass-bleaching event in recorded history.
The warmer Pacific waters and weakened trade winds from El Niño also cause the upwelling of cooler,
nutrient-rich water to temporarily slow or stop, leading to a dire situation where less
phytoplankton means large numbers of fish must migrate or perish. As you can imagine,
this ripples across the food chain and can impact other animals. For coastal families and
communities who rely on those fish for nourishment or income, this El Niño effect can be devastating.
Now that we’ve discussed what it’s like during a neutral ENSO period,
and the destructive changes that can happen with El Niño conditions like we saw in 2023 and 2024,
what can we expect from this upcoming La Niña phenomenon?
La Niña is the other extreme. This period is marked by stronger than usual trade winds,
and cooler than average Pacific sea surface temperatures.
While El Niño usually causes the reversal of neutral conditions,
the best way to understand La Niña is to think of it as a more intense version of neutral
conditions for most parts of the world, with a few exceptions. During La Niña, the neutral
columns of rising warm air above south Asia and eastern North America become more pronounced,
while the typical column of warm air above Africa reverses. Just as your experience of
El Niño is highly dependent on where you are located, the same is also true of La Niña.
As of August 2024, the U.S. National Oceanic and Atmospheric Administration
predicts a 66 percent chance that La Niña will develop between September to November of 2024,
and a 74 percent chance it will last well into the Northern Hemisphere’s winter of 2025 to 2026.
And as of this video, models are predicting a roughly 50 percent chance that this La Niña
event will peak at a moderate strength. However, while forecasts for a La Niña event happening are
usually correct, the predicted strength for these events will likely change from month to month.
A strong El Niño ending in 2024 does not necessarily mean the upcoming La Niña will
be as extreme. Sometimes a strong El Niño leads into a strong La Niña, but other times a strong
El Niño is followed by a weak La Niña. With only 10 times in the historical record where the ENSO
has changed between El Niño and La Niña within a one year time period, as is expected with this
year’s switch, there just isn’t enough historical data to draw many conclusions. Besides, scientists
warn that the strength of an ENSO event does not always line up with the severity of its impacts.
So what do we know about the upcoming La Niña?
For the northern part of North America, La Niña brings with it a colder, wetter winter, while the
southern part of the continent might experience a warmer and more dry winter. U.S. Winter Source
And notably, La Niña will increase the likelihood of a more active hurricane season in the Atlantic,
with the potential for more, and stronger, hurricanes.
For east Asia and Australia, this typically means a significant increase in rainfall.
While in Africa, La Niña can mean some areas to the west are more wet,
while eastern Africa tends to experience more drought.
The connection between ENSO and Europe isn’t quite as clear,
since the continent is farther from the source, but La Niña is expected
to bring lower than average temperatures to central and western Europe, with less
precipitation across the mainland this winter, and more precipitation to the north and south.
There’s one final thing we need to talk about when it comes to La Niña predictions:
The El Niño and La Niña extremes of the ENSO have been happening for millennia,
but what’s less certain is how global warming from climate change will impact this cycle.
While we see short term, localised temperature swings from ENSO, the all-over trend of global
warming continues on an upward trajectory. This means we are entering uncharted territory.
There’s clear evidence that as our planet continues to warm from climate change,
the occurrence of severe weather will escalate. But the ENSO is a complicated, worldwide,
and in many ways, still an unpredictable phenomenon. Just in recent history,
El Niño and La Niña events have become stronger and more frequent, leading to more droughts,
floods, heat waves, wildfires, and severe storms, like we saw during the last La Niña
event that lasted for three years, from 2020 to 2023. Exactly how global warming may impact
the ENSO cycle is unclear, but we do know that climate change is likely to amplify that, too.
Luckily, life on our planet is nothing if not resilient and adaptable, and as
our world continues to change and experience the millennia-old ENSO swings, scientists will learn
more each year and be able to make improved predictions about the complex climate system.
The approaching La Niña will undoubtedly teach us more about our planet's climate. Let's hope we are
paying attention and use these lessons to adapt and prepare for our future in sustainable ways.
I’d love to hear in the comments what question you have about our planet’s climate.
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