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0 / 29 Fotos
Temperature rise in 2023
- In 2023, there was a dramatic rise in the temperature of the Earth. Global temperatures went up by 0.2°C (0.36°F), which was much more than climate models had predicted.
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1 / 29 Fotos
Greenhouse gases as a factor
- Of course, global warming can to a large extent be explained by greenhouse gas emissions, which serve to trap heat in the atmosphere.
© Shutterstock
2 / 29 Fotos
Too dramatic
- However, even taking this into account, the 2023 increase was far too dramatic for climate scientists to ignore or explain away with harmful gases.
© Shutterstock
3 / 29 Fotos
Looking for an explanation
- In a bid to explain the worrying surge, climatologists looked at factors such as the loss of polar ice and the decrease in fine particles (aerosols) in the atmosphere.
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4 / 29 Fotos
Breakthrough
- It was not until the end of 2024, however, that scientists in Germany claimed to have discovered the most important culprit: a decrease in low-level clouds.
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5 / 29 Fotos
Reflective effect
- When it comes to keeping the planet cool, low-level clouds play an important role: they reflect roughly 50% of the sunlight that reaches them, thereby cooling the Earth's surface.
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6 / 29 Fotos
Cause for concern
- According to experts, a decrease in low-level cloud cover is a cause for concern, particularly since the trend may be the result of global warming itself.
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7 / 29 Fotos
Clouds and temperature regulation
- It is helpful, in the first instance, to understand a little bit about how clouds help regulate the temperature of the planet.
© Shutterstock
8 / 29 Fotos
Complex picture
- Unfortunately, the theory is little complex, because clouds actually warm the planet up at the same time as they cool it down.
© Shutterstock
9 / 29 Fotos
Cooling effect
- On the one hand, clouds can block light and heat from the sun, which helps keep the Earth cool. This is the effect that you notice on a cloudy day.
© Shutterstock
10 / 29 Fotos
Warming effect
- On the other hand, clouds also serve to trap any heat from the sun that does make it down to Earth. This effect carries on through the night, even when there is no sunlight.
© Shutterstock
11 / 29 Fotos
Overall impact - Although clouds can have both a cooling and a warming effect, their overall impact depends on their position within the Earth's atmosphere.
© Shutterstock
12 / 29 Fotos
Low vs. high
- Clouds within a mile or so of the Earth's surface tend to have a cooling effect, while clouds higher up in the atmosphere tend to have more of a warming effect.
© Shutterstock
13 / 29 Fotos
The research
- Scientists at the Alfred Wegener Institute in Bremerhaven, Germany, first started to consider clouds as a climate change factor when temperatures rose unexpectedly quickly in 2023.
© Shutterstock
14 / 29 Fotos
NASA imagery
- They started to look at NASA satellite imagery, as well as weather records compiled by the European Center for Medium-range Weather Forecasts (ECMWF).
© Shutterstock
15 / 29 Fotos
Research findings
- Their investigations revealed a deficit of lower-level clouds, while upper-level clouds, on the other hand, appeared to be holding steady.
© Shutterstock
16 / 29 Fotos
Causes
- In terms of what is causing the deficit of low-level clouds, scientists are concerned that it may be a consequence of global warming itself.
© Shutterstock
17 / 29 Fotos
Global warming
- According to Helge Goessling, climate physicist at the Alfred Wegener Institute, there are many climate models that suggest greenhouse gas-induced warming has an impact on clouds, particularly at a low level.
© Shutterstock
18 / 29 Fotos
Reduction in fumes
- Confusingly, the decrease in low-level cloud cover could also be the result of reduced fumes from burning coal and stricter controls on marine shipping exhaust.
© Shutterstock
19 / 29 Fotos
Cloud seeds
- This is because, in an unfortunate twist of fate, the fine particles found in polluted air can actually act as seeds for forming clouds.
© Shutterstock
20 / 29 Fotos
Irony
- The irony is, therefore, that by cleaning up the air, we may actually trigger more climate change.
© Shutterstock
21 / 29 Fotos
Ocean currents
- According to Goessling's colleague, Thomas Rackow, ocean currents may also have a role to play in diminishing low-level cloud cover.
© Shutterstock
22 / 29 Fotos
Global warming
- As the upper layers of the ocean become shallower, as they do periodically, they also start to warm more easily. Studies have shown that this may reduce low-level cloud.
© Shutterstock
23 / 29 Fotos
Time frame
- It is worth bearing in mind that oceanic cycles tend to be long term. Indeed, they are known to vary over the course of decades.
© Shutterstock
24 / 29 Fotos
Changing impacts
- While a particular oceanic circulation may reduce low-level cloud cover and contribute to global warming at one time, it may have the opposite effect at another time.
© Shutterstock
25 / 29 Fotos
Confusing current trends
- This means that it can be very difficult to work out the extent to which these oceanic ups and downs are confounding current trends.
© Shutterstock
26 / 29 Fotos
List of unknowns
- There are still plenty of unknowns when it comes to the relationship between climate change and low-level cloud cover.
© Shutterstock
27 / 29 Fotos
What seems likely
- It seems likely, however, that variations in the amount of low-level cloud are more important than people had previously imagined. Sources: (Astronomy Magazine) (American Association for the Advancement of Science)
© Shutterstock
28 / 29 Fotos
© Shutterstock
0 / 29 Fotos
Temperature rise in 2023
- In 2023, there was a dramatic rise in the temperature of the Earth. Global temperatures went up by 0.2°C (0.36°F), which was much more than climate models had predicted.
© Shutterstock
1 / 29 Fotos
Greenhouse gases as a factor
- Of course, global warming can to a large extent be explained by greenhouse gas emissions, which serve to trap heat in the atmosphere.
© Shutterstock
2 / 29 Fotos
Too dramatic
- However, even taking this into account, the 2023 increase was far too dramatic for climate scientists to ignore or explain away with harmful gases.
© Shutterstock
3 / 29 Fotos
Looking for an explanation
- In a bid to explain the worrying surge, climatologists looked at factors such as the loss of polar ice and the decrease in fine particles (aerosols) in the atmosphere.
© Shutterstock
4 / 29 Fotos
Breakthrough
- It was not until the end of 2024, however, that scientists in Germany claimed to have discovered the most important culprit: a decrease in low-level clouds.
© Shutterstock
5 / 29 Fotos
Reflective effect
- When it comes to keeping the planet cool, low-level clouds play an important role: they reflect roughly 50% of the sunlight that reaches them, thereby cooling the Earth's surface.
© Shutterstock
6 / 29 Fotos
Cause for concern
- According to experts, a decrease in low-level cloud cover is a cause for concern, particularly since the trend may be the result of global warming itself.
© Shutterstock
7 / 29 Fotos
Clouds and temperature regulation
- It is helpful, in the first instance, to understand a little bit about how clouds help regulate the temperature of the planet.
© Shutterstock
8 / 29 Fotos
Complex picture
- Unfortunately, the theory is little complex, because clouds actually warm the planet up at the same time as they cool it down.
© Shutterstock
9 / 29 Fotos
Cooling effect
- On the one hand, clouds can block light and heat from the sun, which helps keep the Earth cool. This is the effect that you notice on a cloudy day.
© Shutterstock
10 / 29 Fotos
Warming effect
- On the other hand, clouds also serve to trap any heat from the sun that does make it down to Earth. This effect carries on through the night, even when there is no sunlight.
© Shutterstock
11 / 29 Fotos
Overall impact - Although clouds can have both a cooling and a warming effect, their overall impact depends on their position within the Earth's atmosphere.
© Shutterstock
12 / 29 Fotos
Low vs. high
- Clouds within a mile or so of the Earth's surface tend to have a cooling effect, while clouds higher up in the atmosphere tend to have more of a warming effect.
© Shutterstock
13 / 29 Fotos
The research
- Scientists at the Alfred Wegener Institute in Bremerhaven, Germany, first started to consider clouds as a climate change factor when temperatures rose unexpectedly quickly in 2023.
© Shutterstock
14 / 29 Fotos
NASA imagery
- They started to look at NASA satellite imagery, as well as weather records compiled by the European Center for Medium-range Weather Forecasts (ECMWF).
© Shutterstock
15 / 29 Fotos
Research findings
- Their investigations revealed a deficit of lower-level clouds, while upper-level clouds, on the other hand, appeared to be holding steady.
© Shutterstock
16 / 29 Fotos
Causes
- In terms of what is causing the deficit of low-level clouds, scientists are concerned that it may be a consequence of global warming itself.
© Shutterstock
17 / 29 Fotos
Global warming
- According to Helge Goessling, climate physicist at the Alfred Wegener Institute, there are many climate models that suggest greenhouse gas-induced warming has an impact on clouds, particularly at a low level.
© Shutterstock
18 / 29 Fotos
Reduction in fumes
- Confusingly, the decrease in low-level cloud cover could also be the result of reduced fumes from burning coal and stricter controls on marine shipping exhaust.
© Shutterstock
19 / 29 Fotos
Cloud seeds
- This is because, in an unfortunate twist of fate, the fine particles found in polluted air can actually act as seeds for forming clouds.
© Shutterstock
20 / 29 Fotos
Irony
- The irony is, therefore, that by cleaning up the air, we may actually trigger more climate change.
© Shutterstock
21 / 29 Fotos
Ocean currents
- According to Goessling's colleague, Thomas Rackow, ocean currents may also have a role to play in diminishing low-level cloud cover.
© Shutterstock
22 / 29 Fotos
Global warming
- As the upper layers of the ocean become shallower, as they do periodically, they also start to warm more easily. Studies have shown that this may reduce low-level cloud.
© Shutterstock
23 / 29 Fotos
Time frame
- It is worth bearing in mind that oceanic cycles tend to be long term. Indeed, they are known to vary over the course of decades.
© Shutterstock
24 / 29 Fotos
Changing impacts
- While a particular oceanic circulation may reduce low-level cloud cover and contribute to global warming at one time, it may have the opposite effect at another time.
© Shutterstock
25 / 29 Fotos
Confusing current trends
- This means that it can be very difficult to work out the extent to which these oceanic ups and downs are confounding current trends.
© Shutterstock
26 / 29 Fotos
List of unknowns
- There are still plenty of unknowns when it comes to the relationship between climate change and low-level cloud cover.
© Shutterstock
27 / 29 Fotos
What seems likely
- It seems likely, however, that variations in the amount of low-level cloud are more important than people had previously imagined. Sources: (Astronomy Magazine) (American Association for the Advancement of Science)
© Shutterstock
28 / 29 Fotos
Could a shortage of low-level clouds be contributing to global warming?
The relationship between clouds and rising temperatures
© Shutterstock
The fact that planet Earth is getting warmer is not news. However, the alarming rate at which it warmed over the course of 2023 took even the most expert of climate scientists by surprise. In an effort to understand what could be responsible, climatologists turned their sights to a previously understudied potential factor in climate change: low-level cloud cover.
Curious? Check out this gallery to find out more.
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