The Nonlinear Library LW - Will 2024 be very hot? Should we be worried? by A.H.
Dec 29, 2023
17:23
Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Will 2024 be very hot? Should we be worried?, published by A.H. on December 29, 2023 on LessWrong.
tl;dr: There are several trends which suggest that global temperatures over the next year will experience a short-term increase, relative to the long-term increase in temperatures caused by man-made global warming.
Credits: Most of the information comes from Berkley Earth monthly temperature updates. Several people on Twitter (Robert Rohde, Zeke Hausfather, James Hansen and Roko) have also been talking about the issues discussed here for a while.
Man-made global warming has been causing a steady, long-term increase in average global temperatures since the industrial revolution. However, recently several trends are lining up which suggest that the next year/few years might experience temporary greater-than-average warming, on top of baseline man-made warming. Some of these factors are already in play and 2023 is 'virtually certain' to be the hottest year on record.
The story can be summed up in this lovely graphic from Berkley earth:
I've had a look into some of the things that are happening and have written up what I've learned. I am not a climate scientist, so take this all with a pinch of salt.
El Niño
What is El Niño?
Periodically, the strength and direction of the winds over the Pacific ocean changes, causing the surface waters to flow differently, which leads to changes in the amount of cold water coming up from the depths of the ocean. This pattern is known as the El Niño-Southern Oscillation. The phase when the surface waters are warmer is known as El Niño, and the phase when the surface waters are cooler is known as La Niña.
These periods occur irregularly every few years and last approximately a year.
How does it affect global temperatures?
Unsurprisingly, during the El Niño period, when surface waters are warmer, more heat is released into the atmosphere, leading to warmer global surface temperatures. In general, years with El Niño are hotter and years with La Niña are cooler on average. This is a pretty reliable generalisation but is not a totally hard-and-fast rule as shown in the figure below[1].
However, like a lot phenomena in climate science, El Niño has different effects depending on what part of the world you are in. Broadly, areas in the southern hemisphere and areas by the coast experience more warming than others. But El Niño can actually cause cooling in some areas, so its important to check where you live.
When averaged out over the globe, global surface temperature during El Niño years is about 0.1-0.2C higher than normal.
What about second-order effects?
This change in temperature can cause all kinds of other effects such as flooding, drought, disease and crop failures, on top of the direct effects of heat.
Are we currently in an El Niño phase?
Yes, it started in early summer this year.
How long will it last?
It is expected to last until (Northern Hemisphere) summer 2024 and expected to peak around (Northern Hemisphere) winter (ie. soon). However, (quoting Berkley Earth) again:
'Due to the lag between the development of El Niño and its full impact being felt on global temperatures, it is plausible that the current El Niño will have a greater impact on global temperatures in 2024 than it does in 2023.'
So it is not over yet. Even though it will peak during Northern Hemisphere winter, its effects will still be felt into the summer, on top of normal seasonal temperature increases.
Is this one going to be bad?
The current El Niño phase is shaping up to be the one of the strongest ever.
However, one thing I don't understand: is this just because of 'standard' increases from man-made warming or is it something about the winds/ocean currents which makes this one strong?
Solar Cycles
What is the solar cycle?
Approximately every 11 years, for reasons I d...
tl;dr: There are several trends which suggest that global temperatures over the next year will experience a short-term increase, relative to the long-term increase in temperatures caused by man-made global warming.
Credits: Most of the information comes from Berkley Earth monthly temperature updates. Several people on Twitter (Robert Rohde, Zeke Hausfather, James Hansen and Roko) have also been talking about the issues discussed here for a while.
Man-made global warming has been causing a steady, long-term increase in average global temperatures since the industrial revolution. However, recently several trends are lining up which suggest that the next year/few years might experience temporary greater-than-average warming, on top of baseline man-made warming. Some of these factors are already in play and 2023 is 'virtually certain' to be the hottest year on record.
The story can be summed up in this lovely graphic from Berkley earth:
I've had a look into some of the things that are happening and have written up what I've learned. I am not a climate scientist, so take this all with a pinch of salt.
El Niño
What is El Niño?
Periodically, the strength and direction of the winds over the Pacific ocean changes, causing the surface waters to flow differently, which leads to changes in the amount of cold water coming up from the depths of the ocean. This pattern is known as the El Niño-Southern Oscillation. The phase when the surface waters are warmer is known as El Niño, and the phase when the surface waters are cooler is known as La Niña.
These periods occur irregularly every few years and last approximately a year.
How does it affect global temperatures?
Unsurprisingly, during the El Niño period, when surface waters are warmer, more heat is released into the atmosphere, leading to warmer global surface temperatures. In general, years with El Niño are hotter and years with La Niña are cooler on average. This is a pretty reliable generalisation but is not a totally hard-and-fast rule as shown in the figure below[1].
However, like a lot phenomena in climate science, El Niño has different effects depending on what part of the world you are in. Broadly, areas in the southern hemisphere and areas by the coast experience more warming than others. But El Niño can actually cause cooling in some areas, so its important to check where you live.
When averaged out over the globe, global surface temperature during El Niño years is about 0.1-0.2C higher than normal.
What about second-order effects?
This change in temperature can cause all kinds of other effects such as flooding, drought, disease and crop failures, on top of the direct effects of heat.
Are we currently in an El Niño phase?
Yes, it started in early summer this year.
How long will it last?
It is expected to last until (Northern Hemisphere) summer 2024 and expected to peak around (Northern Hemisphere) winter (ie. soon). However, (quoting Berkley Earth) again:
'Due to the lag between the development of El Niño and its full impact being felt on global temperatures, it is plausible that the current El Niño will have a greater impact on global temperatures in 2024 than it does in 2023.'
So it is not over yet. Even though it will peak during Northern Hemisphere winter, its effects will still be felt into the summer, on top of normal seasonal temperature increases.
Is this one going to be bad?
The current El Niño phase is shaping up to be the one of the strongest ever.
However, one thing I don't understand: is this just because of 'standard' increases from man-made warming or is it something about the winds/ocean currents which makes this one strong?
Solar Cycles
What is the solar cycle?
Approximately every 11 years, for reasons I d...