The Trees Whisper Of A Looming Crisis
Scientists find horrific evidence of how harsh our future will be.

Every now and then, scientists find uncomfortable truths hidden in plain sight. Simple insights that, when you look a little deeper into them, change our view of the world, who we are, and exactly what we’ve been doing. Well, scientists recently discovered this with tree ring data, which detailed 700 years of previously unknown jet stream history. They were then able to link harvest failures, wildfires, and even the most deadly plague in history to changes in the jet stream. Changes, which will become far more frequent thanks to climate change. Yep, this is how climate change can cause city-destroying wildfires, economy-crushing harvest failures, and even society-crippling pandemics.
Let’s start with what jet streams are. Jet streams are air currents driven by the heat of the equator and the coldness of the poles. Air heats up at the equator and rises, and air cools down at the poles and sinks, creating a circular movement of air. The air moving from the poles to the equator along the Earth’s surface gets disturbed and moves as a slow, wide blanket. Meanwhile, the air moving from the equator to the poles in the upper atmosphere moves fast and contracts into river-like streams that streak across the sky. These are known as jet streams.
These streams don’t flow in the same spot all the time and instead move around, just like the meandering parts of a river. When they snake and curve, they affect the weather systems below them. In fact, the recent “heat dome” the US experienced was the result of a kink in the jet stream above the US trapping a high-pressure system in one place, causing extreme heat and drought for an extended period of time. When these streams shift further north, they bring very cold and extremely wet conditions with them, as they effectively pump more water from the tropics further north. In fact, the recent wet conditions experienced by Britain are likely caused by the jet stream above the area moving further north.
So, how do you map the history of something so ethereal and intangible as a jet stream?
Well, the researchers looked at tree ring data from across Europe. Trees grow at different rates and in different ways depending on the weather, creating “rings” within their trunks. In the winter, they don’t grow, and in the summer, they grow very quickly, creating rings of different densities within the tree’s trunk. But in times of stress, such as during droughts, floods, cold spells, or prolonged heat, the way the tree grows changes, imprinting a record of history within its body. Because certain types of trees can live for well over a thousand years, this record can go back a long, long way.
By looking at 700 years of tree ring data, these scientists were able to infer where the jetstream was located and the way it behaved. For example, if they find consecutive rings that suggest an extended period of cool, wet summers, they can infer the jet stream migrated further north and was stable there for a period of time.
Okay, so what did they find?
Well, they found that patterns in the jet stream lined up with major societally impactful events.
For example, during the period of the Black Death, one of the worst pandemics in the history of humanity that wiped out over a third of Europeans, the jet stream over Europe was extremely far north and very stable there. This led to cold, wet weather during this period, even in summer, causing people to spend more time indoors and creating the perfect conditions for the disease to spread rampantly. Likewise, the period where wildfires ravaged the Balkans and the worst harvest failures of the past 700 years also lined up perfectly with the jet stream migrating northwards.
So why does this matter?
Well, climate change is going to inject far more energy into our weather systems. Scientists have conclusive evidence that this will push jet streams further north in the northern hemisphere and further south in the southern hemisphere. It will also make jet streams far more unstable. But climate scientists were not sure how this would exactly impact weather patterns and our society.
Well, this study and several others are showing just how horrific our lives will become when our jet streams start to change and mutate, thanks to climate change. Pandemics that make COVID look like the common cold, crop failures that cripple the economy and leave millions hungry, and even deadly heatwaves could all become regular occurrences. This shows just how multifaceted the climate challenge is and how we must do more to protect ourselves from this self-made horror.
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Sources: New Scientist, Science Daily, Nature, Phys.org, Will Lockett