How Trees Lift Water
A first study of coast redwoods in heat, reported in October 2026, found that photosynthesis in young trees’ needles roughly halved between 30 and 40 °C, and that in heat waves the trees close the pores on their needles. This film explains why that matters: how a tree lifts water a hundred metres with no pump. A suction pump stops at about ten metres; trees instead pull water up from the top, as evaporation from leaf pores tugs on unbroken threads of water held together by hydrogen bonds inside dead, hollow wood cells. We follow the idea from Dixon and Joly in 1895, see why the threads can snap into air bubbles, why redwoods may top out near 120 to 130 metres, and why fog and heat matter to the tallest trees on Earth. Raise a pump, open and close a leaf’s pores, pull a water thread until it breaks, and grow a tree to its limit.
A hundred metres without a pump
What heat does to the tallest trees.
No suction pump can do it
Why suction stops at about ten metres.
Leaves that leak
Food in, water out.
Water that holds together
A thread of molecules.
Pulled, not pushed
Water under tension.
A branch in a bottle
The theory gets its first test.
Pipes made of dead cells
The tree’s plumbing.
When the thread snaps
Air bubbles in the pipes.
How tall can a tree grow?
A drought at the top.
The tallest tree alive
And where it gets extra water.
Too hot to drink
The new redwood study.
Powered by the sun
A pull from the top, and its limits.
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