Parallax · earth desk · — 19

Cutting the forest lowers the heat it survives

You have been told to watch 1.5°C. Leave this forest alone and it survives 4°C. Keep cutting and 1.5°C is enough.

What heat alone does

With clearing held at today's level, the forest holds to 3.7–4°C.

What most people think

Keep the world under 1.5°C and the Amazon is safe. That is the deal.

What the data shows

3.7–4°C

On heat alone, the forest holds to this much warming.

Even then, warming alone still degrades up to a third of the forest.

THE BARGAIN

The panel above was the slow dial. Here it stands beside the fast one. Add the cutting and two-thirds to three-quarters of the basin could turn to savanna: dry grass and scattered trees.

On heat alone the forest holds to 3.7–4°C. Once 22–28% is cleared it breaks at 1.5–1.9°C.°C
If the cutting stays where it is 3.7–4°C, with clearing held at today's level 3.7 No realistic path this century reaches this much heat.
If the cutting goes on 1.5–1.9°C, once 22–28% of the forest is cleared 1.5 The world reaches this band around 2030.

THE SECOND DIAL

The Amazon's rain starts the way the monsoon does, and you already know that first half. Wet air comes off the sea and moves inland. But in the Amazon the forest itself keeps that air wet.

1
Trees pull water up

Roots draw water from the soil and the leaves breathe it into the air above the canopy.

2
The air drops it again

That moisture drifts inland and falls again. In parts of the basin more than 50% of the rain is made this way.

3
Cut here, kill there

Clear a patch and the air downwind dries, so drought stress can kill trees hundreds of kilometres away that nobody touched.

ITS OWN RAIN

So every patch cleared takes rain with it. Here is where the cutting stands, against the tipping point: the state past which the forest cannot recover on its own.

The reporters put today's clearing at 17%, or roughly 17–18%. Four to five per cent of the forest stands between that and the tipping band.%
0100
17 % of the forest cleared
the tipping band, 22–28%

THE DISTANCE LEFT

So the gap is four to five per cent of the forest. The dates below show how the science found the line, and how the cutting moved.

Feb 2018
The original threshold.
2024
The fire year.
Jul 2025
The lowest since 2014.
The dial moved the right way, with no new treaty.
7 May 2026
The two-dial paper.
The first study to turn both dials, not one.
21 May 2026
The counter-evidence.
28 May 2026
A 1.5°C year, 91% likely.

THE TRAJECTORY

This is what the good year still cost, measured against a city you know.

The Brazilian Amazon's best clearing year since 2014 still took 5,796 km².

Cleared in the Brazilian Amazon, 2025

5,796km²

That was an 11% fall from the year before.

  • Nearly four times the area of Delhi Delhi is about 1,480 km².

THE GOOD YEAR

That's the short version.

Full issue · 8 sections · 8 sources, all linked

Read the full issue →