Without trees, Amazon weather will grow more extreme

Erase the Amazon’s rainforest, and the region doesn’t just dry out. It flips into harsher swings: longer dry spells broken by explosive cloudbursts, hotter days and nights, and stronger surface winds that batter regrowth and raise heat stress for people and wildlife. Annual rainfall may stay similar on paper, but life on the ground gets rougher.

A new high-resolution climate study led by Arim Yoon shows why. The researchers used a storm-resolving global model that can capture the Amazon’s daily convective rhythms.

The team found that total deforestation reshapes the timing and intensity of rain, heat, and wind – changes previous coarse models largely missed.

The work comes from the Max Planck Institute for Meteorology, with collaborators in Austria and Germany.

Mean rainfall masks real impacts

Many past studies linked Amazon dieback to declining annual rainfall after tree loss. But mean totals can hide what really matters to people, rivers, farms, and forests – when the water arrives and how hard it falls.

In Yoon’s simulations, the year’s total barely budges after complete deforestation, yet the hourly picture splits in two. Dry hours multiply, while extreme downpours surge. Violent rain events – more than two inches in a single hour – jump by about 54 percent, even as “no rain” hours almost triple.

Dominick Spracklen, who was not involved in the study, called the modeling approach “really impressive” and said it should “better simulate the climate response to deforestation.” Those details matter because the Amazon’s convection is built from small-scale updrafts that coarse models blur.

Physics of Amazon’s weather flip

Take away the forest and you strip out evapotranspiration, roughness, and canopy shade. The surface dries and heats. Convection becomes harder to start – convective inhibition increases – so you get more empty hours with suppressed showers.

But when storms do fire, they’re juiced by stronger low-level moisture convergence that ramps up vertical motion. The result is fatter tails on both ends of the rain distribution: more nothing and more cloud-bursting somethings.

The study ties the extreme-rain jump to enhanced updrafts rather than extra atmospheric moisture, and it shows lower CAPE alongside higher inhibition – another sign that dynamics, not instability alone, drive the bursts.

Amazon warms without its trees

Temperatures climb across the day and night. Daily minimums rise by roughly 4.9°F (2.7°C), daily maximums by about 9.7°F (5.4°C) under full deforestation. On average, near-surface air warms by about 6.8°F (3.8°C), with a wider swing from day to day and season to season.

In practical terms, post-deforestation nights are as hot as pre-deforestation days across much of the basin, and common heat-stress indices shift into more dangerous zones for a larger fraction of the year.

That added heat comes from a reworked surface energy budget. With fewer leaves transpiring, less energy goes into latent cooling; more becomes sensible heat, and the brighter, smoother surface alters turbulence and radiative exchanges.

The upshot is a warmer boundary layer, shorter relief at night, and a step change in human heat stress and labor capacity – even without changing the global climate backdrop.

Wind that fights the forest

Cutting a tall, rough canopy down to open land dramatically lowers surface roughness. Winds respond. In the simulations, average wind speeds at 33 feet above ground more than tripled, and the 99th-percentile gusts roughly doubled.

Part of that increase is the smoother surface and altered large-scale circulation; part is stronger downdrafts linked to the more violent storms that do occur. For young, shallow-rooted trees trying to recolonize, that combination is bad news.

Amazon communities face harsher weather

More than 30 million people live in the Amazon region, including about 2.7 million Indigenous people. “You’re going to have more extreme rainfall and more extreme temperatures,” said Luis Cattelan from the University of Leeds. “That is basically horrible for everyone who is there.”

The model’s extremes translate to flashier floods, tougher working conditions, more dangerous heat, and stormier winds – stressors that compound across health, infrastructure, agriculture, and forest recovery.

Cattelan also urges caution. “These extreme scenarios are more for scientists to try to understand the signal. But we know it’s not realistic,” he said.

Few expect the entire forest to vanish at once. The value here is to reveal mechanisms and magnitudes, then test how partial clearing maps onto real-world risk.

A better lens for a complex place

The Amazon’s weather is a mosaic of afternoon storms, sea-breeze-like circulations, and seasonally migrating rain belts. Coarse global models, which parameterize much of that small-scale action, tend to smooth away the pulses that shape life on the ground. Storm-resolving models sharpen the picture.

In Yoon’s setup, convection is explicit at three-mile (five-kilometer) resolution, allowing the team to examine hourly rain bins, diurnal temperature cycles, and wind extremes rather than only monthly means.

That’s how you see “more dry hours and more violent hours,” and why annual rainfall totals alone are a poor guide to lived climate.

The real risk of Amazon deforestation

The study doesn’t claim that the Amazon will keep its mean rainfall no matter what. It shows that if you erase the forest, the region’s weather gets jerkier and harsher even if the yearly bucket still fills.

It also doesn’t argue that partial deforestation is harmless. Quite the opposite: the physics on display – less evaporative cooling, more inhibition, sharper moisture convergence, stronger winds – operate well before you reach 100 percent loss.

The next step, as Cattelan suggests, is to map those mechanisms onto more realistic patchwork futures and test how different clearing patterns shift the balance of extremes.

For now, the headline is simple. In this model, total deforestation doesn’t dry the Amazon out uniformly; it makes its weather meaner.

The lived result wouldn’t be a steady fade to drought. It would be a flip to longer quiet spells, fiercer cloudbursts, hotter days and nights, and winds that keep the forest from coming back.

The research is available as a preprint on EGUsphere.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–