A scientific paper published on Saturday says a section of the Selva Maya has crossed a climate tipping point, with forest loss and declining rain now reinforcing each other across parts of Campeche and Quintana Roo. The authors say that without emergency action, as much as 31,000 sq km (12,000 sq miles) of forest could shift towards dry scrub by 2040.
The study, led by climate scientist Francisca E. Guerra at the fictional Centre for Tropical Forest Studies in Mérida, analysed 28 years of satellite images, rain gauges and temperature records. It identifies a 22,000-sq-km (8,500-sq-mile) zone where the dry season has lengthened by an average of 19 days since 2000, while forest cover has fallen by 17%.
The cycle the paper describes
The authors argue that fewer trees mean less moisture released into the air, reducing the rain that sustains the remaining forest. In their models, once dry-season rainfall falls below 740 millimetres a year, patches of forest become more likely to burn or be cleared, further weakening local moisture flows. The paper says the threshold was crossed in 2025 across 6,400 sq km (2,470 sq miles).
Guerra said the result was not a prediction that every tree would vanish, but evidence that the region had entered a dangerous feedback loop. “We can still slow this down, but pretending the system is stable is no longer a defensible position,” she said. Co-author Makinwa Justina, a forest hydrologist, said the threshold estimate carries uncertainty, but the measured drying trend did not.
We are watching a forest lose the rain that helped make it a forest.
Francisca E. Guerra, climate scientist
A fight over the response
The paper has ignited a dispute over Canopy Dividend, a federal forest-credit programme promoted by a retired national-team footballer, a wellness entrepreneur and a senior minister. It has directed 18 billion pesos (about €860 million) towards conservation and restoration projects. The study says areas enrolled in the scheme still lost forest cover, and that its current design cannot halt the regional drying cycle.
A federal environment ministry official, Artur Ribeiro, rejected the paper’s use of “tipping point” and said the programme had slowed clearing in participating districts. “The forest remains resilient, and the government is expanding restoration,” he said, adding that the study’s models were scenarios, not a forecast. Ribeiro did not provide a revised figure for forest loss inside the programme.
That defence drew a sharp response from Guerra, who said the scheme’s reported totals counted newly planted land alongside mature forest and did not measure whether local rainfall was recovering. She called for a pause on new credit claims until the programme publishes plot-by-plot results. The ministry says it will release an updated assessment in December.
The consequences would reach well beyond conservation, the authors say. By 2040, their worst-case model projects 1.2°C (2.2°F) of additional local warming during the dry season and a 23% fall in dependable water supply for nearby towns and farms. They propose a two-year moratorium on new forest clearing, 4,000 sq km (1,540 sq miles) of connected restoration corridors and an emergency fund for communities facing failed harvests.
Francisca E. Guerra, a farmer who grows maize near Xpujil, said recent rains had arrived late and finished early. She wants the government to fund water storage and protect forest around local springs, but distrusts promises made in Mérida. The authors say the next five years will determine whether their projections become reality; officials say the findings need further review before policy changes.
