"People have been warning that it was going to dry out for 20 years, " said Luís Moreno of Spain's Geological and Mining Institute.
But this time the fretting continued in public, as ministers emerged from deliberations in Viana do Castelo (the political fief of their host, the Portuguese foreign minister, Luís Amado).
Some 135 kilometers (85 miles) east of the park, another stretch of dunes pushes inland, near the city of Luís Correia.