By Luis Otero
The Glacier National Park, located in southern Argentina, heads this classification. This nature reserve, located southwest of the province of Santa Cruz, in Argentine Patagonia, is home to the largest ice field in the world outside of the polar zones and Greenland. Most of its 47 glaciers are melting due to rising temperatures, with the consequent impact on the ecosystems of the area. The fires are becoming more frequent, and are destroying the extensive forests of lengas and ñirres that give shelter to huemules, pumas and condors. Also influencing the introduction of domestic species - cows, goats, cats, horses - and human invasion, both by tourists and ranchers who settle in the area. The largest of the glaciers, the Upsala, 53 km long, which flows into Lake Argentino, is in retreat. The Onelli and Perito Moreno glaciers (in the photo) also flow into this lake, perhaps the most spectacular in the world.
The second most threatened protected area is the Wadden Sea - or Watten, in German - located between the Frisian Islands and the North Sea, on the one hand, and the coasts of Holland, Germany and Denmark on the other. It is one of the great intertidal zone ecosystems on the planet, and the largest extension of mud flats and sandbanks. The coastline is known as the intertidal zone where there is the greatest variation between high and low tide levels. The shallow waters and wide tides reveal extensive sandy plains that can be traversed on foot. It is a changing area with many transitional habitats: tidal channels, estuaries, sandbars, brackish marshes, plains, and beaches. Many plants and animals live in them - common seals, porpoises - and between ten and twelve million migratory birds pass through there each year. But human action has altered the coastline, and the rise in sea level due to warming has caused the flooding of marshes and sandbars.