Global warming threatens to decouple ecological processes and may even collapse ecosystems across the world. The impacts of climate change have been visible in one of the most sensitive ecosystems — the Alpine ecosystem. Covering 3 per cent of the earth’s surface, the alpine ecosystems are present across various latitudes at elevated altitudes. Decreasing snow cover in the mountains, retreating glaciers, and earlier snowmelt because of rising temperature has triggered a myriad of changes in the alpine ecosystems. This has made mountain vegetation fragile which could jeopardise the safety of settlements and landscape at alpine as well as lower altitude regions.
Alpine ecosystems can be found in North America Cordillera, the Himalayas and Karakoram of Asia, the Alps and Pyrenees of Europe, Eastern Rift mountains of Africa and the Andes of South America. These ecosystems are characterised by harsh winters — a consequence of adiabatic cooling of air—with low temperatures, nutrient-poor soils and by dramatically changing climate between seasons. Lichens, bryophytes, meadows and shrubs cover most of the region. The vegetation is exposed to blustery winds, the intense radiation of sun, cold, snow and ice and hence they have been adapted to grow close to the ground and they include perennial grasses, sedges and tussock grasses. The colder temperature at high elevation and strong winds in the Alpine tundra do not support any tree growth. Plants have a growing season range from 45 to 90 days, with frost occurring throughout the growing season. Mainly inhabited by small grazers, the ecosystem comprises kea, marmot, mountain goat, Bighorn sheep, chinchilla, Himalayan tahr, yak and pika, among others.
The functional integrity of the ecosystem largely depends on the amount of snow it receives in winter and the time when the snow melts. With the rising temperature, there has been lesser snow, warmer and earlier springs, prolonged summers and more frost damage. This has disrupted the flowering season and seed production of plants which, in turn, has been affecting the small mammals and birds which depend on them for their growth and survival. Recent studies show that higher spring temperature may be good for plant growth, however, higher summer temperature can threaten their survival; rising temperature may favour plants which are better adapted to vertical growth, hence, they may overshadow the low-growing, prostrate vegetation; warmer temperature would bring changes in the snowpack which will influence the growth of the plants — earlier snowmelt would expose them to an increased number of spring frost episodes. For instance, earlier spring snowmelt causes mountain daisies to bloom earlier, making them more vulnerable to frost which can damage them and as a result, their nectar is reduced. Some species of butterflies depend on this nectar for food during egg-laying season. No nectar would mean no eggs which would result in a decline of their population.
Climate change is inducing an upward migration of plants and animals with the rise in temperature. As the glaciers and permafrost melt, the shrubs and grasses have started to grow in the open habitats. Small grazers feed on these shrubs. With the upward movement of vegetation, the rodents and grazing animals would migrate as well. This will put the existing species at risk. Global warming is expected to increase erosion and influence structure of soil which may drastically change the Alpine ecosystem landscape. We have enough pieces of evidence that climate change has triggered a response in the alpine ecosystem and if we do not act now, we might have to face grave consequences of this transformation soon.