Climate change driving vegetation growth higher into the Himalayas
Scientists in the UK have conducted an analysis of satellite data and uncovered a trend of new vegetation growth at high altitudes in the Himalayas. This expanding coverage of plant life is in-line with climate change modeling, with the researchers behind the study conscious of the effects it could have on snow melt and water flow, which could have far-reaching impacts across Asia.
The research was carried out by scientists at the University of Exeter, who drew on data from NASA's Landsat satellites gathered between 1993 and 2018. In doing so, the team was able to assess the coverage of plant growth between the tree-line and the snow-line, which is known as subnival vegetation.
Measurements were broken down into four height brackets between 4,150 and 6,000 meters (13,600 and 20,000 ft) above sea level, with "small but significant" changes observed across all categories.
The most profound change was seen between heights of 5,000 and 5,500 m (16,400 and 18,000 ft), while the area surrounding Mt Everest experienced a significant increase across all four brackets. Around 6,000 m is thought to be close to the height limit of where plants can grow.
According to the research team, this trend of subnival vegetation expansion is consistent with climate change modeling that predicts a decline in what are known as "temperature-limited areas," in the Himalayas. These are regions where it is too cold for plants to grow.
“It’s important to monitor and understand ice loss in major mountain systems, but subnival ecosystems cover a much larger area than permanent snow and ice and we know very little about them and how they moderate water supply," says Dr Karen Anderson, lead author of the study. “Snow falls and melts here seasonally, and we don’t know what impact changing subnival vegetation will have on this aspect of the water cycle – which is vital because this region (known as ‘Asia’s water towers’) feeds the ten largest rivers in Asia.”
The area studied, known as the Hindu Kush Himalayan region, spans eight countries, with more than 1.4 billion people depending on water trickling down into its catchments for their well-being. From here, the researchers hope to carry out detailed fieldwork to validate their findings and better understand the relationship between the new plants at these high altitudes, the soil and the snow.
The research was published in the journal Global Change Biology.
Source: University of Exeter