The recent landslide in February on a glacier in Uttarakhand’s Chamoli and subsequent floods and toll of human life and property has drawn our attention once again to the irony and stark reality of the fragility of the mighty Himalayas. A similar focus emerged when large scale devastation followed a bout of intense rain in 2013 in Kedarnath.
The Himalayas are unique mountain systems from the climate change and natural hazards perspective for at least a few key reasons: they are the highest, the youngest, tectonically active and most geologically unstable mountains anywhere on earth.
They have substantial areas of permanent snow and glaciers (called the third pole of the world) with many temperate biodiversity elements and vegetation communities and yet they also have a strong tropical monsoonal hydro-climatology and have some of the highest rates of warming globally.
Third, the Himalayas have unique water sources such as springs that sustain remote communities but are also an important source of water, carbon and sediment for sustaining downstream socio-ecological systems from flood-plain rivers to the Ganga-Brahmaputra delta and the Bay of Bengal. Fourth, the Himalayas are currently undergoing huge transformations: socio-economic as well as developmental.
We have to recognise that compared to many other mountains the Himalayas are particularly high-energy environments characterised by geological instability, hydro-climatic variability and uncertainty. Furthermore, the hazards are from the movement of diverse processes: rockfalls and debris slides, avalanches and mudslides.
The high energy dimension whether it is from receiving over 100 mm of rainfall in an hour, the ability of its fast-flowing streams and rivers on steep gradients to carry a huge amount of sediment and water adds to the intensity of events while giving very little warning.
A mountain slope with loose debris from previous landslides may give us a false sense of stability and complacency until the right environmental conditions (for example an intense bout of rain) and human factors (such as road widening) triggers a disaster.
What we know
Now, what about the forests and other vegetation of the Himalayas? Here I draw from published work by scholars in summarising what we know. The high rate of warming (0.06 degrees Celsius/year amounting to 1.5 degrees Celsius increase in mean annual temperature in 25 years) has increased the growing season by nearly five days by advancing the growing season.
So, are the Himalayas becoming greener due to climate change? Not necessarily. The available data suggests both greening (higher elevations) and severe browning (lower and mid-elevation) and varies across the mountains from west to east.
The browning is attributed to warming-induced moisture stress in the post-monsoon and dry season on trees especially broad-leaved species such as Oaks. Furthermore, we learn that one important determinant of Western Himalayan forest productivity is the amount of post-monsoon and winter rainfall. The failure of winter and post-monsoon rainfall especially in the Western Himalayas in hot years can hit the vegetation very hard.
One example is 1998-1999 an El Nino year when less than 27 mm of rainfall was received in the Kumaon region between September and May and all of it in just a few days spread apart by months with no rain. So it is a double, jeopardy: drought in the spring and summer and very intense rain events and landslides in the monsoon. Local communities have also been reporting more frequent crop failure in recent decades as well as the decline in spring discharge.
In terms of ecosystem services and biodiversity, a recent study has shown that the loss of old-growth forests or even a few large old trees results in a big loss of carbon stock and cannot be compensated by compensatory plantations elsewhere. The younger plantations may have a bigger demand for moisture leading to stress on them as well as the local moisture regimes adding to the loss of ecosystem services.
Avoiding disaster-prone activities
We need monitoring and early-warning systems in place and careful scrutiny of all development projects whether it is road building or road widening or the location of hydropower projects, and have the maturity and wisdom to redesign or avoid disaster-prone activities.
We need to be careful about the attribution of disasters to natural and anthropogenic processes. Unfortunately, in the aftermath of the recent disaster, the fact that it was the location of hydro-power projects and other infrastructure in vulnerable sites that added to the human toll got mixed up with the discussion on what triggered the landslide on the glacier upstream, which could be a natural phenomenon.
Furthermore, in complex interactions between climate change processes, and natural climate variability with geology and human activities, attribution to any one factor can be difficult. It is tempting for environmental activists to link all sorts of development activities to disasters, but it can lead to clutter and noise in the debate.
It is now clear that infrastructure development project should be allowed, redesigned or avoided based on a proper understanding of geological, hydro-climatic and environmental factors and due diligence has to be exercised. How can we change the discourse on business as usual to climate change and natural hazard resilient development pathways? This is a question that needs urgent attention from our policymakers especially in the NITI Aayog, the Ministry of Environment, Forests and Climate Change, of Power and the Ministry of Road Transport and Highways.
Jagdish Krishnaswamy, Senior Fellow, Ashoka Trust for Research in Ecology and the Environment and Biodiversity Collaborative