View: Yes, glaciers are melting but no need for panic

The current flash flood in Uttarakhand was extensively referred to as a “glacier burst” though glaciers are not balloons and don’t burst. It has spurred renewed warnings that global warming threatens fast melting of the Himalayan glaciers, decimating flows within the Gangetic plain, inflicting desertification and devastating agriculture. Academics like Brahma Chellaney predict wars from water shortage.

In 2007 the International Panel on Climate Change incorrectly predicted that each one Himalayan glaciers would possibly disappear by 2035, and was obliged to appropriate itself. Then setting minister Jairam Ramesh commissioned an impartial examine by glaciologist V Okay Raina. His report stated whereas glaciers had been melting because the finish of the final Ice Age and would proceed doing so, melting had not accelerated in current many years even when temperatures had risen. Raina says glacial soften contributes barely 2% to the circulation of the Ganga at Allahabad: rain is the overwhelming supply of circulation. Corollary: even when all of the glaciers soften centuries therefore, the river and agriculture shall be impacted very modestly.

Even Raina’s 2% estimate could also be too excessive. A 2019 analysis paper by Richard Armstrong, National Snow and Ice Data Center, USA, with 11 worldwide collaborators is the primary examine to interrupt down individually the contribution to river flows in Himalayan river basins by (a) snow on land melting; (b) snow on glaciers melting; (c) glacial ice melting; and (d) rainfall.

The examine covers solely high-altitude areas above 2,000 metres (the altitude of Mussoorie or Darjeeling). This is as a result of river flows within the plains are clearly dominated by rainfall. But even above 2,000 metres, the contribution of uncovered glacial soften to river flows within the Ganga basin is lower than 1%; of snow on glaciers 4%; of snow on land 43%; and of rainfall 52%. The 4 contributions within the Indus basin are 2%, 6%,67% and 23%; and within the Brahmaputra basin 1%, 7%, 26% and 66%.

Many readers shall be astonished that the contribution of glacial soften might be just below 1% even within the greater Himalayas. The estimates of another researchers are far greater. The new examine suggests the opposite researchers have failed to tell apart between snowmelt and glacial soften as a result of the know-how and knowledge to make the excellence was not simply accessible earlier, but makes an enormous distinction.

Raina’s report complained of the woeful lack of Himalayan climate stations to gather knowledge. The Indian Space Research Organisation collects knowledge by satellite tv for pc, and stated in a 2014 report that it had monitored 2,018 Himalayan glaciers between 2001 and 2011. It discovered that solely 248 glaciers have been retreating, 1,752 have been steady and 18 have been advancing. Other research say most but not all glaciers are retreating. There is internet melting but no disaster.

Substantial snow falls in winter. In early summer season, snow on land and glaciers begins melting. Snowmelt from excessive mountains can circulation onto the glaciers and be mistaken for glacial soften. After the snow masking glaciers has melted, the uncovered glacial ice melts too between June and late September.

This coincides with the monsoon, which then dominates river flows. So, Raina emphasises, it’s a fable that glacial soften is crucial for river circulation within the lean pre-monsoon season. Armstrong exhibits snowmelt is the important thing contributor. And snow will proceed to fall, soften, and feed the rivers after each glacier disappears centuries therefore. This ought to shock none: geology exhibits large rivers descending from the Himalayas even earlier than the final Ice Age created the glaciers.

All forecasts of the affect of worldwide warming on Himalayan snowfall are extremely speculative: we actually don’t know. Global warming ought to improve ocean evaporation and clouds, rising rain and snow. Its distribution is unsure.

The space coated by winter snow is many instances larger than that coated by glaciers, so it contributes extra. Even on the snout of glaciers, the place rivers emerge, glacial soften is a minor contributor. Armstrong places it at simply 1-2% at excessive altitudes. This retains falling because the river strikes downhill and is fed by rain.

In frequent parlance, glaciers are typically but misleadingly referred to as the supply of Himalayan rivers. In reality glaciers are merely the very best level of rivers. The precise supply of the Ganga just isn’t the Gangotri glacier but each drop of rain that falls on the 860,000sq km of the basin, after which flows downhill to the river. That creates the circulation.

The research of Raina, ISRO and Armstrong will shock these predicting accelerated melting and famine. But distinguishing between snowmelt and glacial soften is nice science, and results in happier conclusions. Let’s rejoice. Glacial retreat may have some antagonistic side-effects on glacial lakes and wildlife. But not even glacial disappearance will imply dry rivers, famine and conflict.

chilly truths: Contrary to what folks suppose, it’s rain and never glaciers that contribute many of the circulation to Ganga