What of the Future? - Climate Change Impacts on Freshwater Ecosystems - page 288

mountain glaciers had glistened white and the peaks had reflected the orange
light as the sun set in the late summer evenings. The loss from the glaciers was
somehow depressing and the mood was worsened by the rivers, which had been
running with greyer water as the glacier-eroded deposits had steadily washed away
in early summer. Later the water was turbid brown as the upland peats had unfrozen
and eroded, and a tea-like stain had appeared even when the water was filtered.
Sometimes, in the rapid melt of spring, large dams had formed from blocks of river
ice, backing up huge quantities of melt water so rapidly that villages had had to be
rapidly evacuated. In one case, 20 people refusing to leave their homes had been
drowned when the dam gave way and a whole village was obliterated.
There had been some problems with the drinking water supply also. Where it
came from upland lakes, the levels of some heavy metals had increased to above
tolerable levels as the debris below the glaciers, previously frozen solid, had
melted and weathered. The analysts had picked up also an increase in the
conductivity and nitrogen concentrations in the river water, but these had not yet
caused any perceptible problem.
There had been ecological changes in the rivers. Arctic charr, once a favoured
sport fish, had declined, and even disappeared, in parts of the lowlands, though
they could still be caught in the mountains, and some new fish were starting to
move up from the main stem river further south, of which the Erehwomos was a
tributary. Salmon were much scarcer and smaller and the spring runs were not so
prominent, though their decline had been anticipated for many other reasons
than warming. Rising human populations the world over and their need for food
had meant that sea fish stocks had dwindled to almost nothing. The river bottoms
had become more vegetated with willow shrubs, and moose and deer were found
there more frequently. Wolves were heard a little more frequently as they too
responded to the increased production.
The mosquito and blackfly problems had become worse, and the increase in
flooding risks had led to some people moving out. Small farmers had been unable
to cope but the wealthier ones were doing better as they bought up small farms and
amalgamated them into bigger units and in some years risked planting new crops
like barley and wheat that they could not have grown before. The power generators
and foresters were happy too. Hydroelectric power was favoured by a government
now realizing that action to curb carbon emissions should have been taken more
vigorously and much earlier and there was investment to replace the ageing
machinery. But the brown summer water, with the chocolate-coloured banks of
sediment left in August and September when flows had fallen to levels rarely before
experienced, worried the ecologists who were studying the catchment. Just what
was happening to the huge carbon store of the upland plateaux and mountains?
And though the forest growth had increased, so had the rate at which the debris
on the forest floor had rotted. Where did the carbon balance now lie?
By the late 21st century, that question had been partly answered. Warming
had been experienced rather faster than anticipated because carbon had been
respired from the huge peatlands of the north as they warmed and dried in
summer. An inhabitant of the Erehwomos catchment in the 20th century would
barely have recognized it in the late 21st century. Much of the upland tundra
had gone to scrubby forest, clinging to soils that had eroded rapidly; the