What of the Future? - Climate Change Impacts on Freshwater Ecosystems - page 287

a work of collective creative imagination. But it emphasizes the consequences
of links between freshwaters and the human societies that universally depend
on them. It gives a flavour rather than a precise menu, but this is what we think
might happen.
The Arctic/Boreal zone
In the very early 21st century, people in the catchment of the River Erehwomos
enjoyed a varied landscape, for the conifer forests of the lowlands thinned out to
an arctic-alpine tundra on the mountains, where reindeer still grazed in a National
Park of stark beauty, covered with lakes and peatlands. It was cold, of course,
with a mean annual temperature of 5 °C, falling in winter to −10 °C and rising to
15 °C in summer, but the inhabitants were hardy outdoor people for the most
part. The upland soils were permafrosted but the ice left the rivers and the many
lakes in May. The rivers gushed, as the snowpack melted and soon there was a
surge in activity. The salmon fishery, the fish farms and the tourism, logging and
paper industries emerged from the winter quiet. Some of the rivers in the lowlands
had been engineered and cleared of woody debris to smooth the passage of logs
floated down in the past and there were several large hydroelectric dams
generating power for more southerly latitudes. Farming was not prosperous but
in the warmer lowland river valleys, mixed farms, with small herds of dairy cows,
a few sheep and fields of oats and rye, separated the villages, with their ice-
broken road surfaces, from the forests. The winter was lengthy with the days
shortening to only an hour or two by December, but long and bright in summer.
Most of the precipitation of around 1,000mm fell as snow in winter leaving
little to fall as summer rain. The snag, however, was that the low evaporation
rate of only 200mm left water so plentiful on the landscape that mosquitoes
thrived in the many pools and wetlands, and the streams harboured so many
blackfly larvae that a major summer irritation came with their hatch into
aggressively biting adults.
As temperatures rose steadily towards the middle of the 21st century, the
guides who led parties to shoot deer and moose in the forests had noticed that
the tree line had crept upwards by several hundred metres. Their season had
started much earlier, and spring flowers carpeted the soils in late April, rather
than the early June of the 20th century. Foresters had noted increased tree growth
and deer had become more plentiful. To some extent this was creating more
damage around the tree line and restricting the otherwise inexorable advance of
the forest on the upland tundra. Some of the birds, the golden plover for example,
had disappeared northwards but others had come in from the south.
The winter snow depth had increased but the melt came over a month earlier
and the rivers rose much higher than previously, cascading down to threaten the
stability of some of the older hydroelectric dams and to flood the farmlands.
There had been severe erosion of the lower-lying fields, and winter housing for
the cattle had had to be reconstructed in newly bought land (for the few farmers
who could afford it) in cleared forest at higher levels. From their viewpoint in the
valleys, people noted grey patches of rock in summer where, 50 years before, the