According to comprehensive new climate change research, water resources in snow-dominated regions across the Northern Hemisphere will vary more and become more difficult to anticipate by the end of this century.
Even locations that continue to get the same amount of precipitation may have more erratic and unpredictable streamflow as the snowpack melts.
Climate change to water resources
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Even in locations that continue to get roughly the same amount of precipitation, the study team discovered that streamflow will become more erratic and unpredictable, as per ScienceDaily.
As snowpack melts and fails to deliver regular flow in a warmer future, the volume and timing of water supplies will become increasingly dependent on occasional bouts of rain.
Water managers will be at the mercy of individual precipitation events rather than having four to six months to plan for snowmelt and runoff, according to NCAR scientist Will Wieder, the primary author.
Water management systems in snowy regions rely on the predictability of snowpack and runoff, and much of that predictability may be lost as a result of climate change.
Snowpack is already melting sooner and diminishing in several areas, according to observations.
The study cautions that changes in runoff and streamflow are likely to have a domino effect on ecosystems that rely on stable water from snow.
Although the effects will vary by location, more snow-free days and longer growing seasons will strain water supplies, drying out soils in many areas and increasing fire danger.
The analysis assumes that greenhouse gas emissions will continue at a high rate (a scenario known as SSP3-7.0).
The most severe consequences on snowfall, runoff, and ecosystems, according to Wieder, would likely be averted if civilization effectively decreased greenhouse gas emissions.
Many parts of the world rely on snow accumulation in the winter and subsequent melting in the spring and summer to regulate runoff and streamflow.
Scientists have been warning for years that the snowpack will grow smaller and melt sooner as more precipitation falls as rain rather than snow during the colder months, and as melting happens at times during the winter rather than the spring runoff season.
Wieder and his co-authors used a robust NCAR-based climate model, the Community Earth System Model, version 2, to evaluate how diminished snowpack will influence the unpredictability of water resources. They used a freshly constructed simulation database known as the CESM2 Large Ensemble to compare a previous time (1940-1969) with a future period (2070-2099).
The findings shed light on how extensive changes in the timing and breadth of water flows would occur across most of the planet by 2100.
Assuming high greenhouse gas emissions, the Northern Hemisphere will have around 45 extra snow-free days each year.
The greatest increases will occur in moderately warm midlatitudes and high-latitude maritime regions impacted by changes in sea ice.
Many locations that rely on predictable linkages between snowpack and runoff may suffer the most predictability loss as a result of a dramatic drop in consistent pulses of spring runoff.
Climate change will have wildly disparate effects on Europe's water depending on the area. In general, rising temperatures will accelerate the global hydrological cycle, as per European Environment Agency.
Annual precipitation patterns in Europe show that northern Europe has gotten 10%-40% wetter during the previous century, whereas southern Europe has become up to 20% drier.
Annual river discharge has grown in certain parts, such as eastern Europe, while decreasing in others, such as southern Europe, throughout the previous century.
Climate change may also have a significant impact on seasonal variations in river flow. Higher temperatures will raise the snow limit in northern Europe and mountainous areas.
This, along with reduced snowfall, will result in increased winter run-off in northern European and mountain-fed rivers such as the Rhine, Rhône, Po, and the Danube.
Furthermore, earlier spring melt will cause a change in peak flow levels. There will be less water to compensate for the reduced flow rates in summer due to the shrinking snow reservoir and glaciers.
Changes in average water availability are expected to be minor in most European river basins during the next 30 years.
However, most climate change models anticipate that annual average river flow and water availability would grow across northern and eastern Europe in the long run.
The average run-off in southern European rivers, on the other hand, is expected to drop. Some river basins in the Mediterranean area, in particular, which are already under water stress, may witness significant declines in the water supply.
