Mega Hydropower, a Forbidden Climate Change Topic

June 25, 2002

In today’s world, questioning hydropower energy as being “clean”, “green” and
“renewable” is regarded by many in control of climate science as environmental
blasphemy. Yet, when you look at all freshwater flow on Earth, the thousands of dams
and especially the mega dam projects, “…have commandeered almost 60% of that
variability” ( Can we commit to such a
change in the hydrologic cycle and not expect the climate to change?
Especially concerning are the mega hydro dam projects that have proliferated on large
rivers in Canada and Russia since the 1960’s. These dams must be included in climate
change discussions. Their expanding presence has closely coincided with the rather
abrupt, unprecedented and intensified increases in temperature and weather events in
Eurasia and North America. The flow regulation of these dams seizes the icy spring
runoff and then stores the stagnated water in inland sea sized reservoirs. The
impounded water is heated by the summer sun and then released during the long
In the fall and winter before the dams existed, the rivers were locked in ice. Now,
thanks to the warmer deep reservoir releases, their heat pollution is released
downstream over great distances. This has never happened before so abruptly in the
history of the Arctic. Thanks to the warmer reservoir water releases, a fully frozen Arctic
hydrosphere in the cold months no longer exists. To what degree are the present rapid
sea ice and permafrost melting fueled by this human forced thermal pollution?

Water vapor is the strongest greenhouse gas, stronger than even CO2. Now without
precedent, it has been unleashed by the dams upon the Arctic. Especially in the cold
dry months, evaporation in the fall from the water surfaces of these reservoirs and in
the winter, the ever flowing rivers downstream of the hydro turbine discharges are
releasing this most powerful of greenhouse gases. Extreme evaporation rates occur
when super cold dry air is in contact with the exposed warmed discharges. Air and
water temperature differences by as much as 60 to 70 degrees are common in the cold
months. The high winds that often occur across Arctic regions in the fall and winter
increase the evaporation rate further.
Is water vapor emitted from these hydropower projects carried by air currents for
thousands of miles, warming regions like Greenland and the Arctic Ocean? What
about the cascading mega hydro projects in central Siberia? Can they weaken
dominant cold season weather systems in the Northern Hemisphere, like the Siberian
Another worrisome question is to what degree are hydro dams crippling marine life and
its power to reduce CO2 in the atmosphere and oceans? Before the rivers were
dammed, the spring meltwater flowed to the ocean in a powerful freshwater current,
transporting nutrients and young marine life throughout the coastal seas and supplying
the energy to mix and oxygenate saltwater and freshwater layers. North Atlantic
marine plants and animals have adapted their life cycles over many millennia to the
long established timing, flow energy, and volume of this cold spring high flow. The
increasing numbers of huge dams have reduced nutrient delivery and robbed the
energy of the river flows emptying into the Labrador Sea, Hudson Bay, the Gulf of St.
Lawrence and the Gulf of Maine. Diatoms, the super plankton with their unique
efficiency to process and permanently sequester CO2, are a biological engine that can
help cool this planet and drive a healthy marine ecosystem. To what degree these
dams are harming marine diatom populations is a key climate change question.

These questions about the role these dams are playing with climate change and the
demise of marine life must be included along with fossil fuel impacts. Many human
lives and the survival of entire species may depend on our understanding and response
to the climate havoc these dams are generating.

Roger Wheeler


Leave a Reply

Your email address will not be published. Required fields are marked *