Environmental Engineering Reference
In-Depth Information
water masses then return to Central America as cold deep water fl ow, to be heated
up again there.
Due to climate warming, large quantities of meltwater (melted snow and ice) pour
into the North Sea. This fresh water dilutes the warm saltwater. It has already been
determined that the salt content has fallen considerably. If the salt content decreases
even further, the weight of the water will not be suffi cient in the future to allow it
to sink down. The enormous Gulf Stream water pump would get out of step and
very suddenly come to a halt.
Figure 2.11
Principle of the
Gulf Stream.
Climate researchers suspect this was precisely the cause of the temperature jumps
11 000 to 12 000 years ago. After the ice age enormous amounts of meltwater from
the melting glaciers poured through the St Lawrence River into the North Atlantic.
It diluted the sea water with fresh water, so that the uppermost layer of sea water
became noticeably less salty and the water lighter. Therefore, the water no longer
sank to the depths, despite strong cooling. The Gulf Stream was 'turned off ' and
for many years large areas of Northern Europe and Canada were exposed to extreme
cold and covered in ice. As a result, the amount of meltwater decreased again. The
salt content of the water rose. The warm water heater, the Gulf Stream, started
working again.
This is exactly the fate that we are facing again today. No scientist can accurately
predict just how much global warming must increase before the Gulf Stream stops
working. But the assumption is that the critical point will have been reached once
worldwide warming increases by 3 °C. We already have increased the temperature
by a good 0.7 °C. The consequences for us would be catastrophic. The climate would
be erratic for years. Ultimately, it would be so cold and dry in Europe that any kind
