4
Temperatures have already risen by 0.85 °C and are projected to rise anywhere
from 0.3 °C to 4.8 °C in the next half century. Humanity has never experienced such
a dramatic change.
The risk due to warming that people are most familiar with is a rise in sea levels
produced by the melting of the polar ice caps. It will take time for such an enormous
amount of ice to melt, but once the ice is reduced and ocean temperatures start to
rise, it will make it even easier for further melting of the ice. Even if the rise in
atmospheric temperature is halted, it will require an enormous amount of time for
the ocean temperatures to continue to cool enough for ice to form once again.
It is said that if the sea levels rise, then various islands such as Tuvalu in the
South Pacific will sink into the sea. Research indicates the possibility that countries
like Thailand with coastal areas may, depending on conditions, see considerable
parts of those regions sink out of sight. Japan, too, will not go unaffected. If sea
levels rise by around 60 centimeters, it is expected the belts of coastal regions
around Tokyo, Osaka, and elsewhere that currently stand at exactly sea level would
increase by 1.5 times. This would require social capital investments on measures to
cope with flooding and water exposure.
Global warming will also bring about climate change. Even though Europe sits
at a higher latitude than Hokkaido, it has a temperate climate. This is due to the
general circulation of ocean currents wherein the warm Gulf Stream flows north
across the Atlantic Ocean to reach Europe and the waters subside there. However, as
warming proceeds, the amount of precipitation will increase and the saline concentration in sea waters will fall. If the specific gravity is not high enough, the waters
will not subside to the ocean floor and the flow of the Gulf Stream is quite capable
of stopping.
Should that happen, it is possible that Europe will become quite cold even if the
Earth’s temperature on the whole rises. Europe would experience a wave of
extremely cold weather that would set new records for people dying in the thousands due to electric power and other essential utilities being cut to shreds. The
social infrastructure takes the meteorological and climate conditions as they have
been to date as its premise, so countermeasures will not keep up in the event of a
drastic change.
Furthermore, if the Gulf Stream stops flowing to Europe, its heat will remain in
tropical regions and could cause Mexico and the southern U.S. to heat up intensely.
Hurricane Katrina, which practically wiped out the city of New Orleans, is thought
to have been produced by this sort of mechanism.
Another terrifying projection is that of positive feedback in warming. Lurking
beneath the surface of the Siberian permafrost is methane hydrate, with a structure
comprising methane molecules that are surrounded by water. Warming will cause
the ice to melt, releasing methane gas into the atmosphere. Methane has not received
as much attention since the volume of CO 2 emissions has been much higher, but it
has a greenhouse effect that is 10 times that of CO 2 per unit volume. This release of
methane into the atmosphere through warming could generate feedback in that the
greenhouse effects of that methane would cause warming to proceed all the more.
1 The Message in “Vision 2050”
Temperatures have already risen by 0.85 °C and are projected to rise anywhere
from 0.3 °C to 4.8 °C in the next half century. Humanity has never experienced such
a dramatic change.
The risk due to warming that people are most familiar with is a rise in sea levels
produced by the melting of the polar ice caps. It will take time for such an enormous
amount of ice to melt, but once the ice is reduced and ocean temperatures start to
rise, it will make it even easier for further melting of the ice. Even if the rise in
atmospheric temperature is halted, it will require an enormous amount of time for
the ocean temperatures to continue to cool enough for ice to form once again.
It is said that if the sea levels rise, then various islands such as Tuvalu in the
South Pacific will sink into the sea. Research indicates the possibility that countries
like Thailand with coastal areas may, depending on conditions, see considerable
parts of those regions sink out of sight. Japan, too, will not go unaffected. If sea
levels rise by around 60 centimeters, it is expected the belts of coastal regions
around Tokyo, Osaka, and elsewhere that currently stand at exactly sea level would
increase by 1.5 times. This would require social capital investments on measures to
cope with flooding and water exposure.
Global warming will also bring about climate change. Even though Europe sits
at a higher latitude than Hokkaido, it has a temperate climate. This is due to the
general circulation of ocean currents wherein the warm Gulf Stream flows north
across the Atlantic Ocean to reach Europe and the waters subside there. However, as
warming proceeds, the amount of precipitation will increase and the saline concentration in sea waters will fall. If the specific gravity is not high enough, the waters
will not subside to the ocean floor and the flow of the Gulf Stream is quite capable
of stopping.
Should that happen, it is possible that Europe will become quite cold even if the
Earth’s temperature on the whole rises. Europe would experience a wave of
extremely cold weather that would set new records for people dying in the thousands due to electric power and other essential utilities being cut to shreds. The
social infrastructure takes the meteorological and climate conditions as they have
been to date as its premise, so countermeasures will not keep up in the event of a
drastic change.
Furthermore, if the Gulf Stream stops flowing to Europe, its heat will remain in
tropical regions and could cause Mexico and the southern U.S. to heat up intensely.
Hurricane Katrina, which practically wiped out the city of New Orleans, is thought
to have been produced by this sort of mechanism.
Another terrifying projection is that of positive feedback in warming. Lurking
beneath the surface of the Siberian permafrost is methane hydrate, with a structure
comprising methane molecules that are surrounded by water. Warming will cause
the ice to melt, releasing methane gas into the atmosphere. Methane has not received
as much attention since the volume of CO 2 emissions has been much higher, but it
has a greenhouse effect that is 10 times that of CO 2 per unit volume. This release of
methane into the atmosphere through warming could generate feedback in that the
greenhouse effects of that methane would cause warming to proceed all the more.
1 The Message in “Vision 2050”