having lost approximately 1 m of thickness since early 2002. Some scientists
indicate that the mountain has lost 82% of the icecap it had in 1912, when it
was first carefully surveyed.
Climate changes have also been shown to affect ocean temperature, salinity
and flow patterns. Warmer temperatures weaken the ice, making it vulnerable
to current changes and other forces. Some scientists consider that this has
already influenced the stability of ice shelves in the Antarctic. Indeed, two
chunks of ice the size of a small country broke off from the Antarctic
Peninsula’s Larsen Ice Shelf in 1995 and 2002.
3
Scientists in the U.S. and Canada have observed a similar phenomenon
occurring in the Arctic. They report that the largest ice shelf in the Arctic, a
solid feature for 3000 years, has broken up. The report shows that the Ward
Hunt Ice Shelf, on the north coast of Ellesmere Island in Canada (the
northernmost land mass of North America), broke into two main parts,
themselves cut through with fissures. Only 100 years ago, the whole northern
coast of Ellesmere Island was edged by a continuous ice shelf. According to the
report, about 90% of the shelf is now gone. Records indicate an increase of
0.4
C every 10 years since 1967. The average July temperature has been 1.3
C
since that year.
4
Environmental researchers believe that the burning of fossil fuels is slowly
causing the climate to change. Exhaust from burning these fuels increases the
level of carbon dioxide (CO 2 ) and nitrogen oxides (NO x ) and particulate
matter in the atmosphere. This, in turn, causes the earth to retain heat,
warming the globe. The CO 2 level in the atmosphere is already dangerously
high. According to a recent report by the Intergovernmental Panel on Climate
Change, an atmospheric CO 2 level of 540 to 970 ppm and a global temperature
rise of 1.4 to 5.8
C could occur by 2100. Some scientists are concerned about
an even more worrisome effect on future generations. With the long residence
time of CO 2 in the atmosphere and warmer oceans, what are the prospects for
the 22nd century? Many scientists consider that, because of their wealth and
advanced technology, the U.S. and other industrial nations may be able to
cope with the effects of global warming in their own countries in this century,
but are unlikely to escape serious impacts in the following century.
4
Knowledge about the contribution of CO 2 and other greenhouse gases to
global warming has led a number of countries to reduce their emissions. This
trend is particularly marked in several European countries, such as Germany,
France, Italy, and the U.K. By contrast, some Asian countries, including
China, India, and South Korea, have markedly increased their energy-related
carbon emissions over the past two decades (Figure 2.1).
5 The U.S. General
Accounting Office, which released the report, also predicts that China’s
emissions, now equivalent to half the U.S. output, will reach more than 80% of
U.S. output by 2025.
5
An often-debated question is the impact of increased CO 2 levels on
vegetation. Some laboratory studies indicate that the rise of CO 2 levels in the
atmosphere will stimulate plants to grow more abundantly, but others suggest
that is not necessarily the whole story. New research in California has found
14
Environmental Toxicology
[16:55 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-002.3d]
Ref: 4365 MING-HO YU Chap-002 Page: 14 13-30
indicate that the mountain has lost 82% of the icecap it had in 1912, when it
was first carefully surveyed.
Climate changes have also been shown to affect ocean temperature, salinity
and flow patterns. Warmer temperatures weaken the ice, making it vulnerable
to current changes and other forces. Some scientists consider that this has
already influenced the stability of ice shelves in the Antarctic. Indeed, two
chunks of ice the size of a small country broke off from the Antarctic
Peninsula’s Larsen Ice Shelf in 1995 and 2002.
3
Scientists in the U.S. and Canada have observed a similar phenomenon
occurring in the Arctic. They report that the largest ice shelf in the Arctic, a
solid feature for 3000 years, has broken up. The report shows that the Ward
Hunt Ice Shelf, on the north coast of Ellesmere Island in Canada (the
northernmost land mass of North America), broke into two main parts,
themselves cut through with fissures. Only 100 years ago, the whole northern
coast of Ellesmere Island was edged by a continuous ice shelf. According to the
report, about 90% of the shelf is now gone. Records indicate an increase of
0.4
C every 10 years since 1967. The average July temperature has been 1.3
C
since that year.
4
Environmental researchers believe that the burning of fossil fuels is slowly
causing the climate to change. Exhaust from burning these fuels increases the
level of carbon dioxide (CO 2 ) and nitrogen oxides (NO x ) and particulate
matter in the atmosphere. This, in turn, causes the earth to retain heat,
warming the globe. The CO 2 level in the atmosphere is already dangerously
high. According to a recent report by the Intergovernmental Panel on Climate
Change, an atmospheric CO 2 level of 540 to 970 ppm and a global temperature
rise of 1.4 to 5.8
C could occur by 2100. Some scientists are concerned about
an even more worrisome effect on future generations. With the long residence
time of CO 2 in the atmosphere and warmer oceans, what are the prospects for
the 22nd century? Many scientists consider that, because of their wealth and
advanced technology, the U.S. and other industrial nations may be able to
cope with the effects of global warming in their own countries in this century,
but are unlikely to escape serious impacts in the following century.
4
Knowledge about the contribution of CO 2 and other greenhouse gases to
global warming has led a number of countries to reduce their emissions. This
trend is particularly marked in several European countries, such as Germany,
France, Italy, and the U.K. By contrast, some Asian countries, including
China, India, and South Korea, have markedly increased their energy-related
carbon emissions over the past two decades (Figure 2.1).
5 The U.S. General
Accounting Office, which released the report, also predicts that China’s
emissions, now equivalent to half the U.S. output, will reach more than 80% of
U.S. output by 2025.
5
An often-debated question is the impact of increased CO 2 levels on
vegetation. Some laboratory studies indicate that the rise of CO 2 levels in the
atmosphere will stimulate plants to grow more abundantly, but others suggest
that is not necessarily the whole story. New research in California has found
14
Environmental Toxicology
[16:55 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-002.3d]
Ref: 4365 MING-HO YU Chap-002 Page: 14 13-30