including changes in natural gas leaks from Russia,
wetlands, and a drop in the atmospheric concentration of OH, the main oxidant for methane
[171]. More recently, methane growth has resumed;
as of March 2019, its mole fraction was 1866.4 ppb,
compared to less than 700 ppb prior to 1700 [165].
The concentration of nitrous oxide in the atmosphere reached 330 ppb in 2017 with an average
rate of increase of 0.9 ppb per year over the past
decade. Many people have heard about the anthropogenic ozone hole, caused by release of chlorofluorocarbons (CFCs, a type of halocarbon). What
is not as well recognized is that the CFCs are
powerful greenhouse gases and that the Montreal
Protocol, created to protect the ozone layer, is also
the most successful climate treaty in history. The
atmospheric concentration of the CFCs is decreasing, due to international agreements. As the main
substitutes of CFCs, HFCs (hydrofluorocarbons)
and HCFCs (hydrochlorofluorocarbons) are
increasing in concentration as they have no or
small ozone depletion potential.
Oxygen Changes
The concentration of oxygen in the atmosphere has
decreased due fossil fuel combustion (Fig. 5a). The
change in the concentration of O 2 is a few parts per
million per year and is not a threat in itself. The
measurement series is used to calculate the sizes of
the land and oceanic sinks of global CO 2 [21] due
to the mass balance between the amount of carbon
released by human activity, the amount of CO 2
dissolved in the ocean, and the amount taken up
by photosynthesis [22]. By recording the atmospheric ratio of O 2 to N 2 , atmospheric abundance
of CO 2 , and emissions of CO 2 from burning fossil
fuel [23], it is possible to calculate the carbon
dioxide sequestration by terrestrial and marine systems (Fig. 5b).
A series of papers have explored the fate of
CO 2 released into the atmosphere [20–24]. Atmospheric potential oxygen (APO) is “a weighted
sum of O 2 and CO 2 in an air parcel” [24] that “is
essentially the O 2 /N 2 ratio added to 1.1 times the
concurrent CO 2 concentration” [25]. Using the
atmospheric and fossil fuel emission records,
the ocean and land biotic uptake can be deduced.
Manning and Keeling [24] found that from 1990
to 2000, the ocean absorption sink was
1.71 Æ 0.52 Pg C per year and the terrestrial
ecosystems sink was 1.41 Æ 0.66 Pg C per year,
matching data from Manning in 2001 [26].
Oceans
Oceans cover 71% of Earth’s surface and have a
mass a million times higher than the atmosphere
and are therefore able to exert a very large effect
on the atmosphere [5]. Oceans stored 90% of the
additional energy in the climate system between
1971 and 2010 [10], leading to ocean temperature
increases. The largest observed effect is in the
upper layer (0–700 m), where the near-surface
(upper 75 m) temperature increase exceeds
0.1
C per decade, whereas at 700 m, the increase
is only 0.015
C per decade. The ocean temperature rise is most distinct in the Northern Hemisphere due to the concentration of landmass,
population, Arctic sea ice loss, and ocean circulation itself. The ocean warming will spread from
the surface to lower ocean (depth > 1000 m), and
this, in turn, will affect ocean currents. The global
mean sea surface temperature change from 2046
to 2065 is estimated to be in the range of 1–2
C
and from 2081 to 2100 in the range of
1–3.7
C [10].
Ocean warming results in sea level rise due to
thermal expansion of water [10]. There is additional sea level rise due to the melting of land ice,
glaciers, ice caps, and the major ice sheets of
Antarctica and Greenland. Thermal expansion
combined with melting land ice is responsible for
75% of observed sea level rise since 1971. Sea
level is also affected by water storage in terrestrial
systems, for example, irrigation removes water
from reservoirs on land, and dams prevent some
runoff into the ocean.
The rate of global mean sea level rise between
1901 and 2010 was 1.7 mm/year, yielding a total
rise of 0.19 m in that time period. It is likely that
the rate was higher between 1993 and 2010, at
3.2 mm/year. Future projections of sea level rise
estimate that from 2046 to 2065, the global mean
rise will be in the range of 0.24–0.30 m and from
2081 to 2100 in the range of 0.40–0.63 m [10].
Melting ice introduces freshwater to oceans,
thus changing salinity. Salinity also depends on
Air Pollution and Climate Change: Sustainability, Restoration, and Ethical Implications
289
wetlands, and a drop in the atmospheric concentration of OH, the main oxidant for methane
[171]. More recently, methane growth has resumed;
as of March 2019, its mole fraction was 1866.4 ppb,
compared to less than 700 ppb prior to 1700 [165].
The concentration of nitrous oxide in the atmosphere reached 330 ppb in 2017 with an average
rate of increase of 0.9 ppb per year over the past
decade. Many people have heard about the anthropogenic ozone hole, caused by release of chlorofluorocarbons (CFCs, a type of halocarbon). What
is not as well recognized is that the CFCs are
powerful greenhouse gases and that the Montreal
Protocol, created to protect the ozone layer, is also
the most successful climate treaty in history. The
atmospheric concentration of the CFCs is decreasing, due to international agreements. As the main
substitutes of CFCs, HFCs (hydrofluorocarbons)
and HCFCs (hydrochlorofluorocarbons) are
increasing in concentration as they have no or
small ozone depletion potential.
Oxygen Changes
The concentration of oxygen in the atmosphere has
decreased due fossil fuel combustion (Fig. 5a). The
change in the concentration of O 2 is a few parts per
million per year and is not a threat in itself. The
measurement series is used to calculate the sizes of
the land and oceanic sinks of global CO 2 [21] due
to the mass balance between the amount of carbon
released by human activity, the amount of CO 2
dissolved in the ocean, and the amount taken up
by photosynthesis [22]. By recording the atmospheric ratio of O 2 to N 2 , atmospheric abundance
of CO 2 , and emissions of CO 2 from burning fossil
fuel [23], it is possible to calculate the carbon
dioxide sequestration by terrestrial and marine systems (Fig. 5b).
A series of papers have explored the fate of
CO 2 released into the atmosphere [20–24]. Atmospheric potential oxygen (APO) is “a weighted
sum of O 2 and CO 2 in an air parcel” [24] that “is
essentially the O 2 /N 2 ratio added to 1.1 times the
concurrent CO 2 concentration” [25]. Using the
atmospheric and fossil fuel emission records,
the ocean and land biotic uptake can be deduced.
Manning and Keeling [24] found that from 1990
to 2000, the ocean absorption sink was
1.71 Æ 0.52 Pg C per year and the terrestrial
ecosystems sink was 1.41 Æ 0.66 Pg C per year,
matching data from Manning in 2001 [26].
Oceans
Oceans cover 71% of Earth’s surface and have a
mass a million times higher than the atmosphere
and are therefore able to exert a very large effect
on the atmosphere [5]. Oceans stored 90% of the
additional energy in the climate system between
1971 and 2010 [10], leading to ocean temperature
increases. The largest observed effect is in the
upper layer (0–700 m), where the near-surface
(upper 75 m) temperature increase exceeds
0.1
C per decade, whereas at 700 m, the increase
is only 0.015
C per decade. The ocean temperature rise is most distinct in the Northern Hemisphere due to the concentration of landmass,
population, Arctic sea ice loss, and ocean circulation itself. The ocean warming will spread from
the surface to lower ocean (depth > 1000 m), and
this, in turn, will affect ocean currents. The global
mean sea surface temperature change from 2046
to 2065 is estimated to be in the range of 1–2
C
and from 2081 to 2100 in the range of
1–3.7
C [10].
Ocean warming results in sea level rise due to
thermal expansion of water [10]. There is additional sea level rise due to the melting of land ice,
glaciers, ice caps, and the major ice sheets of
Antarctica and Greenland. Thermal expansion
combined with melting land ice is responsible for
75% of observed sea level rise since 1971. Sea
level is also affected by water storage in terrestrial
systems, for example, irrigation removes water
from reservoirs on land, and dams prevent some
runoff into the ocean.
The rate of global mean sea level rise between
1901 and 2010 was 1.7 mm/year, yielding a total
rise of 0.19 m in that time period. It is likely that
the rate was higher between 1993 and 2010, at
3.2 mm/year. Future projections of sea level rise
estimate that from 2046 to 2065, the global mean
rise will be in the range of 0.24–0.30 m and from
2081 to 2100 in the range of 0.40–0.63 m [10].
Melting ice introduces freshwater to oceans,
thus changing salinity. Salinity also depends on
Air Pollution and Climate Change: Sustainability, Restoration, and Ethical Implications
289