Carbon Dioxide Concentration Surges – The amount of
greenhouse gases in the atmosphere reached a new record high in 2013,
propelled by a surge in levels of carbon dioxide. This is according to
the
World Meteorological Organization’s annual Greenhouse Gas Bulletin,
which injected even greater urgency into the need for concerted
international action against accelerating and potentially devastating
climate change.
The Greenhouse Gas Bulletin showed that between
1990 and 2013 there was a 34% increase in radiative forcing – the
warming effect on our climate – because of long-lived greenhouse gases
such as carbon dioxide (CO2), methane and nitrous oxide.
In 2013,
concentration of CO2 in the atmosphere was 142% of the pre-industrial
era (1750), and of methane and nitrous oxide 253% and 121% respectively.
The
observations from WMO’s Global Atmosphere Watch (GAW) network showed
that CO2 levels increased more between 2012 and 2013 than during any
other year since 1984. Preliminary data indicated that this was possibly
related to reduced CO2 uptake by the earth’s biosphere in addition to
the steadily increasing CO2 emissions.
The WMO Greenhouse Gas
Bulletin reports on atmospheric concentrations – and not emissions - of
greenhouse gases. Emissions represent what goes into the atmosphere.
Concentrations represent what remains in the atmosphere after the
complex system of interactions between the atmosphere, biosphere and the
oceans. About a quarter of the total emissions are taken up by the
oceans and another quarter by the biosphere, reducing in this way the
amount of CO2 in the atmosphere.
The ocean cushions the increase
in CO2 that would otherwise occur in the atmosphere, but with
far-reaching impacts. The current rate of ocean acidification appears
unprecedented at least over the last 300 million years, according to an
analysis in the report.
“We know without any doubt that our
climate is changing and our weather is becoming more extreme due to
human activities such as the burning of fossil fuels,” said WMO
Secretary-General Michel Jarraud.
“The Greenhouse Gas Bulletin
shows that, far from falling, the concentration of carbon dioxide in the
atmosphere actually increased last year at the fastest rate for nearly
30 years. We must reverse this trend by cutting emissions of CO2 and
other greenhouse gases across the board,” he said. “We are running out
of time.”
“Carbon dioxide remains in the atmosphere for many
hundreds of years and in the ocean for even longer. Past, present and
future CO2 emissions will have a cumulative impact on both global
warming and ocean acidification. The laws of physics are
non-negotiable,” said Mr Jarraud.
“The Greenhouse Gas Bulletin
provides a scientific base for decision-making. We have the knowledge
and we have the tools for action to try keep temperature increases
within 2°C to give our planet a chance and to give our children and
grandchildren a future. Pleading ignorance can no longer be an excuse
for not acting,” said Mr Jarraud.
"The inclusion of a section on
ocean acidification in this issue of WMO’s Greenhouse Gas Bulletin is
appropriate and needed. It is high time the ocean, as the primary driver
of the planet’s climate and attenuator of climate change, becomes
central part of climate change discussions,” said Wendy Watson-Wright,
Executive Secretary of the Intergovernmental Oceanographic Commission of
UNESCO.
“If global warming is not a strong enough reason to cut
CO2 emissions, ocean acidification should be, since its effects are
already being felt and will increase for many decades to come. I echo
WMO Secretary General Jarraud’s concern – we ARE running out of time,”
she said.
Atmospheric Concentrations
Carbon dioxide accounted
for 80% of the 34% increase in radiative forcing by long-lived
greenhouse gases from 1990 to 2013, according to the U.S. National
Oceanic and Atmospheric Administration (NOAA) Annual Greenhouse Gas
Index.
On the global scale, the amount of CO2 in the atmosphere
reached 396.0 parts per million in 2013. The atmospheric increase of CO2
from 2012 to 2013 was 2.9 parts per million, which is the largest
annual increase for the period 1984-2013. Concentrations of CO2 are
subject to seasonal and regional fluctuations. At the current rate of
increase, the global annual average CO2 concentration is set to cross
the symbolic
400 parts per million threshold in 2015 or 2016.
Methane
is the second most important long-lived greenhouse gas. Approximately
40% of methane is emitted into the atmosphere by natural sources (e.g.,
wetlands and termites), and about 60 % comes from human activities like
cattle breeding, rice agriculture, fossil fuel exploitation, landfills
and biomass burning. Atmospheric methane reached a new high of about
1824 parts per billion (ppb) in 2013, due to increased emissions from
anthropogenic sources. Since 2007, atmospheric methane has been
increasing again after a temporary period of leveling-off.
Nitrous oxide (N2O)
Nitrous
oxide is emitted into the atmosphere from both natural (about 60%) and
anthropogenic sources (approximately 40%), including oceans, soil,
biomass burning, fertilizer use, and various industrial processes. Its
atmospheric concentration in 2013 was about 325.9 parts per billion. Its
impact on climate, over a 100-year period, is 298 times greater than
equal emissions of carbon dioxide. It also plays an important role in
the destruction of the stratospheric ozone layer which protects us from
the harmful ultraviolet rays of the sun.
Ocean Acidification:
For
the first time, this Bulletin contains a section on ocean acidification
prepared in collaboration with the International Ocean Carbon
Coordination Project (IOCCP) of the Intergovernmental Oceanographic
Commission of UNESCO (IOC-UNESCO), the Scientific Committee on Oceanic
Research (SCOR), and the Ocean Acidification International Coordination
Centre (OA-ICC) of the International Atomic Energy Agency (IAEA).
The
ocean currently absorbs one-fourth of anthropogenic CO2 emissions,
reducing the increase in atmospheric CO2 that would otherwise occur
because of fossil fuel combustion. Enhanced ocean CO2 uptake alters the
marine carbonate system and lead to increasing acidity. The ocean's
acidity increase is already measurable as oceans take up about 4
kilogrammes of CO2 per day per person.
The current rate of ocean
acidification appears unprecedented at least over the last 300 million
years, based on proxy-data from paleo archives. In the future,
acidification will continue to accelerate at least until mid-century,
based on projections from Earth system models.
The potential
consequences of ocean acidification on marine organisms are complex. A
major concern is the response of calcifying organisms, such as corals,
algae, mollusks and some plankton, because their ability to build shell
or skeletal material (via calcification) depends on the abundance of
carbonate ion. For many organisms, calcification declines with increased
acidification. Other impacts of acidification include reduced survival,
development, and growth rates as well as changes in physiological
functions and reduced biodiversity.
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