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CO2 to Reach Extremely Dangerous Peak Near 402 PPM for 2014, Methane
Levels Ramp Ominously Higher
28 May, 2014
During 2014, human CO2 forcing continued its long march toward ever-more dangerous and climate-damaging levels. By the peak month of May, global CO2 had ranged well above the 400 parts per million threshold, catapulting Earth at raging velocity toward climate and atmospheric states not seen in at least 3 million years.
According
to May readings from the Mauna Loa Observatory, the more volatile
hourly measures jumped as high as 404 parts per million while daily
and weekly averages tended to settle between 401.4 and 402.3 parts
per million. Given these trends, overall CO2 levels for May of 2014
are likely to peak at near or just below the astronomical 402 ppm
threshold.
(Atmospheric CO2 levels measured by the Mauna Loa Observatory over the past two years. Peak values for 2012 hit near 397 ppm, peak for 2013 hit near 400 ppm, and peak for 2014 is likely to hit near 402 ppm. Image source: The Keeling Curve.)
CO2
levels near 400 parts per million are enough, according to our
developed understanding of paleoclimates, to
increase global temperatures by between 2 and 3 degrees Celsius, to
melt Greenland, West Antarctica and a portion of East Antarctica, and
to raise sea levels by 75 feet if sustained over a long term.
According to recent glacial research, these very high levels, when
combined with additional greenhouse gas forcing and concurrent ocean
and atmospheric warming have already been enough to destabilize or
push large portions of these major ice systems into irreversible
collapse.
(A history of atmospheric carbon dioxide through early this year provided by CIRES and compared to the entire ice core record of the past 800,000 years. Video source: CIRES.)
36
Billion Tons of CO2 Emission per Year and Counting
Measured
from peak to peak, the rate of atmospheric increase is likely near
2.5 to 3.0 parts per million per year over the two year period.
Averages over the whole range of the past two years show increases on
the order of 2.4 parts per million per year — a challenge to recent
rates of increase near 2.2 parts per million a year since 2000.
Steadily
ramping rates of atmospheric CO2 accumulation are driven by extreme
global industrial, agricultural, and land-use emissions. According
to the Global Carbon Project, 2013 saw total global CO2 emissions in
the range of 36 billion metric tons.
This emission was 2.1 percent higher than the 2012 level and about 60
percent higher than the 1990 level at around 22 billion metric tons
of CO2. Such an extraordinary pace of emissions puts severe strain on
both atmospheric carbon levels and on carbon sinks around the globe.
The resulting risk of such a strong continued emission is that global
sinks and stores may soon become sources (see methane monster below).
An issue of amplifying feedbacks that grows ever more perilous with
each passing year.
Rapidly
Increasing CO2 Acting in Concert With Ramping Methane, other
Greenhouse Gasses
Unfortunately,
CO2 is not the only human emission forcing global temperatures
rapidly higher. In addition, methane, nitrous oxide, and numerous
other greenhouse gasses also make their way into the atmosphere each
year through industrial sources. If we combine all these other
greenhouse gasses, the total CO2 equivalent carbon emission is now at
around 50 billion metric tons each year. A veritable mountain of
greenhouse gasses dumped at a pace more than 150 times that of
volcanic emissions each and every year.
Overall,
the total greenhouse gas forcing from all these sources is now likely
in the range of 481 parts per million of CO2 equivalent.
This immense heat forcing, were it to remain in the atmosphere
long-term, is enough to raise global temperatures by 3-4 C and to
melt enough ice to raise sea levels by at least 120 feet. It
is also enough, with only two more years of current emissions, to
likely lock in an inevitable, irreversible and extraordinarily
disruptive increase of 2 C in global temperatures for this century
alone.
First
Glimpses of the Methane Monster
The
most potent and troubling of these additional greenhouse gasses is
methane. Over the course of 20 years, methane is about 80 times as
powerful a heat trapping gas as CO2 by volume. And though atmospheric
methane levels are far less than comparable CO2 levels (at around 1.8
parts per million, or 1/3 the total atmospheric heat forcing of CO2),
there is cause for serious concern.
For
not only is the industrial emission of methane increasing, primarily
through the use of very damaging hydraulic fracturing technologies
(fracking), the global emission of methane from the Earth System also
appears to be ramping higher. Over
recent years, rapidly thawing permafrost and warming oceans both
around the world and, particularly, in the Arctic show signs of
venting an increasing volume of methane into the atmosphere from
terrestrial sources.
Though annual official tracking of total Arctic methane emissions at
this point is practically non-existent, recent research allows for
rational estimation.
Taking
into account known emissions from permafrost and the East Siberian
Arctic Shelf, and adding in expected emissions from the rest of the
thawing Arctic, methane emissions for the entire region are likely
around 40 teragrams per year, or about 7% of the global total. This
emission is equivalent to that of a major industrial nation and
initial indications are that it is growing.
(Atmospheric methane increase since 2007 as measured at the Mauna Loa Observatory. Note the more rapid pace of increase from 2013 through the first quarter of 2014. Image source: NOAA/ESRL.)
The
result of combined increases in the human methane emission and in the
Earth System emission has been enough to continue to push global
levels higher with Mauna Loa readings breaching the 1840 part per
billion average by early 2014. What is even more troubling is that
the Earth System methane store, composed of both permafrost methane
and methane hydrate at the bottom of the world ocean system, is
immense.
In
total, more than 3,000 gigatons of carbon in the form of methane may
be at risk to eventually hit the atmosphere as the Earth continues to
warm under the current human forcing. A very large store that could
easily multiply the current rate of Earth System methane release many
times over. One that represents a clear and present danger for a
potentially very powerful amplifying heat feedback to an equally
extraordinary initial human forcing.
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