CONTENTS
Sustainable CO2
Use
Your Own Climate Model
Solutions
are on another page
SUSTAINABLE LEVEL
The USA
releases 44,000 pounds of CO2 per person per year. This is four
times the world average (11,000). This world average is triple the 3,700 pounds needed to limit
warming to 3.6oF (2oC) above pre-industrial levels.
Reducing from 44,000 to 3.700 pounds is a 92% reduction.
President Obama (like most other candidates) promised and expects an 80% reduction
by 2050. Thus the 92% reduction discussed here is close to mainstream. The
World Wildlife Fund and others have calculated a plan to
reduce UK emissions 80%, starting from a level already half as much as the US.
The present 44,000 pounds per person per year in the US is net. It
includes CO2 in the products we import, excludes our exports, and
gives credit for almost 4,000 pounds per person per year of reforestation.
China releases 7,000 pounds per person per year, and India
releases 2,400 pounds, both
on the same basis as the US, net of imports, exports and reforestation.
The UN Development Program (UNDP) estimates that limiting
emissions to 1.5 trillion metric tonnes of CO2 in this century
will stabilize the atmosphere and limit global warming to 2oC, which
they think the world can handle (2007-8 Human Development Report, pp.46-47 in chapter 1 at http://hdr.undp.org/en/reports/global/hdr2007-2008/chapters/). They divide the
century's 1.5 trillion metric tonnes by 100 years, to give an average 15
billion tonnes of CO2 released worldwide per year, or 32 trillion
pounds.
With 8.8 billion people in the world on average this century (6.9
billion in 2010, annual data are in population tab of worldpath spreadsheet), the
32 trillion pound target for CO2 would allow 3,700 pounds CO2
per person per year, if we could switch to that immediately. In the long term
no country can expect to use more than the average.
UNDP estimates that the above limits will stabilize the atmosphere
at 450 parts per million (ppm), and may limit the increase in
average world temperature to 2oC (3.6oF) above
pre-industrial levels. Their estimates are based on modeling
done for them by the Potsdam Institute for Climate
Impact Research. Their estimates only address CO2,
since they say releases of other greenhouse gases are balanced by releases of
aerosols (dust, etc) which cool the earth (p.199, notes 29-30, quoting
International Panel on Climate Change).
The International Energy Agency's World Energy Outlook
2008 agrees that 450 ppm would provide a 2oC (3.6oF)
increase, and says 550 ppm would provide 3oC (5.4oF)
increase above pre-industrial levels.
World average temperature has already risen about 0.8oC
(1.4oF) above pre-industrial levels, so a goal of 2oC
means 1.2oC warmer than now (2.2oF). (p.6 of http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf).
The 1.4oF rise already endangers species, melts glaciers, and causes
more extreme weather. An additional 2.2oF will have many more
effects.
The atmosphere now has about 386 ppm of CO2,
and many people believe it needs to go down to 350,
not up to 450. It was 280 before industrialization. The alternate target of 350
would require far lower emissions, discussed below.
All these ppm numbers are based on how many molecules of
carbon dioxide are in the atmosphere per million molecules of dry air.
"Dry air" means water molecules are not counted. This is also called
the "dry mole
fraction" or "parts per million by volume" or ppmv. CO2
molecules are heavier (44 grams per mole) than the atmospheric average (28.97 or 28.966,
mostly from N2 and O2 molecules). The current 386 ppm by
volume is about 586 ppm by mass (386*44/28.97=586).
The sustainable
emissions per person will drop in the future, because (a) population
will grow so the annual limit is divided among more people, and (b) we continue
to release CO2 at high rates, using up the century's limit, and
leaving less per year for the rest of the century. These calculations depend on how
fast we cut:
If the world cuts CO2 rapidly for 25
years, and stabilizes at 2,800 pounds per person per year, we will achieve the
needed 3,700-pound average for the whole century, with a 3.6oF rise.
2,800 is near the current level of India.
]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]] 44,000
USA
]]]]]]]]]]]
11,000 World
]]]]]]]
7,000 China
]]] 2,800
Target
]]
2,400 India
If we cut slowly over 50 years, we emit so much
while we are cutting that we have to stabilize much lower at 1,800 pounds per
person per year, to reach the 3,700 pound average. 1,800 is near the current
level of El Salvador and Sri Lanka.
These are 94% and 96% cuts from the US level of
44,000 pounds per person per year. If the US does not cut to 2,800 pounds in 25
years, someone else has to cut deeper, or the US cooks the planet.
If
we could hurry up and cut down our CO2 in 10 years, we would only
have to cut to 3,300, near the level of Uruguay and Sudan. If we take 70 or
more years to cut CO2, the whole world has to cut to zero, since
emissions while we are cutting use up the entire century's CO2
budget.
CO2 Now and in
the Future
|
US
Emissions, 2004 |
44,000 |
44,000 |
44,000 |
Average
pounds per person per year |
|
World
Emissions, 2004 |
11,000 |
11,000 |
11,000 |
Average
pounds per person per year |
|
Years
of Cutting |
10 |
25 |
50 |
Years |
|
World
Emissions after the Cuts |
3,300 |
2,800 |
1,800 |
Average
pounds per person per year |
|
Total
World Emissions during Century |
1.5 |
1.5 |
1.5 |
Trillion
metric tonnes |
|
US
cut by 2020 |
92% |
56% |
29% |
|
|
US
cut by 2030 |
92% |
94% |
48% |
|
|
US
cut by 2050 |
92% |
94% |
86% |
|
|
Total
US cut |
92% |
94% |
96% |
|
A clear review of options to provide energy sustainably is
MacKay's 2008 book, Sustainable Energy http://www.withouthotair.com/download.html
It estimates that large fractions of each country
will need to be covered by solar collectors, wind turbines and/or biomass crops
to produce the energy we use. This expansion will change views and ecosystems,
though not as badly as global warming. MacKay's book does not estimate the CO2
released to manufacture those collectors and turbines, or to clear the land for
biomass crops.
In an interactive model at http://chooseclimate.org you can move a
cross to set a target level for CO2 in the atmosphere. Setting it at
450 ppm (the UNDP recommendation) makes an estimate appear on another graph
showing how many billion metric tonnes of Carbon could be emitted each year,
consistent with this goal. Slide the cursor around on that graph, and you can
read that the graph drops from 7 billion to 2 billion tonnes over the century.
This is an average of 4.5 billion tonnes of Carbon per year, which is 16
billion tonnes of CO2 per year, virtually the same as the UNDP's
estimate of 15 billion.
Changing the target for the atmosphere to 350 ppm yields an
estimate that emissions would have to drop to zero for a while, before
stabilizing at 600 million tonnes Carbon per year, which is 2 billion tonnes CO2
per year, or 700 pounds CO2 per person per year. One sees why 350
ppm is not a popular goal, though the model predicts temperature would only
rise 1.9oF, instead of 3.6oF above pre-industrial levels.
This would still be half a degree warmer than now. (In the chart of Temperature
rises, you can set the baseline year to 1750 to reflect a
"pre-industrial" baseline.)
SOLUTIONS are discussed on another page
Think of other problems humanity has solved. Colonialism, slavery
and serfdom, come to mind. Whole economies and trade links across the world
were built around them. Many people could not imagine how to live without them.
Abolishing them happened in many different ways in different countries, and
they are virtually gone.
Colonialism and slavery were addressed as moral issues. There were
violent struggles in some areas, not in others. There were strong interests
upholding the moral choices: areas without colonies, areas without slaves, and
individual colonists and slave holders who changed course. The parallel now is
areas with low CO2 emissions, such as India, and consumers who cut
back substantially.
At a more pedestrian level, wood stoves and horse-drawn transport
of people and products could not continue when cities became too large. So they
did not continue. (The change to fossil fuels led to our current problem, and
we need to ensure today's solution does not lead to other problems in the
future.)
DDT killed too many birds. People thought they could not produce
crops without it. We changed to other pesticides, and birds are recovering.
We have been hooked on cheap energy drawn out of small, distant
holes in the ground: both oil wells and coal mines. The solutions will be
varied, some cheap, some expensive, some simple, some hard, and different
across the globe.
The fruits of
success will include more food, coral and species saved; fewer floods, droughts
and tropical diseases; and less extreme weather.
The International
Union for Conservation of Nature, which for decades has monitored the risk of
species becoming endangered (the "Red List") says climate change
endangers 35% of the 10,000 bird species studied, 52% of the 6,000 amphibian
species studied and 72% of the 800 coral species studied (Species
Susceptibility to Climate Change Impacts IUCN 2008). These species are
affected by
desynchronization of migrations;
uncoupling of parasite/host, predator/prey,
and mutualisms (e.g. pollinators);
interaction with new pathogens and
invasives;
loss of habitat;
increased stress;
changes in fecundity, sex ratios
and competitive ability;
inability to deposit calcium (e.g.
shells and bones).