Here is some basic climate arithmetic March, 2008 Scientific American

• Today’s anthropogenic CO2 emissions are 36 x 109 tons/year;

• with 29 x 109 tons/year from fossil fuels;

• Predictions are by 2050 (business-as-usual), the economy will be 6X present values and energy use will be 4X present.

• Every 30 x 109 tons CO2 increases ATM levels by 2 ppm. (in the past!)

• “Safe” ATM CO2 levels are estimated (guesses!) at <440 ppm.

• Present CO2 levels are 383 ppm.

• Historical growth rate has been 1.5 ppm/year. • In 2004, it hit 3 ppm/yr. • More recent increase rate is 2 ppm/year.

So the arithmetic is easy.

440 ppm – 383 ppm = 57 ppm (the amount we can emit before we go above the ‘safe’ level).

57 ppm / 2.5 ppm/year (conservative) = 22.8 years.

At the business-as-usual rate.

Other Possible Considerations: • 440 ppm CO2 levels may not be ‘safe’;

• Other factors (i.e., arctic ice melt, Greenland ice sheet collapse) may make unexpected contributions to climate; OR

• We may decide not to continue emitting at the Business-as- Usual rate.

We actually get to choose which path we are on.

Business-as-Usual

Zero carbon footprint, starting tomorrow.

But the time to choose won’t last long.

Can we keep from hitting the 440 ppm ‘wall’ by mid-century (2050)?

Is it hopeless?

We would have to keep cumulative emissions over that period to 900 x 109 tons – or less than 21 x 109 tons/year. (we are now doing 36)

That would require electricity to be emission-free (nuclear, solar, wind, plus capture and sequestration of any coal-powered plants).

We would need transportation to be emission-free (plug-in hybrids that get over 100 mpg).

Industrial emitters would need to capture/sequester carbon, or go emission-free.

Will it cost too much (or be too inconvenient) to survive?

• Carbon capture and sequestration (if the sites can be found), should cost about $0.01 to $0.03/kilowatt/hour. (IPPC estimate)

• Conversion to solar power from coal (for U.S.) would be about $0.04/kwhr.

• A U.S. no-CO2 electric grid would cost about $0.08 to $0.09/kwhr.

• Residential heating by electricity could actually be cheaper than present, with improved insulation program (with Govt subsidy).

For comparison, WA state is about $0.065/kw/hour now.

The technology is available, and the costs seem to be ‘affordable’. There are major problems, but it is really a political issue.

• The silica budget in the ocean is a strong factor (perhaps The silica budget in the ocean is a strong factor (perhaps the primary one) in determining the global climate.the primary one) in determining the global climate.

• Paleoclimatologists believe that the cooling of the climate Paleoclimatologists believe that the cooling of the climate since the Cretaceous was due to the evolution of diatoms since the Cretaceous was due to the evolution of diatoms during that period.during that period.

• And the glacial/interglacial cycles have been linked to And the glacial/interglacial cycles have been linked to diatom growth cycles…diatom growth cycles…

But in any case, dissolved silica is important.But in any case, dissolved silica is important.

Marine biology may also help to save us…Marine biology may also help to save us…

The Importance of Silica in the OceansThe Importance of Silica in the Oceans

WHAT IS “DISSOLVED SILICA” IN THE OCEAN?WHAT IS “DISSOLVED SILICA” IN THE OCEAN?

HH44SiOSiO44 or Si(OH) or Si(OH)44

• A weak acid (silicic acid) that is soluble (1800 A weak acid (silicic acid) that is soluble (1800 mol/L) at mol/L) at room temperature.room temperature.

• Primary silica source into the oceans is rock weathering, Primary silica source into the oceans is rock weathering, via riverine input.via riverine input.

• A limiting nutrient for diatoms in the oceans. A limiting nutrient for diatoms in the oceans.

• That means - if you add more silica, you get more That means - if you add more silica, you get more diatoms.diatoms.

WHY WOULD ANY REASONABLE PERSON (i.e. a geologist) CARE ABOUT DISSOLVED SILICA IN

THE OCEAN?

• Dissolved silica in the ocean is linked to the carbon cycle.

• The carbon cycle in the ocean determines atmospheric CO2 inventory.

• The atmospheric CO2 inventory determines the GLOBAL

CLIMATE.

SO – If you care about climate, you should care deeply about the oceanic silica inventory.

HOW DOES THIS WORK?

There are two broad classes of plankton in the upper ocean.

Both are part of the BIOLOGICAL PUMP that removes carbon Both are part of the BIOLOGICAL PUMP that removes carbon from the upper ocean to the seafloor - and increases the COfrom the upper ocean to the seafloor - and increases the CO22

flux from the atmosphere into seawater!flux from the atmosphere into seawater!

DIATOMSDIATOMS

1. Those with outer coatings of silica (diatoms) and

COCCOLITHSCOCCOLITHS

2. Those with calcareous shells (coccoliths, forams)

Both plankton types extract carbon Both plankton types extract carbon from the upper ocean during growth from the upper ocean during growth and bury it, increasing the flux of COand bury it, increasing the flux of CO2 2

from atmosphere; cooling the earth. from atmosphere; cooling the earth.

BUT – as we pointed out previously - carbonate shelled plankton evolve a molecule of CO2 during their shell formation…

That is -

Ca+2 (from rocks via rivers) + H2O + 2 CO2 (atmos ↓) =

CaCO3 (plankton shells) + H2O + CO2 (atmos ↑)

Diatoms, with their amorphous silica (non-carbonate) shells, don’t evolve a molecule of CO2 when they form.

In areas of the upper ocean where DIATOMS dominate, uptake In areas of the upper ocean where DIATOMS dominate, uptake of atmospheric of atmospheric CO2 into the ocean is high (this is a good thing).

It’s not easy It’s not easy being greenbeing green

If you provide enough SILICA in the ocean, DIATOM populations will dominate over carbonate-shelled plankton. (OR – if you make carbonate unavailable, like the end-Cretaceous event, the diatoms will dominate).

Diatom shells are heavier than carbonate ones, so they sink faster (speeding up The Pump), and they don’t dissolve in mid-water – slowing the remineralization of the carbon.

So more diatoms in the upper oceans means more CO2

sequestration from the atmosphere!

So – if Ocean Acidification reduces the population of carbonate-shelled plankton –

There is a chance that the increased diatom blooms may increase the biological ‘pump’ (without the foram competition), and continue to reduce pull CO2 out of the

atmosphere.

At least eventually: we don’t know how long this would take to be effective…

But there is hope.But there is hope.

Coal is a cheap fossil fuel — it costs just

US$1.69 to generate a million British thermal units of energy with coal,

(1 million Btu = 10 gal gas)

compared with US$6.94 for natural gas and

US$6.23 for petroleum.

And there's plenty of it.

COAL – Villain or Hero?

Abundant supplies mean continued use of coal. Map shows total recoverable coal reserves according to a

2005 EIA report.

North America holds one-quarter of all known coal reserves in the world, and there are also significant reserves in China and Europe.

Proven recoverable reserves total 998 gigatons (905 gigatonnes), according to the US Energy Information Administration (EIA).

The World Coal Institute says that's enough to last 147 years at current production levels.

The problem with coal is that it's dirty, emitting twice as much carbon dioxide per unit of energy delivered as natural gas.

Globally, coal accounts for more than 37 percent of all carbon dioxide emissions.

And that figure is projected to rise to 43 percent by 2030, according to the EIA, owing in part to increasing coal use in India and China.

China alone is constructing the equivalent of two 500-megawatt coal-fired power plants per week,

each of which will produce 3 million tons per year of the potent greenhouse gas.

Underground Coal Gasification (UCG)

In ICG, the coal doesn't have to be mined:

it is converted to a gas known as syngas (from synthesis gas) in the ground and extracted through a well.

And since the converted coal leaves space in the ground, the captured carbon can be pumped back to where it was taken from.

Gasifying coal underground involves drilling two wells into a suitable coal seam, igniting the coal at one well and pumping in air or oxygen.

Controlled Air or O2 inSynGas out

COAL

Controlled Burn

Underground Coal Gasification – the cartoon.

Because the amount of oxygen available is limited, only part of the coal is used to provide heat that converts the rest to combustible gases,

including hydrogen, butane, methane, carbon monoxide and carbon dioxide.

This syngas is removed from the second well. It can be burned as it is, but is a relatively dirty fuel in its raw state.

It is also possible to remove all of the carbon from the gas, producing pure hydrogen. But that option is relatively expensive.

Instead, plans are to remove about half of the carbon, which should produce a fuel that is fairly cheap and still cleaner than natural gas.

BUT - Carbon (as CO2) could leak out, or it could cause environmental problems, such as groundwater contamination.

But it IS a possible path to less CO2 emissions.