Ocean Iron Fertilisation. Does This Work?

Last post I talked about the impact of Ocean acidulation on marine animals and food net. How do we mitigate this?

Most potential methods used to mitigate ocean acidification are controversial. There is no known effective way to prevent the pH value of ocean continue decreasing as the carbon dioxide concentration of the atmosphere is increasing constantly.

On the one hand, long term scale of the value of ocean pH is mainly controlled by the input of eroded (or dissolved) rocks which give negative and positive ions. On the other hand, on short term scale, the ocean pH value if affected by the dissolved weak acid or alkali, for example, carbonate acid and borate. As I mentioned before, the increase of atmospheric carbonate acid accelerated the production of carbonate acid in the ocean.

Recently, there are several geo-engineer projects are proposed. One of them is “Iron fertilization”. It is the introduction of iron into the upper ocean in order to stimulate phytoplankton blooms. Schiermeier (2012) stated that “Each atom of added iron pulled at least 13,000 atoms of carbon out of the atmosphere by encouraging algal growth which, through photosynthesis, captures carbon.” Moreover, diatom contributes to about 40 per cent of all oceanic Carbon sequestration (Jones, 2012).

The most recent open ocean trial of ocean iron fertilization was conducted from January to March 2009 in the South Atlantic. Another one, in July 2012, iron fertilization was carried out in the ocean off western Canada by the Haida Salmon Restoration Corporation (Tollefson, 2012).

Ocean iron fertilisation seems to be an effective method to mitigate ocean acidification. However, some scientists suggested that massive ocean iron fertilization might cause toxic algal blooms or deplete oxygen levels in the middle of the water column.

 Reference:

• Aumont, O.; Bopp, L. (2006) Globalizing results from the ­­­­­­ocean in situ iron fertilization studies. Global Biogeochem Cycles
• Tollefson, J. (2012). Ocean-fertilization project off Canada sparks furore. Nature 490 (7421)
• Schiermeier, Q.(2012). Dumping iron at sea does sink carbon
• Jones, V. (2012). Global Biogeochemical Cycles. Global environmental change lecture powerpoint.
• ­Cao, L.; Caldeira, K.(2010) Can ocean iron fertilization mitigate

  ocean acidification?

A Short Video Explains How Ocean Acidification Affects Marine Species

Here is a short video talking about ocean acidification and its impacts on sea lives and different depth of sea water.

The ocean absorbs almost a third of the carbon dioxide which released into the atmosphere every year, then carbon dioxide reacts with sea water to form carbonic acid. As a result, the acidity of sea water increases. Even a small change of seawater pH value may cause significant impacts on marine species. Consequently the food web is affected indirectly. Moreover, ocean acidification is impacting shallower area much more than deep area. 

Next post, I will talk about potential methods used by geo-engineers to slow down ocean acidification.

What Happened To the Oceans?

From this post I will talk about how the increases of concentration of atmospheric carbon dioxide affects the ocean and carbon reduction methods used related to the ocean.

Ocean acidification is one of the major results as the increases of concentration of atmospheric carbon dioxide. Frank (2004) stated that up to 30 per cent of anthropogenic CO₂ are dissolved into the oceans, lakes and rivers. Carbon dioxide reacts with water to produce carbonic acid H₂CO₃. Carbonic acid is soluble acid which gives hydronium ions (H⁺).

The chemical reaction is

CO₂ + H₂O = H₂CO₃ = 2H⁺ +CO₃^2-

As the concentration of H+ ions in the ocean increases, the acidity of the ocean rises (pH value reduces). The Copenhagen Diagnosis (2009) described that the acidity of surface ocean waters has increased by approximately 30 per cent, and the amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by near 2 billion tons per year. Currently, the average pH value of surface ocean was around 8.07, however, the value was 8.179 before industrial revolutions (Orr. 2005), meanwhile it is predicted that the average pH value of surface ocean will continue to grow , and the number may reach about 7.95 by the year 2050.

The increase of ocean acidity may cause numerous results. Firstly the change in pH value of the ocean has serious impacts on marine lives, especially oceanic calcifying organisms (e.g. corals, foraminifera and coccoliths). The rate of dissolution of calcareous material increases when the acidity rises, as a result, calcification rate of those oceanic calcifying organisms is reduced significantly.

A research by Albright (2010) specified that, by the end of this century, coral reefs will be erode quicker than they can be built. This may have massive impacts on the long-term viability of these ecosystems and perhaps affect more than one million species that depend on coral reef habitat.

The photos from National Geographic below show what happens to a pteropod’s shell when placed in sea water with pH and carbonate levels projected for the year 2100. The shell slowly dissolves after 45 days.

Reference:

• Frank, J.; et al. (July 2004). Impact of Anthropogenic CO2 on the CaCO3 System in the Oceans. Science 305(5682).
• The Copenhagen Diagnosis: Climate Science Report:http://www.copenhagendiagnosis.org/
• Orr, James C.; et al. (2005). Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437 (7059): 681–686.
• Albrighta, R.; et al. (2010) Ocean acidification compromises recruitment success of the threatened Caribbean coral Acropora palmate.
• What is Ocean Acidification. http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F

What Else Besides the Warming?

Last time I posted some videos about the global warming caused by the increase of atmospheric carbon dioxide concentration. The leading global surface temperature reconstructions illustrated that Earth has warmed since 1880.  The 20 warmest years have happened from the year of 1981 and with all 10 of the warmest years occurring in the past 12 years. 

Besides global warming, there are many other effects directly or indirectly caused by the atmospheric carbon dioxide increases.

Sea level rises

Global sea level has been rising around 17 centimeters for the last hundred years. The sea level rising rate in the past ten years was almost double that of the last century. Moreover, the sea level is still continue to grow at this moment.

Glacial retreat and shrinking ice sheets

Data from NASA's Gravity Recovery and Climate Experiment show that Greenland lost 150 to 250 cubic kilometers of ice every year from 2002 to 2006 while Antarctica lost around 152 cubic kilometers of ice from the year of 2002 to 2005. Meanwhile, The national snow and ice data center of the USA stated that glaciers are declining universally in the world, including in the Himalayas, Alps, Rockies, Alaska and Andes. The Greenland and Antarctic ice sheets have reduced massively.

Both the size and thickness of Arctic sea ice has declined rapidly over the last several decades

Here are comparison photo form NSIDC

 Ocean acidification

The increase of atmospheric carbon dioxide has increased the acidity of the oceans.  

The Copenhagen Diagnosis indicated that, ever since the start of the Industrial revolutions, the acidity of

surface ocean waters has increased by approximately 30 per cent. This increase is the consequence of individuals releasing more carbon dioxide into the atmosphere and thus, more being absorbed into the oceans. The amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by near 2 billion tons per year.

Extreme events

The increase of carbon dioxide in the atmosphere is one fundamental source of the increase number of extreme events. The high temperature events records of the USA has increased since last 50 years while the records of low temperature events reduced.

After reading week, I am going to discuss potential methods we could use to reduce the concentration of atmospheric carbon dioxide.

Reference:

• U.S. Energy Information Administration:  http://www.eia.gov/energyexplained/index.cfm?page=environment_how_ghg_affect_climate
• The Copenhagen Diagnosis: Climate Science Report:  http://www.copenhagendiagnosis.org/
• NSIDC:  http://nsidc.org/cryosphere/sotc/glacier_balance.html
• NASA GISS Surface Temperature Analysis (GISTEMP):  http://data.giss.nasa.gov/gistemp/
• NOAA, Global Surface Temperature Anomalies http://www.ncdc.noaa.gov/cmb-faq/anomalies.php 

Videos About Global Warming

  One of the most well-known results of increase of atmospheric carbon dixoide is the "Global Warming". Here are several videos from Youtube talk about how the carbon dioxide and other greenhouse gases changed the climate.

The Earth’s climate has warmed over the last hundred years, and human activity changing the atmospheric composition is likely a significant driving factor. National Energy Information Center (NEIC) in May 2001 specified that "Greenhouse gases are accumulating in Earth’s atmosphere as a result of human activities, causing surface air temperatures and sub-surface ocean temperatures to rise. Temperatures are, in fact, rising. The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes is also a reflection of natural variability."


Reference:

• National Energy Information Center (NEIC), http://www.eia.gov/oiaf/1605/ggccebro/chapter1.html

The Carbon Cycle and Atmospheric Carbon Dioxide Sources

The principal source of carbon dioxide is degassing of the Earth from volcanic activities, mid-ocean ridges, hotspots or subduction-related volcanism. Carbon is converted into different forms through the atmosphere, hydrosphere, and lithosphere. Part of the outgassed carbon dioxide remains in the atmosphere, some of them is dissolved in the oceans, some carbon is preserved as biomass in living or dead organisms, and some is deposited as carbonate rocks such as limestone. 
 

Here, is a table shows Carbon pools in the major reservoirs on earth from Wikipedia:

Pool	Quantity (gigatons)
Atmosphere	720
Oceans (total)	38,400
Total inorganic	37,400
Total organic	1,000
Surface layer	670
Deep layer	36,730
Lithosphere
Sedimentary carbonates	> 60,000,000
Kerogens	15,000,000
Terrestrial biosphere (total)	2,000
Living biomass	600 - 1,000
Dead biomass	1,200
Aquatic biosphere	1 - 2
Fossil fuels (total)	4,130
Coal	3,510
Oil	230
Gas	140
Other (peat)	250

Approximately eighty per cent of atmospheric carbon dioxide is from the Earth’s outgassing(Hibbard. 2000). Meanwhile, respiration and fuel combustion are other two major source of atmospheric carbon dioxide.

Respiration consumes oxygen from the atmosphere and produces carbon dioxide.

Oxygen + carbohydrate > energy + water + carbohydrate

O₂ + CH₂O > energy + H₂O + CO₂

On the other hand, photosynthesis takes carbon dioxide from the atmosphere and produce oxygen.

6CO₂ + 6H₂O (+ light energy) > C₆H₁₂O₆ + 6O₂

The combustion of organic matters will release carbon dioxide to the atmosphere.

C + O₂  > CO₂

Moreover, some of carbon dioxide is produced and released into the atmosphere via metamorphism of limestone （CaCO₃ + SiO₂ > CO₂ + CaSiO₃） and the precipitation of Calcium carbonate from calcium and bicarbonate in the ocean by maritime organisms such as corals.（Ca²⁺ + 2HCO₃^- > CaCO₃ + CO₂ + H₂O）  

Here is a short vedio from NASA briefly describes the carbon cycle of the Earth and the change of atmospheric carbon dioxide. 

From next post, I am going to talk about the impacts of change in atmospheric carbon dioxide, then I will    discuss about the potential methodologies of carbon reduction.

Reference: 

• Carbon pools in the major reservoirs on earth. http://en.wikipedia.org/wiki/Carbon_cycle#cite_note-GlobalCarbonCycle-1
• Falkowski, P.; Scholes, R. J.; Boyle, E.; Canadell, J.; Canfield, D.; Elser, J.; Gruber, N.; Hibbard, K. et al. (2000). "The Global Carbon Cycle: A Test of Our Knowledge of Earth as a System". Science 290 (5490): 291–296.
• The Carbon Cycle and Earth's Climate. http://www.columbia.edu/~vjd1/carbon.htm 
• Chemical precipitation: terrestrial carbon cycle. Encyclopædia Britannica, Inc.

Change of Carbon Dioxide and Temperature in History

The amount of Carbon dioxide changed through the history.  The value of atmospheric carbon dioxide had fluctuated from near 190 ppm to 280 ppm from 400,000 years ago till Pre - industrial time. It was around 180 during ice ages, and the number had reached to 325 ppm by the year 1970. After that, the concentration of atmospheric carbon dioxide increased dramatically to 380 ppm at the beginning of this century. In September of 2012, Mauna Loa dataset shows that the value was 391.07 ppm. It is predicted that the concentration might continue to grow till 400 ppm by the year 2015. On the other hand, the average temperature of the earth changed almost followed the change of atmospheric carbon dioxide concentration.  Especially the recent one hundred years, the global mean temperature and the concentration of carbon dioxide both increased considerably after the industrial revolution. 

IPCC (2007) described that "for the global average, warming in the last century has occurred in two phases, from the 1910s to the 1940s (0.35°C), and more strongly from the 1970s to the present (0.55°C). An increasing rate of warming has taken place over the last 25 years, and 11 of the 12 warmest years on record have occurred in the past 12 years."

As the Global mean temperature figure shows, the global surface temperatures had risen by approximately 0.74°C during the last 100 years from 1906 and 2005. Meanwhile, the concentration of carbon dioxide had increased by about 100 ppm over last hundred years.



Reference:

• IPCC, 2007: Observations: Surface and Atmospheric Climate Change. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change