What does Toxicologist think of Chemical Hazard?

of High Risk %
HI % by Risk Level of Specific Chemical

Electricity by Nuclear: OECD 2008

Nuclear % by Country

Sweden: Electricity Production Mode

Alternative Energy in Sweden

Math! CO2 emission by short-distance vs long-distance flight

A reader (apparently very well knowledge in aviation) reminded me of some very crude assumption I made when calculating CO2 emission for different type of aircraft/aeroplane in the previous post. I must admit that it was not a very detailed math work. I made very bold assumptions such as taking out plane take-off phase out from whole fuel burn/CO2 emission from calculation because firstly these numbers are not readily available to me (from the plane maker/manufacturing site) and secondly I assume that the plane take-off time is relatively short compared to whole cruising time. This could be true for the long-distance (may be more than 600km above?) or cross-continental flight, but the take-off period will be significantly mean something for shorter distance. And the calculation below might show you how…

Scandinavian Airlines (SAS) has this webpage which can be used to calculate your CO2 emission for the flight you take and offer you to buy carbon offset. Well, the latter part is not my point here, and I am just conveniently borrowing their readily available calculator to show that how short distance flight emit more CO2 than the long-distance flight.

Here, I am using Helsinki (HEL) as my base. The places I choose are: Oslo (OSL), Stockhol (ARN), Kuopio (KUO), JFK Airport, New York (JFK), Jyväskylä (JYV) and London Heathrow Airport (LHR). The table below here shows the cabin factor [CF] (%), distance (km) and CO2 produced in kg. Since the cabin factor and type of aircraft is same in each class, CO2 per km is easily calculated:

In the first group (Avro RJ85-small plane), a person who take the trip from Helsinki to Oslo with a CF 71% produced 147kg CO2 while flying from Helsinki to Kuopio (a shorter distance) on the same plane and CF will emit 89kg CO2. By comparing CO2 per km factor, trip to Oslo is emitting only 0.193 kg CO2 per km while 0.266 kg CO2 per km to Kuopio, an almost 1.38 times higher than Oslo trip.

Another example is taking KF average aircraft group. A flight to Heathrow London emits 0.133 kg CO2 per km for long distance, but on shorter distance like flying from Helsinki to Jyväskylä emit 0.272 kg CO2 per km distance travelled, which is 2x the number for Hel-London trip!

Now, it is quite obvious to note the relationship of distance travelled is inverse with CO2 emission kg per km. What if I want to fly to New York from Helsinki? That is 6602km away. SAS gave a different average CF for this flight: 88%. That is higher than the other flight in compared here (71%). To make it an apple-to-apple comparison:

Total CO2 emission for flight with 88% CF (or let’s say 88 persons):

          Total CO2 = 88 x 462 kg = 40 656 kg 

Total CO2 emission is the same for flight with 88% CF or 71% CF, therefore CO2 emission person in 71% CF (or 71 persons) flight:

          CO2 per person = 40 656 kg ÷ 71 = 572.6 kg

Therefore the CO2 emission per km is: 572.6 kg ÷ 6602 km = 0.087 kg CO2 per km for flying from Helsinki to New York.

In terms of absolute number, long distance flight inevitably produces more CO2 compared to the short one. However, if we take the CO2 emission per km as a fair comparison, short distance flight is shown to be less CO2 environmentally friendly. And my great suspect would be that the plane take off phase as I mentioned earlier in the beginning of this post, becomes significant especially for short-distance flight (e.g. 10 minutes take-off in 40 min. vs 400 min. flight). Could the altitude which the plane fly influence on the fuel efficiency as well? (short flight -> low altitude -> higher air density-> higher friction -> higher fuel consumption?)

P/S: SAS webpage says something about the accuracy in their CO2 calculator – The estimation of aircraft emissions is still not a perfect science and is subject to debate. Actual emission levels for each flight are dependent on operating parameters like load onboard, flight profile, temperature, winds, fuel and engine/aircraft characteristics. Assumed flight average and calculation method can vary from operator to operator, making comparisons difficult.

Math! How much CO2 is released by Aeroplane?

Another math time! 😀

After car, another transport vehicle which under the sportlight of GW issue is aeroplane. Thus, this time I set out to search for how much CO2 is emitted by plane flight.

According to Energy Information Association of US, the emission coefficient of greenhouse gases for certain type of fuel is listed. Among the fuels which associated with aviation are:

  1. Aviation Gasoline: 18.355 pounds CO2 per gallon or 2.199 kg CO2 per liter.
  2. Jet Fuel: 21.095 pounds CO2 per gallon or 2.527 kg CO2 per liter.
  3. Kerosene: 21.537 pounds CO2 per gallon or 2.580 kg CO2 per liter.

Most of the jet or commercial plane is using kerosene. Thus, the CO2 emission coefficient value of 2.58 kg/L will be used for all the calculation below.

Let’s assume that a person is about to travel for a distance of 1000 km. With this distance, how much CO2 will be emitted if he is:

1. Taking a private jet, Bombardier Learjet 45 Super-Light Business Jet.

  • Normal cruise speed = 846 km/h
  • Fuel consumption at average cruise = 579 L/h
  • Passenger capacity = 9 (max)
  • Fuel consumption per km = 579 ÷ 846 = 0.684 L/km

Thus, CO2 emission rate = 0.684 x 2.580 = 1.766 kg/km

2. Taking Airbus series, like

    a) Airbus A321

  • Cruising speed = 853 km/h
  • Fuel consumption = 3000 L/h
  • Passenger capacity = 189 (max)
  • Fuel consumption per km = 3000 ÷ 853 = 3.517 L/km

Thus, CO2 emission rate = 3.517 x 2.580 = 9.074 kg/km

    b) Airbus A320

  • Cruising speed = 853 km/h
  • Fuel consumption = 3025 L/h
  • Passenger capacity = 150 (max)
  • Fuel consumption per km = 3025 ÷ 853 = 3.546 L/km

Thus, CO2 emission rate = 3.546 x 2.580 = 9.149 kg/km

3. Taking Boeing series

    a) 737-400

  • Cruising speed = 809 km/h
  • Fuel consumption = 2377 kg/h or 2935 L/h (kerosene density = 0.81 kg/L)
  • Passenger capacity = 168 (max)
  • Fuel consumption per km = 2935 ÷ 809 = 3.628 L/km

Thus, CO2 emission rate = 3.628 x 2.580 = 9.360 kg/km

    b) 737-600

  • Cruising speed = 853 km/h
  • Fuel consumption = 1932 kg/h or 2385 L/h (kerosene density = 0.81 kg/L)
  • Passenger capacity = 145 (max)
  • Fuel consumption per km = 2385 ÷ 853 = 2.796 L/km

Thus, CO2 emission rate = 2.796 x 2.580 = 7.214 kg/km

    c) 747-400

  • Cruising speed = 910 km/h
  • Passenger capacity = 409 (max)
  • Fuel consumption per km = 11.875  L/km (5 gallon per mile)

Thus, CO2 emission rate = 11.875 x 2.580 = 30.638 kg/km

4. Taking SAS Airline. SAS Blue Airline offer the emission calculator which can be used to find out the CO2 emission for 3 types of flight: RJ100, RJ85 and MD90.

    a) RJ100

  • Passenger capacity = 99 (max)
  • Distance travelled = 1846 km (assuming from Helsinki to London Heathrow)
  • Fuel burned = 7442 L
  • CO2 emission = 18754 kg

Thus, CO2 emission rate = 18754 ÷ 1846 = 10. 159 kg/km

    b) RJ185

  • Passenger capacity = 84 (max)
  • Distance travelled = 1846 km (assuming from Helsinki to London Heathrow)
  • Fuel burned = 6904 L
  • CO2 emission = 17398 kg

Thus, CO2 emission rate = 17398 ÷ 1846 = 9.425 kg/km

    c) MD90

  • Passenger capacity = 166 (max)
  • Distance travelled = 1846 km (assuming from Helsinki to London Heathrow)
  • Fuel burned = 8461 L
  • CO2 emission = 21269 kg

Thus, CO2 emission rate = 21269 ÷ 1846 = 11.522 kg/km

All these emission rate will be normalized to the CO2 per person who travel 1000 km, on various type of aeroplanes. And assuming the average cabin factor of 70% (i.e. 70% out of full passenger capacity), the comparison is made in the table below:

So, a range of 68.7 to 159.7 kg of CO2 is emitted for the same travelling distance, 1000km, depending on type of plane a person takes.

On another note, remember my ex-small compact car, Kelisa? On average, Kelisa emits 121g CO2 per km. For 1000km, 121kg of CO2 will emitted by this car. However, if it is more than 1 person in the same car, the CO2 emission per person will be reduced and smaller value than the plane.

Math! How much can the tree or forest sequester CO2?

Yes, I am intrigued by such question: how much really a tree or forest can capture or sequester the CO2 released anthropogenically (fossil fuel and natural gas being the primary target)?

Thus, I set out to search for the calculations, and awared that a lot of people are using tree/plant for CO2 sequesteration program, like in the carbon offset bussiness. This whole bussiness thing is a complex one, and my question is relatively a simple or crude one: how much CO2 is absorbed or sequestered by tree/plant or forest in a quantitative way?

Few values or data related to this field are found. Let’s start with the number from established organization like Environmental Protection Agency, US:

Claim#1: Afforestation: 0.6 to 2.6 metric tons of C per acre per year.
             Reforestation: 0.3 – 2.1 metric tons of C per acre per year.

Next, in this report, it is claimed that:

Claim#2 (a): … 1 m3 of growth in forest biomass (stem, roots, branches, etc.) absorbs 0.26 tCe (Brown et al., 1986), … the average rate of growth is 15 m3/ha/year. And,

Claim#2 (b): This is equivalent to 815 million (m^3) bone-dry tonnes of wood, which in turn corresponds to 0.41 GtCe.

Claim#2 (c): Assuming a yield for hardwoods of 35 m3/ha/year, this would mean sequestering about 9 tCe of CO2 /ha/year.

According this paper:

Claim#3: In addition, the rate of C sequestration based on biomass change in vegetation was recorded to assess the optimum land use that can absorb the carbon dioxide emitted by the power project. These are as follows: (a) tree plantations (10.09 tC/ha/yr) >coconut (4.78 tC/ha/yr) >brushland (4.29 tC/ha/yr) > (b) natural forest (0.92 tC/ha/yr).

Ok, now it is time to make all these data comparable, if possible:

Thus, let’s say if I need to plant the tree to capture or sequester the CO2 which spewed by my car, as calculated here, with a daily mileage of 25km and emitted roughly 1104.1 kg CO2, or 301.1 kg of Carbon equivalent (1 tonne Carbon equivalent = 3.667 tonnes CO2) per year, I would need:

Claim#1 (a): Afforestation area = 0.301 ÷ 3.633 = 0.0828 ha = 828 m^2.

Claim#1 (b): Afforestation area = 0.301 ÷ 15.873 = 0.0190 ha = 190 m^2.

Claim#2 (c): Hardwood plant area = 0.301 ÷ 9.00 = 0.0334 ha = 334 m^2 .

Claim#3 (a): Tree plantation area = 0.301 ÷ 10.09 = 0.030 ha = 300 m^2.

Claim#3 (b): Natural forest area = 0.301 ÷ 0.920 = 0.327 ha = 3270 m^2.

Claim#2 (a): Biomass volume required = 0.301 ÷ 0.260 = 1.157 m^3.

Claim#2 (b): Biomass volume of bone-dry woods required = 0.301 ÷ 0.503 = 0.598 m^3.

So, an area ranging from 190 m^2 to 3270 m^2, depending on the efficiency of carbon sequesteration rate (which in turn a lot of factors are playing in) is required to absorb/capture the amount of CO2 emitted via my car. I wonder how much do I have to spend if I bought the land in Malaysia in order to do this? And if 26 millions of Malaysians need to do this, how much land area is required, per year? Hmmmm….

Math! CO2 Emission by my ex-car – Kelissa GXi SE

Yup, it was the same car which trashed by Jeremy Clarkson (I think, not sure about the model though :P).

But this is not the main theme of this post. Rather, I am interested to find out how much CO2 had I spewed out for the past 3.5 years, during my ownership of Kelisa.

According this link, Kelissa GXi SE emits 121 g CO2 per km (one of the lowest CO2 emission you can get from the vehicles available around the automobile market?). I forgot what was my car mileage before I sold it off, but if I put it 2 scenarios: a) worst case scenario – roughly around 10 000 km for every 3 months (as the car maintenance/service requirement). Or b) normal scenario – everyday I travel about 25km. Thus, my CO2 emission was (approximately):

a) Annual CO2 emission = 0.121 kg x 40 000 km = 4840 kg

                                           or

b) Annual CO2 emission = 0.121 kg x 25 km x 365 days = 1104. 125 kg

And according to World Bank’s report on world CO2 emission per capita for year 2002, on average Malaysian emitted 6.32 metric tons per capita, or 6320 kg CO2 per year.

For scenario (a), wow my car alone accounted to almost 76.6% of total CO2 emission per capita, on my share! The figure from (a) is quite unlikely for me because for me to use up all 10 000 km mileage in 3 months, on average I will be travelling 109.9 km per day. Or (b)  CO2 emission from my beloved kelisa only take up 18.0% of my personal CO2 quota  😛

More, some CO2 emissin data for other Malaysia-made cars:

  • GEN2 1.3 GLS = 164 g/km (or extra 35.5% of Kelissa’s CO2 emission)
  • GEN2 1.6 GLS/X (Manual) = 172 g/km (42.1% extra)
  • GEN2 1.6 GLS/X (Auto) = 176 g/km (45.5%)
  • Proton Savvy = 134 g/km (10.7%)
  • Proton Impian 1.6 GLS (Manual) = 167 g/km (38.0%)
  • Proton Impian 1.6 GLS (Auto) = 172 g/km

More CO2 emission by car can be found here.

OECD and Malaysia: Water Consumption (Part II)

Table above show the sector breakdown of water consumption among OECD countries and Malaysia. While Ireland and Iceland using virtually none of their water resources for agriculture purpose, Greece, Portugal and Australia are using a big share of their water consumption in agriculture sector, as high as above 75% of total water resources.

On the other hand, Finland, Ireland and United Kingdom is using a lot of their water resources for industrial purposes.

As shown in the previous post, Dutch using very little water (29.9 m^3) in the domestic sector, as low as 6.1% of the total water resources they have. New Zealand use as high as 48.5% of their water resources on domestic sector, and 254.1 m^3 per year. Sweden and Austria consume as high as 36.7% and 35.1% of the total water resources on domestic sector, or corresponding to 119.9 m^3 and 104.1 m^3 per year.

source: Finland Statistic Department, World 2003

OECD and Malaysia: Water Consumption (Part I)

US has the highest water consumption in the world, followed by Japan and Germany. However, when the water consumption is broken down to domestic usage (along with agriculture and industrial), Canada consumes highest water volume per capita, as high as 288 m^3 per year. This is followed by New Zealand (254.1 m^3) and US (208.9 m^3). Netherlands consumed the least amount of water, as 10x lower than Canada. In another words, Dutch people survive by using the water amount 0.082 m^3 per day, or equivalent to 82kg water (assuming water density =1000 kg/m^3). It would be interesting to note what are the activities or difference in lifestyle that drive so much variations in terms of domestic water consumption among OECD countries.

source: Statistic Finland Department, World Figure 2003

World: Top 15 Country on Highest Number of Sheep

  1. China: 143.8 million
  2. Australia:  99.3 million
  3. India: 61.8 million

Total sheep in top 15 countries: 655 573 656, or roughly 64.0% of world total sheep count.

source: FAO, GLiPHA 2003.

Math! How much CH4 is released by Sheep around the World?

Cow is not the only ruminant livestock which produce CH4 gas, though it is a major one. Other livestock is generating CH4 as well, and I shall check up each one of them (if I could find the neccessary information :P). How much of CH4 is emitted throughout these livestocks each year?

For time being, let’s look at sheep. After some googling, 2 claims for sheep (so far) are found.

Claim#1: Individual sheep emission rates were highly variable and averaged 19.5 ± 4.8 (SD) g CH4 per sheep per day. (source here)

Thus, a sheep can produce 7.12 kg of CH4 per year.

And, claim#2: New Zealand`s 70 million sheep create 350 million methane gallons daily. (source here)

70 million sheeps for 350 million gallons methane, 5 gallons CH4 per sheep per day, or equivalent to 18.93 L of CH4.

Divide by standard volume molar (22.414 L/mol), the weight of CH4 produced by sheep per day = 0.844 mol x 16 g (CH4 molecular weight) = 13.51 g per day.

In a year, a sheep is producing 4.93 kg CH4. And this value is lower than the claim#1.

As of year 2003, there is around 1 billion, or 1 024 070 182 sheeps (not including the sheep for milk) around the world. Thus, the total annual CH4 emission by sheeps for:

Claim#1: Total CH4 = 1 024 070 182 x 7.12 kg = 7.291 million tonnes.

Claim#2: Total CH4 = 1 024 070 182 x 4.93 kg = 5.049 million tonnes.

Apparently sheep is not emitting much CH4, compared to cow/cattle.

source: FAO, Global Livestock Production and Health Atlas

New York City Emits 1% of US Green House Gasses

Intresting to know that…

New York City produces nearly 1 percent of the nation’s greenhouse gas emissions — an amount that puts it on par with Ireland or Portugal — according to a city study.

The study found that the buildings, subways, buses, cars and decomposition of waste in America’s most populous city produced a net emission of 58.3 million metric tons of greenhouse gases in 2005.

The U.S. total was 7.26 billion metric tons for that year.

But it is also noted that

The city has 2.7 percent of the country’s population — 8.2 million of 300 million — and the average New York City resident contributes less than a third of the emissions generated by a typical American.

Average, Americans emit 20.23 metric tons of CO2 per year (2002), and New Yorkers would be emitting around 7.11 metric tons of CO2. Comparing this number to other OECD countries CO2 emission per capita (list here), New Yorker is still doing slightly worse than Switzerland, Sweden, Portugal, France and Malaysia but on par with Spain and Italy.

Math! How much CO2 is released by Dairy Cow?

Yes, I did it on CO2 emission by human being, CH4 emission by dairy cow, and this time: CO2 by dairy cow! Yes, dairy cow, just like any other animal being, do respiration, and exhale CO2 as well.

From this paper, the lactating cows are emitting 6137 ± 505 L CO2 per day (before correcting the gas emission from manure) or 5756L (value#1) per day (after substraction of CO2 emission from manure). The value of CO2 emission from some other references is cited in the same paper as well: 4940L (value#2), 5396L (value#3) and 6515L (value#4) per day.  These 4 values will be used to calculate how much CO2 is released by all the dairy cows in the world in 1 year and is shown with the table below:

And compared this value to human being on earth (as of year 2007), human population is breathing about 1362 million tonnes (case#1) or 2618 million tonnes (case#2) CO2 per year. By comparing the numbers here, dairy cow is pretty much catching up with human being, even though their number 0.238 billion is far less than human population, 6.6 billion.

World: Top 15 Country on Highest Number of Dairy Cow

Top 15 countries on the number of dairy cow according to FAO 2003. India has almost 40 million dairy cow, almost double the number of Brazil, the second highest dairy cow owner in the world.

Total number of dairy cow in the top 15 countries is 145 475 926, while total dairy cow around the world is 237 928 359. Thus, the top 15 countries accounted 61.1% of total dairy cow in the world.

source: FAO, GLiPHA 2003

Math! How much CH4 is released by Dairy Cow?

After cattle/beef cow, now let’s move on to dairy/milking/lactating cow. There are few papers found on the data of CH4 emission by dairy cow.

  1. According to this paper‘s finding (paper#1), dairy cow is measured releasing 587 ± 61.3 L CH4 per day. And compared to the values obtained from other references cited: 420L, 500L, 552L and 560L.
  2. According to this paper (paper#2), the lactating Holstein dairy cows produced 458.7g CH4 per day.
  3. According to this paper from India (paper#3), (i) the milking crossbred cattle produced 106.4g CH4 per day while (ii) the milking indigenous cattle emitted 98.57g CH4 per day.

According o FAO’s statistic, there are 237 928 359 (238 millions) milked cow around the world in 2003.  Thus, the total CH4/methane emission by dairy cow around the world with the summary of all the number above is listed in the table below:

source: FAO, Global Livestock Production and Health Atlas, 2003

Math! How much CH4 is released by Cattle/Beef Cow? (Part II)

More CH4 emission by cattle or beef cow is found! Thefore, I shall continue from the previous post from here.

Claim#3: according to this paper, beef cow produces 262L CH4 per day.

1L CH4 weigh about 0.714g. Thus, the weight of CH4 in 262L CH4 gas is about 187.03g per day.

Or 68.26 kg per year.

Claim#4: from this paper (citing another referecence), “…the average daily CH4 emissions predicted from this SF6 technique (11.6 ± 0.7 L h-1) were similar to those measured using open circuit respiration calorimetry (12.9 ± 0.7 L h-1)”.  

So 2 very close numbers are obtained: (4-a) 11.6L per hour and (4-b) 12.9L per hour. Total CH4 by weight in a year:

Thus, CH4 annual emission by weight is (4-a) 72.54kg or (4-b) 80.67kg.

Claim#5: CH4 from livestock in India is listed in this paper. Methane gas emitted from various type of cattles can be found, and the summary is listed in the table below.

Thus, CH4 emission is (5-a) 36.31kg and (5-b) 32.95kg. Noted that the value here is comparitively much lower than the other value from claim#1-4.

To calculate the total CH4 emission from 1.33 billion cattle/beef cow around the world in 1 year:

Claim#3: Total CH4 = 1.33 x 10^9 x 68.26 kg = 90.78 million tonnes.

Claim#4-a: Total CH4 = 1.33 x 10^9 x 72.54 kg = 96.48 million tonnes.

Claim#4-b: Total CH4 = 1.33 x 10^9 x 80.67 kg = 107.29 million tonnes.

Claim#5-a: Total CH4 = 1.33 x 10^9 x 36.31 kg = 48.29 million tonnes.

Claim#5-b: Total CH4 = 1.33 x 10^9 x 32.95 kg = 43.82 million tonnes.

Combining all the claims found so far, the summary of total CH4 emission by cattle/beef cow in year 2003 is listed in the table below:

Math! How much CH4 is released by Cattle/Beef Cow?

Math time again! 🙂

This time, I am set out to find how much CH4 is released by cow, or cattle around the world. Total cows/cattle in the world, according to FAO, in year 2003 is around 1 331 526 305. Note that this number does not include the dairy cow, or the cow for milking purpose.

Next, the quantity of CH4 gas emitted by a cow/cattle is searched. So far there are 2 claims, and may be more will be found in the future.

Claim#1:  according to wikipedia,

An average cow is thought to emit between 542 litres (if located in a barn) and 600 litres (if in a field) of methane per day through burping and flatulence, making commercially farmed cattle a major contributor to the greenhouse effect.

Let’s say the adult cow emits 550L of CH4 per day. Divide by standard volume molar (22.414 L/mol), the number of mole of CH4 is 24.538 mol.

Thus, the weight of CH4 = 24.538 x 0.016 kg = 0.3926 kg per day.

Or, 143.3 kg CH4 per year.

Claim#2: according to US Enviromental Protection Agency,

An adult cow … emitting only 80-110 kg of methane (annually).

It is noted that claim#1 is almost 43% higher than claim#2, if the value of 100kg per year is assumed.

Therefore, total CH4 released by cattle/cow annually in weight for year 2003 is:

Claim#1: Total CH4 = 143.3 x 1 331 526 305 = 190.81 x 10^9 kg = 190.81 million tonnes.

Claim#2: Total CH4 = 100 x 1 331 526 305 = 133.15 x 10^9 kg = 133.15 million tonnes.

More livestock’s impact on environment can be read from UN’s news release and the report.

source: FAO, Global Livestock Production and Health Atlas.

Monthly Reading on CH4 Atmospheric Concentration

This graph show the CH4 atmospheric concentration measurement at Oregon, California.  

There are two clear patterns shown in this graph:

  1. CH4 concentration shows cyclic pattern throughout the year. CH4 concentration shows a dip in the month of July while remain quite consistent the other time of the year. Could it be the reason that most of the livestocks were slaughtered during that time of the year?
  2. A steady increase of CH4 concentration annually. And the table below shows the rise of CH4 atmospheric concentration each year.

It seemed that CH4 increment has been slowed down since year 1983, from 18.2 ppbv in 1980 to 13.1 ppbv in 1986. However, this trend of rise does not go along well with the estimated CH4 emission, which increase consistently to year 1991. Annual range or month-to-month variation also seeing fluctuation between 28.7 to highest 61.8 ppbv.

source: CDAIC, Atmospheric Methane

CH4: Annual Emission Estimate

Methane (CH4) , another main component in greenhouse gases (GHG). Below here is the estimated number on CH4 release into atmosphere and the main processes releasing it.   

Conversion unit: 1 Teragram = 1 million tonnes.

Livestocks release most CH4, followed by rice farming.  Estimated every year 370 million tonnes of CH4 is released, but this value is dwarfed by CO2 (24 billion tonnes).

source: CDAIC, Annual Estimates of Global Anthropogenic Methane Emissions: 1860-1994

Monthly Reading on CO2 Atmospheric Concentration

The graph above shows the monthly CO2 atmospheric concentration reading collected at Mauna Loa (19°28′46.3″N, 155°36′09.6″W), North Hemisphere. The CO2 fluctuation pattern is consistent thoughout the year: rising high in the month of April-June and decrease in August to October, and September being the lowest point. Hmmm, why more CO2 is released in April (spring time) and CO2 is absorbed or taken away from atmosphere in September (autumn)? The decomposition of plant at the end of autumn or beginning of winter should explain the increasing CO2 trend starting from November, especially for north hemisphere.  

The steady increment of CO2 atmospheric concentration reading is also noted as the year increase. For example, the highest peak of CO2 reading in 1996 is 365.41 ppmv (April)  while lowest valley point is 359.46 ppmv (September). Two years later in 1998, the value of CO2 raised to 369.29 ppmv for the peak point while 363.9 ppmv is read in September, the lowest point in the year. An increment of 3.88 and 4.44 ppmv is recorded in April and September respectively. Thus, an average of 2 ppmv of CO2 is added annualy, or roughly 1.59E+10 tonnes in weight.

Next, the variation of month to month comparison is compared for the 10 years period, at the site of Maona Loa. Within a year itself, the range of CO2 atmospheric reading (highest and lowest recording point) is about 5.20 to 6.60 ppmv. By converting the concentration value in ppmv, the weight of CO2 is calculated (like example here). The weight of CO2 is listed in the table below:

As we see the values above, each year there is a huge amount of CO2 is fluctuating in the  atmosphere. It might look small in concentration reading (as small as 5-6 ppmv), but in terms of weight,  it is almost 2-2.5 times of human activity related CO2 emission: 2.413E+10 tonnes.

Another comparison is made as well. There are 10 sites recording the CO2 atmospheric concentration, as listed previously here. The average reading of one year recording at each site is compared to other 9 locations. The range of the reading is as big as 4.44 ppmv among these locations around the world. Translating this concentration number into CO2 weight, a difference of 2.931E+10 (or 29.31 billion) tonnes to 34.70 billion tonnes of CO2 is noted. Again, this number is exceeding the anthroprogenic CO2 emission (24.13 billion tonnes).

source: CDIAC

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