Background information (based on present knowledge and on approximate calculations)
The “global warming effect” has been illustrated by NASA in graphs showing the key indicators for the global climate change. One of their graphs below named “Global Land-Ocean Temperature Index” updated in 2011 shows a temperature increase of about 0.8◦ Centigrade from year1880 to year 2008 with a generally accelerating trend during the last decades. The “global warming effect” seems now to be generally accepted.
Except for a leveling off between the 1940s and 1970s, the surface temperature of
our planet has increased since 1880. The last decade has seen global temperatures
rise to the highest levels ever recorded. This graph illustrates the change in global
surface temperature relative to 1951-1980 average temperatures. As shown by the
red line, long-term trends are more apparent when temperatures are averaged over
a 5-year period. The green error bars represent the uncertainty on measurements.
Most scientists seem to agree that “the global warming effect” is due to the increase of the so called greenhouse gases in the atmosphere. In the following the four “major greenhouse gases” are discussed in view of a solution of the problems of climate change.
Each one of the four major greenhouse gases: CO2, CH4, N2O and H2O contributes considerably to the global warming effect. Their current concentrations in the atmosphere of the northern hemisphere were 2010 according to Earthscan Atlas of Climate Change, 3rd edition, and others:
- - For CO2 389 ppm (parts per million)
- - For CH4 1.870 ppb (parts per billion) = 1870 ppm
- - For N2O 0.322 ppb = 322 ppm
- - For H2O its concentration in the atmosphere is widely variable and is assumed to vary from abt. 0 and up to abt. 7%. The average concentration is said to be fluctuating between 2 and 4% and could be assumed to be abt. 3% or 30 000 ppm.
The increases of their concentrations during the period after abt. year 1750 are:
- - For CO2 109 ppm, or 39%
- - For CH4 1170 ppm, or 167%
- - For N2O 52 ppm, or 19%
- - For H2O a study has shown that during the period 1973 – 2002 the observed global mean specific humidity increased by 0.07 g per kg and per decade. Another study has shown that the total atmospheric moisture content over oceans has increased by 0.41 kg/M2 per decade over the period 1988 – 2006 and that this increase has been primarily human-caused.
The anthropogenic (human-caused) emissions of the major greenhouse gases primarily come from the fossil fuels: Coal, Oil, Natural gas and also from waste from households and agriculture. Drying of food and of various other products and emissions from cooling towers in the industry are also contributors of H2O emissions.
The yearly world production of the fossil fuels from year 1980 to and including year 2010 has according to the United States Energy Information Administration been:
- Crude oil: 59 420 → 72 361 Million Barrels per Day or an increase of 21 %.
- Coal: 3 796 → 7 984 Million short Tons per year or an increase of 210 %
- Natural Gas: 52 670 → 112 090 Trillion cubic feet per year or an increase of 213 %.
(For some years the production has decreased, but the general trend in production is upwards for these 31 years for the three major fossil fuels.)
The worldwide daily emissions from the major sources that were used as fuels in 2010 were calculated to be (by simply assuming that all that was produced was also burnt):
- From coal: varies greatly depending on grade and composition, an estimation of its average emissions gives 60 million metric tons of CO2 + 4 million metric tons of H2O (incl. drying).
- From oil: 40 million metric tons of CO2 + 9 million metric tons of H2O.
- From natural gas: 20 million metric tons of CO2 + 15 million metric tons of H2O.
- From waste: 2 million metric tons of CH4 + 0.1 million metric tons of N2O.
- From waste and other sources: 4 million tons of H2O (estimated).
The total amount of average daily emissions worldwide of anthropogenic major greenhouse gases (only primary emissions but none secondary, like CH4 from swampy areas or H2O from seas or other open waters due to the warming effects, included) are thus estimated to be:
- For CO2: 120 million metric tons
- For CH4: 2 million metric tons
- For N2O: 0,1 million metric tons
- For H2O: 30 million metric tons
and the average daily increases of emissions from year to year during the last 30 years according to a rough estimate:
- For CO2: Abt. 2 million tons
- For H2O: Abt. 0.75 million tons
- For CH4: Abt. 20 thousand metric tons (= Population Growth Rate)
- For N2O: Abt. 1 thousand metric tons (= Population Growth Rate)
The greenhouse effect factors generally used to compare the four major gases are:
- For CO2 1
- For CH4 30
- For N2O 300
- For H2O 40 (estimated)
The total yearly greenhouse effect of each one of the four major anthropogenic gases has thus during the last 30 years been:
- For CO2 120 million tons of CO2 equivalents
- For CH4 60 million tons of CO2 equivalents
- For N2O 30 million tons of CO2 equivalents
- For H2O 1200 million tons of CO2 equivalents
The yearly increase of the effect of the anthropogenic greenhouse gases emitted during the last 30 years has been calculated:
- For CO2: 2 million tons of CO2 equivalents
- For H2O: 30 million tons of CO2 equivalents
- For CH4: 0.6 million tons of CO2 equivalents (= Population Growth rate)
- For N2O: 0.3 million tons of CO2 equivalents (= Population Growth rate)
The residence time in the atmosphere for the four major greenhouse gases after having been emitted are stated to be:
- For CO2 : 100 years
- For CH4 : 12 years
- For N2O : 100 years
- For H2O : 9 days
The comparison of the emissions of the four major anthropogenic greenhouse gases thus results in the following conclusions:
- CO2 has the highest total amount emitted as well as highest increase of emissions (counted as daily tons).
- H2O has the highest greenhouse effect (more than 70% of the total and more than 90% of the increase of the emissions during the last three decades).
- The increase of the H2O emissions give presently (not long time perspective) much higher increase of the greenhouse effect – abt. 15 times higher - than the increase of the CO2 emissions.
To bring about a reduction of the increase of the global warming effect by the greenhouse gases thus requires that in the first place the anthropogenic emissions of H2O (water vapor) and secondly that the emissions of CO2 are substantially reduced. Reductions of both H2O and CO2 emissions need to be started now.
(Another unit of measuring the greenhouse effect is the so called GWP = Global Warming Potential which is used by IPCC. It is an index for well mixed gases that combines the effects of their residence times and ability of absorbing radiation. Although water vapor is a strong infrared radiation absorber its GWP is not calculated. The greenhouse gases are generally not well mixed in the real world.)