Global Warming
[This is part 5 of the Global Warming Summary series at www.appinsys.com/GlobalWarming]
Part 5: The Earth’s Greenhouse Gas – CO2 and IPCC Climate Modeling
The Earth’s climate system is very complex and many attempts have been made to model it. There is an interaction of solar radiation, land, ocean, atmosphere, clouds, gases released by anthropogenic processes (agriculture, burning of carbon-based fuels) and natural processes (volcanoes, etc.). In this system, the sun provides the primary heating of the earth through solar radiation in various wavelengths. Some of the solar radiation is reflected by clouds, thus reducing the heating from solar radiation (analogy: cloudy days in summer are typically cooler than sunny days because the clouds block heat from the sun). Heat is re-radiated by the Earth’s surface. Some of this heat is absorbed by “greenhouse gases” and re-emitted in the atmosphere, thus contributing to warming the Earth (analogy: cloudy days in winter are typically warmer than sunny days because the clouds keep heat in). Figure 5-1 provides a simplified conceptual overview of the process.
Figure 5-1: Greenhouse [ From: UNEP/GRID-Arendal. Greenhouse effect. UNEP/GRID-Arendal Maps and Graphics Library. 2002. http://maps.grida.no/go/graphic/greenhouse_effect. ]
The temperature varies with altitude. Figure 5-2 provides a general indication of the variation of temperature with altitude and indicates the parts of the atmosphere referred to as the troposphere and the stratosphere. The stratosphere is warmer due to increased ozone levels absorbing ultraviolet radiation. The greenhouse gas (GHG) theory indicates that increasing GHGs should result in warming of the troposphere and cooling of the stratosphere.
Figure 5-2: Temperature Variation By Altitude
The most important greenhouse gases in Earth's atmosphere include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), water vapor (H2O), ozone (O3), and the chlorofluorocarbons (CFCs). In addition to reflecting sunlight, clouds are also a major greenhouse substance. Water vapor and cloud droplets are in fact the dominant atmospheric absorbers.
Figure 5-3 shows the estimated radiative forcing components as defined by the IPCC in the latest scientific basis report (May 2007). The report states: “Energy consumption by human activities, such as heating buildings, powering electrical appliances and fuel combustion by vehicles, can directly release heat into the environment. Anthropogenic heat release is not an RF, in that it does not directly perturb the radiation budget; the mechanisms are not well identified and so it is here referred to as a non-initial radiative effect.” This leaves out the highly variable cooling effect of volcanic emissions (which may be decreasing in recent centuries).
A good explanation of climate sensitivity is provided by Nir Shaviv, describing how the cosmic ray flux and effect on cloud cover is insufficiently modeled. [http://www.sciencebits.com/OnClimateSensitivity]
Data regarding volcanic aerosols is very sparse. A recent NASA study found that the levels of cooling volcanic aerosols has been declining in recent decades, as shown in Figure 5-4. (Global 'Sunscreen' Has Likely Thinned, Report NASA Scientists 3/15/07) [http://www.nasa.gov/centers/goddard/news/topstory/2007/aerosol_dimming.html]
The National Research Council (National Academy of Sciences) in their study “Climate Change Science: An Analysis of Some Key Questions, said “The monitoring of aerosol properties has not been adequate to yield accurate knowledge of the aerosol climate influence”.
Figure 5-3: Estimated Radiative Forcing Components (Figure FAQ 2.1 – 2 in the IPCC AR4)
Figure 5-4: Atmospheric Volcanic Aerosols 1981 – 2006 Showing General Declining Trend
The sources of greenhouse gases (GHG) come from various sectors including transportation, industrial processes, power generation for residential consumption, agriculture and deforestation. According to the United Nations Food and Agriculture Organization (FAO), deforestation accounts for 25 to 30 percent of the release of GHG [http://www.fao.org/newsroom/en/news/2006/1000385/index.html]. The report states: “Most people assume that global warming is caused by burning oil and gas. But in fact between 25 and 30 percent of the greenhouse gases released into the atmosphere each year – 1.6 billion tonnes – is caused by deforestation.”. From 1990 to 2000, the net forest loss was 8.9 million hectares per year. From 2000 to 2005, the net forest loss was 7.3 million hectares per year.
The ten countries with the largest net loss of forest per year (2000 – 2005) are: Brazil, Indonesia, Sudan, Myanmar, Zambia Tanzania, Nigeria, Democratic Republic of the Congo, Zimbabwe, and Venezuela (combined loss of 8.2 million hectares per year). The ten countries with the largest net gain of forest per year (2000 – 2005) are: China, Spain, Viet Nam, United States, Italy, Chile, Cuba, Bulgaria, France and Portugal (combined gain of 5.1 million hectares per year). [http://www.fao.org/forestry/site/28821/en/]
Figure 5-5 a) shows a generalized source of GHG from various sources. However, this does not include deforestation (the number one cause of GHG). Various studies show various differing contributions by sector, since not all consider the same factors. In addition, the contributions by sector vary regionally (for example, in Washington State where a large portion of power generation is hydroelectric).
Figure 5-5 a): Estimated Greenhouse Gas Emissions By Sector
Figure 5-5 b) GHG emissions by sector [http://www.idosi.org/aejaes/jaes3(5)/1.pdf] - data from IPCC 1996
Figure 5-5 a) ignores one of the largest sources of GHG – deforestation and shows a smaller impact other anthropogenic land use change effects than most studies. The following figure shows the effect of land-use change on atmospheric CO2
[http://cdiac.ornl.gov/trends/landuse/houghton/houghton.html]
Figure 5-5 c) Annual Effect of Land-Use Change on Atmospheric CO2
Becoming vegetarian would be more efficient in reducing greenhouse gases than driving a hybrid car. The United Nations Food and Agriculture Organization (FAO) released a report in November 2006 [http://www.fao.org/newsroom/en/news/2006/1000448/index.html ] that states: “the livestock sector generates more greenhouse gas emissions as measured in CO2 equivalent – 18 percent – than transport…. the livestock sector accounts for 9 percent of CO2 deriving from human-related activities, but produces a much larger share of even more harmful greenhouse gases. It generates 65 percent of human-related nitrous oxide, which has 296 times the Global Warming Potential (GWP) of CO2…it accounts for 37 percent of all human-induced methane (23 times as warming as CO2) ” [http://www.un.org/apps/news/story.asp?NewsID=20772&Cr=global&Cr1=environm ]
The atmospheric CO2 has been shown to lag the temperature in the past warming cycles, as shown in Figure 5-6 (From http://calspace.ucsd.edu/virtualmuseum/climatechange2/07_2.shtml).
Figure 5-6: Vostok Ice Core Temperature and CO2 Trends for Past 450,000 Years
In fact the IPCC, in the AR4 Scientific Basis report, Part 6 (May 2007), makes the following statements:
- “Ice core records show that atmospheric CO2 varied in the range of 180 to 300 ppm over the glacial-interglacial cycles of the last 650 kyr”
- “Variations in CO2 over the last 420 kyr broadly followed Antarctic temperature, typically by several centuries to a millennium“
- “The quantitative and mechanistic explanation of these CO2 variations remains one of the major unsolved questions in climate research.”
- “In conclusion, the explanation of glacial-interglacial CO2 variations remains a difficult attribution problem. “
The NOAA Earth System Research Laboratory – Global Monitoring Division [http://www.esrl.noaa.gov/gmd/aggi/] provides data from a network of CO2 monitoring stations around the world (with data for Mauna Loa starting in 1970). Figure 5-7 shows the location of the monitoring locations and the global average CO2 concentration from these sites.
Figure 5-8 shows the IPCC graph of atmospheric CO2 as measured at Mauna Loa, Hawaii (left), while the right-hand graph compares the CO2 at Mauna Loa and the South Pole. They show a similar trend in slope. In fact the CO2 plots from any of the CO2 stations in the NOAA database show a similar CO2 trend. It can be seen from Figure 5-8-right that the CO2 is greater in the summer than the winter (the CO2 is not causing seasons, but it is a response to the seasonal change in temperature).
Comparing the various CO2 trends available from the NOAA database shows a consistent trend in atmospheric CO2 rise around the world (as illustrated by comparing Figure 5-7 Right with 5-8 Left and Right). But the temperature trends vary greatly by region. In fact the temperature trend at Mauna Loa shows no correspondence with the CO2 trend. Figure 5-9 shows the Mauna Loa CO2 along with the temperature trend from the nearest station in the NASA GISS database (Hilo, Hawaii) clearly illustrating the lack of correspondence between the two.
Figure 5-7: NOAA/ESRL CO2 Monitoring Locations (Left) and Global Average CO2 Concentration (Right)
Figure 5-8: Left: Atmospheric CO2 at Mauna Loa (Figure 2.3 in the IPCC AR4) Right: Atmospheric CO2 at Mauna Loa (Red) and at South Pole (Blue) from the NOAA Database
Figure 5-9: Atmospheric CO2 at Mauna Loa (Figure 2.3 in the IPCC AR4) with Temperature Trend from the NASA GISS Database for Hilo.
Reconstruction of past CO2 (prior to coninuous measurements) have been made from various sources. The IPCC uses reconstruction from ice cores. Other reconstructions show different trends. The following figure shows CO2 reconstruction from pine needle stomatal density. [http://icecap.us/images/uploads/200705-03AusIMMcorrected.pdf]
The conclusion that the current global warming trend is significant and caused mainly by anthropogenic CO2, is a result of theoretical climate models (GCM’s) in which the human-defined models are able to reproduce current global temperature trends by increasing the CO2 levels. The IPCC AR4 Scientific Basis report (Part 6) states: “Climate models are used to simulate episodes of past climate... Models allow the linkage of cause and effect in past climate change to be investigated. Models also help to fill the gap between the local and global scale in palaeoclimate, as palaeoclimatic information is often sparse, patchy and seasonal. For example, long ice core records show a strong correlation between local temperature in Antarctica and the globally mixed gases CO2 and methane, but the causal connections between these variables are best explored with the help of models.” One major problem is that Antarctica does not match the models and is now ignored by the IPCC.
The following Figure 5-10 is from the IPCC AR4 report (2007). It does not show modeling of Antarctica, because Antarctica does not fit the models.
Figure 5-10: From IPCC AR 4 Figure 9.6
The following Figure 5-11, shows (left) from the IPCC TAR report (2001). In it the models show warming in Antarctica with cooling around the Antarctic Peninsula and in the adjacent Weddell Sea – exactly the opposite of the observed trend. The following figure (right) shows the observed temperature trend in the “cooling” area.
Figure 5-11: Left: From IPCC TAR Figure 9.2 – Modeled geographical distribution of temperature differences from 1975 to 1995 to the first decade in the 21st century. Right: From NASA / GISS database.
Unlike the northern hemisphere, temperature measurements in Antarctica only started in the 1950’s, and there are very few stations covering a 40-year period to the present. Figure 5-12 shows two of the available non-peninsula temperature stations’ measurements are shown in the following figures (plots from stations in the NASA / GISS database). [http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=700896640008&data_set=1&num_neighbors=1 ]
See http://www.appinsys.com/GlobalWarming/RS_Antarctica.htm for a more detailed regional study of Antarctica.
Figure 5-12: Typical Antarctica Temperature Station Trends
The NOAA Earth System Research Laboratory – Global Monitoring Division maintains a network of CO2 monitoring stations around the world. [http://www.esrl.noaa.gov/gmd/aggi/]. Figure 5-13 compares the recent CO2 trends at Palmer Station (on the Antarctic Peninsula) and the South Pole. There is virtually no difference between the two locations, although there is a substantial temperature difference as seen in the previous temperature trend graphs. Figure 5-14 compares CO2 and temperature trend at the South Pole showing the lack of correlation between the two.
Figure 5-13: CO2 Trends at Palmer Station and at the South Pole
Figure 5-14: Combining CO2 and South Pole Temperature Trends
The greenhouse hypothesis suggests the warming would be greatest in the atmosphere (troposphere) and that the warming would be significant both day and night. It would also be greatest in the polar regions because gases like CO2 are most effective at trapping the heat in very cold temperatures. The reason that the warming should be greatest at the polar regions is due to the following: CO2 in the atmosphere absorbs and re-emits infra-red radiation in distinctive wavebands, particularly around 12 - 18 microns. Radiation at other wavelengths simply passes through the atmosphere without being intercepted by CO2. The wavelength of infrared radiation from the earth's surface depends on the temperature of the surface. All bodies emit infrared over a wide band of wavelengths, but peak at a `dominant wavelength' determined by the temperature of the emitting surface. For example, an object with a temperature of 32°C will radiate most intensely at 9.5 microns. At 15°C (the mean surface temperature of the earth), the dominant wavelength will be 10 microns. At -25°C, it becomes 11.7 microns, and at -50°C becomes 13 microns. The problem is that the observations do not match the CO2 hypothesis.
In an assessment of the IPCC modeling, a paper by: Bellamy, D. and Barrett, J. (2007). “Climate stability: an inconvenient proof”, (Proceedings of the Institution of Civil Engineers – Civil Engineering, 160, 66-72) states: “The climate system is a highly complex system and, to date, no computer models are sufficiently accurate for their predictions of future climate to be relied upon.”
In another review of IPCC modeling (Carter, R.M. (2007). “The myth of dangerous human-caused climate change” The Aus/MM New Leaders Conference, Brisbane May 3, 2007) Carter examined evidence on the predictive validity of the general circulation models (GCMs) used by the IPCC scientists. He found that “while the models included some basic principles of physics, scientists had to make “educated guesses” about the values of many parameters because knowledge about the physical processes of the earth’s climate is incomplete. In practice, the GCMs failed to predict recent global average temperatures as accurately as simple curve-fitting approaches. They also forecast greater warming at higher altitudes in the tropics when the opposite has been the case.”
A 2008 study “On the Credibility of Climate Predictions” (D. Koutsoyiannis, A. Efstradiadis, N. Mamassis & A. Christofides, Department of Water Resources, Faculty of Civil Engineering, National Technical University of Athens, Greece) states: “Geographically distributed predictions of future climate, obtained through climate models, are widely used in hydrology and many other disciplines, typically without assessing their reliability. Here we compare the output of various models to temperature and precipitation observations from eight stations with long (over 100 years) records from around the globe. The results show that models perform poorly, even at a climatic (30-year) scale. Thus local model projections cannot be credible, whereas a common argument that models can perform better at larger spatial scales is unsupported.” [http://www.atypon-link.com/IAHS/doi/pdf/10.1623/hysj.53.4.671]
A study of model feedbacks “Validating and Understanding Feedbacks in Climate Models” (D-Z. Sun, T. Zhang, and Y. Yu, NOAA-CIRES/Climate Diagnostics Center) states: “The models tend to overestimate the positive feedback from water vapor in El Nino warming. … [and] tend to underestimate the negative feedback from cloud albedo in El Nino warming.”
The National Research Council (National Academy of Sciences) produced a study called “Climate Change Science: An Analysis of Some Key Questions” [http://books.nap.edu//html/climatechange/]. Here are a couple of statements from that report:
- “Because of the large and still uncertain level of natural variability inherent in the climate record and the uncertainties in the time histories of the various forcing agents (and particularly aerosols), a causal linkage between the buildup of greenhouse gases in the atmosphere and the observed climate changes during the 20th century cannot be unequivocally established. The fact that the magnitude of the observed warming is large in comparison to natural variability as simulated in climate models is suggestive of such a linkage, but it does not constitute proof of one because the model simulations could be deficient in natural variability on the decadal to century time scale.”
- “Knowledge of the climate system and projections about the future climate are derived from fundamental physics and chemistry through models and observations of the atmosphere and the climate system… A major limitation of these model forecasts for use around the world is the paucity of data available to evaluate the ability of coupled models to simulate important aspects of past climate. In addition, the observing system available today is a composite of observations that neither provide the information nor the continuity in the data needed to support measurements of climate variables.”
- “Solar irradiance, the amount of solar energy striking Earth, has been monitored accurately only since the late 1970s. However, indirect measures of solar activity suggest that there has been a positive trend of solar irradiance over the industrial era… It is not implausible that solar irradiance has been a significant driver of climate during part of the industrial era, as suggested by several modeling studies. However, solar forcing has been measured to be very small since 1980, and greenhouse gas forcing has certainly been much larger in the past two decades”
The sun provides the energy that warms the earth. And yet according to the NOAA National Climatic Data Center [http://www.ncdc.noaa.gov/oa/climate/globalwarming.html ] “Our understanding of the indirect effects of changes in solar output and feedbacks in the climate system is minimal”. The importance of fluctuations and trends in solar inputs in affecting the climate is inadequately modeled. Although the sun exhibits varies types of energy related events (sunspots, solar flares, coronal mass ejections), sunspots have been observed and counted for the longest amount of time.
A 2007 paper by Syun-Ichi Akasofu at the International Arctic Research Center (University of Alaska Fairbanks) provides an analysis of warming trends in the Arctic. [http://www.iarc.uaf.edu/highlights/2007/akasofu_3_07/index.php ] They analyzed the capability of climate models (GCMs) to reproduce the past temperature trends of the Arctic (shown in Figure 5-15): “we asked the IPCC arctic group (consisting of 14 sub-groups headed by V. Kattsov) to “hindcast” geographic distribution of the temperature change during the last half of the last century. To “hindcast” means to ask whether a model can produce results that match the known observations of the past; if a model can do this, we can be much more confident that the model is reliable for predicting future conditions … Ideally, the pattern of change modeled by the GCMs should be identical or very similar to the pattern seen in the measured data. We assumed that the present GCMs would reproduce the observed pattern with at least reasonable fidelity. However, we found that there was no resemblance at all.”
Figure 5-15: Model vs Observed temperature Changes [from Akasofu]
The authors’ conclusions: “only a fraction of the present warming trend may be attributed to the greenhouse effect resulting from human activities. This conclusion is contrary to the IPCC (2007) Report, which states that “most” of the present warming is due to the greenhouse effect. One possible cause of the linear increase may be that the Earth is still recovering from the Little Ice Age. It is urgent that natural changes be correctly identified and removed accurately from the presently on-going changes in order to find the contribution of the greenhouse effect… The fact that an almost linear change has been progressing, without a distinct change of slope, from as early as 1800 or even earlier (about 1660, even before the Industrial Revolution), suggests that the linear change is natural change”
A recent paper studying the effect of “brown clouds” (caused by biomass burning) on warming in Asia (Ramanathan, V., M.V. Ramana, G. Roberts, D. Kim, C. Corrigan, C. Chung, and D. Winker, 2007. “Warming trends in Asia amplified by brown cloud solar absorption”. Nature, 448, 575-578) concludes “atmospheric brown clouds contribute as much as the recent increase in anthropogenic greenhouse gases to regional lower atmospheric warming trends”.
A study comparing the models to observations from satellites and balloons (1979-2004) also shows a problem with the models. The following figure is from the study. “A comparison of tropical temperature trends with model predictions”, by Douglass, D.H., J.R. Christy, B.D. Pearson, and S.F. Singer, 2007 - International Journal of Climatology. [http://www.scribd.com/doc/904914/A-comparison-of-tropical-temperature-trends-with-model-predictions]. The models exhibit the CO2 theory of most warming occurring in the troposphere. However, the satellite and balloon based observations show warming only at the surface of the earth. The report stated: “Model results and observed temperature trends are in disagreement in most of the tropical troposphere, being separated by more than twice the uncertainty of the model mean. In layers near 5 km, the modelled trend is 100 to 300% higher than observed, and, above 8 km, modelled and observed trends have opposite signs. … On the whole, the evidence indicates that model trends in the troposphere are very likely inconsistent with observations that indicate that, since 1979, there is no significant long-term amplification factor relative to the surface. If these results continue to be supported, then future projections of temperature change, as depicted in the present suite of climate models, are likely too high.”
The University of Alabama at Huntsville provides monthly plots of worldwide temperature anomalies for the troposphere since 2000 [http://climate.uah.edu/]. The following figure is from UAH and shows the temperature trend (degrees per decade) for 1978 to 2006. According to the CO2 theory, warming should be occurring over both poles – but this is not happening.
The atmospheric CO2 generally has a low correlation with temperature. The following figure shows the global temperatures and CO2 from 1998 to 2008 (comparing the satellite-measured lower troposphere temperature and the Hadley Climatic research Unit data (used by IPCC). [http://intellicast.com/Community/Content.aspx?a=127]. While CO2 has steadily increased over the last decade, temperatures have not.
A 2008 study of the satellite-era temperature data (Christy & Douglass: “Limits on CO2 Climate Forcing from Recent Temperature Data of Earth”) [http://arxiv.org/ftp/arxiv/papers/0809/0809.0581.pdf]. “The recent atmospheric global temperature anomalies of the Earth have been shown to consist of independent effects in different latitude bands. The tropical latitude band variations are strongly correlated with ENSO effects. …The effects in the northern extratropics are not consistent with CO2 forcing alone … These conclusions are contrary to the IPCC [2007] statement: “[M]ost of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”” They found that the underlying trend that may be due to CO2 was 0.07 degrees per decade.
The following two figures are from the above Christy & Douglass study. The first shows the satellite-based temperature anomalies for the Tropics (red), globe (black), northern extratropics (blue) and southern extratropics (green). The second figure shows the correlation between the tropical temperatures and the ENSO3.4 (El Nino SSTs for area 3.4)
A study published in 2008 reports that China (which was excluded from the Kyoto requirements) became the largest emitter of CO2 from fossil fuel combustion and cement production in 2006. (Gregg, J. S., R. J. Andres, and G. Marland, “China: Emissions pattern of the world leader in CO2 emissions from fossil fuel consumption and cement production”, Geophysical Research Letters 35, 2008) [http://www.agu.org/pubs/crossref/2008/2007GL032887.shtml]. The following figures are from that study. The left-hand figure compares the US annual carbon emissions with China’s since 1950. The right-hand figure compares the monthly carbon for 2001 – 2007. The study states: “the annual emission rate in the US has remained relatively stable between 2001–2006 while the emission rate in China has more than doubled.”
The UN periodically produces an assessment of the worldwide ozone depletion. The most recent report: WMO/UNEP: “Scientific Assessment of Ozone Depletion: 2006” by the Scientific Assessment Panel of the Montreal Protocol on Substances that Deplete the Ozone Layer [http://www.wmo.ch/pages/prog/arep/gaw/reports/ozone_2006/pdf/exec_sum_18aug.pdf] states: “Model simulations suggest that changes in climate, specifically the cooling of the stratosphere associated with increases in the abundance of carbon dioxide, may hasten the return of global [(60°S-60°N)] column ozone to pre-1980 values by up to 15 years”. Perhaps CO2 isn’t all-bad.
Studies of crop growth rates under various concentrations of CO2 also show a positive effect of the current increase in atmospheric CO2. The following figure shows an example.
