The myth that that the earth will regulate itself towards an optimum for life no matter what humans do to the atmosphere. The term Gaia refers to the biosphere regulating itself, but the neo-Gaiaists apply the concept to geophysical processes as well. Opposite of Tipping Point
There is no doubt that man's effect on the environment can overwhelm the ability of any local natural process to compensate. One simple example: bulldoze a few acres of virgin ecosystem anywhere in the world and then keep accessing it by vehicle or even by foot. In most cases exotic (non-native) weeds will take over and in most cases greatly slow or prevent natural restoration. If the topsoil washes away natural restoration may be impossible forever.
The preceding outcome can be quite different once human intervention is recognized and humans take steps to mitigate their actions. Restoring native habitat is very doable once the ecological processes are understood. Extended globally, the same principles apply except that gases mix and spread across the globe quickly which deceptively appears to mitigate their effect. But the global effects may or may not be mitigated naturally, and may end up overwhelming the ability of global natural processes to compensate. But like local effects, the needed restoration actions will inevitably be well understood by using global models. If it becomes necessary, models will reveal the most cost effective cooling solutions. Regardless of which cooling methods are needed or used or whether governments are involved or not, the cooling, if needed, is not going to be provided by nature.
In the global warming debate the neo-Gaiaists conveniently adapt Gaiaism to exclude their own actions and similar ones by other humans since true adherence to Gaia would require diligent consideration of all ecological effects before undertaking any action. There is no longer any doubt that the actions of mankind have an effect on the atmosphere, although the extent and the climate consequences are still in doubt. The measured increases in CO2 can partly be explained as a response to warming or other natural effects, but there is ample evidence that human releases are part of the rise. The article Why does atmospheric CO2 rise? points out the lag between rises in the northern and southern hemispheres, the decline in 13C/12C ratio, the decline in 14C, etc. This evidence, taken together, point to the rise in CO2 being from fossil fuels. Although the amount of the CO2 rise coming from fossil fuels is in question (see Myth: all "extra" CO2 is human), the manmade component is certainly not negligible and consequential rise in temperature is also not a negligible amount.
Myth: Tipping Point
The hypothesis that the earth has reached or will soon reach a point where greenhouses gases will cause predominantly positive feedbacks to occur, for example warmth causing increases in greenhouse gases causing more warmth. An offshoot of Gaianism and the opposite of Neo-Gaianism The creator of the Gaia theory, James Lovelock, postulates a tipping point in his book The Revenge of Gaia Noted scientist Jim Hansen describes a tipping point scenario in a NY Times book review: The Threat to the Planet:
...But if CO2 emissions are not limited and further warming reaches three or four degrees Fahrenheit, all bets are off. Indeed, there is evidence that greater warming could release substantial amounts of methane in the Arctic. Much of the ten-degree Fahrenheit global warming that caused mass extinctions, such as the one at the Paleocene-Eocene boundary, appears to have been caused by release of "frozen methane." Those releases of methane may have taken place over centuries or millennia, but release of even a significant fraction of the methane during this century could accelerate global warming, preventing achievement of the alternative scenario and possibly causing ice sheet disintegration and further long-term methane release that are out of our control.
As can be seen in the discussion at RealClimate: Runaway tipping points of no return the science of climate tipping points is very loose. It consists mostly of cherry-picking and hypothesizing positive feedbacks while ignoring and refusing to hypothesize negative ones. For example, the answer given to the question of negative feedbacks (#142 in the previous link) was that positive feedbacks are overwhelming the negative ones (i.e. it's ok to ignore negative feedback). But since actual CO2 forcing can account for more than the observed warming even without modeled water vapor feedback, it appears that some negative feedbacks are already occuring (or a lot of negative forcing). The IPCC 2007 report states that no large nonlinear feedbacks have yet taken place for carbon since the carbon cycle flow percentages have remained relatively unchanged since 1958. That doesn't address other potential warming feedback loops such as methane, but short term feedback is more likely to be negative (long term is more likely to be positive) and short term effects are more easily countered than long term ones. For example it is much easier and cheaper to get a little short term cooling (if that becomes necessary) than to lower long term warming (which will probably never become necessary).
The main problem with climate tipping point science is that water vapor, by far the largest and fastest feedback, is not well modeled. The reason is that water vapor is unevenly distributed throughout the atmosphere by the weather and to determine the warming effect of that water vapor (and cooling effect of some types of clouds) we must model the weather in detail (although forecasting is not necessary, see Climate Forecasting is not Weather Forecasting). Also the full extent of evaporation, condensation and precipitation must be modeled since all provide large amounts of warming and cooling at various levels of the atmosphere. Water vapor as a greenhouse gas is unlikely to provide a tipping point since as its concentration gets higher, its distribution becomes more uneven which is a negative feedback. But it is also possible that water vapor could become more evenly distributed especially at higher altitudes which would provide positive feedback. We won't know for sure until the resolution in climate models is improved.
Myth: If they can't predict the weather...
Longer term weather forecasting is very difficult because weather systems are deterministically chaotic because the weather is somewhat sensitive to initial conditions (i.e. butterfly effect). It is possible to predict near term weather because any small scale effects take time to propagate into large scale changes. See Numerical Weather Prediction inFAQ and Chaos and Climate
Climate forecasting, on the other hand, does not depend on weather forecasting in order to make predictions. Weather patterns matter to climate and must be modeled in some way that isn't oversimplified (see Oversimplified models), but the weather models inside the climate models do not have to accurately predict weather for any time or location. The must rather only depict weather with enough overall fidelity to calculate its impact on climate. As a very simple example, it doesn't matter if a weather model says it is 20 degrees at my house and 40 at your house or 40 at mine, 20 at yours, or 30 at both if they both are averaged into a single climate statistic. Likewise it doesn't matter at all if the rain comes on tuesday or on thursday if what matters is the rainfall for the week.
Myth: If it's this cold/warm GW must be false/true
Everyone agrees that natural variation is part of the weather and climate, yet almost everyone seems to make this simple mistake over and over: warm or unusual weather is proof of global warming or cold weather must be proof that human-caused global warming or global warming itself doesn't really exist. Mostly the comment is made tongue-in-cheek, but often it is made as if it proves something.
One example of many: Lubos Motl implied the record cold in November 2006 was due to billions of years worth of natural variability Florida, Yukon: record cold temperatures There's little doubt the climate is getting warmer and indeed it may be just natural variability, but the record cold doesn't prove that natural variability is the only factor involved.
In another recent example, a poster at RealClimate noted the anomalous weather around Hudson Bay in Feb 2006 and claimed model predictive accuracy: Thundershowers in February over South Central Baffin Island above the Arctic circle (approx. 65 degrees North), totally unheard of But looking at the records for a Baffin Island station at 66 degrees north CAPE DYER A there are no February days with rain but there was one in January 1977 (the record starts in 1959). Like 2006, 1977 was the start of an El Nino and it would be interesting to know if that was part of the model that was claimed to have predicted this event.
Myth: Pinatubo released more "greenhouse gases" than...
Typically finished with "mankind since the industrial revolution". It is an attempt to obfuscate the water vapor from the volcano with long lasting gases from mankind. It is nonetheless completely false since the water vapor emitted by Pinatubo (491 Mt) was far less than the 20,000 Mt of water vapor emitted by fossil fuel burning each year ( http://www.hyweb.de/Knowledge/Vapour.htm) and both are dwarfed by the natural 505,000,000,000,000 Mt (500,000 km3) in the natural water cycle. In short, water vapor release by man, volanoes, or anything other than evaporation and transpiration are trivial.
There are more specific and easily disproven claims about CO2 and other gases, e.g. Slicing with Occam's Razor: ...one Mt. Pinatubo sized volcano puts out more CO2 in a day of belching than mankind in a year... But by analyzing preeruption magma vapor potential, emissions from the 1991 Pinatubo eruption were 42 Mt of CO2 and the worldwide totals from http://www.eia.doe.gov/oiaf/1605/gg97rpt/chap1.html are 150,000 Mt natural and 7100 Mt manmade.
Myth: Current global
warming can be explained by...
Indirect influence by the sun such as altering the cosmic ray flux also cannot explain Global Warming on Mars or Global warming on Jupiter (article also has links to warming on other planets and moons) since the cosmic ray cloud formation processes are unique to earth. Those extraterrestrial solar warmings are relevant in only two ways: showing generically that planets can warm (which is an obvious fact), or that the increased luminosity from the sun is causing part of the warming on earth and other bodies in the solar system. But the luminosity changes are small along with their contribution to warming. Since temperature of a body (without any other feedback effects) is proportional to the fourth root of the radiation flux (see below) and the solar variation over 2000 years has been about 0.1%, the corresponding temperature change would be a little less than 0.2 C over 2000 years.
The "back of an envelope calculation" in
http://www.junkscience.com/Greenhouse/cause.html compares a 0.2%
increase in irradiation to a 0.2% increase in earth's temperature.
This is incorrect. As explained in Stefan-Boltzmann
law the energy radiated from a black body is proportional to the
4th power of the temperature of that body. The earth is in
equilibrium so the energy received from the sun equals the energy
transmitted back into space. The earth's black body temperature can
be calculated (without albedo or greenhouse effect) as going from:
4th root of ((1364 / 4) / (5.67 x (10^(-8)))) = 278.479243
at 1364 w/m2 to:
4th root of ((1367.23 / 4) / (5.67 x (10^(-8)))) = 278.643959
at 1367.23 w/m2 or a 0.2% increase in solar radiation causes a 0.05% increase in temperature.
Henrik Svensmark's cosmic ray flux explanation for global warming doesn't explain why there isn't a dramatic 22 year climate cycle since the 22 year cycle (and correlating cycle in low clouds as Svensmark demonstrates) dwarfs the long term decline in cosmic ray flux. Performing Fourier transforms on local or global temperatures does not reveal any significant 22 year frequency component. CO2 also does not have a significant 22 year frequency component although it has a very distinct seasonal fluctuation caused by the northern hemisphere growing season. Cosmic ray flux changes may yet provide important explanations of long term climate changes but it is unlikely that they have had any significant impact on 20th century climate change.
Milankovitch forcing is slow cyclic changes in the earth's orbit and tilt that trigger large changes in climate and CO2. They are illustrated by the cyclic changes in ice cores shown below. Although the resultant changes are substantial shifting the climate from warm periods to ice ages, they are very slow and could not account for any short term temperature or CO2 changes and currently point to long term (thousands of years) of cooling and diminishing CO2.
warmest year in the last...
Part of the warming observed over the last 400 years is due to the end of the Little Ice Age 400 years ago, and 12,000 years ago was the depths of a real ice age. But despite the expected warming from those events there is no reliable way to tell that recent years are the warmest. The reason is that prehistorical temperature measurements are obtained from proxies which contain varying amounts of natural smoothing. The physics and biology that produces the temperature proxy and how it is reflected by the smoothing of the data must be analyzed to determined the "uncertainties" in the measurements, not statistical comparisons between and within data sets. To make the million year claims, older measurements are needed such as from ice cores, with less complex physics, but with much less resolution so as to easily miss a thousand year spike, much less a sub-century spike like the current one. See below for a discussion of ice cores.
The recent measurements from most proxies show little warming, see "Global Warming" Proxies and compare them to the graph from Mann below. The "uncertainty" represented by the gray area in Mann's chart is purely statistical, comparing proxy to proxy, not on the physics and biology behind the measurements which matter. Comparing measurements from ancient readings to modern ones within one proxy is the only valid method to analyze temperature trends. To superimpose the instrument record with the red line as shown is to juxtapose exact instrument readings containing a spike with proxy readings that will smooth out spikes. It is misleading to imply that they are they are equivalent measurements and there could therefore be no similar spikes in the historical record. The extent to which the spikes were smoothed is a function of the physics and biology of the proxy and cannot be determined through statistical analysis of the data as was performed to produce the figure above.
The main argument for obtaining the hockey stick shape from the proxy data is that the past warming shown in various proxies are not synchronized globally. For example, the regional warming in European and North American proxies from roughly 1000-1400 AD is not seen in many southern hemisphere and remote NH proxies. But most of those proxies don't show the current warming either. The choice of proxies is critical for Mann's graph particularly in matching up to the instrument record. Regardless of its 20th century conclusions, the hockey stick also tends to downplay natural climate variation, particularly cooling, and thus hides natural warmings (e.g. before 1000) that are larger and faster than todays.
Myth: The most CO2 in 650,000 years
An even more blatant example of ignoring physics and publishing improperly juxtaposed measurements as fact is CO2 in ice cores compared to modern instrument measurements. A similarly unsupportable claim for methane is:
The historic record of atmospheric CH4 obtained from ice cores has been extended to 420,000 years before present (BP) (Petit et al., 1999). As Figure 4.1e demonstrates, at no time during this record have atmospheric CH4 mixing ratios approached today's values ( http://www.grida.no/climate/ipcc_tar/wg1/135.htm)
The ice core used for the methane and CO2 claims is Vostok Ice Core CO2 Data which contains very sparse measurements of highly smoothed data. The instruments measuring the CO2 are not in question, the problem lies in the minimum thickness of a slice and how much time that slice represents. The CO2 measurement made from that slice is then a distribution, perhaps roughly gaussian, of the atmospheric CO2 present over that period of time and more since the CO2 diffuses through the ice. An example from another ice core: Proposed Drill Site... implies above figure 7 that hundreds of years are compressed into 1 cm of ice. [Note, still looking for a reference that would indicate the resulting resolution]. This vostok data shows the readings to be between 1000 and 4000 years apart. The higher resolution of more modern ice cores is completely irrelevant although they are often juxtaposed as in the IPCC methane example from above where the old, smoothed measurements shown in (e) above are implied to be equivalent to modern ice core measurement shown as dots above in (a). But the dots in (a) can be determined with much higher resolution as the snow and ice is not nearly as compacted and annual layers are still visible and analyzable.
The main problem with the conclusion CO2 'highest for 650,000 years' and charts like this one: from wikipedia is that they mislead nonscientists into believing that the ice cores measurements provide proof of CO2 boundedness when they obviously can't. The only way to show that the current spike is not natural is to show that physical processes could not release the quantities of CO2 seen today which is unlikely, or that if they did, that the elevated CO2 levels would last for 1000's of years to be picked up in the ice core record. Most AGW proponents choose the latter as seen in the response to post 130 at Real Climate
To calculate the impulse response from a spike of CO2, one must add an increased diffusion of CO2 into oceans and increased uptake into plants. The figure below shows flows at equilibrium, more or less equal, although the numbers don't quite add up implying that carbon is currently not in equilibrium. The atmosphere is measured to have 3.8Gt of new carbon per year, but with the manmade addition of 6.2Gt and the other flows shown in the figure, there should be 4.6Gt added to the atmosphere each year. (from http://cdiac.esd.ornl.gov/pns/graphics/c_cycle.htm). The impulse response from a spike of CO2 similar to the current spike shows a decline of CO2 back to 40% in about 50 years and 20-30% in 500 years (see figure 4 in http://isam.atmos.uiuc.edu/atuljain/publications/WuebblesEtAl.pdf) The impulse response does not explain where such an impulse would come from, but a pulse of CO2 similar to the present increase (if it ended as abruptly as it has appeared) would be invisible in the older ice core measurements.
Myth: All "extra" CO2 is
Unlike what is implied in this article: How do we know that recent CO2 increases are due to human activities?, there are natural variations in C13/C12 that result from natural climate changes. The article fails to quantify the natural changes (implies they are zero) and thus fails to quantify the manmade changes and validate the article title. This study Implications of a 400 year tree ring based 13C/12C chronology concludes that "...shifts in 13C/12C prior to 1850 resulted from a climate-induced perturbation in the Ci/Ca ratio". In other words, the temperature and humidity changed enough that changes in vegetation caused changes in the 13C/12C ratio as measured in the ice cores.
As shown in this poster: http://www.holivar2006.org/abstracts/pdf/T3-032.pdf, the initial decline in the 13C/12C ratio began in the 1700's before the "industrial revolution". The supposed start of the industrial revolution in 1850 is not significant looking at the carbon emission data: http://cdiac.ornl.gov/ftp/ndp030/global.1751_2003.ems. The amounts of anthropogenic carbon reached 0.1% of the natural carbon flows in the 1870's and 1% in the 1950's making it unlikely that the isotope ratio changes were anthropogenic until recently. Another possible factor not included in this data is land use, but that is historically small and hard to distinguish from natural "land use" changes in historic data. In short, some part of the isotope ratio changes are natural and some are anthropogenic, which suggests further that part of the observed CO2 rise is of natural biotic (low ratio) origins.
Myth: Only 0.28% of the
"greenhouse effect" is human
As pointed out in this article: Water Vapor Rules the Greenhouse System, water vapor dominates the greenhouse effect. True, but irrelevant for consideration of human effects. The science is straightforward, see Water vapour: feedback or forcing?. Removing CO2 from the atmosphere would leave about 90% of the greenhouse effect. Removing water vapor would leave about 65%. A similar table is in the references to the Water Vapor Rules... article: http://www.eia.doe.gov/cneaf/alternate/page/environment/appd_d.html. The quote that 95% of the earth's greenhouse effect comes from water vapor is incorrect, it only applies to the troposphere and does not distinguish between forcing and feedback. It is the warming from rest of the greenhouse gases that causes the water to evaporate and cause its warming. A simple example should suffice: if the earth's atmosphere contained no CO2, all the water vapor would quickly freeze and stay frozen regardless of any plausible solar forcing changes.
The bottom line is that the 10% or more of GH effect from CO2 is being divided artificially into a human and nonhuman component. Since the models are tuned and accurate to today's CO2 concentrations, we would need to estimate the percentage of CO2 of human origin. As seen in the section above, it's not 100% of the increase from preindustrial times. But nor is it zero. Splitting the difference would mean 1/2 of the 30% (increase) of the 10% of the total GH effect or 1.5%, not 0.28% But the real bottom line is that the number isn't meaningful.
Both sides in the global warming debate have a tendency to oversimplify models. The most common flaw is to substitute assumptions or real-world measurements for a model parameter, then use the model to make predictions without modeling the parameter. For example, earth's albedo can measured using satellites and inserted into a simple energy balance model. But those albedo measurements cannot be projected in a model without detailed simulation of weather. Some specific modeling problems are mentioned here: http://climatesci.colorado.edu/2006/05/11/uncertainty-identified-in-gcms-with-respect-to-albedos/ such as under and overestimation of albedo. A small error in modeled parameters like albedo can lead to large errors in model results. Using the Stefan-Boltzmann equation from above (itself a gross oversimplification):
the 4th root of (((1 367 / 4) * 0.7) / (5.67 x (10^(-8)))) = 254.862463
and the 4th root of (((1 367 / 4) * 0.707) / (5.67 x (10^(-8)))) = 255.497244
or a 1% decrease in albedo can account for more than a 0.6 degree C temperature increase. The observed albedo can fluctuate more than that in a year mainly from volcanic eruptions as shown here: but any projection of albedo by itself is an oversimplification since the albedo changes come mostly from cloud changes which change the heat trapped by the greenhouse effect, convection, and heat released from the water cycle.
There are numerous examples of model failure typically explained away as weather which is not predictable versus climate which is. One recent example is the lack of prediction of the Recent Cooling of the Upper Ocean But climate modelers also attempt to match model results with reality by postulating ocean heat storage (e.g. http://naturalscience.com/ns/articles/01-16/ns_jeh3.html Sydney Levitus (Reference 4) has analyzed ocean temperature changes of the past 50 years, finding that the world ocean heat content increased about 10 watt-years, consistent with the time integral of the planetary energy imbalance. Levitus also found that the rate of ocean heat storage in recent years is consistent with our estimate that the energy balance of the Earth is now out by 0.5 to 1 W/m2 But without warming oceans there is no longer an explanation of where the extra energy is going to maintain a continuous imbalance of energy (except for certain volcanic events) as shown in their figure 5. Clearly their model is missing or inaccurately modeling large amounts of energy transfer.
CO2 alternatives are generally not factored into climate models, for example the warmer and drier conditions downwind from large wind farms. Some advocates of hybrid cars do not consider the energy costs to manufacture and ship the batteries nor account for their limited lifespan. The results of this study: Hummer Over Prius are heavily biased by a questionable three times longer lifespan for the Hummer, but the Hummer doesn't have hybrid parts and complexity. Other conclusions are less intuitive, for example a bicycle with a motor might be less energy intensive than one run by food: http://www.ebikes.ca/sustainability/Ebike_Energy.pdf Combined with the uncertainties and known inaccuracies of the climate models, the substitution of some limited aspect of CO2 production (e.g. electricity use) for warming or "carbon credits" to reduce global warming impact is absurdly oversimplified and in many cases, false and counterproductive.
Ultimately it will become routine for the general public to have their own models telling them the consequences of all of their relevant actions, particularly their use of energy or items with high energy inputs. But this will require full integration of environmental inputs and outputs along with sufficiently detailed modeling to account for small changes. An economic incentive would have to be added to the model, e.g. a tax on activities with warming consequences, to encourage changes in behavior if those are necessary (although politicians would end up making that decision, not scientists, so it is vital to make the models transparant and publicly available). There is no doubt the current models are not able to model warming consequences accurately or even roughly for individuals and companies. But there is also no doubt that warming models will be accurate in 20 years or so with better science and greatly increased computer power.