Global warming

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Annual average global warming by the year 2060 simulated and plotted using EdGCM

Global warming is the increase in the average temperature of the Earth's near-surface air and oceans in recent decades and its projected continuation.

Global average air temperature near the Earth's surface rose 0.74 ± 0.18 °C (1.33 ± 0.32 °F) from 1906 to 2005. One view, as represented by the science academies of the major industrialized nations[1] and the Intergovernmental Panel on Climate Change (IPCC),[2] is that most of the temperature increase since the mid-20th century has been very likely caused by increases in atmospheric greenhouse gas concentrations produced by human activity. Another view suggests that global warming and global cooling are recurring natural events with little or no anthropogenic influences.

Climate models project that global surface temperatures are likely to increase by 1.1 to 6.4 °C (2.0 to 11.5 °F) between 1990 and 2100.[2] The range of values reflects the use of differing assumptions of future greenhouse gas emissions and results of models that differ in their sensitivity to increases in greenhouse gases.[2] The latest IPCC report, Working Group I Chapter 8 (see pages 600-647) [3], contains pages of admissions regarding the shortcomings of climate models, which still cannot accurately predict both temperature and precipitation at the same time. IPCC concerns reflect reality as the climate models the IPCC used as a primary basis for their predictions and conclusions routinely fail to accurately predict climate. [4][5] The reasons are not hard to discover. Climate models have known significant shortcomings. [6] [7] The consensus view is that they are incapable of performing their primary task. [8] The IPCC practice is to accept that each of the climate models has serious shortcomings. Their methodology is to take all the known wrong answers and sum them together then bless the result as correct.

An increase in global temperatures will in turn cause sea level rise, glacier retreat, melting of sea ice, and changes in the amount and pattern of precipitation. Though world climate catastrophe meetings and news media reports featured dire warnings about changes in the frequency and intensity of extreme weather events, anecdotal evidence suggests otherwise, particularly with respect to repeated warnings regarding global warming's effects on tropical cyclones. After an unusually robust North Atlantic hurricane season in 2005 dire predictions that anthropogenic warming would cause worse seasons in 2006 and 2007 failed to translate into fact. Both seasons were decidedly tame. [9] In truth no valid link exists that connects specific weather events, or any trend in them, to global warming whatever the true cause, anthropogenic or natural. Patterns of drought and deluge, heat and cold have exhibited unpredictable variability long before alleged anthropogenic climate change alarmism became sexy and trendy. Changes to the climate will produce a range of practical effects, such as changes in agricultural yields and impacts on human health as they have in the past according to historical records, which show that colder times feature severe illness and major crop failures while warmer times feature robust health and substantially increased crop yields.

Remaining scientific uncertainties include the exact degree of climate change expected in the future, and how changes will vary from region to region around the globe.[10] There is ongoing political and public debate regarding what, if any, action should be taken to reduce future warming or to adapt to its consequences as it is pointed out by some that the trillions of dollars proposed to be spent in vain attempts to stop what may in fact turn out to be irresistible natural forces could better be spend on real world problems with proven causes and solutions. The Kyoto Protocol, an international agreement aimed at reducing greenhouse gas emissions, was adopted by 169 nations, yet it exempted the two most populous and most polluting nations on Earth, India and China. During more recent climate talks in Bali in 2007, China made it clear that the world should not expect any emissions reductions even though China was recently acknowledged to be the number one carbon dioxide emitter in the world. Furthermore China bluntly informed the delegates gathered in Bali that emissions will drastically increase as China embarks on a program to build over 550 coal-fired powerplants over the next 20 years. Even as the meetings that produced Kyoto were winding down, delegates to Kyoto, including Al Gore, were admitting that the treaty would do little if anything to solve what they saw as the main problem - anthropogenic greenhouse gas emissions. They were right. In the years since it was written even those who formally ratified it found ways to adjust their efforts to comply to make them even more meaningless. [11] Naturally, failure of Kyoto led to the usual political response - proposal of taxes. [12] The one true consensus regarding global warming seems to be that Kyoto was indeed a complete failure. [13]

Terminology

The United Nations Framework Convention on Climate Change (UNFCCC) uses the term "climate change" for human-caused change, and "climate variability" for other changes.[3] The terms "anthropogenic global warming" and "anthropogenic climate change" are sometimes used when focusing on human-induced changes.

Causes

The climate system varies both through internal processes and in response to external forcing. External forcing includes solar activity, volcanic emissions, variations in Earth's orbit , and atmospheric composition. The scientific consensus[4] is that most of the warming observed since the mid-twentieth century is very likely due to increased atmospheric concentrations of greenhouse gases produced by human activity. Some other hypotheses have been offered to explain most of the observed increase in global temperatures but these are not broadly supported in the scientific community. This is just another version of the typical "consensus" argument which was responsible for past conclusions that all matter was made of four elements, earth, air, fire and water as well as the common beliefs that the Earth was flat and that the sun and other planets in the solar system revolved around the Earth. One sure sign that compelling arguments are unavailable is reliance on consensus arguments. The simple fact is that there is compelling evidence that warming and cooling cycles are caused by natural fluctuations in the climate, that warming is mainly a result of variations in solar radiation,[5] or that warming is caused by changes in cloud cover due to variations in galactic cosmic rays.[6] Despite claims by some that such ideas are not well supported in the scientific community CERN found it reasonable to devote signficant resources to a major experiment regarding the influence of solar variation on cosmic rays, cloud formation and resulting global warming or cooling.

The effects of forcing are not instantaneous. Due to the thermal inertia of the oceans and the slow responses of some feedback processes, Earth's climate is never in perfect equilibrium with the imposed forcing. Climate commitment studies indicate that even if greenhouse gases were stabilized at present day levels there would be a further warming of about 0.5 °C (0.9 °F) as the climate continued to adjust toward equilibrium.[7]

Greenhouse gases in the atmosphere

Existence of the greenhouse effect itself is not disputed. It is the process by which emission of infrared radiation by atmospheric gases warms a planet's atmosphere and surface. Naturally occurring greenhouse gases warm the Earth by about 33 °C (59 °F). Without this natural greenhouse effect, the average temperature of Earth would be about -18 °C (0 °F) making the planet uninhabitable.[8] The major natural greenhouse gases are water vapor, which causes about 36–70% of the greenhouse effect (not including clouds); carbon dioxide (CO2), which causes 9–26%; methane (CH4), which causes 4–9%; and ozone, which causes 3–7%.[9]

The main issues are whether or not carbon dioxide causes or comes from increased global temperatures and whether or not it actually plays a measurable role in climate change as suggested. Proponents of catastrophic anthropogenic climate change alarmism theories always had difficulty explaining how the estimated 1/20 anthropogenic contribution to the carbon cycle dominated the 19/20 natural contribution and were dogged by more careful and detailed studies of available evidence which suggested conclusions regarding historic atmospheric carbon dioxide levels were erroneous and that modern day atmospheric carbon dioxide increases were driven not by man but by an easily explained process involving known upwelling of cold, deep, carbon dioxide rich ocean water and subsequent well understood outgassing as those waters were heated.[14]

The present atmospheric concentration of CO2 is about 383 parts per million (ppm) by volume.[10] From geological evidence it is believed that CO2 values this high were last attained 20 million years ago.[11] About three-fourths of man-made CO2 emissions over the past 20 years have come from the burning of fossil fuels. Most of the rest is due to land-use change, mainly deforestation.[12] Measured trends in atmospheric composition and isotope ratios (namely the simultaneous depletion of 13C, 14C, and O2) confirm that the increased atmospheric CO2 mainly comes from fossil fuels and not from other sources such as volcanoes or the oceans.[13]

Future CO2 concentrations will depend on uncertain economic, sociological, technological, and natural developments. If the years since Kyoto are any guide we can expect lots of talk but little actual concrete action. Since emissions have continued to climb at ever increasing rates yet climate seems to have levelled off or even to have entered a cooling phase we may soon see some interesting reconsideration of what some have referred to as "settled" science. The IPCC Special Report on Emissions Scenarios gives a wide range of future CO2 scenarios, ranging from 541 to 970 ppm by the year 2100.[14] Fossil fuel reserves are sufficient to reach these levels and continue emissions past 2100, if coal, tar sands, or methane clathrates are extensively used.[15] Positive feedback effects such as the release of methane from the melting of permafrost peat bogs in Siberia (possibly up to 70,000 million tonnes) may lead to significant additional sources of greenhouse gas emissions[16] not included in climate models cited by the IPCC.[2]

Feedbacks

Catastrophic anthropogenic climate change alarmism suggests that climate feedback processes tend to all be positive. Indeed they must be programmed that way, well beyond anything actually found in nature, in climate models in order to produce the sort of rampant warming scenarios most often featured in IPCC announcments and sensationalized media reports. The problem with this scenario is simple. We know from geological and other evidence that the Earth has experienced significant periods of much warmer and much colder climate yet it always reverts back. If climate processes featured such overwhelmingly reinforcing feedbacks as alarmist theories suggest there is simply no way climate, once it embarked on a path of significant warming or cooling, could reverse and therefore life as we know it would not exist. Experience teaches us that feedback mechanisms necessary to support theories that attribute any signficiant portion of global warming to anthropogenic emissions require those mechanisms to be grossly overstated and sometimes to have the reverse effect than that actually observed in the real world. Removing the grossly overestimated and improperly signed feedback parameters from climate models might allow for the removal of other unnatural checks and balances necessarily built into them to prevent the models from automatically going into runaway scenarios.

The effects of forcing agents on the climate are modified by feedback processes. One of the most important feedbacks is caused by the evaporation of water. Increased greenhouse gases from human activity cause a warming of the Earth's atmosphere and surface. The increased warmth in turn increases the evaporation of water into the atmosphere. Since water vapor itself is a greenhouse gas, this causes still more warming; the warming causes more water vapor to be evaporated, and so on. Eventually a new dynamic equilibrium concentration of water vapor is reached at a slight increase in humidity and with a much larger greenhouse effect than that due to CO2 alone.[17]

The radiative effects of clouds are a major source of uncertainty in climate projections. Seen from below, clouds emit infrared radiation to the surface, and so have a warming effect. Seen from above, clouds reflect sunlight and emit infrared radiation to space, and so have a cooling effect. The cloud feedback effect is influenced not only by the amount of clouds but also by their distribution; for example, high clouds are at colder temperatures than low clouds, and thus radiate less energy to space. Increased global water vapor content may or may not cause an increase in global or regional cloud cover, since cloud cover is affected by relative humidity rather than the absolute concentration of water vapor. Cloud feedback is second only to water vapor feedback and has been found to have a net warming effect in all the models that contributed to the IPCC Fourth Assessment Report.[17]

Another important process is ice-albedo feedback.[18] Warming of the Earth's surface leads to melting of ice near the poles. As the ice melts, land or open water takes its place. Both land and open water are on average less reflective than ice, and thus absorb more solar radiation. This causes more warming, which in turn causes more melting, and the cycle continues.

The ocean's ability to sequester carbon is expected to decline as it warms, because the resulting low nutrient levels of the mesopelagic zone limits the growth of diatoms in favor of smaller phytoplankton that are poorer biological pumps of carbon.[19]

Solar variation

It has been hypothesized that variations in solar output, possibly amplified by cloud feedbacks, may have been a secondary contributor to recent warming.[20] Natural phenomena, such as solar variation and volcanoes, probably had a net warming effect from pre-industrial times to 1950 and a small cooling effect since 1950.[21] Some research indicate that the Sun's contribution may have been underestimated. These results suggest that the Sun may have contributed about 40–50% of the global surface warming between 1900 and 2000 and about 25–35% of the warming between 1980 and 2000.[22] Stott and coauthors suggest that climate models overestimate the relative effect of greenhouse gases compared to solar forcing; they also suggest that the cooling effects of volcanic dust and sulfate aerosols have been underestimated.[23] Nevertheless, they conclude that even with an enhanced climate sensitivity to solar forcing, most of the warming during the latest decades is attributable to the increases in greenhouse gases.

Climate change since the Industrial Revolution

According to the instrumental temperature record, mean global temperatures (both land and sea) have increased by 0.75 °C (1.35 °F) relative to the period 1860–1900. This measured temperature increase is not significantly affected by the urban heat island effect.[24][25][26] Since 1979, land temperatures have increased about twice as fast as ocean temperatures (0.25 °C per decade against 0.13 °C per decade).[27] Temperatures in the lower troposphere have increased between 0.12 and 0.22 °C (0.22 and 0.4 °F) per decade since 1979, according to satellite temperature measurements. Temperature is believed to have been relatively stable over the one or two thousand years before 1850, with possibly regional fluctuations such as the Medieval Warm Period or the Little Ice Age.

Based on estimates by NASA's Goddard Institute for Space Studies, 2005 was the warmest year since reliable, widespread instrumental measurements became available in the late 1800s, exceeding the previous record set in 1998 by a few hundredths of a degree.[28] Estimates prepared by the World Meteorological Organization and the Climatic Research Unit concluded that 2005 was the second warmest year, behind 1998.[29][30] Global temperatures in 1998 were exceptionally warm because the strongest El Niño in the instrumental record occurred in that year.[31]

Anthropogenic emissions of other pollutants—notably sulfate aerosols—can exert a cooling effect by increasing the reflection of incoming sunlight. This partially accounts for the cooling seen in the temperature record in the middle of the twentieth century,[32] though the cooling may also be due in part to natural variability.

Still unexplained is the fact that even as emissions of anthropogenic greenhouse gasses accelerate at an accelerating rate, 1998 remains "the hottest year ever" and global temperatures seem to be in either a holding pattern or may even be showing signs of declining. In 1998 the "proof" of unusual global warming that could only be attributed to human causes involved the unusually warm sea surface waters in the Pacific known as El Nino. Interestingly enough now that those same waters are unusually cool you don't hear similar claims it is equal proof of global cooling today.

Climate models

Scientists have studied global warming with computer models of the climate. These models are based on physical principles of fluid dynamics, radiative transfer, and other processes, with some simplifications being necessary because of limitations in computer power. These models predict that the net effect of adding greenhouse gases is to produce a warmer climate. However, even when the same assumptions of fossil fuel consumption and CO2 emission are used, the amount of projected warming varies between models and there is a considerable range of climate sensitivity. Including uncertainties in future greenhouse gas concentrations and climate modeling, the IPCC report projects a warming of 1.1 °C to 6.4 °C (2.0 °F to 11.5 °F) between 1990 and 2100.[2]

Models have also been used to help investigate the causes of recent climate change by comparing the observed changes to those that the models project from various natural and human derived causes. Climate models can produce a good match to observations of global temperature changes over the last century, but cannot yet simulate all aspects of climate.[33] These models do not unambiguously attribute the warming that occurred from approximately 1910 to 1945 to either natural variation or human effects; however, they suggest that the warming since 1975 is dominated by man-made greenhouse gas emissions.

Global climate model projections of future climate are forced by imposed greenhouse gas scenarios, generally one from the IPCC Special Report on Emissions Scenarios (SRES). Less commonly, models may also include a simulation of the carbon cycle; this generally shows a positive feedback, though this response is uncertain (under the A2 SRES scenario, responses vary between an extra 20 and 200 ppm of CO2). Some observational studies also show a positive feedback.[34][35][36]

The representation of clouds is one of the main sources of uncertainty in present-generation models, though progress is being made on this problem.[37] There is also an ongoing discussion as to whether climate models are neglecting important indirect and feedback effects of solar variability.

The most interesting note about climate models is the fact that none of them agree nor do any of them come close to producing long-term realistic predictions with regards to both temperature and precipitation at the same time. Interestingly enough the IPCC takes all the known wrong answers, sums them together then blesses the result as valid.

Attributed and expected effects

Some effects on both the natural environment and human life are, at least in part, already being attributed to global warming. A 2001 report by the IPCC suggests that glacier retreat, ice shelf disruption such as the Larsen Ice Shelf, sea level rise, changes in rainfall patterns, and increased intensity and frequency of extreme weather events, are being attributed in part to global warming.[38] Oddly enough, nobody finds it appropriate to mention that the Antarctic is experiencing record cold temperatures over most of it's area and the 2007 Antarctic ice extent shattered past records. Possible explanations for these facts is that despite attempts to claim anthropogenic global warming would cause severe extremes of cold, ice and snow nobody's quite daring enough to see if the public is gullible enough to swallow such ridiculous claims repeatedly. While changes are expected for overall patterns, intensity, and frequencies, it is difficult to attribute specific events to global warming. Other expected effects as a result of warmer temperatures include water scarcity in some regions and increased precipitation in others, changes in mountain snowpack, and adverse health effects.

Increasing deaths, displacements, and economic losses, similar to those featured throughout recorded history yet now magically projected due to extreme weather attributed to global warming without any scientific basis for the link may be exacerbated by growing population densities in affected areas, although temperate regions are projected to experience some minor benefits, such as fewer deaths due to cold exposure.[39] A summary of probable effects and recent understanding can be found in the report made for the IPCC Third Assessment Report by Working Group II.[38] The newer IPCC Fourth Assessment Report summary reports that there is observational evidence for an increase in intense tropical cyclone activity in the North Atlantic Ocean since about 1970, in correlation with the increase in sea surface temperature, but that the detection of long-term trends is complicated by the quality of records prior to routine satellite observations. The summary also states that there is no clear trend in the annual worldwide number of tropical cyclones.[2] Such tentative attempts to link increases in hurricane frequency or intensity to an anthropogenic cause fell flat on their face when dire warnings of severe north Atlantic hurricane seasons in 2006 and 2007 gave way to a reality of two of the mildest seasons since the 1930s.

Additional anticipated effects include sea level rise of 110 to 770 millimeters (0.36 to 2.5 ft, or 20 feet according to Al Gore) between 1990 and 2100,[40] repercussions to agriculture, possible slowing of the thermohaline circulation, reductions in the ozone layer, increased intensity and frequency of hurricanes and extreme weather events, lowering of ocean pH, and the spread of diseases such as malaria and dengue fever. One study predicts 18% to 35% of a sample of 1,103 animal and plant species would be extinct by 2050, based on future climate projections.[41] McLaughlin et al. have documented two populations of Bay checkerspot butterfly being threatened by precipitation change, though they state few mechanistic studies have documented extinctions due to recent climate change.[42]

Mitigation and adaptation

The broad agreement among climate scientists that global temperatures will continue to increase has led nations, states, corporations, and individuals to implement actions to try to curtail global warming or adjust to it. Many environmental groups encourage action against global warming, often by the consumer, but also by community and regional organizations. There has been business action on climate change, including efforts at increased energy efficiency and (still limited) moves to alternative fuels. One innovation has been the development of greenhouse gas emissions trading through which companies, in conjunction with government, agree to cap their emissions or to purchase credits from those below their allowances.

The world's primary international agreement on combating global warming is the Kyoto Protocol, an amendment to the UNFCCC, negotiated in 1997. The Protocol now covers more than 160 countries globally and over 55% of global greenhouse gas emissions.[43] The United States and Kazakhstan have not ratified the treaty. China and India, two other large emitters, have ratified the treaty but, as developing countries, are exempt from its provisions. This treaty expires in 2012, and international talks began in May 2007 on a future treaty to succeed the current one.[44]

The world's primary body for crafting a response is the Intergovernmental Panel on Climate Change (IPCC), a UN-sponsored activity which holds periodic meetings between national delegations on the problems of global warming, and issues working papers and assessments on the current status of the science of climate change, impacts, and mitigation. It convenes four different working groups examining various specific issues.

Related climatic issues

A variety of issues are often raised in relation to global warming. One is ocean acidification. Increased atmospheric CO2 increases the amount of CO2 dissolved in the oceans.[45] CO2 dissolved in the ocean reacts with water to form carbonic acid resulting in acidification. Ocean surface pH is estimated to have decreased from approximately 8.25 to 8.14 since the beginning of the industrial era.[46] The key word here is "surface", keeping in mind that the surface of the ocean accounts for a miniscule portion of the total ocean volume. Plus as the surface of the ocean warms known physical processes drive dissolved carbon dioxide out of solution, suggesting theories of ever decreasing pH due to increasing dissolved carbon dioxide gas are flawed. Nevertheless, it is estimated that it will drop by a further 0.14 to 0.5 units by 2100 as the ocean absorbs more CO2.[2][47] Note that this is between two and five times the suggested present observed change and it is projected to occur over signficantly less time. As with past IPCC and general alarmist predictions which never managed to come true this one will have to be seen to be believed. Since organisms and ecosystems are adapted to a narrow range of pH, this raises extinction concerns, directly driven by increased atmospheric CO2, that could disrupt food webs and impact human societies that depend on marine ecosystem services except for the fact that the observed and any reasonably projected future changes are still within those narrow ranges, of course. [48]

Another related issue that may have partially mitigated global warming in the late twentieth century is global dimming, the gradual reduction in the amount of global direct irradiance at the Earth's surface. From 1960 to 1990, human-caused aerosols likely precipitated this effect. Scientists have stated with 66–90% confidence that the effects of human-caused aerosols, along with volcanic activity, have offset some of global warming, and that greenhouse gases would have resulted in more warming than observed if not for these dimming agents.[2]

References

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  42. ↑ McLaughlin, John F.; et al. (2002-04-30). "Climate change hastens population extinctions" (PDF). PNAS 99 (9): 6070–6074. DOI:10.1073/pnas.052131199. Retrieved on 2007-03-29. Research Blogging.
  43. ↑ Kyoto Protocol Status of Ratification (PDF). United Nations Framework Convention on Climate Change (2006-07-10). Retrieved on 2007-04-27.
  44. ↑ Climate talks face international hurdles, by Arthur Max, Associated press, 5/14/07.
  45. ↑ The Ocean and the Carbon Cycle. NASA (2005-06-21). Retrieved on 2007-03-04.
  46. ↑ Jacobson, Mark Z. (2005-04-02). "Studying ocean acidification with conservative, stable numerical schemes for nonequilibrium air-ocean exchange and ocean equilibrium chemistry" (PDF). Journal of Geophysical Research 110 (D7). DOI:10.1029/2004JD005220. D07302. Retrieved on 2007-04-28. Research Blogging.
  47. ↑ Caldeira, Ken; Wickett, Michael E. (2005-09-21). "Ocean model predictions of chemistry changes from carbon dioxide emissions to the atmosphere and ocean". Journal of Geophysical Research 110 (C09S04): 1–12. Retrieved on 2006-02-14.
  48. ↑ Raven, John A.; et al. (2005-06-30). Ocean acidification due to increasing atmospheric carbon dioxide (ASP). Royal Society. Retrieved on 2007-05-04.

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