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Global Warming Science

http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr_spm.pdf (181) is IPCC AR4 The Earth's climate has changed a number of times over the course of its history, changing between ice ages and times of extreme warmth, as a result of natural factors, however, during the last 150-200 years, humans have altered this heating/cooling cycle by adding a huge amount of greenhouse gases to the atmosphere, introducing a new factor into the climate equation that has been accelerating changes. Greenhouse gases are essential to life on this planet, naturally having a mean warming effect of about 59 degrees F, but the increase in greenhouse gases since the Industrial Revolution has been unprecedented, with CO2 reaching its highest level in possibly as long as 20 million years, with fossil fuel burning accounting for approximately 75% of this increase and deforestation making up the rest of it. As a result of this, there have been a number of recent temperature increases. Global temperatures have increased by 0.75 °C (1.35 °F) since 1860-1900. Since 1979, the land temperatures have increased at a rate of 0.25 °C per decade and sea temperatures at a rate of 0.13 °C per decade and lower troposphere temperature increases have been between 0.12 and 0.22 °C per decade. Prior to 1850, the temperature is believed to have been relatively stable for one or two thousand years and 2005 was the warmest year on record according to NASA's Goddard Institute for Space Studies since reliable data became available in the late 1800s Check to see if its gotten hotter . The Earth has gone through periods of heating and cooling in the past, with eight glacial cycles in the last 800,000 years according to Antarctic ice cores, but what's concerning about this warming is that it is believed to be outside of the cycle due to human behaviors and is also occurring at a rather rapid rate. Trying to figure out how much of this warming is due to humans and how much warming will occur in the future is done through complex climate models that try to take into account as many of the natural processes occurring as possible and also try to estimate what the future outputs of various greenhouse gases will be. Climate models have difficulty determining whether warming that occurred from 1910 to 1945 was from human or natural effects, but agree that warming since 1975 is predominantly a result of human behaviors. They also predict future warming from human behaviors, somewhere in the range of a 1.1 °C to 6.4 °C (2.0 °F to 11.5 °F) temperature increase by the end of the 21st century when compared to 1980-1999 levels. (174) \"Monitoring the current status of climate: Testing for spatial dependence between independently measured values in an ordered set is based on applying Fisher’s F-test to the variance of a set and the first variance term of the ordered set. Charting statistically significant variance terms gives a sampling variogram that shows where spatial dependence in our sample space of time dissipates into randomness. The lag of a sampling variogram is a statistically robust measure for a change in a climate statistic. Scientists use \"Indicator time series\" that represent the many aspects of climate and ecosystem status. The time history provides a historical context. Current status of the climate is also monitored with climate indices.\" Somehow this has to become English

Below are some additional, indirect evidences of climate change, in addition to the direct temperature measurements described above:

• Pollen Analysis: The study of contemporary and fossil palynomorphs Define is used to infer the geographical distribution of plant species, which vary under different climate conditions. Different groups of plants have pollen with distinct shapes and surface textures and tend to have an outer surface that resists degradation, allowing the pollen to be used to get historical data on plant types.
• Beetles: Similar to pollen analysis, different beetles are known to exist in different climates, so looking at the remains of beetles in an area with respect to age of the remains can help map climate.
• Glacial Geology: Advancing glaciers leave behind a number of easily distinguishable features. Similarly, the lack of glacier cover can be identified via a number of means, allowing glacier presence or absence to be easily mapped. The IPCC considers glaciers to be one of the most sensitive climate indicators.

It is possible to use core samples to determine past temperature and CO2 levels by using air bubbles trapped in ice that have been formed by snow falls in areas where melting rarely occurs getting compressed into ice and trapping some air from the current atmosphere. Fairly accurate time scales for ice cores can be developed for at least the last 10,000 years, and estimates have been made going as far back as 420,000 years.

Important Notes About Climate

Climate is the average temperature, humidity, precipitation, days of sunlight, severe weather events, etc. that occur within a certain region. This is to be distinguished between weather, which is the daily state of the atmosphere and is highly unpredictable and unstable. There are a huge number of forces that act to affect a region's climate, many of which are discussed below:

• Variations in the Earth's orbit around the Sun: Changes in the Earth's orbit affect the amount of sunlight that reaches the Earth's surface. These variations are considered teh driving factors underlying the glacial and interglacial cycles of the latest ice age.
• Solar luminosity: There is some degree of uncertainty regarding how sensitive the Earth's climate is to solar effects, which changes the amount of warming attributed to greenhouse gases, although it is still a significant amount by most studies. In addition, the sun's intensity is increasing on very long time scales and also modulates on 11-year and longer cycles, although these shorter variations in output via sunspot variations are thought to have less of a role in affecting Earth's climate.
• Ocean variability: On the scale of decades, climate changes can result from the interaction between the atmosphere and the oceans and the way the oceans store heat. Oceans can store heat in a number of ways and heat can move between different reservoirs. On a longer time scale, ocean processes such as thermohaline circulation can have a great effect on climate Something to look up
• Greenhouse gases: Work to trap heat close to the Earth's surface. Have been implicated in severe warming in the past, including the Paleocene-Eocene thermal maximum, the Permian-Triassic extinction event, and the end of the Varangian snowball earth event, plus the current warming period. Look up after effects of each
• Plate tectonics: The moving of continents affects the ability of bodies of water to mix, altering climate. The Isthmus of Panama, which shut off direct mixing between the Atlantic and Pacific Oceans, is thought to have intensified the latest ice age.
• Volcanism: A single eruption can cause cooling for a period of a few years by throwing sediment into the air, blocking some of the sun's radiation from reaching the Earth's surface. Although most of the dust reaches the Earth's surface again within six months, the climate affects can last a few years. A huge eruption, the sort that occurs only a few times every hundred million years can drastically affect climate for long periods of time and cause mass extinctions. These eruptions are also a part of the long-term carbon cycle, releasing carbon from underground to make up for that lost to sedimentary rock. This effect is on such a large time scale that it is not worth paying attention to on a human time scale.
• Human Influences: Human influences on climate vary in how obvious and direct the relationship is, but there are a number of different influences to consider. The greatest concern is fossil fuel burning, which is blamed for a large amount of the increase in atmospheric CO2 concentrations from 280ppm as recently as the 1880s, to nearly 390ppm today Check exact number and update and which has also helped increase methane levels, another greenhouse gas. The second largest concern is aerosols, which cause a net cooling by blocking some sunlight from reaching the Earth's surface. The greatest concern is sulphate aerosols released by the burning of fossil fuels. While these would seem to cancel out the warming influence of greenhouse gases, the atmosphere is far more complex than this and in fact both of these have negative effects. Another concern is the amount of CO2 released when calcium carbonate is heated to produce lime for cement manufacture. Between this CO2 release, and the release from fossil fuel burning used to fuel the process, the cement industry accounts for 5% of global man-made CO2 emissions, amounting to approximately 900kg of CO2 released for every 1000kg of cement produced. Another thing that manipulates climates is land use changes including irrigation, deforestation, and agriculture, all of which disrupt the naturally occurring climate by altering key players such as ground cover, sunlight, and carbon sinks. Finally, livestock are capable of altering climate by producing greenhouse gases, especially methane, and by resulting in deforestation to produce grazing land. Livestock produces an estimated 18% of the world's greenhouse gases measured in CO2 equivalents.

In addition to all of the above direct effects on climate, it is important to remember that climate affects climate, and that not all factors interact in straightforward manners. Climates tend to cycle on their own due to a huge number of interplaying factors that have results on different time scales and which can magnify or diminish one another. It is estimated that all of what has currently been introduced to the climate system will result in a warming of about 0.5 °C (0.9 °F) even if everything were to return to 2000 levels immediately. Interactions tend to be referred to as positive or negative feedbacks, with positive feedbacks causing more of the same, and negative feedbacks limiting their own effects over time. For example, warming of the Earth can cause reductions in glaciation, which can reveal darker ground and less ice cover, allowing less sunlight to be reflected off the Earth's surface, which would in turn lead to more heating and further reductions in ice cover. The primary positive feedback involves water vapor, which is a greenhouse gas and increases its concentration in the atmosphere as warming occurs, leading to more warming. The largest negative feedback is the relationship between temperature and radiation, where radiation increases to the fourth power of an increase in temperature, so as the Earth's temperature increases, so will its thermal radiation. Below are a few more hypothesis of positive feedbacks on warming effects:

• Ocean ecosystems' abilities to sequester carbon are expected to decline as it warms because of lower nutrient levels resulting in less carbon-intensive life form growth.
• Methane stored in Arctic permafrost is being released at an alarming rate as the ice melts. One report suggests that an instantaneous introduction of about 11 times all the methane currently in the atmosphere is possible if a particular sheet of ice in the Siberian Arctic opens up. This would have an equivalent effect as doubling atmospheric CO2 concentrations.
• A similar concern is referred to as the Clathrate gun hypothesis, which states that methane clathrate stored in deep sea beds. It is theorized that warming of deep oceans will release methane from these deep ocean deposits and that this has already been responsible for two extinction events, the Permian-Triassic extinction event and the Paleocene-Eocene Thermal Maximum. Get more information on these events

Oftentimes, climate changes are discussed in terms of global averages, for example, the average surface area of the Earth has increased about 0.6° ± 0.2°C during the twentieth century and are projected to increase from 1.4 to 5.8 degrees by 2100, which may not seem like very much considering the daily fluctuations we typically see. However, global averages can be deceiving, as the difference between the global average temperature today and during the last Ice Age was only about 5 degrees C. This increase over the last 100 years has put the world at its highest temperature in the last 1000 years.

One of the key points made by the IPCC report is that the ultimate form climate change will take is not very predictable and will likely be different in different areas because of these complex interactions. There are a number of possible climate futures laid out in the IPCC report, but the fact that warming is occurring is not under debate, just how much of an effect that warming will have and what the effect will be.

Increases in atmospheric temperatures can change the way clouds form and dissipate, with warmer temperatures near the ground causing lower clouds to evaporate, letting heat rise farther into the atmosphere, forming higher clouds, which tend to absorb heat, as opposed to lower clouds, which tend to reflect light.

Another question mark is how oceans will change, because water temperatures affect seawater densities, which directly affect ocean currents. For example, the Gulf Stream, which warms Western Europe, relies on warm water current from the Gulf of Mexico moving towards Northwestern Europe. Changes in water temperature could disrupt ocean currents, slowing them or even shutting them down. There is the threat of global warming shutting down the Gulf Stream, creating a significant cooling in Northwestern Europe, resulting in a large negative feedback. In addition, changes in ocean currents could change the habitats of sea organisms and affect rainfall by altering the rate of evaporation of seawater.

There are also the compounding factors of plant growth. Photosynthesis is a carbon sink of about 60 billion tons every year, which is by far the strongest mechanism for carbon dioxide removal from the atmosphere. Increases in the level of CO2 in the atmosphere could promote plant growth, which would allow for more carbon being sequestered in plants.

Global Warming Skeptics

http://www.sciencedaily.com/articles/g/global_warming_controversy.htm (180) has a number of additional useful links about skeptics and the consensus regarding global climate change The conclusion that global warming is caused mainly by human activity and will continue if greenhouse gas emissions are not reduced has been endorsed by at least 30 scientific societies and academies of science, including all of the national academies of science of the major industrialized countries, and yet there has been a history of controversy over whether or not there is in fact a scientific consensus on this fact. A 2004 essay by Naomi Oreskes in Science reported a survey of 928 abstracts of peer-reviewed papers related to global climate change found no papers disagreeing with the consensus position. There have been complaints from both sides that there is political and cultural pressure to claim one position or the other or face a loss of funding and there have been claims that scientific journals are rejecting dissenting papers simply because they would question the consensus. There are still those out there, however, who agree with one or more of the following points:

• There is no conclusive evidence that climate change is happening
• The changes we are seeing in temperature are part of natural cycles
• The changes we are seeing are not necessarily caused by humans
• Even if the changes are human induced, the scale is not large enough to make changes
• The economic impact of making substantial cuts in greenhouse gas emissions on the scale suggested by the IPCC or other groups is too large.

One of the most high profile controversy's regarding global warming consensus is the Heartland Institute's list put out on April 29, 2008 that revealed \"500 Scientists with Documented Doubts of Man-Made Global Warming Scares\" that included at least 45 scientists who disagreed with its contents and wanted to be removed from the list, instead, however, the Heartland Institute revised the name of the list to claim that these people's research disagreed with the consensus and that the only reason why these people denied it was to help push through policies that would fund more climate research. In 1997, the \"World Scientists Call For Action\" petition was presented to the world leaders meeting to negotiate the Kyoto Protocol and declared that “A broad consensus among the world's climatologists is that there is now ‘a discernible human influence on global climate.’\" It urged governments to make “legally binding commitments to reduce industrial nations' emissions of heat-trapping gases”, and called global warming “one of the most serious threats to the planet and to future generations.” It was signed by more than 1,500 senior scientists, including the majority of Nobel laureates in science. However, Fred Singer's Science and Environmental Policy Project lists 4 petitions that claim to show that the number of scientists refuting global warming is growing:

• The 1992 \"Statement by Atmospheric Scientists on Greenhouse Warming\" was signed by 47 scientists and claims that assumptions of catastrophic global warming follows from the burning of fossil fuels are unsupported.
• The 1992 \"Heidelberg Appeal\" signed by over 4000 scientists including 72 Nobel Prize winners asks for policy based on \"scientific criteria and not on irrational preconceptions\" but does not mention climate change or any other specific issue.
• Singer has produced 2 \"Leipzig Declaration on Global Climate Change\" petitions, in 1995 and 1997, but most of the signatories lack credentials in climate research or even physical science in general, plus twelve of the signatories denied having signed the Declaration or had never heard of it.
• The \"Oregon Petition\" is a self-signed petition starting in 1998 and which was circulated again in late 2007 and presented in May 2008 with 31,000 claimed signatories, all of whom they claim are qualified scientists with \"technical training suitable for the evaluation of the relevant research data\", however, anyone with a degree was entitled to sign the list and the list only mentions \"catastrophic heating\" not the broader issue of global warming.

In April 2006, a group of sixty scientists signed an open letter to the Canadian Prime Minister to ask that he revisit the science of global warming, however, as with other petitions, critics point out that many of the signatories are not scientists, only 2 of the 60 actually indicated having current appointments in a university department or a recognized research institute in climate science. After the IPCC report was released, a joint statement issued by the Australian Academy of Sciences, Royal Flemish Academy of Belgium for Sciences and the Arts, Brazilian Academy of Sciences, Royal Society of Canada, Caribbean Academy of Sciences, Chinese Academy of Sciences, French Academy of Sciences, German Academy of Natural Scientists Leopoldina, Indian National Science Academy, Indonesian Academy of Sciences, Royal Irish Academy, Accademia Nazionale dei Lincei (Italy), Academy of Sciences Malaysia, Academy Council of the Royal Society of New Zealand, Royal Swedish Academy of Sciences, and Royal Society (UK) said: \"The work of the Intergovernmental Panel on Climate Change (IPCC) represents the consensus of the international scientific community on climate change science. We recognise IPCC as the world’s most reliable source of information on climate change and its causes, and we endorse its method of achieving this consensus. Despite increasing consensus on the science underpinning predictions of global climate change, doubts have been expressed recently about the need to mitigate the risks posed by global climate change. We do not consider such doubts justified.\" There are a number of other scientific academies and scientific organizations support the conclusions of the IPCC.

The following story is important to tell I think, but needs to be rewritten and researched In Naomi Oreskes's talk The American Denial of Global Warming,Oreskes recounted the following incident: “In 1995, the IPCC concluded that the human effect on climate is now discernible. The lead author of the key chapter on detection and attribution...was a scientist of the Lawrence Livermore National Laboratory named Benjamin J. Santer. When the IPCC report came out, Seitz, Nierenberg, and now a 4th physicist — a man by the name of S. Fred Singer — launched a highly personal attack on Santer. In an open letter to the IPCC, which they sent to numerous members of the US Congress, Singer, Seitz, and Nierenberg accused Santer of making \"unauthorized\" changes to the IPCC report [... They followed this with an op-ed piece in the Wall Street Journal entitled \"A Major Deception on Global Warming\". This piece was written by Seitz, in which he claimed that the effect of the alleged changes was \"to deceive policy makers and the public\". Now Santer replied, in a letter to the editor of the Wall Street Journal, and in the response he explained that he had made changes, but those changes were in response to the peer review process. In other words, totally normal scientific practice...This account was corroborated by the Chairman of the IPCC and by all of the other authors of the chapters. In fact, over 40 scientists were co-authors of this chapter. This letter was signed by Santer and 40 others and published in the Wall Street Journal in June 1996. And Santer was also formally defended by the American Meteorological Society. But neither Seitz nor Singer ever retracted the charges, which was then repeated — many times, over and over again — by industry groups and think-tanks. And in fact, if you google \"Ben Santer\", these same charges are still in the Internet today. In fact, one site said that it was proven in 1996 that Santer had fraudulently altered the IPCC report.\"

There have, however, been some disagreements with the IPCC reports. One primary concern has been that those writing the IPCC report are in climate research fields, which benefit with more research grants if there is a problem to be studied, so that they may be more alarmist, but these scientists are unfortunately the only ones qualified to speak in detail on these problems and so it is a conflict of interest that we won't see go away. There have also been complaints that some scientific data was left out and that some parts of the report were based on in-press data that are not widely reviewable. There have also been a couple of scientists who left the IPCC report process because they felt it had an agenda. The point has also been made that contributing authors and reviewers each have only a small influence, so that the entire report is not necessarily something that everybody who worked on it agrees with entirely. In addition to these critics, there are those that believe that the IPCC reports are too conservative because of the need to secure consensus among such a broad range of constituents including a number of governmental representatives. The complaint has also been made that the IPCC reports focus too much on the global effect of CO2 and doesn't address the multitude of ways humans are altering their local and global climates. There are some theories about the causes of global warming that put less blame on greenhouse gases. The first criticism of the attribution of global warming to greenhouse gases is that the tropospheric warming predicted by climate models is not verifiable due to large uncertainties from observational bias Give a description . There is also the argument that ice cores have shown carbon dioxide levels rise and fall with up to a 1000 year delay with respect to temperature variations. This claim argues that this climate change is the same as all climate change in the past, however this warming is believed to be due to anthropogenic releases of CO2 as opposed to historical climate change that is due to astronomical forcing. An analysis of carbon isotopes in atmospheric CO2 shows that recent observed CO2 increase cannot have come from oceans, volcanoes, or the biosphere and so is not likely to be subject to the same lags with temperature changes. Yet another argument against greenhouse gases causing warming is that while greenhouse gases were increasing from 1940 to 1970, global temperatures went down slightly, although this is likely due to the cooling effect of sulphate aerosols. Finally, Seth Young, a doctoral student in earth sciences at Ohio State found that the Earth had much higher CO2 levels during an ice age in the Ordovician period of the Paleozoic Era, however, a recent study suggests that this period began with a reduction in CO2. This serves as a reminder that one can not be as concerned about absolute values of something like CO2 concentrations, but the trends in these concentrations. Decide if we like this last sentence There are a number of alternative theories as to why global warming is occurring. One such theory is that an increase in solar activity either through directly heating up the Earth more or by affecting cloud formation. However, most scientists conclude that solar activity can explain only a small fraction, if any, of the changes in global temperature trends. Solar variation, combined with volcanic activity, probably caused some warming from pre-industrial times to 1950, but probably actually had a cooling effect since. There has been no significant link found between cosmic rays coming to Earth and cloudiness and temperature since 1985. There is also the theory that Internal Radiative Forcing has affected climate and has accounted for up to 70% of the warming trend we have seen. This theory is put forward by Roy Spencer. More on this The only way climate models have been able to simulate the temperature record of the past century is when greenhouse gas forcing is included, leading scientists to conclude that greenhouse gas forcing, largely the result of human activities, has very likely caused most of the observed global warming over the last 50 years. Some critics question the accuracy of the instrumental temperature record for a number of different reasons. The urban heat island effect is used by skeptics who claim that stations located in more populated areas could show warming due to increased heat generated by cities rather than a global temperature rise. The IPCC 3rd AR acknowledges the urban heat island as an important local effect but that the effect on global temperature is no more than 0.05°C through 1990. There has also been concern over the siting of a number of weather stations in the US. Despite all of these criticisms, there have been a number of skeptics who have changed their position on anthropogenic global warming. A list of them are found in. There is a reason for not being so critical of anthropogenic global warming, which is referred to as the precautionary principle. The principle is that even without certainty regarding global warming, it is worth acting on because the expected value of acting on it is greater than the expected value of inaction.

Controversies:

The Antarctic cooling controversy relates to the question of whether or not current temperature trends in Antarctica cast doubt on the theory of global warming, despite the fact that observations show the Peninsula to be warming. The trends elsewhere in the continent do show both warming and cooling, but are smaller and dependent on season and timespan. Even those whose research is used to support the idea that Antarctica is cooling refute the idea. There has been some controversy over the funding sources of those who do not acknowledge anthropogenic global warming. Several skeptical scientists have been linked to ExxonMobil and Philip Morris for the purpose of promoting global warming skepticism. There are a number of groups employing global warming skeptics that have been criticized for their ties to fossil fuel companies. The Union of Concerned Scientists have produced a report titled \"Smoke, Mirrors, and Hot Air\" that criticizes ExxonMobil for \"underwriting the most sophisticated and most successful disinformation campaign since the tobacco industry.\" At the same time, there has been controversy over the funding of global warming research, with critics claiming that funding goes preferentially to those who support the prevailing theory. There has been a lot of controversy regarding the political pressure put on scientists to alter their findings. A survey of climate scientists which was reported to the US House Oversight and Government Reform Committee noted that \"nearly half of all respondents perceived or personally experienced pressure to eliminate the words 'climate change', 'global warming', or other similar terms from a variety of communications.\" A report by NASA's Office of the Inspector General showed that NASA officials censored and suppressed data on global warming. US officials have repeatedly edited scientific reports from government scientists to refrain from discussing climate change. There have been opposite accusations as well, especially more recently. Officials who doubt the certainty of human influence on climate or who doubt its severity are being criticized. Another source of controversy over global warming has been with regards to litigation over global warming. The largest, and most successful, case was Massachusetts v. Environmental Protection Agency, which forced the government to regulate greenhouse gases as air pollutants under the Clean Air Act. A couple of notable failed cases were California v. General Motors Corp., which tried to force car manufacturers to reduce vehicles' emissions of CO2 and Comer v. Murphy Oil USA, Inc., which was an effort to force fossil fuel and chemical companies to pay for damages caused by global warming.