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#41 Rogerdodger

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Posted 30 January 2007 - 10:00 PM

I wonder how long before these authors go on trial for blasphemy?


Two New Books Confirm Global Warming is Natural; Not Caused By Human Activity
Tue Jan 30 2007 10:02:32 ET

Two powerful new books say today’s global warming is due not to human activity but primarily to a long, moderate solar-linked cycle. Unstoppable Global Warming Every 1500 Years, by physicist Fred Singer and economist Dennis Avery was released just before Christmas. The Chilling Stars: A New Theory of Climate Change, by Danish physicist Henrik Svensmark and former BBC science writer Nigel Calder (Icon Books), is due out in March.

Singer and Avery note that most of the earth’s recent warming occurred before 1940, and thus before much human-emitted CO2. Moreover, physical evidence shows 600 moderate warmings in the earth’s last million years. The evidence ranges from ancient Nile flood records, Chinese court documents and Roman wine grapes to modern spectral analysis of polar ice cores, deep seabed sediments, and layered cave stalagmites.

Unstoppable Global Warming shows the earth’s temperatures following variations in solar intensity through centuries of sunspot records, and finds cycles of sun-linked isotopes in ice and tree rings. The book cites the work of Svensmark, who says cosmic rays vary the earth’s temperatures by creating more or fewer of the low, wet clouds that cool the earth. It notes that global climate models can’t accurately register cloud effects.

The Chilling Stars relates how Svensmark’s team mimicked the chemistry of earth’s atmosphere, by putting realistic mixtures of atmospheric gases into a large reaction chamber, with ultraviolet light as a stand-in for the sun. When they turned on the UV, microscopic droplets—cloud seeds—started floating through the chamber.

“We were amazed by the speed and efficiency with which the electrons [generated by cosmic rays] do their work of creating the building blocks for the cloud condensation nuclei,” says Svensmark.

The Chilling Stars documents how cosmic rays amplify small changes in the sun’s irradiance fourfold, creating 1-2 degree C cycles in earth’s temperatures: Cosmic rays continually slam into the earth’s atmosphere from outer space, creating ion clusters that become seeds for small droplets of water and sulfuric acid. The droplets then form the low, wet clouds that reflect solar energy back into space. When the sun is more active, it shields the earth from some of the rays, clouds wane, and the planet warms.

Unstoppable Global Warming documents the reality of a moderate, natural, 1500-year climate cycle on the earth. The Chilling Stars explains the why and how.


#42 grizzly

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Posted 17 February 2007 - 08:05 PM

FYI -from EPA's Climate Change Website, http://www.epa.gov/c...nce/pastcc.html

Known causes or “drivers” of past climate change include:

Changes in the Earth's orbit: Changes in the shape of the Earth's orbit (or eccentricity) as well as the Earth's tilt and precession affect the amount of sunlight received on the Earth's surface. These orbital processes -- which function in cycles of 100,000 (eccentricity), 41,000 (tilt), and 19,000 to 23,000 (precession) years -- are thought to be the most significant drivers of ice ages according to the theory of Mulitin Milankovitch, a Serbian mathematician (1879-1958). The National Aeronautics and Space Administration's (NASA) Earth Observatory offers additional information about orbital variations and the Milankovitch Theory.

Changes in the sun's intensity: Changes occurring within (or inside) the sun can affect the intensity of the sunlight that reaches the Earth's surface. The intensity of the sunlight can cause either warming (for stronger solar intensity) or cooling (for weaker solar intensity). According to NASA research, reduced solar activity from the 1400s to the 1700s was likely a key factor in the “Little Ice Age” which resulted in a slight cooling of North America, Europe and probably other areas around the globe. (See additional discussion under The Last 2,000 Years.)

Volcanic eruptions: Volcanoes can affect the climate because they can emit aerosols and carbon dioxide into the atmosphere. Aerosol emissions: Volcanic aerosols tend to block sunlight and contribute to short term cooling. Aerosols do not produce long-term change because they leave the atmosphere not long after they are emitted. According to the United States Geological Survey (USGS), the eruption of the Tambora Volcano in Indonesia in 1815 lowered global temperatures by as much as 5ºF and historical accounts in New England describe 1815 as “the year without a summer.”

Carbon dioxide emissions: Volcanoes also emit carbon dioxide (CO2), a greenhouse gas, which has a warming effect. For about two-thirds of the last 400 million years, geologic evidence suggests CO2 levels and temperatures were considerably higher than present. One theory is that volcanic eruptions from rapid sea floor spreading elevated CO2 concentrations, enhancing the greenhouse effect and raising temperatures. However, the evidence for this theory is not conclusive and there are alternative explanations for historic CO2 levels (NRC, 2005). While volcanoes may have raised pre-historic CO2 levels and temperatures, according to the USGS Volcano Hazards Program, human activities now emit 150 times as much CO2 as volcanoes (whose emissions are relatively modest compared to some earlier times).
These climate change “drivers” often trigger additional changes or “feedbacks” within the climate system that can amplify or dampen the climate's initial response to them (whether the response is warming or cooling). For example:

Changes in greenhouse gas concentrations: The heating or cooling of the Earth's surface can cause changes in greenhouse gas concentrations. For example, when global temperatures become warmer, carbon dioxide is released from the oceans. When changes in the Earth's orbit trigger a warm (or interglacial) period, increasing concentrations of carbon dioxide may amplify the warming by enhancing the greenhouse effect. When temperatures become cooler, CO2 enters the ocean and contributes to additional cooling. During at least the last 420,000 years, CO2 levels have tended to track the glacial cycles (IPCC, 2001). That is, during warm interglacial periods, CO2 levels have been high and during cool glacial periods, CO2 levels have been low (see Figure 1).

Figure 1: Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400,000 years as inferred from Antarctic ice-core records. The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006. From A. V. Fedorov et al. Science 312, 1485 (2006). . Reprinted with permission of AAAS* .


Changes in ocean currents: The heating or cooling of the Earth's surface can cause changes in ocean currents. Because ocean currents play a significant role in distributing heat around the Earth, changes in these currents can bring about significant changes in climate from region to region.


Rates of Change
Studies of the Earth's previous climate suggest periods of stability as well as periods of rapid change. Recent climate research suggests:

Interglacial climates (such as the present) tend to be more stable than cooler, glacial climates. For example, the climate during the current and previous interglacials (known as the Holocene and Eemian interglacials) has been more stable than the most recent glacial period (known as the Last Glacial Maximum). This glacial period was characterized by a long string of widespread, large and abrupt climate changes (NRC, 2002).
Abrupt or rapid climate changes tend to frequently accompany transitions between glacial and interglacial periods (and vice versa). For example, a significant part of the Northern Hemisphere (particularly around Greenland) may have experienced warming rates as large as 16ºF in 50 years at the end of the Younger Dryas event 11,500 years ago as the planet was emerging from the last ice age (IPCC, 2001).
While abrupt climate changes have occurred throughout the Earth's history, human civilization arose during a period of relative climate stability.



The Last 2,000 Years
During the last 2,000 years, the climate has been relatively stable. Scientists have identified two minor departures from this stability, known as the Medieval Climate Anomaly (also referred to as the Medieval Warm Period) and the Little Ice Age:

The Medieval Climate Anomaly: Between roughly 900 and 1300 AD, evidence suggests Europe, Greenland and Asia experienced relative warmth. While historical accounts and other evidence document the warmth that occurred in some regions, the geographical extent, magnitude and timing of the warmth during this period is uncertain (NRC, 2006). The American West experienced very dry conditions around this time.

The Little Ice Age: A wide variety of evidence supports the global existence of a "Little Ice Age" (this was not a true "ice age" since major ice sheets did not develop) between about 1500 and 1850 (NRC, 2006). Average temperatures were possibly up to 2ºF colder than today, but varied by region.
Together, these two periods define the upper and lower boundaries of the climate's recent natural variability and are a reflection of changes in climate drivers (the sun's variability and volcanic activity) and the climate's internal variability (referring to random changes in the circulation of the atmosphere and oceans). The issue of whether the temperature rise of the 20th century crossed over the warm limit of the boundary has been a controversial topic in the science community. The National Academy of Sciences recently completed a study to assess the efforts to reconstruct temperatures of the past one to two millennia (see Figure 2) and place the Earth's current warming in historical context (NRC, 2006).


Figure 2: Reconstructions of (Northern Hemisphere average or global average) surface temperature variations from six research teams (in different color shades) along with the instrumental record of global average surface temperature (in black). Each curve illustrates a somewhat different history of temperature changes, with a range of uncertainties that tend to increase backward in time (as indicated by the shading). Reference: NRC, 2006. (Figure reprinted with permission from Surface Temperature Reconstructions© (2006) by the National Academy of Sciences, Courtesy of the National Academies Press , Washington, D.C.)


According to the study (NRC, 2006):

There is a high level of confidence that the global average temperature during the last few decades was warmer than any comparable period during the last 400 years.
Present evidence suggests that temperatures at many, but not all, individual locations were higher during the past 25 years than any period of comparable length since A.D. 900. However, uncertainties associated with this statement increase substantially backward in time.
Very little confidence can be assigned to estimates of hemisphere average or global average temperature prior to A.D. 900 due to limited data coverage and challenges in analyzing older data.


References
IPCC, 2001: Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change [Houghton, J.T., Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden, X. Dai, K. Maskell, and C.A. Johnson (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 881pp.
National Research Council (NRC), 2002: Abrupt Climate Change, Inevitable Surprises. National Academy Press, Washington, DC. National Academy Press, Washington, DC
National Research Council (NRC), 2005: Radiative Forcing of Climate Change. National Academy Press, Washington, DC. National Academy Press, Washington, DC
National Research Council (NRC), 2006. Surface Temperature Reconstructions For the Last 2,000 Years. National Academy Press, Washington, DC.