jmog wrote:
FYI Derek, temperature data alone just shows the situation at hand, it does NOT prove what causes it.
I know you have little scientific knowledge and just like to use wikipedia graphs as your proof, but look up some actual science behind this stuff, what affects our global climate, and then come back to me.
lol...right.
http://www.gcrio.org/CONSEQUENCES/winter96/sunclimate.html
In the latter part of the 19th century, there were many claims of new-found connections between sunspots and climate. It began with the announcement by the amateur astronomer Heinrich Schwabe, in 1843, that sunspots come and go in an apparently regular eleven-year cycle. What followed was a flood of reported correlations, not only with local and regional weather but with crop yields, human health, and economic trends. These purported connections-- that frequently broke down under closer statistical scrutiny--lacked the buttress of physical explanation and were in time forgotten or abandoned.
After more than a century of controversy, the debate as to whether solar variability has any significant effect on the climate of the Earth remains to be settled, one way or the other. This long unanswered question has of late emerged anew, and with some urgency--in the context of widespread concerns of impending global greenhouse warming. For in order to gauge the possible impacts of anthropogenic greenhouse gases on the present or future climate, we must first know the natural variations on which our own activities are imposed.
The Sun and Climate
by Judith Lean and David Rind
Of the many objects in the universe, only two are essential for life as we know it: the Earth itself, and the Sun: the star around which it circles, year after year. Burning steadily in stable, middle age, the Sun--now about five billion years old--provides an unfailing source of light and energy. The Sun's heat is so intense that at a distance of 93 million miles it warms the surface of the otherwise cold and lifeless Earth some 250°Centigrade, to -18°C (0°Fahrenheit). Thus warmed, the solid Earth releases a portion of its heat in the form of infrared radiation, which is trapped by atmospheric greenhouse gases, further raising the surface temperature to a more comfortable 15°C (59°F). In this way, the Sun's radiation and the Earth's blanket of greenhouse gases sustain the mean global temperature at a level supportive of life. Sunlight also powers photosynthesis, and provides energy for the atmospheric and oceanic circulations that profoundly affect all living things.
Like other stars of similar age, size, and composition, the Sun shows many signs of variability. Most pronounced and by far the most familiar is a cycle of about eleven years in the number of dark spots on its glowing surface (Fig. 1). But although the Sun is known to be a variable star, its total output of radiation is often assumed to be so stable that we can neglect any possible impacts on climate. Testimony to this assumption is the term that has been employed for more than a century to describe the radiation in all wavelengths received from the Sun: the so-called "solar constant," whose value at the mean Sun-Earth distance is a little over 1 1/3 kilowatts per square meter of surface.
In truth, the solar "constant" varies. Historical attempts to detect possible changes from the ground were thwarted by variable absorption in the air overhead. Measurements from spacecraft avoid this problem, and the most precise of these, made continuously since 1979 (Fig. 2a, b), have revealed changes on all time scales--from minutes to decades--including a pronounced cycle of roughly eleven years. Sunspots and other forms of solar activity are produced by magnetic fields, whose changes also affect the radiation that the Sun emits, including its distribution among shorter and longer wavelengths. The most highly variable parts of the Sun's spectrum of radiation are found at the very shortest wavelengths--the ultraviolet (UV) and X-ray region--and in the very longest and far less energetic band of radio waves.
New insights into the variable nature of the Sun have almost always been followed by efforts to find possible impacts on the Earth--chiefly through comparisons with weather and climate records. Initially the quest was not so much a detached inquiry as a determined effort to demonstrate a long-sought hope: that keys found in the cyclic nature of solar behavior might open the doors of down-to-Earth predictions.
In the latter part of the 19th century, there were many claims of new-found connections between sunspots and climate. It began with the announcement by the amateur astronomer Heinrich Schwabe, in 1843, that sunspots come and go in an apparently regular eleven-year cycle. What followed was a flood of reported correlations, not only with local and regional weather but with crop yields, human health, and economic trends. These purported connections-- that frequently broke down under closer statistical scrutiny--lacked the buttress of physical explanation and were in time forgotten or abandoned.
After more than a century of controversy, the debate as to whether solar variability has any significant effect on the climate of the Earth remains to be settled, one way or the other. This long unanswered question has of late emerged anew, and with some urgency--in the context of widespread concerns of impending global greenhouse warming. For in order to gauge the possible impacts of anthropogenic greenhouse gases on the present or future climate, we must first know the natural variations on which our own activities are imposed.
THE MANY CAUSES OF CLIMATIC CHANGE
Between 1850 and 1990 the global-mean temperature at the surface of the Earth warmed by approximately 0.5°C (about 1°F). During the same period, the amount of carbon dioxide measured in the Earth's atmosphere increased by about 25 percent, as a consequence of our ever- increasing use of fossil fuels (Fig. 3c). This raises the possibility that the two trends are directly connected, and that the century-long warming is a long- anticipated sign of the climate system's response to human activities.
Still, more factors were obviously perturbing the climate system than the lone hand of greenhouse gases. The global-mean temperature did not rise steadily: statistical analyses of the temperature record since 1850 reveal significant year-to-year and decade-to-decade variability. Moreover, what is known of the longer climatic record suggests that surface temperatures may have been systematically increasing since the late 17th century (Figure 3d), well before the onset of the Industrial Revolution, when greenhouse gas concentrations first began their upward climb.
Other natural perturbations, which have also varied during the past few centuries, might help explain the difference between the change expected from a simple increase in greenhouse gases and what has been observed.
Like the concentrations of greenhouse gases, solar activity has risen systematically through the past 100 years, as recorded in the number of sunspots (Fig. 1). An upward trend is also found in the number of solid particles, or aerosols, in the lower atmosphere. The burning of fossil fuels that has led to an increase in greenhouse gases has introduced as well an ever-increasing load of sulfur-bearing or sulfate aerosols, which also affect the temperature at the surface of the Earth. In contrast, the aerosols ejected into the atmosphere by volcanic eruptions decreased markedly during most of the twentieth century, compared to conditions in the century preceding (Fig. 3b), as a result of a presumably random drop in the long-term average of volcanic activity. Other potential causes of climate change include the depletion of stratospheric ozone in recent decades, again through human activities, and global changes in the surface reflectivity--or albedo--of the planet, as we modify the patterns of vegetation that cover the land. In conjunction with possible internal system changes such as variations in ocean circulation, these influences define the most likely causes of climatic change in the recent era.
Different influences on climate affect the system in ways that in principle can be distinguished on the basis of geography, altitude, and time history. More often, however, the impacts of multiple influences are mixed together, and further confused by imperfect knowledge of how each of them has changed, and uncertainties in how climate itself has varied.
In global average, increases in greenhouse gas concentrations or in solar radiation bring warmer surface temperatures since they add energy to the climate system. In contrast, increased industrial and volcanic aerosols restrict the penetration of solar radiation to the Earth's surface and lead to surface cooling. A drop in the concentration of ozone in the lower stratosphere should also produce a net cooling at the surface. Changes in albedo that increase the planet's reflectivity will lead to cooling, and those that make it less reflective and more absorbing, to a temperature rise.
