Some researchers believe that the solar cycle influences global climate changes. They attribute recent warming trends to cyclic variation. Skeptics, though, argue that there's little hard evidence of a solar hand in recent climate changes.
Now, a new research report from a surprising source may help to lay this skepticism to rest. A study from NASA’s Goddard Space Flight Center in Greenbelt, Maryland looking at climate data over the past century has concluded that solar variation has made a significant impact on the Earth's climate. The report concludes that evidence for climate changes based on solar radiation can be traced back as far as the Industrial Revolution.
Past research has shown that the sun goes through eleven year cycles. At the cycle's peak, solar activity occurring near sunspots is particularly intense, basking the Earth in solar heat. According to Robert Cahalan, a climatologist at the Goddard Space Flight Center, "Right now, we are in between major ice ages, in a period that has been called the Holocene."
Thomas Woods, solar scientist at the University of Colorado in Boulder concludes, "The fluctuations in the solar cycle impacts Earth's global temperature by about 0.1 degree Celsius, slightly hotter during solar maximum and cooler during solar minimum. The sun is currently at its minimum, and the next solar maximum is expected in 2012."
According to the study, during periods of solar quiet, 1,361 watts per square meter of solar energy reaches Earth's outermost atmosphere. Periods of more intense activity brought 1.4 watts per square meter (0.1 percent) more energy.
While the NASA study acknowledged the sun's influence on warming and cooling patterns, it then went badly off the tracks. Ignoring its own evidence, it returned to an argument that man had replaced the sun as the cause current warming patterns. Like many studies, this conclusion was based less on hard data and more on questionable correlations and inaccurate modeling techniques.
The inconvertible fact, here is that even NASA's own study acknowledges that solar variation has caused climate change in the past. And even the study's members, mostly ardent supports of AGW theory, acknowledge that the sun may play a significant role in future climate changes.
quote: Earth's climate depends on the delicate balance between incoming solar radiation, outgoing thermal radiation and the composition of Earth's atmosphere. Even small changes in these parameters can affect climate. Around 30 percent of the solar energy that strikes Earth is reflected back into space. Clouds, atmospheric aerosols, snow, ice, sand, ocean surface and even rooftops play a role in deflecting the incoming rays. The remaining 70 percent of solar energy is absorbed by land, ocean, and atmosphere. "Greenhouse gases block about 40 percent of outgoing thermal radiation that emanates from Earth," Woods said. The resulting imbalance between incoming solar radiation and outgoing thermal radiation will likely cause Earth to heat up over the next century, accelerating the melting polar ice caps, causing sea levels to rise and increasing the probability of more violent global weather patterns.
quote: Non-Human Influences on Climate Change Before the Industrial Age, the sun and volcanic eruptions were the major influences on Earth's climate change. Earth warmed and cooled in cycles. Major cool periods were ice ages, with the most recent ending about 11,000 years ago. "Right now, we are in between major ice ages, in a period that has been called the Holocene,” said Cahalan. “Over recent decades, however, we have moved into a human-dominated climate that some have termed the Anthropocene. The major change in Earth's climate is now really dominated by human activity, which has never happened before." The sun is relatively calm compared to other stars. "We don't know what the sun is going to do a hundred years from now," said Doug Rabin, a solar physicist at Goddard. "It could be considerably more active and therefore have more influence on Earth's climate." Or, it could be calmer, creating a cooler climate on Earth similar to what happened in the late 17th century. Almost no sunspots were observed on the sun's surface during the period from 1650 to 1715. This extended absence of solar activity may have been partly responsible for the Little Ice Age in Europe and may reflect cyclic or irregular changes in the sun's output over hundreds of years. During this period, winters in Europe were longer and colder by about 1 C than they are today. Since then, there seems to have been on average a slow increase in solar activity. Unless we find a way to reduce the amount of greenhouse gases we put into the atmosphere, such as carbon dioxide from fossil fuel burning, the solar influence is not expected to dominate climate change. But the solar variations are expected to continue to modulate both warming and cooling trends at the level of 0.1 to 0.2 degrees Celsius (0.18 to 0.26 Fahrenheit) over many years.