Articles Tagged "Doug L. Hoffman"

Difference in winter surface climate for solar minimum minus solar maximum.

The impact of solar irradiance variations on Earth’s surface climate has been debated by many in the past. Based on correlations between solar variability and meteorological changes, the Sun-climate link seems obvious but, as is often stated, correlation does not prove causation. Previously, any link was disputed because the amount of energy delivered by the Sun was deemed too small to have a significant impact. New satellite measurements indicate that variations in solar ultraviolet irradiance may be larger than previously thought, forcing a reevaluation of the impact of solar variation. A recent report in the journal Nature Geoscience claims to show just that—a link between the 11 year solar cycle and Northern Hemisphere winters.

Using older measurements of solar variability over the 11 year solar cycle as input, climate models have proven incapable of establishing linkage between insolation and climate. Still, there have been tantalizing reports of such linkage in the past (see “The Sun's Hidden Power”). In a report in the August 28, 2009, issue of the journal Science entitled “Amplifying the Pacific Climate System Response to a Small 11-Year Solar Cycle Forcing,” Gerald A. Meehl et al. described a possible mechanism that could explain how seemingly small changes in solar output can have a big impact on Earth's climate. Their work explained how the upper atmosphere can act as a solar heat amplifier when UV radiation from the Sun increases.

Now, new, more accurate measurements taken by satellites have revised the amount of variability in insolation, particularly in the ultraviolet frequencies. In “Solar forcing of winter climate variability in the Northern Hemisphere,” Sarah Ineson et al. have applied these new data to a revised climate model and report positive linkage between insolation variability and climate. The researchers explain the importance of the new satellite data.

No phenomenon in astronomy has been studied more closely than solar flares, gigantic eruptions on the Sun that can affect Earth's climate and even disrupt power grids. Scientists have been watching the Sun with ground based instruments and orbiting satellites for years, so it might be thought that we know a lot about such eruptions. Well think again. A new report from NASA has revealed that, like earthquakes, solar flares often have aftershocks. Moreover, the aftershocks can emit bursts of ultraviolet (UV) radiation more powerful than the original eruption. Combine this new finding with the recently uncovered linkage between fluctuating UV levels and El Niño, and the Sun-Climate connection looks stronger than ever.

In a report, published in The Astrophysical Journal, NASA scientists are reporting that solar flares generate considerably more energy than previously suspected. About 1 flare in 7 experiences an “aftershock” around ninety minutes after the flare dies down. “We call it the ‘late phase flare,’” says Thomas N. Woods, a physicists at the University of Colorado and lead author. “The energy in the late phase can exceed the energy of the primary flare by as much as a factor of four.” The major findings are detailed in the article's abstract below:

Much fanfare was associated with the reappearance of sunspots earlier this year, marking the beginning of a new period of high solar activity. Now come a number of reports saying the Sun is most likely headed for a prolonged period of low activity, possibly rivaling the Maunder minimum. Three independent studies of the Sun's dynamics all predict that the next solar cycle will be significantly delayed and might even be skipped. The Maunder minimum is associated with a prolonged period of climate cooling known as the Little Ice Age. Whether Earth's climate is headed for a significant cooling trend has become a matter of heated debate, while at the same time NASA is warning that a quite Sun can also be a deadly Sun. In the 1850s, following a period of low sunspot activity, the largest coronal ejection event ever witnessed caused havoc with telegraphs and ship's compasses around the world. Such an ejection today could cause widespread power outages and failure of electronic equipment. Will our star turn both quiet and deadly?

Sunspots are relatively cool, dark blemishes on the Sun's surface that indicate regions of intense magnetic activity. Some sunspots are gigantic, often wider than Earth with magnetic fields reaching far into space. For centuries scientists have been using sunspots to gauge solar activity, discovering that visible activity waxes and wains in a regular 11 year cycle. After an unusually quiet period we are now in Solar Cycle 24, which should peak sometime in 2013. But it is what solar scientists are predicting to come after SC 24 that is causing concern among climate scientists.

Newly reported solar observations, including fading sunspots and weakening magnetic activity near the poles, could be indications that the Sun could be less active in the coming years. Three independent studies by solar experts all predict that the next solar cycle may not happen, or at least be significantly delayed. Astrogeophysicist Frank Hill and colleagues at the National Solar Observatory, have been monitoring solar cycles using a technique called helioseismology. Hill was the lead author on the first of three papers on these results presented at the American Astronomical Society conference in New Mexico. Using data from the Global Oscillation Network Group (GONG) of six observing stations around the world, the team translates surface pulsations caused by sound reverberating through the Sun into models of its internal structure.

Beginning in 2008, sunspots almost completely disappeared for two years. Solar activity dropped to hundred-year lows and the Sun’s magnetic field weakened, allowing cosmic rays to penetrate the Solar System in record numbers. More troubling, Earth's upper atmosphere cooled and collapsed by an unprecedented amount. Solar physicists openly wondered what was happening to our neighborhood star. Now, an international team of scientists funded by NASA claims to have figured out what was going on. Their explanation was just published in the March 3, 2011, edition of Nature.

The almost complete absence of sunspots during the last prolonged solar minimum has been a puzzlement to scientists around the world. There has been much speculation regarding the link between solar activity, sunspots and Earth's climate. From historical records, scientists have found a strong correlation between low sunspot activity and a cooling climate. Now a new paper, “The unusual minimum of sunspot cycle 23 caused by meridional plasma flow,” reveals that science may be closer to being able to accuratly predict solar cycles.

Since the Mid-Brunhes Event, around 430,000 years ago, interglacial periods have grown warmer and their CO2 levels higher. Research confirms that Croll and Milankovitch were right: Earth's orbital cycles seem to be the cause of these documented cases of true global warming, with CO2 playing a supporting role, not the lead. Many of the catastrophic events warned of by climate change alarmists turn out to be well within the range of natural variation. Moreover, new findings indicate that the effects of the cycle induced changes, through their impact on the environment in the Southern Hemisphere, are not correctly accounted for in the IPCC models.

One of the big questions in climate science comes from studying recent interglacial periods—those relatively warm periods between bouts of ice age glaciation. It has been known for some time, that average temperatures during recent interglacials were warmer than during older ones. Writing in the April, 2010, edition of Nature Geoscience, Q. Z. Yin and A. Berger propose an answer as to why the amplitude (i.e. warming) of the glacial interglacial cycles increased significantly after the Mid-Brunhes Event (MBE) with cooler interglacials before the MBE than after. In their paper, entitled “Insolation and CO2 contribution to the interglacial climate before and after the Mid-Brunhes Event,” they describe their work as follows:

In parallel to the reconstruction of palaeoclimate based on proxy records, climate models are used to better understand past climate behaviour. In particular, efforts have been made over the past decade on modelling the most recent interglacials, namely the Holocene, the Eemian and the past five interglacials. Here, we focus on the forcing and global response of the climate system at the interglacial peaks of the past 800 kyr, using snapshot simulations to try to understand the difference between the post-MBE and the pre-MBE interglacials. The model used is LOVECLIM, with the atmosphere, ocean, sea ice and vegetation components interactively coupled and the ice sheets kept as today.

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Asking the somewhat obvious question, “are cold winters in Europe associated with low solar activity?” a group of scientists have announced that the answer is yes. While this may seem unsurprising, the finding is another indication that Earth's climate is not simply driven by greenhouse gas emissions. Even so, some scientists are only grudgingly accepting the finding, cautioning that this only applies in the central UK and refusing to admit that the Sun could affect global mean temperatures as well. Still, the researchers found that average solar activity has declined rapidly since 1985 and cosmogenic isotopes suggest a possible return to Maunder minimum conditions within the next 50 years. This could be a sign that climate science is starting to recover from its CO2 fixation.

Writing in Environmental Research Letters, Mike Lockwood et al. have verified that solar activity does seem to have a direct correlation with Earth's climate—at least in the central UK. The reason that the scope of the study is limited to that area, or at most Europe, is that it is one of the few regions that there is a reliable, continuous temperature record going back to the Little Ice Age. The authors explain their work:

Lower winter temperatures were common in Europe during the second half of the 17th century, famously allowing frost fairs to be held on the Thames in London before riverine developments increased the flow rate. These cold winters coincided with the Maunder minimum in solar activity when the Sun remained virtually free of sunspots for almost 50 years. However, establishing that this was not just a chance occurrence requires that the relationship continue to hold over a long interval, such that cold European winters become less frequent when solar activity is high and then more common again when solar activity falls. Various indicators show that during the recent minimum of the 11 year sunspot cycle, the Sun has been quieter than at any time in the previous 90 years. This yields an opportunity for a better test of the relationship between solar activity and cold European winters. To do this, we require two long and homogeneous time series: one which quantifies solar outputs relevant to seasonal/regional climate and the other relevant to European winter temperatures. We here use the Central England temperature (CET) data set which is the world's longest instrumental record of temperature and extends back to 1659, at the start of the Maunder minimum.

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For decades, the supporters of CO2 driven global warming have discounted changes in solar irradiance as far too small to cause significant climate change. Though the Sun's output varies by less than a tenth of a percent in magnitude during its 11-year sunspot cycle, that small variation produces changes in sea surface temperatures two or three times as large as it should. A new study in Science demonstrates how two previously known mechanisms acting together amplify the Sun's impact in an unsuspected way. Not surprisingly, the new discovery is getting a cool reception from the CO2 climate change clique.

Scientists have long suspected that changes in solar output may have triggered the Little Ice Age that gripped Europe several centuries ago, as well as droughts that brought down Chinese dynasties. Now, in a report in the August 28 issue of the journal Science entitled “Amplifying the Pacific Climate System Response to a Small 11-Year Solar Cycle Forcing,” Gerald A. Meehl et al. have demonstrated a possible mechanism that could explain how seemingly small changes in solar output can have a big impact on Earth's climate. The researchers claim that two different parts of the atmosphere act in concert to amplify the effects of even minuscule solar fluctuations.

Increased insolation 20,000 years ago caused deglaciation in the Norther Hemisphere, according to a new report in the August 7, 2009, edition of Science. Further more, it was the onset of deglaciation of the West Antarctic Ice Sheet, which occurred between 14 - 15 thousand years ago, that was the source of sea-level rise at the beginning of the Holocene warming. Such events are often associated with rising CO2 levels by climate catastrophists but the evidence says otherwise.

The Last Glacial Maximum (LGM) is typically defined as the most recent interval in Earth history when global ice sheets reached their maximum volume. This is conventionally calculated from sea-level records but, according to Peter U. Clark et al. this is an overly simplistic approach. Sea-level records do not distinguish between globally synchronous ice-sheet maxima and temporary regional ice-sheet maxima that can combine to produce apparent sea-level low points that can last for a thousand years or more. In their report the author's describe their improved approach as follows:

The lingering cool temperatures being experience by much of North America has weather forecasters wondering it we are entering a new Little Ice Age—a reference to the prolonged period of cold weather that afflicted the world for centuries and didn't end until just prior to the American Civil War. From historical records, scientists have found a strong correlation between low sunspot activity and a cooling climate. At the end of May, an international panel of experts led by NOAA and sponsored by NASA released a new prediction for the next solar cycle: Solar Cycle 24 will be one of the weakest in recent memory. Are we about to start a new Little Ice Age?

According to the report, Solar Cycle 24 will peak in May 2013 with a sunspot count well below average. “If our prediction is correct, Solar Cycle 24 will have a peak sunspot number of 90, the lowest of any cycle since 1928 when Solar Cycle 16 peaked at 78,” says panel chairman Doug Biesecker of the NOAA Space Weather Prediction Center. This does not mean that we won't feel the results of renewed solar storm activity here on Earth.