Scientists have long suspected that the orbital cycles of our planet are responsible for the periodic climate variation that causes alternating glacial and interglacial periods. Milankovitch's theory of orbital cycles suggests that summer insolation at high northern latitudes drives the glacial cycles. Moreover, statistical analyses have demonstrated that the glacial cycles are indeed linked to eccentricity, obliquity and precession. Now, researchers have confirmed that a combination of two of the Milankovitch cycles conspire to start and stop ice ages. The 100,000-year eccentricity cycle amplifies the influence of the 23,000-year wobble of Earth's spin axis called precession. The new modeling also suggests that the great accumulation of mass by the North American ice sheet causes the abrupt end of glacial periods. CO2 is involved, but is not determinative, in the evolution of the 100,000-year glacial cycles say the scientists.
For some reason a lot of people have become fixated on Antarctic ice—is it waxing or waning, accumulating or melting. Climate alarmists have striven mightily to show that ice at the poles in on the decline, melting in the face of rising global temperatures. Antarctica, with the largest store of glacial ice on the planet, is the primary focus of attention. If Antarctica’s ice sheets were to melt it would be a calamity for mankind. Unfortunately, Earth's climate system contains many cyclic trends, operating on decadal and longer periods of time. In the past, what some claim are clear trends have turned out to be only short term in nature. A new report, just published online, concludes that it is unclear if changes in atmospheric circulation over West Antarctica during the past few decades are part of a longer-term trend. In fact, ice cores reveal a significant increase in the oxygen isotopes from precipitation over the past 50 years, but the anomaly cannot be distinguished from natural climate variability.
A newly released study from the Research Council of Norway has climate change alarmists abuzz. One of the things the alarmists have been pushing for is to halt warming at a 2°C increase at any cost (and they mean that literally). In the Norwegian study, much to the alarmists' dismay, researchers have arrived at an estimate of 1.9°C as the most likely level of future warming. The report also recognizes that temperatures have stabilized at 2000 levels for the past decade even though CO2 levels have continued to rise. Meanwhile, a reconstruction of the Eemian interglacial from the new NEEM ice core, published in the journal Nature, shows that in spite of a climate 8°C warmer than that of the past millennium, the ice in Northern Greenland was only a few hundred meters lower than its present level. This finding casts doubt on the projected melting of ice sheets and resulting sea-level rise.
A new “comprehensive” report about the melting of Antarctic and Greenland ice sheets is being touted by climate alarmists as “grim news” but in fact says no such thing. This latest estimate, published this week in Science, combines data from many sources including 20 years of satellite data and 32 years of ice-sheet simulations to arrive at a mixed conclusion. It estimates that, between 1992 and 2011, the Antarctic and Greenland ice sheets lost 1350 ± 1010 and 2700 ± 930 Gt of ice, respectively. That is equivalent to an increase in global mean sea level of 11.2 ± 3.8 mm, less than 1/2 an inch. Moreover, while some areas were losing ice mass others were gaining mass from snowfall. The East Antarctic Ice Sheet (EAIS), which occupies over 75% of Antarctica, experienced mass gains during the final years of the study.
There has been a wave of triumphal announcements by climate change proponents recently, almost giddy over the summer shrinkage of the Arctic ice sheet. “Lowest level ever!” they proclaim, thought that is not quite true. Nonetheless, The Arctic pack ice has been receding over the last decade or so, but that is only natural. You see, there is a well known, if poorly understood, linkage between the ice at the north pole and the ice in and around Antarctica—and the ice around Antarctica is doing quite well. Satellite radar altimetry measurements indicate that the East Antarctic ice sheet interior increased in mass by 45±7 billion metric tons per year from 1992 to 2003. This trend continues today, reinforcing recent scientific investigations into this millennial scale oscillation between the poles. According to studies, this is how things have been for hundreds of thousands of years.
Another group of researchers has weighed in on the continuing scientific scuffle over whether the Himalayan glaciers are melting. A letter to Nature Geoscience reports that the Karakoram glaciers, a part of the greater Himalaya north of the actual Himalaya Range, are actually gaining mass. Outside the ice sheets in Greenland and Antarctica, the Karakoram is the most heavily glaciated part of the world, containing nearly 3% of the planet's total ice area. But because they are so large, difficult to get to and dangerous to travel on, they have not been measured by conventional survey methods. Scientists have instead, been relying on satellite measurements, whose accuracy is now called into question. This impressive new study says that the Karakoram glaciers are not only not shrinking, they are accumulating enough ice each year to cause a slight decrease in ocean sea-level.
The last interglacial period (LIG)—the Eemian—is commonly believed by scientists to have been warmer than the current Holocene interglacial. Along with that balmier climate there is evidence that sea levels were significantly higher than today. Previous studies have pegged Eemian sea levels at 4 to 6m higher than today. Recently, a new investigation raises that estimate, reporting that ancient sea levels peaked between 6.6 and 9.4 m (~20 to 30 feet). Modern day accounts of flooding in low lying coastal areas and tropical islands abound, with ominous suggestions of links to global warming. How high the oceans will rise is a topic of debate for IPCC members, the news media and assorted climate alarmists, but they are asking the wrong question. Instead, they should ask why are sea levels so low?
One of the claims put forth by climate change alarmists is that Earth's glaciers are rapidly melting. This supposedly causes all sorts of problems, from rising sea levels to failing water supplies. A recent report in the journal Nature uses NASA's Gravity Recovery and Climate Experiment (GRACE) satellite to measure the loss of glacial ice around the globe. Analysis of the satellite data on Earth's changing gravity field delivers some unexpected results and the results have surprising implications for both the global contribution of glaciers to sea level and the changes occurring in the mountain regions of Asia.
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.
In 2009, the International Commission on Stratigraphy, the body charged with formally designating geological time periods, decided the Anthropocene concept “has some merit.” To investigate further they formed the Anthropocene Working Group, which published their initial findings this past February in a special issue of the Philosophical Transactions of the Royal Society A. The group reported a wide range of human impacts that could leave a stratigraphically significant mark on the planet's geological record. There is no doubt that humans have changed the world we live in, but has the change been significant enough to declare a whole new epoch? The Anthropocene debate is continuing this week at the 2011 Geological Society of America conference.
The glaciers of Alaska and northwestern Canada are a major contributor of fresh water to the world's oceans. They have long been considered important contributors to global sea level, but their remoteness has complicated efforts to measure changes in ice mass. As described in a new perspective article, published in the May 27 issue of Science, satellite measurements of Earth's gravitational field and improved on-site measurements have been used to generate global maps of water-mass variation, confirming the large role Alaska glaciers play in global sea-level regulation. Climate change advocates would claim that global warming will melt Alaska's glaciers, flooding low lying countries, but determining the rate at which the glaciers are melting is not a simple thing. Far from solving the puzzle, the new observations are revealing unexpected complexities in the magnitude and rate at which Alaska glaciers respond to climate.
Fluctuations in surface melting are known to affect the speed of glaciers and ice sheets, while the contribution of glaciers and ice caps to global sea-level rise is uncertain at best. Much has been made of the “accelerating” loss of ice from the Greenland glaciers. Over the past decade, Arctic sea ice retreated substantially during the summer months, and some predicted that the ice loss could be irreversible, a tipping point that would boost global warming. A number of new papers in Nature, Geophysical Research Letters and Nature Geoscience, shed new light on these subjects, and the answers are not the ones usually heard in the media.
Climate change activists have long warned of a bleak and impoverished future due to the ravages of global warming. But evaluating the effects of climate change in the long term is an extremely complex issue. There are no reliable, accurate predictions for future climate, demographic change, economic development, or technological progress. A new study in the Proceedings of the National Academy of Sciences (PNAS) finds that if the climate of the 2080s were to occur today, the annual loss in household welfare in the European Union (EU) would range between 0.2–1%. Furthermore, this minuscule change was derived using aggressive IPCC scenarios for temperature and sea-level rise. Regardless of the claims made by climate change doomsayers, the future is not going to suck after all.
Climate alarmists have been slow to learn that their over-reliance on computer models and unproven theories has harmed their public credibility. In an attempt to counter the richly deserved bad press that climate science has been garnering these days, a number of global warming true believers are trying a different, more fact based approach to scaring the public. One such attempt recently appeared in the journal Science—not as a paper describing original research but as a perspective article. In it, a Senior Scientist at the National Center for Atmospheric Research, in Boulder, Colorado, attempts to “weave together” some carefully selected “threads in the discussion of climate” to arrive at a very familiar and unconvincing conclusion.
Time after time, the public has been harangued by climate change “experts” predicting all form of devastation due to anthropogenic global warming. The Greenland and Antarctic glaciers will melt, as will the sea ice covering the Arctic Ocean. Temperatures will rise by 2-6°C, perhaps more in higher latitudes. Weather patterns will shift, there will be droughts and torrential monsoon rains, cyclones will increase in intensity—where will it all end? Here's a thought, we might find the world a nicer place after a bit of global warming. In fact, given the general cooling trend seen over the Holocene (the period since the last glacial period ended around 14,000 years ago) and the Cenozoic (the time since the dinosaurs died, around 65 million years ago) human CO2 may be, in some small way, the only thing delaying another devastating ice age.