Marine and terrestrial proxy records suggest that there was a peak in global warming between 10,000 and 6,000 years ago, following the end of the last glacial period. Since the Holocene Thermal Maximum, Earth has undergone global cooling. The physical mechanism responsible for this global cooling has remained unknown and doesn't fit in with the current CO2 based climate models. Those climate models generate a robust global annual mean warming throughout the Holocene, mainly in response to rising CO2 levels and albedo changes due to retreating of ice sheets. In other words, the models disagree with reality, and when models disagree with nature the models have a credibility gap. A new paper in the Proceedings of the National Academy of Sciences (PNAS) says this model-data inconsistency indicates a critical reexamination of both proxy data and models is called for.
News media around the world have been all abuzz, with headlines declaring “Irreversible collapse of Antarctic glaciers has begun” and “West Antarctic Ice Sheet collapse is under way.” The “rapid” collapse threatens to cause sea level change of 4 to 13 feet. Calamity will surely follow. “Collapse will change the coastline of the whole world” shrieked the UK's Guardian, always a good source for mindless rumor mongering. What they are referring to are a pair of new reports that say the West Antarctic Ice Sheet (WAIS) has pushed its way over a submerged ridge that had been impeding its forward progress, causing the ice sheet to become unstuck from the sea floor. The WAIS is now flowing more freely, and hence more rapidly, into the sea. What the alarmist headlines don't say is that any impacts from this change are centuries to millennia in the future.
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.
It's everywhere on Earth, on the other planets and moons of the solar system, and even in comets from deep space. It is the frozen form of water, commonly called ice. Something so ubiquitous and familiar, one would think that science knows a lot about ice. It turns out science knows less than we might suppose. In a commentary in the journal Nature, an ice scientist raises ten open questions about ice. For example, the article states: “We cannot predict with certainty when and where ice clouds will form in the atmosphere; areas of the sky remain humid when we would expect them to freeze.” Ice is a fundamental part of Earth's climate, yet these questions and others remain unanswered. How can climate science claim to predict the fate of the polar ice sheets or mountain glaciers when we do not really understand the substance that they are made of?
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.
Over the past 50 years or so, the Antarctic Peninsula, the northernmost part of the mainland of Antarctica, has experienced rapid warming and the collapse of a number of ice shelves. A new temperature record derived from an ice core drilled on James Ross Island, has triggered a reassessment of what triggered the recent warming trends. This new core provides the best record of climate events on the peninsula going back at least 20,000 years, and may extend back as far as 50,000 years. From this new data a team of researchers has constructed the most detailed history of climate on the Antarctic Peninsula known to science and it has revealed a number of interesting things. Most important of these is the fact that this area undergoes bouts of rapid warming periodically and that things were at least as warm on the peninsula 2,000 years ago. So much for “unprecedented” warming on the Antarctic Peninsula.
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.
Melting glaciers are once again in the news, along with the associated threat of rising sea levels. NASA satellites have reported wide spread melting across Greenland which has the climate change alarmists all atwitter. But the NASA satellites are providing data never before available, so it is hard to say if the summer melting pattern is unusual. Meanwhile, some 80 year old scientific data has revealed that this is not the first time that there has been a period of glacial retreat in Greenland. This formerly lost data shows that many land-terminating glaciers underwent a more rapid retreat in the 1930s than in the 2000s. Even more interesting is that the two periods of retreat were interrupted by a period of widespread advance from 1943 to 1972. Greenland's glaciers seem to be oscillating with a period of around a century.
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.
Many of the more strident reports regarding runaway global warming center on rapid ice loss from the glaciers of Greenland. During the early 2000s the Greenland Ice Sheet experienced the largest ice-mass loss since accurate instrument readings have been kept. This was largely caused by the acceleration, thinning and retreat of large outlet glaciers in West and southeast Greenland. Now a new study in Nature Geoscience confirms that ice loss from the Helheim Glacier between 2003 and 2005 was the worst recorded—at least since the last period of rapid ice loss during the late 1930s.
An iceberg the size of Berlin is forming in Antarctica and is expected to break off from the Pine Island Glacier soon. As sure as night follows day, climate change alarmists will pronounce this a result of anthropogenic global warming—and they will be dead wrong. NASA scientists have already predicted the event and proclaimed it a part of a natural, ten year cycle that they have been studying for decades. The sad state of climate science is underlined by the fact that the researchers felt compelled to state that global warming is not the cause of the ice-shelf collapse.
Recent days have seen a number of announcements about our changing climate. As it turns out Arctic ice is rebounding, sea levels are dropping and things just are not going according to the IPCC's plan for catastrophic global warming. Faced with reversal after reversal, it might seem logical for mainstream climate scientists to admit that they are wrong, that global warming is not taking place at a breakneck pace, but this has not happened. Instead, climate change apologists are weaving a tangled web of excuses—hot is cold, wet is dry, up is down. No matter what happens to the world we live in, the root cause according to the doomsayers is always the same: it's always global warming's fault.
A pair of researchers has published a new report in the Proceedings of the National Academy of Sciences (PNAS) in which two out of three glaciers studied were disappearing. In a report that was edited by James Hansen, of the Goddard Institute for Space Studies, it would appear that the glaciers of the Himalaya are melting rapidly, but that is not how the report ends. The authors state that poor selection of study sites have led to the widespread use of non-representative data. Moreover, the IPCC report and others overstate the disappearance of Himalayan glaciers.
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.
Scientists have always thought that the vast majority of ice contained in the Antarctic ice cap was formed from frozen precipitation. Recent research has revealed that this is not totally correct. Over a large fraction of East Antarctica, the deepest part of the ice sheet contains ice that did not originate as surface snow but developed when subglacial meltwater was frozen onto the underside of the ice sheet. The amount of ice involved is much larger than the estimated volume of Antarctic subglacial lakes and may even exceed the volume of all glaciers on Earth outside of the two polar ice sheets. Current computer models predict that subglacial water escapes toward the ocean. These new findings indicate that water from areas of basal melting actually migrate to areas of basal freezing, something not accounted for by current ice sheet models. To scientists' surprise, the East Antarctic Ice Sheet is getting thicker from the bottom up.