Ice Melt in Alaska, Antarctica, Greenland Accelerating

2 trillion tons of ice in Alaska, Antarctica and Greenland melted since 2003, NASA says

About 2 trillion tons of ice in Alaska, Antarctica  and Greenland has melted since 2003,  NASA scientists say, due to accelerating climate change.

Analyzing data from NASA’s Gravity Recovery and Climate Experiment, GRACE, in which two orbiting satellites are used to measure the “mass balance” of a glacier, that is the net difference between ice accumulation and ice loss each year, NASA geophysicist Scott Luthcke says the losses are colossal.

“The ice tells us in a very real way how the climate is changing,” said Luthcke. “A few degrees of change [in temperature] can increase the amount of mass loss, and that contributes to sea level rise and changes in ocean current.”

Greenland has lost about 160 gigatons (one billion tons) each year for 5 consecutive years, enough to raise global sea levels about .5 mm per year,  according to another NASA researcher, Jay Zwally.

“Every few extra inches of sea level have very significant economic impacts, because they change the sea level, increase flooding and storm damage,” said Zwally. “It’s a warning sign.”

“We’re seeing the impacts of global warming in many areas of our own lives, like agriculture,” he said.

Citing the pine beetle infestation in the forests of Colorado and western Canada [how about Alaska?] he said: “[The pests] were believed to be spreading because the winter was not cold enough to kill them, and that’s destroying forests.”

Sermersuaq (Humboldt) Glacier, Greenland

acquired August 30, 2008 – NASA Earth Observatory


acquired August 30, 2000 – NASA Earth Observatory

Stretching about 90 kilometers across Kane Bassin in the Nares Strait, northwestern Greenland’s Sermersuaq Glacier, also called Humboldt Glacier, is the Northern Hemisphere’s widest tidewater glacier—a glacier that begins on land, but terminates in water. The Sermersuaq is a major source of icebergs in the strait, which connects the Lincoln Sea in the north to Baffin Bay in the south.

This pair of images shows the retreat of the Sermersuaq Glacier between 2000 and 2008. In these natural-color images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite, the approximate terminus of the glacier on August 31, 2000 (bottom image), is traced with a yellow line on an image from August 30, 2008 (top). Although the southern part of the terminus showed little change during the period, significant retreat is visible in the northern part, where a fast-flowing ice stream is located. In both images, the deep blue waters of Kane Bassin are littered with ice, which may include icebergs and sea ice.

Having a “toe” in the water adds complexity to the natural cycle of advance and retreat that a glacier experiences in response to climate changes. The behavior of tidewater glaciers is affected not only by melting and snowfall on land, but also by the shape of the fjord or coastline where the glacier enters the water, the depth of the water, tides, and the thickness of the moraine (a shoal of sediment and rock) that builds up underwater at the tip of the glacier.

Even in the absence of human-caused climate change, tidewater glaciers naturally experience century-long cycles that include phases of rapid retreat. After decades of slow advance, the terminus of the glacier eventually becomes grounded on its own moraine. The shoal can become so thick that it stops icebergs from calving for extended spans of time. The support of the shoal allows the glacier to grow larger than it could if it were free-floating.

A small amount of thinning or retreat at the terminus can trigger a rapid retreat once the glacier—too large to float—is ungrounded from the shoal. The initial thinning or retreat of a tidewater glacier may result from a warming climate, but the extremely rapid retreat thereafter has as much to do with topography and the laws of physics as it does with the current climate.

NASA image created by Jesse Allen, using data obtained from the Goddard Level 1 and Atmospheric Archive and Distribution System (LAADS). Caption by Rebecca Lindsey.

Instrument: Terra – MODIS

Date Acquired: August 30, 2008

Global Warming or Climate Change

From NASA with Love!

What’s in a Name? Global Warming vs. Climate Change

December 5, 2008

The Internet is full of references to global warming. The Union of Concerned Scientists [aka, the snakeoil merchants] website on climate change is titled “Global Warming,” just one of many examples. But we don’t use global warming much on this website. We use the less appealing “climate change.” Why?

By any other name … Whether referred to as “global warming” or “climate change,” the consequences of the widescale changes currently being observed in Earth’s climate system could be considerable.

To a scientist, global warming describes the average global surface temperature increase from human emissions of greenhouse gases. Its first use was in a 1975 Science article by geochemist Wallace Broecker of Columbia University’s Lamont-Doherty Geological Observatory: “Climatic Change: Are We on the Brink of a Pronounced Global Warming?”

Broecker’s term was a break with tradition. Earlier studies of human impact on climate had called it “inadvertent climate modification.”  This was because while many scientists accepted that human activities could cause climate change, they did not know what the direction of change might be. Industrial emissions of tiny airborne particles called aerosols might cause cooling, while greenhouse gas emissions would cause warming. Which effect would dominate?

For most of the 1970s, nobody knew. So “inadvertent climate modification,” while clunky and dull, was an accurate reflection of the state of knowledge.

The first decisive National Academy of Science study of carbon dioxide’s impact on climate, published in 1979, abandoned “inadvertent climate modification.” Often called the Charney Report for its chairman, Jule Charney of the Massachusetts Institute of Technology in Cambridge, declared: “if carbon dioxide continues to increase, [we find] no reason to doubt that climate changes will result and no reason to believe that these changes will be negligible.”

In place of inadvertent climate modification, Charney adopted Broecker’s usage. When referring to surface temperature change, Charney used “global warming.” When discussing the many other changes that would be induced by increasing carbon dioxide, Charney used “climate change.”

Within scientific journals, this is still how the two terms are used. Global warming refers to surface temperature increases, while climate change includes global warming and everything else that increasing greenhouse gas amounts will affect.

Definitions:
Global warming: the increase in Earth’s average surface temperature due to rising levels of greenhouse gases.
Climate change: a long-term change in the Earth’s climate, or of a region on Earth.

During the late 1980s one more term entered the lexicon, “global change.” This term encompassed many other kinds of change in addition to climate change. When it was approved in 1989, the U.S. climate research program was embedded as a theme area within the U.S. Global Change Research Program.

But global warming became the dominant popular term in June 1988, when NASA scientist James E. Hansen had testified to Congress about climate, specifically referring to global warming. He said: “global warming has reached a level such that we can ascribe with a high degree of confidence a cause and effect relationship between the greenhouse effect and the observed warming.”  Hansen’s testimony was very widely reported in popular and business media, and after that popular use of the term global warming exploded. Global change never gained traction in either the scientific literature or the popular media.

But temperature change itself isn’t the most severe effect of changing climate. Changes to precipitation patterns and sea level are likely to have much greater human impact than the higher temperatures alone. For this reason, scientific research on climate change encompasses far more than surface temperature change. So “global climate change” is the more scientifically accurate term. Like the Intergovernmental Panel on Climate Change, we’ve chosen to emphasize global climate change on this website, and not global warming.

Erik Conway
Global Climate Change

[Text, image, caption: NASA Earth Observatory; comment on UCS: FEWW]

Images of the Day: Burning Coal

Live by the coal, die by the coal.

Lit, warmed, changed, soaked and choked by coal!

The sun rises behind Fiddlers Ferry coal fired power station near Liverpool, northern England, December 15, 2008. REUTERS/Phil Noble. Image may be subject to copyright.

Laborers search for usable coal at a cinder dump site near a power plant in Changzhi, Shanxi province December 15, 2008. REUTERS/Stringer. Image may be subject to copyright.

Volcanoes Killed Off Dinosaurs

Researchers say volcanism more likely caused K-T extinction; not asteroid impact

Addressing the age-old question of what really happened to dinosaurs, researchers at Princeton University say they have found more evidence that it was volcanism, not an asteroid impact that killed them off.

According to the asteroid-impact theory, put forward in 1980 by physicist Luis Walter Alvarez, the Cretaceous-Tertiary extinction, or the K-T mass extinction, which killed off the dinosaurs and caused the extinction of about 70 percent of life on Earth, was caused by a massive impact.

Artist’s rendering of bolide impact. Made by Fredrik. Cloud texture from public domain NASA image.

The asteroid-impact theory is supported by Chicxulub crater in Mexico’s Yucatan Peninsula, which was discovered by geophysicist Glen Penfield, while searching for oil. The 65-million year old crater occurred about the time of the K-T event.

Other theories citing climate change and volcanism have been suggested more recently. Gerta Keller of Princeton University says her studies point the blame toward volcanism.

The Deccan Traps

An intense period of colossal volcanic eruptions, which began about 67 million years ago, earlier than the impact, was regarded as another potential culprit. The eruptions  formed the Deccan Traps in India.

The Deccan Traps formed between 60 and 68 million years ago, at the end of the Cretaceous period. The bulk of the volcanic eruption occurred at the Western Ghats (near Mumbai) some 66 million years ago. This series of eruptions may have lasted fewer than 30,000 years in total. The gases released in the process may have played a role in the Cretaceous–Tertiary extinction event, which included the extinction of the dinosaurs. [Wikipedia]

The Deccan Traps are a large igneous province located on the Deccan Plateau of west-central India (between 17-24N, 73-74E) and one of the largest volcanic features on Earth. They consist of multiple layers of solidified flood basalt that together are more than 2,000 m thick and cover an area of 500,000 km². The term ‘trap’, used in geology for such rock formations, is derived from the Swedish word for stairs (trappa, or sometimes trapp), referring to the step-like hills forming the landscape of the region.

Before the Deccan Traps region was reduced to its current size by erosion and continental drift, it is estimated that the original area covered by the lava flows was as large as 1.5 million km², approximately half the size of modern India. The present volume of directly observable lava flows is estimated to be around 512,000 km³.

The release of volcanic gases during the formation of the traps “contributed to an apparently massive global warming. Some data point to an average rise in temperature of 8 °C (14 °F) in the last half million years before the impact at Chicxulub.” [Wikipedia]

Climate Change

Extreme climate change may have been caused by both the bolide impact and the volcanic explosions; in either case  massive volumes of sulfur dioxide [creating acid rains,] dust and other particles into the atmosphere would have significantly altered the climate.

In fact, some researchers believe a combination of events may have caused the mass extinction, with the asteroid impact finalizing the event.

According to Keller, however, the asteroid-impact “theory is now facing perhaps it’s most serious challenge from the Deccan volcanism and perhaps the Chicxulub impact itself.” She said at a news conference at the annual meeting of the American Geophysical Society in San Francisco.

The Cretaceous–Tertiary extinction event, which occurred approximately 65.5 million years ago (Ma), was a large-scale mass extinction of animal and plant species in a geologically short period of time. Widely known as the K–T extinction event, it is associated with a geological signature known as the K–T boundary, usually a thin band of sedimentation found in various parts of the world. K is the traditional abbreviation for the Cretaceous Period derived from the German name Kreidezeit, and T is the abbreviation for the Tertiary Period (a historical term for the period of time now covered by the Paleogene and Neogene periods). The event marks the end of the Mesozoic Era and the beginning of the Cenozoic Era.[1] “Tertiary” being discouraged as a formal time or rock unit by the International Commission on Stratigraphy, the K-T event is now called the Cretaceous—Paleogene (or K-Pg) extinction event by many researchers. [Wikipedia]

Deccan Traps near Pune, state of Maharashtra in western India. This file is licensed under the Creative Commons Attribution 3.0 Unported License. Credit: Kppethe.

Keller and her colleagues have recently analyzed geological records in India, Mexico and Texas to  determine the time of impact and the period of volcanic activities in relation to the K-T event. Their examination of sediment layers suggests that the crater impact occurred about 300,000 years before the K-T boundary, and had little or no effects to biota.

“There is essentially no extinction associated with the impact,” Keller said.

On the other hand, the peak of the Deccan volcanic explosions seems to have occurred “just before the K-T boundary,” according to a University of Paris geophysicist, Vincent Courtillot.

After the first volcanic flow, “the species disappear; we have essentially very few left [their recovery is stalled by the two subsequent flows and] by the fourth flow, the extinction is complete,” Keller said.

Courtillot study compares the amounts of sulfur dioxide emitted to the atmosphere by various events as follows, concluding that the Deccan traps are much more likely to have caused the K-T event than the asteroid impact :

• The 1991 Pinatubo eruption: 0.017 billion tons of sulfur dioxide (SO2)
• The Chicxulub crater:  500 billion tons of SO2
• The Deccan traps: 10,000 billion tons SO2.

“If there had been no impact, we think there would have been a mass extinction anyway,” Courtillot said.

Confirming Courtillot’ team and her own findings, Keller added: “Deccan volcanism is the likely culprit behind the K-T mass extinction.”

Related Links:

• Volcanoes, Not Asteroid, May Have Killed Off Dinosaurs