| bjkeefe |
11-15-2010 02:50 AM |
Safest prediction ever
Here is something that will get absolutely no attention in the House for the next two years, at least: new (worse) projections on rising sea levels.
Quote:
Recent research suggests that the volume of the ocean may have been stable for thousands of years as human civilization has developed. But it began to rise in the 19th century, around the same time that advanced countries began to burn large amounts of coal and oil.
The sea has risen about eight inches since then, on average. That sounds small, but on a gently sloping shoreline, such an increase is enough to cause substantial erosion unless people intervene. Governments have spent billions in recent decades pumping sand onto disappearing beaches and trying to stave off the loss of coastal wetlands.
Scientists have been struggling for years to figure out if a similar pace of sea-level rise is likely to continue in this century — or whether it will accelerate. In its last big report, in 2007, the United Nations group that assesses climate science, the Intergovernmental Panel on Climate Change, said that sea level would rise at least seven more inches, and might rise as much as two feet, in the 21st century.
But the group warned that these estimates did not fully incorporate “ice dynamics,” the possibility that the world’s big ice sheets, as well as its thousands of smaller glaciers and ice caps, would start spitting ice into the ocean at a much faster rate than it could melt on land. Scientific understanding of this prospect was so poor, the climate panel said, that no meaningful upper limit could be put on the potential rise of sea level.
That report prompted fresh attempts by scientists to calculate the effect of ice dynamics, leading to the recent, revised projections of sea-level rise.
Satellite evidence suggests that the rise of the sea accelerated late in the 20th century, so that the level is now increasing a little over an inch per decade, on average — about a foot per century. Increased melting of land ice appears to be a major factor. Another is that most of the extra heat being trapped by human greenhouse emissions is going not to warm the atmosphere but to warm the ocean, and as it warms, the water expands.
With the study of the world’s land ice still in its early stages, scientists have lately been trying crude methods to figure out how much the pace might accelerate in coming decades.
One approach, pioneered by a German climate researcher named Stefan Rahmstorf, entails looking at the past relationship between the temperature of the earth and sea level, then making projections. Another, developed by a University of Colorado glaciologist named Tad Pfeffer, involves calculations about how fast the glaciers, if they keep speeding up, might be able to dump ice into the sea.
Those two methods yield approximately the same answer: that sea level could rise by 2 1/2 to 6 1/2 feet between now and 2100. A developing consensus among climate scientists holds that the best estimate is a little over three feet.
Calculations about the effect of a three-foot increase suggest that it would cause shoreline erosion to accelerate markedly. In places that once flooded only in a large hurricane, the higher sea would mean that a routine storm could do the trick. In the United States, an estimated 5,000 square miles of dry land and 15,000 square miles of wetlands would be at risk of permanent inundation, though the actual effect would depend on how much money was spent protecting the shoreline.
[...]
Moreover, scientists point out that if their projections prove accurate, the sea will not stop rising in 2100. By that point, the ice sheets could be undergoing extensive melting.
“Beyond a hundred years out, it starts to look really challenging,” said Richard B. Alley, a climate scientist at Pennsylvania State University. “You start thinking about every coastal city on the planet hiding behind a wall, with storms coming.”
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Bring on the ostriches!
Quote:
After a decade of budget cuts and shifting space priorities in Washington, several satellites vital to monitoring the ice sheets and other aspects of the environment are on their last legs, with no replacements at hand. A replacement for ICESat will not be launched until 2015 at the earliest.
“We are slowly going blind in space,” said Robert Bindschadler, a polar researcher at the University of Maryland, Baltimore County, who spent 30 years with NASA studying ice.
Several federal agencies and two presidential administrations, Democratic and Republican, have made decisions that contributed to the problems.
For instance, an attempt by the Clinton and Bush administrations to combine certain military and civilian satellites ate up $5 billion before it was labeled a “horrendous and costly failure” by a Congressional committee.
A plan by President George W. Bush to return to the moon without allocating substantial new money squeezed budgets at NASA.
Now, the Obama administration is seeking to chart a new course, abandoning the goal of returning to the moon and seeking a substantial increase in financing for earth sciences. It is also promising an overall strategy for improving the country’s environmental observations.
Major elements of the administration’s program won support from both parties on Capitol Hill and were signed into law recently, but amid a larger budget impasse, Congress has not allocated the money President Obama requested.
[...]
The satellite difficulties are one symptom of a broader problem: because no scientifically advanced country has made a strategic priority of studying land ice, scientists lack elementary information that they need to make sense of what is happening.
They do not know the lay of the land beneath most of the world’s glaciers, including many in Greenland, in sufficient detail to calculate how fast the ice might retreat. They have only haphazard readings of the depth and temperature of the ocean near Greenland, needed to figure out why so much warm water seems to be attacking the ice sheet.
The information problems are even more severe in Antarctica. Much of that continent is colder than Greenland, and its ice sheet is believed to be more stable, over all. But in recent years, parts of the ice sheet have started to flow rapidly, raising the possibility that it will destabilize in the same way that much of the world’s other ice has.
Certain measurements are so spotty for Antarctica that scientists have not been able to figure out whether the continent is losing or gaining ice. Scientists do not have good measurements of the water temperature beneath the massive, floating ice shelves that are helping to buttress certain parts of the ice sheet in West Antarctica. Since the base of the ice sheet sits below sea level in that region, it has long been thought especially vulnerable to a warming ocean.
But the cavities beneath ice shelves and floating glaciers are difficult to reach, and scientists said that too little money had been spent to develop technologies that could provide continuing measurements.
Figuring out whether Antarctica is losing ice over all is essential, because that ice sheet contains enough water to raise global sea level by nearly 200 feet. The parts that appear to be destabilizing contain water sufficient to raise it perhaps 10 feet.
Daniel Schrag, a Harvard geochemist and head of that university’s Center for the Environment, praised the scientists who do difficult work studying ice, but he added, “The scale of what they can do, given the resources available, is just completely out of whack with what is required.”
Climate scientists note that while the science of studying ice may be progressing slowly, the world’s emissions of heat-trapping gases are not. They worry that the way things are going, extensive melting of land ice may become inevitable before political leaders find a way to limit the gases, and before scientists even realize such a point of no return has been passed.
“The past clearly shows that sea-level rise is getting faster and faster the warmer it gets,” Dr. Rahmstorf said. “Why should that process stop? If it gets warmer, ice will melt faster.”
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