Click here for current theater and arts listings! Owners Project Manager Dan Tavares told the School Building Committee the project is on schedule and abatement is scheduled for completion in mid-December. He said the roof removal is scheduled in early December, which would lead to demolition just before Christmas. All this will lead to the timely opening of the new 5 through 12 school by September These were a few of many updates at the last SBC meeting.
How do ice cores work? Current period is at right. From bottom to top: Milankovitch cycles connected to 18O. From top to bottom: Ice sheets have one particularly special property.
They allow us to go back in time and to sample accumulation, air temperature and air chemistry from another time. Ice core records allow us to generate continuous reconstructions of past climate, going back at leastyears.
By looking at past concentrations of greenhouse gasses in layers in ice cores, scientists can calculate how modern amounts of carbon dioxide and methane compare to those of the past, and, essentially, compare past concentrations of greenhouse gasses to temperature.
Ice coring has been around since the s. Ice cores have been drilled in ice sheets worldwide, but notably in Greenland and Antarctica[4, 5]. Through analysis of ice cores, scientists learn about glacial-interglacial cycles, changing atmospheric carbon dioxide levels, and climate stability over the last 10, years.
Many ice cores have been drilled in Antarctica. Antarctic ice core drill sites with depth and record duration. This photograph shows an ice core sample being taken from a drill.
This picture shows a traversing field camp from December The team were travelling across the West Antarctic Ice Sheet to study snow accumulation. They spent two nights at each site, first collecting radar data and secondly collecting a 15 m shallow ice core.
This schematic cross section of an ice sheet shows an ideal drilling site at the centre of the polar plateau near the ice divide, with ice flowing away from the ice divide in all direction.
The large Greenland and Antarctic ice sheets have huge, high plateaux where snow accumulates in an ordered fashion. Slow ice flow at the centre of these ice sheets near the ice divide means that the stratigraphy of the snow and ice is preserved.
Drilling a vertical hole through this ice involves a serious effort involving many scientists and technicians, and usually involves a static field camp for a prolonged period of time.
Shallow ice cores m long are easier to collect and can cover up to a few hundred years of accumulation, depending on accumulation rates. Deeper cores require more equipment, and the borehole must be filled with drill fluid to keep it open.
The drill fluid used is normally a petroleum-derived liquid like kerosene. It must have a suitable freezing point and viscosity. Collecting the deepest ice cores up to m requires a semi permanent scientific camp and a long, multi-year campaign. Layers in the ice If we want to reconstruct past air temperatures, one of the most critical parameters is the age of the ice being analysed.
Fortunately, ice cores preserve annual layers, making it simple to date the ice. Seasonal differences in the snow properties create layers — just like rings in trees. Unfortunately, annual layers become harder to see deeper in the ice core.
Other ways of dating ice cores include geochemisty, layers of ash tephraelectrical conductivity, and using numerical flow models to understand age-depth relationships.
This 19 cm long of GISP2 ice core from m depth shows annual layers in the ice. This section contains 11 annual layers with summer layers arrowed sandwiched between darker winter layers.
Although radiometric dating of ice cores has been difficult, Uranium has been used to date the Dome C ice core from Antarctica.
Dust is present in ice cores, and it contains Uranium. The decay of U to U from dust in the ice matrix can be used to provide an additional core chronology.
Information from ice cores Accumulation rate The thickness of the annual layers in ice cores can be used to derive a precipitation rate after correcting for thinning by glacier flow. Melt layers Ice cores provide us with lots of information beyond bubbles of gas in the ice.
For example, melt layers are related to summer temperatures. More melt layers indicate warmer summer air temperatures. Melt layers are formed when the surface snow melts, releasing water to percolate down through the snow pack. They form bubble-free ice layers, visible in the ice core.
The distribution of melt layers through time is a function of the past climate, and has been used, for example, to show increased melting in the Twentieth Century around the NE Antarctic Peninsula.This essay delves deeply into the origins of the Vietnam War, critiques U.S.
justifications for intervention, examines the brutal conduct of the war, and discusses the .
The table below presents an abbreviated geologic time scale, with times and events germane to this essay. Please refer to a complete geologic time scale when this one seems inadequate. 11 thoughts on “ My Climate Change ” Frank Mancuso February 19, at am. Seems to me that no matter how we feel about our planet or eloquently write about what we know is happening to it nothing of any significance changes.
Another great essay. I enjoy your writing so much Mr. Kingsworth– its like having my innermost feelings, thoughts and ideas given voice in . I originally introduced the term “orthorexia” in the article below, published in the October issue of Yoga Journal. Some of the things I said in the article are no longer true of me, or of what I currently believe.
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