The last supper leonardo da vinci essays goku personality analysis essay?
An apparent downward trend from a "Medieval Warm Period," roughly as warm as the s, into the cooler "Little Ice Age" gave way to a steep rise in the 20th century.
The movement from warm to cool and back toward warm had been debated by Lamb and other historians and climatologists since the s; what was new and startling was the abrupt climb since the s. The temperatures of the s soared to the top of the chart.
Apparently had been not just the warmest year of the century, but of the millennium. The graph shown below was widely reprinted and made a strong impression. It was dubbed the "hockey stick" because it displayed a flat thousand-year trend followed by a sharp upward turn.
The image immediately became a powerful tool for people who were trying to raise public awareness of global warming — to the regret of some seasoned climate experts who recognized that, like all science at the point of publication, the graph was preliminary and uncertain. The dedicated minority who denied that there was any global warming problem promptly attacked the calculations.
For example, in a few scientists argued that the Earth had been as warm a thousand years ago as in the late 20th century. They found a scattering of warm and cold periods in different places at different times, overall below the level of the recent general warming. It turned out that the supposed Medieval Warm Period had caught the eye of historical climatologists because it was prominent in well-studied parts of the Northern Hemisphere.
Greenland had been particularly warm. The Arctic in general, however, had been mostly cool until the steep rise of the late 20th century. Northern continental areas and a few southern regions had been particularly cold, but some other regions had been about as warm as at present. None of this was as striking a global phenomenon as the recent rapid warming.
One study, signed by 78 authors in a massive collaboration, used tree rings and other proxies in seven continental areas to check the findings of Mann's team.
They found that the world at the opening of the 21st century was unquestionably warmer than at any time in the past two millennia. The other study used a variety of climate proxies from sea-floor sediments, plus some terrestrial ones, to get highly accurate data far into the past. Their graph showed a rise at the end of the last glacial period, fairly steady temperatures to around BCE, and then a gradual decline — until the abrupt rise in the 20th century, shooting back to the level of the warm period around BCE and on track to climb beyond.
A few critics continued to seek confirmation of their denial of the warming in data on air temperatures from weather stations and satellites.
In particular, former TV weatherman Anthony Watts established a popular website that mobilized people to report continental U. A study by members of the NOAA National Climatic Data Center separately analyzed the sites that Watts's volunteers identified as faulty, comparing them with the acknowledged good sites.
They found that any bias introduced by poor siting had been mostly compensated for by the data reduction, which was designed precisely to remove biases by comparisons over regions and time.
But if the raw data only were considered, the poor sites did not tend to overestimate warming compared with what NOAA had reported, as Watts had assumed; if anything the warming from these sites was greater than NOAA's earlier figures.
A painstaking re-analysis of land-station data was organized by warming skeptic Richard Muller and funded by oil billionaire Charles G. Koch, a leading sponsor of groups that attacked the climate consensus.
The study, using different methods and more data than earlier teams, only confirmed what every other study had found.
There was a marked recent rise, Muller's group announced inthat could only be explained as human-caused. People dedicated to denying global warming retreated to an old claim based on a different dataset, the satellite measurements of mid-atmosphere temperatures Christy and Spencer data, see above.
A temperature graph based on convoluted analysis of the raw data, displayed even in the US Senate, had not risen above the peak.
As before, the analysis was found to have problems that had concealed an actual rise compatible with the models.PTE Academic most repeated essay writings with helpful tips provided and essay solution to form a complete essay using the hints given.
The heat content of the upper layers of the world's oceans is the most comprehensive measure of changes in the temperature of the planet. For as new heat is added, far more goes into the oceans than into the thin atmosphere.
Updated 13 March, The Tragedy of the Commons by Garrett Hardin, Published in Science, December 13, For copyright permission, click here.. The author is professor of biology, University of California, Santa Barbara.
One of the common features of an epic is the "fabulous loci" for the hero to visit. Fantasy novels can have some loci that are quite pretty or terrifying, but science . To get a look at the oil sand mines we rented this Cessna which the pilot was allowed to bring down to 1, feet — from there, through the open window and with a long lens we were able to.
Professional chemists will be m ore precise and say that fluorine is the most “electronegative” element, meaning that it is the most aggressive electron “thief,” because the alkali metals are the most “electropositive” elements, meaning their affinity to “give away” an electron, and electronegativity and electropositivity are not easy to compare, as far as “reactivity” goes.