Friday, January 25, 2013

Cooling down of universe

 follows Big Bang theory

MELBOURNE: Astronomers have made the most precise measurement ever of how the universe has cooled down during its 13.77 billion year history just as predicted in Big Bang theory.

They studied molecules in clouds of gas in a galaxy 7.2 billion light years away — so far that its light has taken half the age of the universe to reach us. Using the Australia Telescope Compact Array, a team from Sweden, France, Germany and Australia has measured how warm the Universe was when it was half its current age. "This is the most precise measurement ever made of how the Universe has cooled down during its 13.77 billion year history," said Robert Braun, chief scientist at CSIRO Astronomy and Space Science in a statement.

Because light takes time to travel, when we look out into space we see the Universe as it was in the past — as it was when light left the galaxies we are looking at. So to look back half-way into the Universe's history, we need to look halfway across the Universe.

The astronomers studied gas in an unnamed galaxy 7.2 billion light-years away. The only thing keeping this gas warm is the cosmic background radiation — the glow left over from the Big Bang. By chance, there is another powerful galaxy, a quasar called PKS 1830-211 , lying behind the unnamed galaxy.

A global-warming wish









The start of a year, always a time of forecasts—with reference to which, see p. 26—can be the occasion for wishes, as well. Here's one: that popular debate about global warming starts to address real issues.
In the Dec. 23 New York Times, eminent columnist Thomas L. Friedman demonstrated everything wrong about the global-warming conversation in a column entitled "Send in the Clowns," in which he offered advice to the political right from somewhere closer to the other end of the ideological spectrum. "If Republicans continue to be led around by, and live in fear of, a base that denies global warming after Hurricane Sandy and refuses to ban assault weapons after Sandy Hook—a base that would rather see every American's taxes rise rather than increase taxes on millionaires—the party has no future," he wrote.
In this broad smear, the scientific mystery of global warming shrinks into a single, simple wrinkle on the craggy face of political caricature. The implication is that anyone who "denies global warming" is, like everyone not aglow with liberal wisdom on other subjects, simply wrong-headed.
Yet who, precisely, "denies global warming," a natural phenomenon in the absence of which humans could not exist? And how, exactly, does a single weather event relate to climate phenomena?
To the superior intellects who take their political cues from the New York Times, questions such as these are trivial. They know what Friedman means: Anyone reluctant to make economic sacrifice to possibly unfounded concern surrenders the privilege of being taken seriously in polite company. Therefore, Republicans who wonder aloud about the efficacy of costly remedies, let alone the need for them—the phrase "deny global warming," decoded—deprive their party of legitimacy.
This is not argumentation. This is snobbery.

Case suffers

The case for costly precaution against global warming has, in fact, suffered lately. It has suffered politically, economically, and scientifically.
The political case began to fray when well-placed university researchers in the UK and at the Intergovernmental Panel on Climate Change were found to have subordinated science to politics in many instances. The mischief included, for example, publication in an important IPCC report of unfounded predictions about the melting of Himalayan glaciers—a politically incendiary error that the IPCC brushed off as minor oversight. More recently, British Broadcasting Corp., a persistent and politically potent source of dire warming forecasts, was found to have decided not to report contrary views on the advice of environmental activists.
The fear-driven political agenda sustained these blows to its credibility while global economic malaise forced attention to cost, providing a context most unpromising for proposals to displace fossil energy with much more-expensive alternatives.
And then there's the problem—for activists—of science. Satellite temperature measurements over the last decade or so haven't tracked predictions by computer models the IPCC uses to predict dangerous warming. According to some interpretations, average global temperature has quit rising.

Observation vs. prediction

To the extent discrepancies exist between observation and prediction, questions gain strength about modeling assumptions concerning the sensitivity of measured temperature to rising concentrations of greenhouse gases. Scientists disagree over the extent of that discrepancy and what it means. Their work in this still-murky area of climate science is important.
But the question that should be central to policy-making remains open: Do humans, with the emissions of GHGs for which they're responsible, contribute so much to warming that by cutting emissions they can meaningfully influence global average temperature? The answer, because warming has many causes and the climate has offsetting mechanisms not yet well understood, might be no.
To point this out is not churlish. And reluctance to impose heavy cost on the mere chance that worst-case scenarios, generated by systems shown to have predictive lapses, might come true is not evidence of political illegitimacy.
For more than 30 years, the activists of global-warming politics have predicted doom and insisted on immediate precaution, whatever the cost. They've answered reasonable questions about their urgent agenda by mischaracterizing questions and disparaging questioners. And they've been caught in multiple instances of propagandist excess.
This would be a good year for a conversation about global warming not overheated by zealotry, finally, to begin.

Global warming has stalled since 1998: UK Met office

LONDON: Global warming has stalled since 1998, and in the next few years Earth's temperature will not rise as rapidly as feared, UK Met officials have claimed.

Over the next five years temperatures will be 0.43 degrees above the 1971-2000 average, instead of the previously forecast 0.54 degrees - a 20 per cent reduction, the Met office in UK has confirmed.

This rise would be only slightly higher than the 0.4-degree rise recorded in 1998, an increase which is itself attributed by forecasters to an exceptional weather phenomenon, the 'Daily Mail' reported.

With all but 0.03 degrees of the increase having occurred by 1998, it means that no further significant increases to the planet's temperature are expected over the next few years.

The figures have been seized on by sceptics of man-made climate change, who claim that global warming has flatlined despite a large rise in greenhouse emissions in recent decades.

"That the global temperature standstill could continue to at least 2017 would mean a 20-year period of no statistically significant change in global temperatures," Dr David Whitehouse, science adviser to the Global Warming Policy Foundation, said.

"Such a period of no increase will pose fundamental problems for climate models. If the latest Met Office prediction is correct, then it will prove to be a lesson in humility," Whitehouse said.

"Global warming is not 'at a standstill' but does seem to have slowed down since 2000, in comparison to the rapid warming of the world since the 1970s," Dr Richard Allan of the University of Reading said.

"In fact, consistent with rising greenhouse gases, heat is continuing to build up beneath the ocean surface," Allan added.

He was backed by Bob Ward of the London School of Economics, who said it would be wrong to interpret that warming had stopped.

The Met Office said the updated five-year predictions were a result of a new modelling system, which takes into account changes in ocean surface temperatures, and was released as soon as practically possible.

It claims the slow-down in temperature rises after a steep increase in the 1990s could be explained by natural variability, changes in solar activity, and the movements of the oceans.

"A lot of people were claiming, in the run-up to the Copenhagen 2009 conference, that warming was accelerating and it is all worse than we thought," Professor Myles Allen of the University of Oxford said.

"What has happened since then has demonstrated that it is foolish to extrapolate short-term climate trends," Allen said.