Re: Climate change could mean the extinction of our species
Quote:
Originally Posted by
danthepoetman
Correct me if I'm wrong, but I think the objects in orbit will fall eventually. On the moon, you're right: forget it: it will be there till the expansion of the sun.
Satellites will not stay in orbit forever. How long they stay up depends on how high they are and the satellite's ballistic coefficient, or mass/frontal area. The drag from our atmosphere decreases with height. Satellites in low orbits, say 500 km, will decay in a few years. At 1000 km they will stay up perhaps a century. Above a few thousand km they would stay practically forever. Space Junk is becoming a serious problem.
There's the two Voyager spacecraft - "1" is about 2 x 10^10 km away and about to enter interstellar space. She should last!!
Re: Climate change could mean the extinction of our species
Climate change, not the national debt, is the legacy we should care about
Worry about the grandchildren? Then stop global warming, but don't pretend deficit reduction by slashing pensions is for them:
http://www.guardian.co.uk/environmen...al-debt-legacy
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Re: Climate change could mean the extinction of our species
What are those humans doing to this place??
Re: Climate change could mean the extinction of our species
New evidence that the Mayan civilisation was destroyed due to climate change.
Did Climate Change Kill the Mayans?
http://science.time.com/2012/11/09/mayans/
There are a lot of things that didn’t kill the Mayans: asteroid strikes, planet-wide quakes, global cataclysms prophesied by shamans and etched into ancient calendars. What did wipe them out was likely something that is far less mystical, and indeed is entirely familiar to modern civilizations: climate change. If you want a look at what we could face in the decades and centuries ahead, look at what one of the world’s greatest cultures suffered a millennium ago. That’s the conclusion of a newly released study and what it lacks in Hollywood-friendly drama, it makes up in sound — and scary — science.
The arc of the Mayan rise and fall is well known: The civilization first took hold in 1,800 BC, in the Central American region that now includes and surrounds Guatemala. It grew slowly until about 250 A.D. At that point, a great expansion of the culture — known to archaeologists as the Classic Period — began and continued to 900 A.D., yielding the architectural, political and textual artifacts that have so mesmerized scientists. But a decline began around 800 A.D. and led to a final collapse about 300 years later.
The Mayan arc was hardly smooth and steady, and there were periods of turbulence and decline even during the golden era. The great settlement of El Mirador, which once might have been home to 100,000 people, collapsed around 300 A.D, for example. From the fifth to eights centuries A.D., there was an explosion of the rich tablet texts that provided so many insights into how the Mayans lived and worked. Suddenly, however, starting in 775 A.D., the number of texts began to plunge by as much as 50%, a bellwether of a culture that was declining too.
There have been a lot of theories for what accounted for such cycles, with climate among the most-mentioned. The better the year-to-year weather — with plenty of rainfall and reasonably steady and predictable temperatures — the better crops do, and the more the culture and economy can expand. The texts have hinted at declines in productivity, perhaps climate-related, coinciding with generations of unrest, but there was never a precise way to confirm those writings. Analysis of lake sediments can yield a reliable reading of the levels of sulfur, oxygen isotopes and other atmospheric markers at various points in history, which reveal a lot about rainfall and other critical variables. But the Mayans themselves often unwittingly disturbed those sediments, with deforestation — including wide-scale burnings — and fishing.
Anthropologist Douglas Kennett of Penn State University, leader of an international team of researchers from the U.S., Belize, Switzerland, Germany and elsewhere thus decided to look at another, less vulnerable, source of evidence: stalagmites in caves. Some of the rainfall absorbed by the ground over the course of centuries will seep into caves and be incorporated into the drip-drip-drip of wet limestone that causes stalagmites to form. Oxygen isotopes entrained in the rain can provide an indicator of how wet a region was at any one point in history.
As Kennett and his colleagues reported in the current issue of Science, they focused their investigation on a cave in the jungles of Belize, which is within 1.5 km (.9 mi.) of one significant Mayan site and 19 mi. (30 km) of three others. In 2006, the scientists harvested a 22-in. (56-cm) stalagmite from deep within the cave. Knowing the rate at which stalagmites develop, they could calculate that the top 16.3 in. (415 mm) of it had been growing continuously since 40 B.C. Every 0.1 millimeter — or about four one-thousandths of an inch — corresponded to about 0.5 years. That’s an awfully fine-grained way to look at history, and the analysis led to some awfully detailed conclusions.
Droughts lasting at least a few decades each occurred from 200 to 1100 AD, and repeatedly coincided with struggles and upheaval in the Mayan culture. There were dry periods in the 640 to 660 window, for example, and there was also a lot of warfare in that period, which makes sense for a culture fighting over swindling resources. Droughts from 820 to 870 similarly were associated with an outbreak of fighting, as well as the disintegration of local polities, or ruling bodies. The decline in historical texts began not long before another period of severe drying, and the collapse of the Mayan culture itself, directly corresponds to the most severe period of drying, from 1020 to 1100.
Broadly, explains Kennett, the most generous period of rainfall during the millennium or so the Mayans thrived was from 450 to 660. “This led to the proliferation of cities like Tikal, Copan and Carasol,” he says. “The new climate data show that this salubrious period was followed by a general drying trend…that triggered a decline in agricultural productivity and contributed to social fragmentation and political collapse.”
The cause of the climate upheaval that claimed the Mayans was not, of course, human activity, since their culture thrived and died long before the industrial age. Instead it was caused by the combined effects of El Niño events and changes in the northeast and southeast equatorial winds known as the intertropical convergence zone. “The preceding conditions stimulating societal complexity and population expansion helped set the stage for later stress on [Mayan] societies and the fragmentation of political institutions.”
This should not give comfort to the dwindling band of modern-day climate-change deniers likely to take the study as proof that the planet’s current climate woes are merely natural fluctuations. The Mayan drying trend played out over centuries, after all. What we’ve been experiencing is the more abrupt, short time-scale variety, a phenomenon that was first foreseen in climate models nearly 40 years ago, and has been unfolding pretty much on schedule and as predicted. The Mayans had no such power to forecast events and certainly couldn’t correct them. We can do both, and the lesson of the study is that we may pay mightily if we choose to take no action. No culture, as the vanished Mayans so starkly illustrate, is too big to fail.
More: Butterflies Moving North to Escape Climate Change
Read more: http://science.time.com/2012/11/09/m...#ixzz2BvS5Fk1m
Re: Climate change could mean the extinction of our species
Re: Climate change could mean the extinction of our species
Quote:
Originally Posted by
trish
Thanks for an interesting link, Trish....but...only yesterday the papers were full of the report from the International Energy Agency (see link) which claims the development of shale reserves in the US will free it from dependency on foreign imports and even make it a larger producer of petroleum than Saudi Arabia, thereby increasing carbon emissions in the US over a span of time when they are supposed to be falling...in addition to which we could end up with more petroleum than water in places like China...however...this does assume that all of the indigenous sources of shale oil and gas in the US are developed, which in itself is a controversial and as yet untested policy decision...it also assumes an uninterrupted and continuing growth of demand for oil and gas throughout the world, and that isn't a given either....
http://www.worldenergyoutlook.org/
Re: Climate change could mean the extinction of our species
I am always dubious of "breakthrough" stories. that's not generally how science proceeds.
So I wonder what the scientists here make of this story given front page treatment recently in a British Newspaper? I've not seen reports on it anywhere else?
http://www.independent.co.uk/news/uk...s-8217382.html
Exclusive: Pioneering scientists turn fresh air into petrol in massive boost in fight against energy crisis
Is scientific breakthrough a milestone on the road to clean energy?
A small British company has produced the first "petrol from air" using a revolutionary technology that promises to solve the energy crisis as well as helping to curb global warming by removing carbon dioxide from the atmosphere.
Air Fuel Synthesis in Stockton-on-Tees has produced five litres of petrol since August when it switched on a small refinery that manufactures gasoline from carbon dioxide and water vapour.
The company hopes that within two years it will build a larger, commercial-scale plant capable of producing a ton of petrol a day. It also plans to produce green aviation fuel to make airline travel more carbon-neutral.
Tim Fox, head of energy and the environment at the Institution of Mechanical Engineers in London, said: "It sounds too good to be true, but it is true. They are doing it and I've been up there myself and seen it. The innovation is that they have made it happen as a process. It's a small pilot plant capturing air and extracting CO2 from it based on well known principles. It uses well-known and well-established components but what is exciting is that they have put the whole thing together and shown that it can work."
Although the process is still in the early developmental stages and needs to take electricity from the national grid to work, the company believes it will eventually be possible to use power from renewable sources such as wind farms or tidal barrages.
"We've taken carbon dioxide from air and hydrogen from water and turned these elements into petrol," said Peter Harrison, the company's chief executive, who revealed the breakthrough at a conference at the Institution of Mechanical Engineers in London.
"There's nobody else doing it in this country or indeed overseas as far as we know. It looks and smells like petrol but it's a much cleaner and clearer product than petrol derived from fossil oil," Mr Harrison told The Independent.
"We don't have any of the additives and nasty bits found in conventional petrol, and yet our fuel can be used in existing engines," he said.
"It means that people could go on to a garage forecourt and put our product into their car without having to install batteries or adapt the vehicle for fuel cells or having hydrogen tanks fitted. It means that the existing infrastructure for transport can be used," Mr Harrison said.
Being able to capture carbon dioxide from the air, and effectively remove the principal industrial greenhouse gas resulting from the burning of fossil fuels such as oil and coal, has been the holy grail of the emerging green economy.
Using the extracted carbon dioxide to make petrol that can be stored, transported and used as fuel for existing engines takes the idea one step further. It could transform the environmental and economic landscape of Britain, Mr Harrison explained.
"We are converting renewable electricity into a more versatile, useable and storable form of energy, namely liquid transport fuels. We think that by the end of 2014, provided we can get the funding going, we can be producing petrol using renewable energy and doing it on a commercial basis," he said.
"We ought to be aiming for a refinery-scale operation within the next 15 years. The issue is making sure the UK is in a good place to be able to set up and establish all the manufacturing processes that this technology requires. You have the potential to change the economics of a country if you can make your own fuel," he said.
The initial plan is to produce petrol that can be blended with conventional fuel, which would suit the high-performance fuels needed in motor sports. The technology is also ideal for remote communities that have abundant sources of renewable electricity, such solar energy, wind turbines or wave energy, but little in the way of storing it, Mr Harrison said.
"We're talking to a number of island communities around the world and other niche markets to help solve their energy problems.
"You're in a market place where the only way is up for the price of fossil oil and at some point there will be a crossover where our fuel becomes cheaper," he said.
Although the prototype system is designed to extract carbon dioxide from the air, this part of the process is still too inefficient to allow a commercial-scale operation.
The company can and has used carbon dioxide extracted from air to make petrol, but it is also using industrial sources of carbon dioxide until it is able to improve the performance of "carbon capture".
Other companies are working on ways of improving the technology of carbon capture, which is considered far too costly to be commercially viable as it costs up to £400 for capturing one ton of carbon dioxide.
However, Professor Klaus Lackner of Columbia University in New York said that the high costs of any new technology always fall dramatically.
"I bought my first CD in the 1980s and it cost $20 but now you can make one for less than 10 cents. The cost of a light bulb has fallen 7,000-fold during the past century," Professor Lackner said.
Re: Climate change could mean the extinction of our species
Quote:
Originally Posted by
Prospero
I am always dubious of "breakthrough" stories. that's not generally how science proceeds.
So I wonder what the scientists here make of this story given front page treatment recently in a British Newspaper? I've not seen reports on it anywhere else?
Try this for an answer:
Are British Engineers Really Producing Petrol from Air Technology?
Posted October 22, 2012
Robert Webb
The UK press has gone mad over a new energy technology in recent days. I’ve been asked whether it is really as exciting as it seems?
“Exclusive: Pioneering scientists turn fresh air into petrol in massive boost in fight against energy crisis” ran the headline in the Independent on 19th October, and the story was picked up by the BBC on various channels. “we have been inundated here at AFS with requests for media interviews and comments from social media forums” says the home page of the company’s website - Air Fuel Synthesis.
So is it real? Well it certainly has a highly credible and solid technology foundation - the company was founded by Professor Tony Marmont, who has worked on aspects of renewable energy for many years.
Is it highly novel? Not really. The basic idea is that petrol, like all fossil fuels, is made of hydrocarbons - that is, long chains of hydrogen and carbon atoms. So if you use the right catalysts and processes, you can combine hydrogen and carbon to make fuel, which is what they do.
The hydrogen comes from the electrolysis of water and the carbon can come from the air - though the company speak about highly concentrated sources of CO2 like breweries, distilleries or aerobic digesters.
The problem is of course the question of how much energy is needed to run the whole process. The energy can come from renewable sources - and needs to, in order to keep it carbon-neutral - but the question is whether that energy is better used elsewhere, and more to the point, how much it costs to use it here.
I have seen statements for similar technology that it would require about 20 kWh to produce a litre of fuel. I very much doubt that this includes the energy which would be required if the carbon dioxide were to come from the air (concentrated sources are not that widespread). But even assuming that it does include this and is therefore extendable on a large scale, the problem is that that 20 kWh from a wind turbine or other clean energy source would power an electric car to travel about 60 km, whereas that litre of fuel (which will contain about 10 kWh) would power an internal combustion engined car only 15 km.
Let’s recap those numbers - they are surprisingly stark: we would get four times more mobility out of the primary energy if we used it in electric cars, than if we produced air fuel - at least four times, given the CO2 extraction energy issue and given the fact electric cars are still early stage technology. The difference expands to seven times if you take the efficiency of a Tesla Roadster.
About 13% of our transport fuel is used in applications which require liquid fuel - aviation and shipping - and this innovation has a great and potentially lucrative market there. But for the largest share of the transport market - private cars - the weight of the numbers strongly suggests that EVs are likely to be more successful.
I hate to splash even a few drops of cold water on new innovators’ work, as I’ve spent many years innovating myself - however I’ve also come to the conclusion that our media’s slightly hysterical obsession with the "new new thing" is destructive to the progress of clean energy. The fact is that the physics is quite simple, we have almost the technology we need already, and the main issue is not innovation, but deployment (and the incremental innovations and cost reductions that will follow from large scale deployment).
* The Numbers
Energy consumption of petrol car: 70 kWh/100 passenger-km (typical family car)
For electric car: 34 kWh/100p-km - Nissan Leaf, according to the US EPA.
For Tesla Roadster (2-seater sports car): 21 kWh/100p-km - EPA.
http://theenergycollective.com/node/133691
Re: Climate change could mean the extinction of our species
Re: Climate change could mean the extinction of our species
