Earth's Hot Past Could Be Prologue to Future Climate

The study, by National Center for Atmospheric Research (NCAR) scientist Jeffrey Kiehl, will appear as a "Perspectives" piece in this week's issue of the journal Science.

Building on recent research, the study examines the relationship between global temperatures and high levels of carbon dioxide in the atmosphere tens of millions of years ago. It warns that, if carbon dioxide emissions continue at their current rate through the end of this century, atmospheric concentrations of the greenhouse gas will reach levels that existed about 30 million to 100 million years ago, when global temperatures averaged about 29 degrees Fahrenheit (16 degrees Celsius) above pre-industrial levels.

Kiehl said that global temperatures may gradually rise over centuries or millennia in response to the carbon dioxide. The elevated levels of carbon dioxide may remain in the atmosphere for tens of thousands of years, according to recent computer model studies of geochemical processes that the study cites.

The study also indicates that the planet's climate system, over long periods of times, may be at least twice as sensitive to carbon dioxide than currently projected by computer models, which have generally focused on shorter-term warming trends. This is largely because even sophisticated computer models have not yet been able to incorporate critical processes, such as the loss of ice sheets, that take place over centuries or millennia and amplify the initial warming effects of carbon dioxide.

"If we don't start seriously working toward a reduction of carbon emissions, we are putting our planet on a trajectory that the human species has never experienced," says Kiehl, a climate scientist who specializes in studying global climate in Earth's geologic past. "We will have committed human civilization to living in a different world for multiple generations."

The Perspectives article pulls together several recent studies that look at various aspects of the climate system, while adding a mathematical approach by Kiehl to estimate average global temperatures in the distant past. Its analysis of the climate system's response to elevated levels of carbon dioxide is supported by previous studies that Kiehl cites. The work was funded by the National Science Foundation, NCAR's sponsor.

Learning from Earth's past

Kiehl focused on a fundamental question: when was the last time Earth's atmosphere contained as much carbon dioxide as it may by the end of this century?

If society continues on its current pace of increasing the burning of fossil fuels, atmospheric levels of carbon dioxide are expected to reach about 900 to 1,000 parts per million by the end of this century. That compares with current levels of about 390 parts per million, and pre-industrial levels of about 280 parts per million.

Since carbon dioxide is a greenhouse gas that traps heat in Earth's atmosphere, it is critical for regulating Earth's climate. Without carbon dioxide, the planet would freeze over. But as atmospheric levels of the gas rise, which has happened at times in the geologic past, global temperatures increase dramatically and additional greenhouse gases, such as water vapor and methane, enter the atmosphere through processes related to evaporation and thawing. This leads to further heating.

Kiehl drew on recently published research that, by analyzing molecular structures in fossilized organic materials, showed that carbon dioxide levels likely reached 900 to 1,000 parts per million about 35 million years ago.

At that time, temperatures worldwide were substantially warmer than at present, especially in polar regions -- even though the Sun's energy output was slightly weaker. The high levels of carbon dioxide in the ancient atmosphere kept the tropics at about 9-18 degrees F (5-10 degrees C) above present-day temperatures. The polar regions were some 27-36 degrees F (15-20 degrees C) above present-day temperatures.

Kiehl applied mathematical formulas to calculate that Earth's average annual temperature 30 to 40 million years ago was about 88 degrees F (31 degrees C) -- substantially higher than the pre-industrial average temperature of about 59 degrees F (15 degrees C).
For more info- http://www.sciencedaily.com/releases/2011/01/110113141607.htm

When the Black Hole Was Born: Astronomers Identify the Epoch of the First Fast Growth of Black Holes

Now a team of astronomers from Tel Aviv University, including Prof. Hagai Netzer and his research student Benny Trakhtenbrot, has determined that the era of first fast growth of the most massive black holes occurred when the universe was only about 1.2 billion years old -- not two to four billion years old, as was previously believed -- and they're growing at a very fast rate.

The results will be reported in a new paper soon to appear in The Astrophysical Journal.

The oldest are growing the fastest

The new research is based on observations with some of the largest ground-based telescopes in the world: "Gemini North" on top of Mauna Kea in Hawaii, and the "Very Large Telescope Array" on Cerro Paranal in Chile. The data obtained with the advanced instrumentation on these telescopes show that the black holes that were active when the universe was 1.2 billion years old are about ten times smaller than the most massive black holes that are seen at later times. However, they are growing much faster.

The measured rate of growth allowed the researchers to estimate what happened to these objects at much earlier as well as much later times. The team found that the very first black holes, those that started the entire growth process when the universe was only several hundred million years old, had masses of only 100-1000 times the mass of the sun. Such black holes may be related to the very first stars in the universe. They also found that the subsequent growth period of the observed sources, after the first 1.2 billion years, lasted only 100-200 million years.

The team found that the very first black holes -- those that started growing when the universe was only several hundred million years old -- had masses of only 100-1000 times the mass of the sun. Such black holes may be related to the very first stars in the universe. They also found that the subsequent growth period of these black holes, after the first 1.2 billion years, lasted only 100-200 million years.

The new study is the culmination of a seven year-long project at Tel Aviv University designed to follow the evolution of the most massive black holes and compare them with the evolution of the galaxies in which such objects reside.

Other researchers on the project include Prof. Ohad Shemmer of the University of North Texas, who took part in the earlier stage of the project as a Ph.D student at Tel Aviv University, and Prof. Paulina Lira, from the University of Chile.
For more info- http://www.sciencedaily.com/releases/2010/12/101227101113.htm

Climate Change - The Coming Crisis

While many contend that there are different reasons behind the changing of our climate, few can deny that our planet is going through a period of immense changes. While some may discredit the science, global warming is one of the main hypothesis for why our planet is heating up. In this article, we'll try to explain some of the science behind global warming so that you can understand the problem more clearly.

According to numerous scientific studies, our planet\'s surface temperature has increased by about 1 degree Fahrenheit within the last century. Most of this change has occurred in the past two decades, prompting the question: are our lifestyles accelerating this global change? The evidence definitely seems to point in that direction.

Many scientists point to the emission of greenhouse gases as one of the leading reasons that we are undergoing this global change. Carbon dioxide, methane, and nitrous oxide are some of the main compounds that we are releasing more and more, causing something known as the 'Greenhouse Effect'. This occurs due to the fact that these gases tend to trap heat, and when they are released into our upper atmosphere, they trap some of the heat energy that would normally be reflected by our earth's natural processes.

It's an undisputed fact that there is more greenhouse gas in our atmosphere due to humanity. Since the beginning of the industrial revolution, it is estimated that the amount of carbon dioxide in the atmosphere has increased by as much as thirty percent. While a little greenhouse gas helps to keep our planet warm, the more and more that we release, the hotter the planet is going to get. That is an important fact to consider, being that our biosphere is finely tuned to live at the temperatures at which our planet currently operates. Many forms of both plant and animal life run the risk of extinction should the temperature change be accelerated. Fossil fuels are primarily responsible for the amount of greenhouse gases that we are releasing, and to help fix the problem, we are going to need to find an alternate source of energy, and quick. Research into alternative fuels has yielded several possible options, including the use of corn in the production of ethanol, which has already had proven usage in places such as Venezuela. The most accelerated period of temperature change has occurred in the past twenty years, and it's clearly evident that we need to address this problem while we still can.

Source- http://www.ezine-articles.org/ezinearticles/science/climate-change-the-coming-crisis.html 

What Are Flow Meters?

Basically speaking, flow meters are devices which are used to measure the velocity of a gas or liquid in the given passage. There are many, many types of flow meters, each having their own specific use. Their application too is very diverse, as you will find the use of flow meters in aeronautics, meteorology, engineering and so on.

What Do The Flow Meters Actually Do?

Well, as mentioned above, the flow meters measure how much gas or liquid has passed through a device by the help of the velocity of the gas/liquid. The flow meters measure the mass and not the volume. The accuracy of the reading and overall results will depend upon the purity of the liquid or gas, as well as whether the flow meters and its parts were clean and free of any obstacles.

There are a great variety of these devices and each one of them has typical applications. Some are used to measure air, some are used to measure fuel, and some are used to measure oil and so on. For each type of liquid and or gas, the specification, the use and the application of the device will differ.

Thankfully, the variety and the science that backs the concept gives very accurate answers which helps in a number of automotive and mechanical applications. It is lovely how far science has progressed and developed this simple device of flow meter which as a matter of fact, was used even in the Roman Empire.

This fact shows first of all, that man's interests have not changed too much in the last so many decades that passed; it also shows that the ancient civilizations were much more knowledgeable than we give them credit for. The fact that the concept of the flow meters was found applied so much far in the past, forces the modern man to reconsider their knowledge and beliefs about the ancient civilizations and their understanding of science and how it can be applied for the promotion of a better and more comfortable life.

There are a great deal of developments in the field of the flow meters today, as their applications too have been diversified according to the development of technology and advancement of science. However, the basic fact remains that the concept is as old as the Romans, and may be even before that. This is something that gives the modern man a wake-up call regarding the science of the ancient civilization, which we have so far, ignored as superstitions and pagan rites and beliefs.

This article is taken from- http://www.ezine-articles.org/ezinearticles/science/what-are-flow-meters.html