Universe Today

Earth's surface temperatures have mainly increased since 1880. Credit: NASA

A new NASA report says the past decade was the warmest ever on Earth, at least since modern temperature measurements began in 1880. The study analyzed global surface temperatures and also found that 2009 was the second-warmest year on record, again since modern temperature measurements began. Last year was only a small fraction of a degree cooler than 2005, the warmest yet, putting 2009 in a virtual tie with the other hottest years, which have all occurred since 1998. This annual surface temperature study is one that always generates considerable interest — and some controversy. Gavin Schmidt, a climatologist at NASA's Goddard Institute for Space Studies (GISS) offered some context on this latest report, in an interview with the NASA Earth Science News Team.
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Atmosphere layers. Image credit: NASA

Among the minority are the greenhouse gases, carbon dioxide being the most prominent of them all. These gases are presently cast as harmful to the planet, being the primary cause of global warming. Of course, they're only harmful because they've exceeded their ideal levels. Anything that comes in excess is not good, right?

At ideal levels, greenhouse gases play an important role in keeping our planet warm enough for us and other organisms to live comfortably. Unfortunately, the rapid rate of industrialization has caused greenhouse gases to accumulate, forming a layer too thick for infrared radiation (which originally came in from the Sun as solar radiation) to escape.

The different gases in the atmosphere actually make up five principal layers. Starting from the lowest layer, there's the Troposphere, followed by Stratosphere, then the Mesosphere, then Thermosphere, and finally the Exosphere.

The peak of Mount Everest, high as it is, is still part of the Troposphere. The Stratosphere is the layer at which most weather balloons fly. The Mesosphere is where meteors mostly ignite. The Thermosphere is where the International Space Station orbits.

Since the Karman line (which serves as the boundary between the Earth's immediate atmosphere and outer space) is found in the lower region of the Thermosphere, much of this layer of gases in the atmosphere is considered outer space. Finally, the exosphere, being the outermost layer, is where you can find the lightest gases: hydrogen and helium.

Many properties of the gases in the atmosphere are dependent on the altitude at which they are found. For instance, average density of these gases generally decrease as one rises to higher altitudes. As a result, the pressure (being due to the collisions of the particles that make up the gas) also decreases in the same manner.

Since the force of gravity pulls down on the masses of these gases, the heavier gases are typically found near the surface of the Earth while the lightest ones (e.g. hydrogen and helium) are found in higher altitudes. All these properties are just generalizations though. Temperature and fluid dynamics also influence these properties.

Want to learn more about the atmosphere and air pressure? You can read about both here in Universe Today.

Of course, you can find more info at NASA too. Follow these links:
Earth's Atmosphere
Earth

Tired eyes? We recommend you let your ears do the work for a change. Here are some episodes from Astronomy Cast:
Atmospheres
Plate Tectonics

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Although the effects of global warming are gradual, here are some pictures of global warming captured by satellite, so you can really see some of the changes happening to the Earth right now.

This is a picture of the retreat of Jakobshavn Glacier in Greenland. This glacier drains out about 6.5% of the Greenland ice sheet into the ocean. It's one of the fastest moving glaciers in the world, moving at a speed of 20 meters/day. It's one of the glaciers that contributes the most to potential sea level rise.

This image shows the predicted temperature rise from global warming in 2070-2100 over temperatures from the 1960s to the 1990s.

This is an image of the Larsen B ice shelf in Antarctica, which has been crumbling over the last few years. Some of the largest icebergs ever seen have broken away from this shelf.

This is an image of the rise in global carbon dioxide levels matched with the rise in global temperatures.

We've written many articles about global warming for Universe Today. Here's an article about how cosmic rays don't increase global warming, and here's an article about the effects of global warming.

If you'd like more info on global warming, check out NASA's Worldbook on global warming, and here's a link to NASA's Earth Observatory about global warming.

We've also recorded an episode of Astronomy Cast about Earth. Listen here, Episode 51: Earth.

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Ever since some Global Warming advocates drew a connection between Global Warming and hurricanes, more people have grown a deeper concern regarding the environment. Why wouldn't they? They've seen what hurricanes like Katrina and Andrew can do. Well, if we know how hurricanes are formed, we can draw that connection ourselves.

Hurricanes develop when great amounts of water vapor condense rapidly in the atmosphere. How does this happen? Well, how does water vapor form in the first place? That's right – through evaporation. But what causes evaporation? Again, you've got that right – heat. Since higher water temperatures mean more heat, it also means more evaporation.

Now, when the rate of evaporation is high, water vapor accumulates very fast. However, does this necessarily mean the rate of condensation should likewise be very fast?

The rate of condensation does not depend substantially on the rate of evaporation. However, it does depend on the heat of the atmosphere immediately above the body of water. If the temperature in the atmosphere is also high, then the air (and the great amount of water vapor in it) will rise quickly. This rapid ascent is also accompanied by a rapid expansion.

Now, when air expands, it cools. When its temperature subsequently drops, so does its dew point – or the point when a particular body of air experiences condensation. Ah, so there's the connection now. A rapidly rising and expanding air, which is largely caused by the presence of high temperatures, can also result in rapid condensation – and subsequently, rain formation.

As soon as the air ascends rapidly, it leaves a low pressure area in the region below it. This enables air from the surroundings to rush in and fill the void. These onrushing winds collide and are then forced to likewise move upward. As it does, more moisture is added to the air. Again, the rapidly rising air also causes condensation and more rain.

But that's not the end of the story. The condensation also releases great amounts of heat. Remember how heat started this little low pressure area in the first place? Well, the newly released heat can further fuel this low pressure area and allow it to develop into a tropical depression.

If this build-up of energy, moisture, wind velocities, and rain continues, it can then develop into a hurricane. So now that you know how hurricanes are formed, let me ask you – is there a connection between Global Warming (that means warmer oceans) and hurricanes?

Aside from hurricanes, what are the other effects of Global Warming? We've got answers to that question here in Universe Today. Click these links to learn more about them:
Effects Of Global Warming
Global Warming Effects

Can rising temperatures really shut down plate tectonics? Find out here in Universe Today. Another interesting question: Could cosmic rays influence global warming?

An article in NASA talks about how the recent warming in the Arctic may affect worldwide climate. There's another one that discusses short-term ocean cooling and how it suggests a global warming 'speed bump'.

Relax and listen to some interesting episodes at Astronomy Cast. Want to know more about Ultraviolet Astronomy? How different is it from Optical Astronomy?

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There is a growing awareness and concern on global warming and its effects on our agricultural, economic, and political landscape. There is however another threat that we should be more worried about – it's called abrupt climate change.

The global warming that we know of is predicted to take place in a gradual but sure pace and expected to last for centuries. That is, after a century, the global temperature may rise by up to 5.8 degrees. The consequences are disastrous: rising sea levels that can submerge the world's major cities as well as violent weathers such as super droughts and super hurricanes.

However, because of human intelligence, the effects can be mitigated. One century will give us ample time to set up our defenses or to relocate to higher ground if necessary. But what if climate changes will happen much faster than expected? What if it will happen in a decade or two? Surely, no government will be prepared to handle the effects of such an abrupt climate change.

Is it possible for an abrupt climate change to occur? Well, it has happened before; it can happen again. There's the Younger Dryas, which occurred 12,800 to 11,500 years ago; the 25 climate shifts known as the Dansgaard-Oeschger cycles; the Paleocene-Eocene Thermal Maximum, which may have happened some 55 million years ago; and the Permian-Triassic Extinction Event, which is believed to have caused the extinction of up to 95% of the Earth's species.

Such events typically last relatively quickly, unlike global warming. For instance, the Younger Dryas was believed to have lasted only a little over a century. The problem main problem however lies in the abruptness of the occurrence, which usually gives the Earth's inhabitants very little time to prepare.

How can an abrupt climate change occur?

One possible switch that can trigger an abrupt climate change is the shutdown of the thermohaline circulation. The thermohaline circulation (THC) is a part of the global ocean circulation that is driven by temperature and salinity differences. The THC is largely responsible for regulating the Earth's global temperatures.

It draws warm and salty water into the North Atlantic, releases heat to the relatively cooler regions of Northern Europe, and allows the remaining salty water to plunge to the bottom. After which, it allows this current to flow in the deeper regions, into the South Atlantic and then to the other oceans, thus completing the cycle.

Once this cycle is stopped, Northern Europe will stop receiving heat and plunge into extreme coldness. In the same breadth, other parts of the world will experience mega droughts.

It is for this reason why some scientists are more concerned with abrupt climate change than global warming in general.

Can rising temperatures really shut down plate tectonics? Find out here in Universe Today. Another interesting question: Could cosmic rays influence global warming?

An article in NASA talks about how the recent warming in the Arctic may affect worldwide climate. There's another one that discusses short-term ocean cooling and how it suggests a global warming 'speed bump'.

Relax and listen to some interesting episodes at Astronomy Cast. Want to know more about Ultraviolet Astronomy? How different is it from Optical Astronomy?

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Ice cores and deep sea bed cores provide the best available record of changes in global temperature and CO2 content of the atmosphere going back 800,000 years. The data shows a clear periodicity in global temperatures which is thought to be linked to the Milankovitch cycle.

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In Al Gore's documentary film, "An Inconvenient Truth", he mentioned that Global Warming is now causing more violent and more frequently occurring hurricanes. To establish the connection between the two (GW and hurricanes), let's try to dissect the origins of these hurricanes and answer first the question, "How do hurricanes form?"

Hurricanes are typically formed in the oceans of tropical regions, where the temperatures are at least 27 degrees Celsius and there is lots of moisture in the air. Why is this necessary?

Because when the temperatures are high, water can easily evaporate and add water vapor into the atmosphere. Also, when air in the atmosphere is warm, it starts to expand. As it expands, its density drops and it begins to rise. The higher the temperature in the region, the faster the air rises.

This event of course leaves a low pressure region right below it. Air in the surroundings then promptly move in to fill the void. Always remember – moving fluid (that includes air) always goes from a region of relatively high pressure to a region of relatively low pressure.

The rising, expanding air naturally cools as it goes higher. As a result, condensation ensues and storm clouds and rain develop. The condensation process in turn releases heat, which fuels the slowly developing tropical depression.

As winds converge at the bottom of the low pressure region, more air is pushed upward. This air reinforces the rising air mentioned earlier. The cycle continues for as long as there is sufficient moisture and heat.

When this low pressure area is accompanied by wind speeds of up to 38 mph, it is known as a tropical depression. When the wind speeds reach 39 to 73 mph, it is then classified as a tropical storm. Finally, when the wind speeds exceed 74 mph, you'll then have a hurricane in your hands.

Notice how important the presence of heat and moisture is in the development of a hurricane. Without them, a tropical depression cannot hope to evolve into a hurricane.

Now that we know the answer to the question, "How do hurricanes form?", we can now easily identify the link between hurricanes and Global Warming. With Global Warming, you can bet that the temperatures in tropical regions can get higher than usual. This will naturally result into more heat and more moisture.

Aside from hurricanes, what are the other effects of Global Warming? We've got answers to that question here in Universe Today. Click these links to learn more about them:
Effects Of Global Warming
Global Warming Effects

Can rising temperatures really shut down plate tectonics? Find out here in Universe Today. Another interesting question: Could cosmic rays influence global warming?

An article in NASA talks about how the recent warming in the Arctic may affect worldwide climate. There's another one that discusses short-term ocean cooling and how it suggests a global warming 'speed bump'.

Relax and listen to some interesting episodes at Astronomy Cast. Want to know more about Ultraviolet Astronomy? How different is it from Optical Astronomy?

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Temperature trends in the Arctic. Image credit: NASA

The North Polar Basin is divided into two oceanic basins, the Eurasian and the Amerasian, by the Lomonosov Ridge. The Lomonosov Ridge, which is about 1800 km long, stretches from the New Siberian Islands, over the central part of the Arctic Ocean, and ending in an island in the Canadian Arctic Islands.

The Eurasian Basin and the Amerasian Basin, which have maximum depths of about 4.5 km and 4 km respectively, are further subdivided by underwater ridges into the Canada, Makarov, Fram, and Nansen basins. A large part of the Arctic Ocean is shallower than the maximum depths mentioned earlier. In fact, the average depth of the Arctic Ocean is only about 1.04 km.

Not only is the Arctic Ocean the shallowest and smallest of the five major oceans, it also has the lowest salinity. This is because of the influx of freshwater from rivers and streams in the surrounding land masses. This rate of influx is believed to be increasing due to global warming and may eventually result in the ocean being ice free between 2013 and 2040.

If a substantial amount of fresh meltwater is introduced into the North Atlantic, which is connected to the Arctic Ocean via the Greenland Sea and Labrador Sea, it may cause unpredictable changes in the global ocean current.

The area covered by and within the vicinity of the Arctic Ocean is the natural habitat of polar bears, the largest land-based carnivore species. It specifically dwells along the Arctic ring of life, where seals, the polar bear's main prey, are abundant. Due to global warming, which can melt the sea ice on which the polar bears hunt, these giant creatures are under threat.

Another area in the Arctic Ocean of major concern is Greenland, the world's largest island (excluding continental islands). Greenland is covered by colossal ice sheets, which when melted, can cause water levels around the world to rise. It is predicted that the melting of the Greenland ice sheet can submerge major cities like New York, Shanghai, London and Tokyo.

Want to learn more about the Arctic Sea Ice? Read about it here in Universe Today. Did you know that the Arctic Sea Ice extent is the third lowest on record?

NASA has an article talking about the Arctic warming and its effect on worldwide climate. Here's a more recent article, also from NASA, talking about Arctic sea ice changes that have led to record lows in 2007.

Tired eyes? Listen to some episodes at Astronomy Cast. Here's what we recommend:

The Sun, Spots and all
Comets, Our Icy Friends From the Outer Solar System

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If you've started asking the question, "How to stop global warming?", you've made one step to the right direction. Here are some simple tips that can guide your way.

Since automobile emissions are the top contributors to global warming, a lot can be achieved by decreasing them.

A lot of emissions can be done without every time you leave your car in the garage. So take a public transport or participate in a car pool. You might find these practices very inconvenient but they're nothing compared with the inconveniences that may accompany global warming. Think of a submerged city, floods, and powerful hurricanes, and those practices won't be so tiresome anymore.

When you really need to take your car out, drive efficiently. That is, make sure your air filters are clean and your tires have the right pressure. These minute details can make your car perform optimally. A lot of fuel is consumed when you accelerate so, as much as possible, avoid accelerating. To achieve this, drive slow and avoid traffic or circuitous routes.

If you're planning to purchase a new car, go for those models with better gas mileage. If you can, choose hybrid cars. They are typically powered by two different types of energy sources. For instance, a Hybrid Electric Vehicle (HEV) operates through a gas internal combustion engine and an electric motor.

Much can be done even inside your house to help solve global warming.

For instance, you may replace all your light bulbs with compact fluorescent light bulbs. They consume lesser electricity than incandescent or fluorescent versions having the same brightness. Now, regardless of the type of bulb you use, make it a point to switch them off when you don't need them.

When buying a new appliance, look for the Energy Star logo. Computer monitors, refrigerators, heaters, air conditioners that bear the Energy Star logo consume lesser energy for the same expected output. Just like light bulbs, the less frequent appliances are allowed to operate, the better it is for our environment, so switch them off when you don't need them.

Now that you've found out how to stop global warming, it's time to make that first step and actually apply what you learned.

Curious to know why global warming may be irreversible? We've got an article about that here in Universe Today. Also here, an article about the accelerating rate of global warming.

Want more solutions? Here are ten solutions from the Union of Concerned Scientists. Check out the Energy Star site too while you're at it.

Tired eyes? Let your ears help you learn for a change. Here are some episodes from Astronomy Cast that just might suit your taste:
Nucleosynthesis: Elements from Stars
Advanced Propulsion Systems

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Even if we bring down carbon emissions to acceptable levels, the effects of global warming will not stop. This is because it takes a lot of time before our oceans can release the substantial amount of heat it already absorbed. What we hope to achieve is to decelerate the rate of that warming and eventually tone down the effects.

In essence, the global warming solutions we implement today, will not bear fruit for us. Rather, it will be future generations that will stand to benefit from our efforts. So if you're concerned about the future of humanity, do read on.

Take part in or organize a carpool. Talk to your officemates or schoolmates about the benefits of carpooling. Not only will you be doing mother nature a favor, you'll also be bringing down your fuel expenses. If three grown-ups from different households take part in a carpool, they will have reduced their carbon emissions to practically a third.

Plan your route before you drive. Choose the shortest path with the least amount of traffic because low gears consume more fuel. If you need to make some stops to buy some stuff, look for a less circuitous route. If possible, choose one-stop shops. Each time you step on the breaks, you'll need to step on the accelerator to speed up again. This consumes more fuel than a steady drive.

Replace your incandescent and fluorescent bulbs with compact fluorescents. Although one light bulb's contribution to your electricity consumption is but a small fraction of the whole, I'm pretty sure you have more than a handful of bulbs in your home. Compact fluorescents, which are definitely more energy efficient, are initially more expensive but they'll help you save in the long run as they can last way longer than regular bulbs.

Always look for the Energy Star when buying a new appliance see image above. Appliances marked with the Energy Star logo are more efficient. You can find them in computer monitors, television sets, air conditioners, refrigerators, freezers, water heaters, and others.

Plant trees. That's right, what environmentalists have been preaching way back still hold true today. Trees consume carbon dioxide for their food processes. What's more, they can prevent floods from escalating because they can suck up a great amount of water. Thus, tree planting provides two global warming solutions: one that prevents global warming and one that deals with one of its devastating effects, i.e., flooding.

Curious to know why global warming may be irreversible? We've got an article about that here in Universe Today. Also here, an article about the accelerating rate of global warming.

Want more solutions? Here are ten solutions from the Union of Concerned Scientists. Check out the Energy Star site too while you're at it.

Tired eyes? Let your ears help you learn for a change. Here are some episodes from Astronomy Cast that just might suit your taste:
Nucleosynthesis: Elements from Stars
Advanced Propulsion Systems

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Icebergs coming off of a collapsed ice bridge on the Wilkins Ice Shelf in Antarctica. Credits: ESA (Annotations by A. Humbert, Münster University)

An Antarctic ice shelf is generally much thicker than sea ice, with thickness ranging from 100 to 1,000 meters.

Antarctica's major ice shelves include (by order of decreasing size): Ross, Ronne-Flichner, Amery, Larsen C, Riiser-Larsen, Fimbul, Shackleton, George VI, West, and Wilkins. Ross, at about 473,000 square kilometers, is even larger than the State of California.

Because of Global Warming, many of the Antarctic's ice shelfs are under threat. In fact, a number of them have lost a substantial amount of mass due to melting, calving, or complete disintegration. This is the reason why scientists are extensively monitoring these colossal structures.

Perhaps the most widely publicized degradation of an Antarctic ice shelf is the disintegration of the Larsen Ice Shelf, which was featured in Al Gore's Global Warming documentary, "An Inconvenient Truth". The Larsen Ice Shelf broke up into tiny pieces – about hundreds of meters wide. That's very small considering the massive sizes of these structures.

The biggest Antarctic ice shelf that is about to break away is the Wilkins Ice Shelf, which is about 150 km x 110 km. That's roughly the size of Hawaii.

Although only found in extremely cold regions like Antarctica, Greenland, and Canada, massive ice shelves can raise water levels worldwide when they melt. This is because the water making up the ice shelf is fresh water, which is less dense compared to sea water.

To understand why this will happen, try to observe a floating ice cube placed in a glass of water. Mark the water level and cover the opening so as to prevent any water molecule from escaping as water vapor. Notice that when the ice cube totally melts, the water level remains the same.

That's because the density of water that makes up the ice cube is equal to the density of the water in the glass. Because of this, the volume of water displaced to keep the ice cube afloat should just be equal to the volume of water that makes up the ice cube.

Now, consider an ice cube containing the same volume of water as in the previous scenario but with a lesser density (yes, it's an imaginary kind of water too). If you dropped this imaginary ice cube into the same glass of water, a lesser amount of water will be displaced to keep the ice cube afloat.

Since we mentioned that the imaginary water making up the ice cube contained the same volume as the cube in the previous example, this volume will exceed that of the displaced water. As a result, when the ice cube totally melts, the water level in the glass will rise.

Curious to know why global warming may be irreversible? We've got an article about that here in Universe Today. Also here, an article about the accelerating rate of global warming.

Want more solutions? Here are ten solutions from the Union of Concerned Scientists. Check out the Energy Star site too while you're at it.

Tired eyes? Let your ears help you learn for a change. Here are some episodes from Astronomy Cast that just might suit your taste:
Nucleosynthesis: Elements from Stars
Advanced Propulsion Systems

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I came across a site today that ranked second in the Google search results for the keyword "global warming. It had different views regarding global warming compared with the one ranked as number one. So if you're looking for an answer to the question, "What is global warming?", you'll end up with more questions than answers if you ended your search with these two.

Now, I don't think you'll end your search here either, most of what you'll find on this article come from two reliable sources of information on the Web when it comes to our planet and its climate: NASA and the IPCC (Intergovernmental Panel on Climate Change). What do they have to say as with regards the question, "What is global warming?"

Global warming is the rise in average temperature of the Earth's surface. In the current warming, it is predicted that the average temperature will increase by an additional 5.8 degrees C by the year 2100.

This will result in the melting of polar ice (well, actually, the polar ice HAS started to melt), which in turn can raise the water levels worldwide. When this happens, cities near coastlines will be greatly affected. Even if the levels won't rise to 20 feet (as claimed by some), the mere intrusion of the sea inland would increase the salinity of water underground. This would affect many communities that would have had freshwater from a deep well.

The current global warming is mainly attributed to the accumulation of greenhouse gases in the atmosphere; most notably, carbon dioxide. The increase in carbon dioxide as well as other greenhouse gases during the recent years has been caused by human activities. That essentially means, humans can provide the solution as well … by decreasing those activities perhaps?

Studies have shown a remarkable increase in the occurrence of extreme weather conditions like heat waves, droughts, floods, and hurricanes. These have been identified as some of the effects of global warming.

Most recent findings show that the effects of global warming won't stop immediately even if we implement drastic measures now to reduce greenhouse gas emissions. This is mainly due to the substantial amount of heat absorbed by the Earth's oceans. This heat will have to be gradually released to bring back the average temperature to past levels.

We've got a good bunch of interesting articles related to global warming here in Universe Today. Here are my personal favorites:

• NASA Administrator Isn't Sure Global Warming is a Problem
• There Is No Sun-Link with Global Warming

Here's an article at NASA that defines what global warming is.

I also found a neat pdf of FAQs regarding global warming from the IPCC site.

Tired eyes? Let your ears help you learn for a change. Here are some episodes from Astronomy Cast that just might suit your taste:
The Search for Extraterrestrial Intelligence
Advanced Propulsion Systems

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Water has a much higher specific heat capacity than most substances. That means, it can absorb a lot of heat before its temperature will change. That also means, a slight increase in water temperature is a hint that it has already taken in a lot of heat.

Now, there's one reason why scientists are very concerned with the rising average ocean water temperature. For such huge bodies of water to experience even the slightest increase in average temperature, they should have absorbed a great amount of heat.

We'll go back to that later. First, let's have a short discussion on the effects of heat absorbed between the land and the ocean.

Compared to the ocean, land requires a much smaller amount of heat in order for its temperature to rise. On a regular hot day, practically the same amount of heat gets absorbed both by land near the ocean and the ocean itself. However, the land's temperature rises faster.

This causes air above the land to heat up, expand, and rise much faster than the air above the ocean, creating a relatively lower pressured region in the space it once occupied before rising. To fill in the partial void, air from above the ocean moves in. That's the reason why, on a normal day, the wind blows inland.

Anyway, what I'd like you to focus on is the fact that the temperature on land rises faster. Thus, if the ocean water temperature has risen to levels higher than normal, what does it mean for temperatures on land? It means that land temperature must have risen much more rapidly!

No wonder why the permafrost and Greenland's ice sheet is melting fast.

There's an even more alarming consequence of the rising ocean water temperature. Remember how water can absorb huge amounts of heat first before experiencing a rise in temperature? Because of the ocean's enormous heat capacity, it must have taken a very long time for the temp to reach the levels it is currently in.

Consequently, it will also have to take a great amount of time before all the excess heat is given off and the ocean water temperature to return to normalcy. Recent findings show that the effects of global warming will continue even beyond the year 2100 because this.

There's little we can do to remove all that heat from the ocean. We can, however, slow down whatever is causing the heat to further build up there.

Can rising temperatures really shut down plate tectonics? Find out here in Universe Today. Another interesting question: Could cosmic rays influence global warming?

An article in NASA talks about how the recent warming in the Arctic may affect worldwide climate. There's another one that discusses short-term ocean cooling and how it suggests a global warming 'speed bump'.

Relax and listen to some interesting episodes at Astronomy Cast. Want to know more about Ultraviolet Astronomy? How different is it from Optical Astronomy?

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As governments continue to debate about how to tackle global warming (some even argue as to whether it is in fact exactly as described by the IPCC), its effects are becoming more evident. In fact, some of the global warming effects are turning out to be more serious than they were initially expected to be.

One such effect is the rate of shrinkage of the Arctic. It is turning out to be faster than was predicted by the IPCC or Intergovernmental Panel on Climate Change. As the Arctic ice reduces in size and more and more water is exposed, lesser heat from the sun gets reflected and more of it gets absorbed by the body of water in that region.

This will further accelerate the shrinkage and subsequently hasten other effects felt in other areas in the globe.

As the Earth's surface raises its temperature, rainfall patterns become unpredictable. In certain areas, there may be heavy rainfall, while others (even adjacent ones) may experience very little or no rainfall at all.

Among the recently experienced weather phenomena which may be counted among global warming effects are the extremely powerful hurricanes and typhoons. Those who have experienced the wrath of Hurricane Katrina in the US and Typhoon Ketsana in Southeast Asia will be first to attest that these weather conditions were the worst in their lifetime.

Perhaps the most dreaded effect of all is the rise in sea levels. When this happens, economic, environmental and health-related impacts are expected to be disastrous.

As the sea advances inland, areas with freshwater will become saline, making them less usable for drinking or even bathing. Mosquito levels, which are dependent on sea levels, will also rise. Thus, places which are currently mosquito free will later on be infested with these pests.

Many of the world's highly populated cities will be affected by the rising sea levels. Among them are New York, London, Miami, New Orleans, Cairo, Mumbai, Amsterdam, Tokyo, and Shanghai. Millions of people are living in these cities, so imagine the effects when they become displaced.

It is expected that global warming effects will persist even if governments implement the most drastic measures to bring down carbon dioxide emissions. This is because oceans, due to water's very high heat capacity, should have been able to absorb huge amounts of heat for the temperatures to have risen this high.

As a result, it will take a great amount of time before what has been absorbed to be released and ocean temperatures to return to normal.

Can rising temperatures really shut down plate tectonics? Find out here in Universe Today. Another interesting question: Could cosmic rays influence global warming?

An article in NASA talks about how the recent warming in the Arctic may affect worldwide climate. There's another one that discusses short-term ocean cooling and how it suggests a global warming 'speed bump'.

Relax and listen to some interesting episodes at Astronomy Cast. Want to know more about Ultraviolet Astronomy? How different is it from Optical Astronomy?

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A new national survey conducted by Pew Research shows that more Americans are growing skeptical of global warming. This, despite the fact that the scientific opinion on climate change remains steadfast in endorsing the position of the IPCC (Intergovernmental Panel on Climate Change), which attributes most of the global warming observed over the last 50 years to human activities.

So what exactly are the human-related factors that cause global warming?

The most impactful global warming causes fall under one general heading: the increasing concentration of greenhouse gases in the atmosphere. This is largely due to emissions brought about by human activity. First, we'll identify the greenhouse gases, then we'll pinpoint their most likely sources.

The gases that have been largely identified with the greenhouse effect are: water vapor, which accounts up to 70%, carbon dioxide (up to 26%), then methane and ozone.

It is in carbon dioxide emissions where humans are identified as accomplices to global warming causes. The rise in carbon dioxide emissions can be traced back to the start of the Industrial Revolution in the 18th century.

About 75% of the increase in atmospheric carbon dioxide over the past 20 years is attributed to fossil fuel burning, while much of the remaining percentage is believed to be caused by deforestation (also a man-made activity).

While fossil fuel burning results in emissions of up to 21 billion tonnes of carbon dioxide every year, only half of that can be used up by the environment. As such, the remaining 10.5 billion tonnes are accumulated in the atmosphere, preventing heat from the Sun from leaving.

Some products of fossil fuels are gasoline, diesel and coal. These materials are used in automobiles, coal-powered plants, and other machines. What machine do you know that doesn't run purely on these materials? Not many, right? The vehicles you ride each day and the electricity you consume in your homes and offices all rely heavily on fossil fuel.

Is it therefor still surprising that carbon dioxide levels are rising?

Not everyone is quick to point an accusing finger to human beings and their activities as major contributors to global warming causes. There are those who believe it (global warming) as a consequence of increased solar output, volcanic activity, and other variables related to the Earth's orbit around the Sun.

If the question however is, what does the scientific community say? Well, we already know the answer.

Want to see some pictures of global warming? We've got them here in Universe Today. Perhaps you'd also want to read the peculiar article: NASA Uses 90 Rubber Ducks to Study Global Warming.

Since we've mentioned NASA, here are some global warming related articles from their site.

Global Warming
NASA Study Predicts More Severe Storms With Global Warming

Here are some interesting episodes from Astronomy Cast:

Galileoscope, Black Hole Time, and What Exactly is Energy
Energy Levels and Spectra

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