A LOOK AT THE SCIENCE BEHIND THE FUSS
THIS IS FOR THE INTERESTED NON-SCIENTIST, BUT ANYONE IS WELCOME
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About Me - Who am I to think anyone would believe me on a subject like this?
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Quick Links to the Chapters and More
Global warming (climate change, if you prefer) is not just a political issue. It has been the subject of intense scientific study in recent years. If a study is scientific, it must, among other things, be based on evidence. In Chapter 1, the first slide show, called "Ancient Ice Sheets And Climate Evidence" you can see a few examples of evidence of ancient climates, some of which were cold enough to cover whole continents with ice sheets.
(In these slide shows, you may want to explore the links to references with more detail and then come back to the same slide. You should right click on the link and then pick "Open in New Window". Depending on circumstances, you may need to hold down the Control (Ctrl) Key while you are doing this. When you are ready to come back, just close or minimize the new window.)
The funny thing is that the full extent of the ice ages seem to have occured with the global average temperature not too much below the current one. It may have been as little as about 6 or 8 degrees Celsius (11 to 14 deg. Fahrenheit) below the current temperatures. The ice age climate was substantially different from now at an even smaller temperature difference, maybe 3 degrees C (5 deg. F) or so lower. Our current warming could take us 2 or 3 degrees C higher than now without much effort during the 21st century.
By the way, climate is average weather. We are not going to get into trouble trying to predict the daily weather here, just the average weather over large pieces of the world.
One indication of average weather is average temperature, and that is going up, at least around this planet. There are direct records of this, using thermometers of varioius types, going back about 150 years. However, it has been a big job to check the quality of all this data and match one set of measurements up against another. There is a look at this problem in Chapter 2, the second slide show, called "Increasing Global Temperature". Chapter 2 also shows you how much the temperature is going up. If you don't want to go through the whole slide show, you can see a global temperature graph here and also, with more explanation, down below in the pictures column.
But there are skeptics! And they have raised many questions. Now, here is the thing about skeptics - we need them. Scientists themselves are champion skeptics, and their questions to one another have strengthened science immeasurably. There have been intense debates about efforts to extend our knowledge of average global temperature to the time before thermometer-based records. Most of this work, however, has said that the current global temperature is the highest in at least the last 1000 years. You can also find a look at this debate in Chapter 2.
Here is another thing about skeptics, whether they are scientists or not - sometimes they are right, sometimes they are wrong, and sometimes they are silly. Chapter 3, "Scientists Must Be Skeptics", is a little essay on such ideas. It does not deal directly with global warming, just skepticism. For example, "They laughed at Galileo," we always say. But was he always right?
It is well known that the building materials in cities absorb more sunlight than the green areas of the countryside, so cities are warmer. Critics have claimed that this accounts for the observed warming - too many weather stations are in cities. But this is not true; the critics are wrong. Both urban and rural temperatures are increasing, and you can find the details in Chapter 4, "City Heat".
There are methods of looking at the Earth's temperature by Earth satellite, and for a while the satellite records seemed to contadict the ground-based measurements. Critics have jumped on this, but the satellites themselves had problems for at first. They have been straightened out, as described in Chapter 5, "The Satellite Story", and there is no longer any conflict between these two measurement methods.
Everyone talks about glaciers and how the world's glaciers are shrinking. But not all glaciers do shrink. Some are doing just fine, and this includes most of the glaciers that tourists see from cruise ships. There is a good reason for this: you can't even find most of the shrinking ones from cruise ships these days. However, many skeptics have used the advancing glaciers to suggest that the shrinking ones do not really imply anything special. I heard this idea repeatedly on a recent cruise. We saw Alaska's Hubbard Glacier, for example, which is advancing so fast that it threatens to cut off some important fishing areas. Some people on the ship thought that global warming was thereby disproven. You can check out many of my glacier pictures from this cruise here.
Unfortunately, glacier behavor actually supports global warming. There have been detailed scientific surveys of glacier mass loss, and the enormous scale of this loss is clear as are the special circumstances that cause some glaciers to continue to advance. You can check this out in some detail in Chapter 6, "Solid Flowing Rivers", which gives some background information about glaciers, and in Chapter 7, "Where Did Those Glaciers Go?". Chapter 7 uses the infomation from Chapter 6 to check out the current state of glacier science. It does not find anything to contradict global warming.
As of 2008, the old dream of a Northwest Passage (a natural water route between the Atlantic and the Pacific) seems close to reality, thanks to the dramatic summer melting of the floating ice around the North Pole. In Chapter 8, "The Melting Pole", you can discover just how rapidly this floating ice is deserting us. In fact its rate of decrease is greater than any single theory of global warming mechanisms, such as greenhouse gas, can explain. So researchers are studying it intensely, but this melting does seem associated with the warming of the rest of the world.
The ice sheet in Greenland is sitting on land and is up to two miles thick. But it is draining around the edges through outlet glaciers that have been speeding up. Chapter 9, "Greenland Becoming Greener" shows some of this as well as the increased melting on top of this ice sheet.
By far the largest reservoir of ice on earth is located around the South Pole in the Antarctic Ice Sheet. In Chapter 10, "Poles Apart, The Antarctic", you can see that most of antarctica is effectively isolated from the climate of the rest of the world. Therefore any warming that is taking place over most of the Earth is not penetrating into Antarctica. But there are some areas along the coastline where that is not true, and ice is being lost through speeding outlet glaciers and collapsing ice shelves (floating ice just off the coast).
Now, if you dump a lot of ice into the ocean, the water level will rise. That is not true when floating ice melts, but Greenland ice, most Antarctic ice, and mountain glaciers are not floating - they are sitting on land. So there has been a continuing rise in the level of the worlds oceans, something that is also fed by thermal expansion of the water itself. It turns out that the oceans, on the average, have been warming too, and generally warm things expand. Explore how much sea level rise there has been and some of the consequences in Chapter 11, "Rising Sea (coming soon)".
Something has been detected down the track.
Other Evidence- Wildlife etc.
What could be doing this?
Whut's a Greenhouse Gas?
Critics-Why Didn't I Reference More of Them? (It is not that I am ignoring them, but I just don't think that a lot of the criticism is right, and I will outline why. (And I'll point you to some of the critical sites anyway.)
What to do? What to do?
Basically, these gasses trap heat that is radiated away from the earth toward space and throw some of it back thus warming the earth. The picture below illustrates this. Click on it for a larger version.
