Background on the Global Warming Debate

As you may or may not know one of the more controversial topics in the world today is global warming.

• Some people believe that global warming is a serious threat to our society, economically, socially, politically, and action must be taken immediately to try to alleviate it's effects.
• Others believe global warming to be a myth and any actions taken in response to global warming will be harmful to the economy and therefore society as a whole.
• These are the extreme viewpoints. There are many who believe somewhere in the middle when it comes to global warming issues (such as, it's happening, but it is not a threat, or it can lead to minor problems, so let's find a way to adjust), and equally many who simply do not have an opinion.

This week, part one of the Global Warming Debate, we will present the facts about global warming, the basic arguments presented by both sides, and the political climate with regards to global warming. You will be responsible for interpreting various viewpoints on an issue, and formulating your own opinion based on the facts, and the quality of the reasoning. It is perfectly possible for two people to look at the same facts, and hear the same arguments, and come to different conclusions about what needs to be done.

So what is the problem?

The problem is that the global average temperature has been rising in recent decades. NASA-Goddard Institute for Space Studies has a page showing these changes of the global average temperature, as well as changes locations and in different seasons. The 2000 year temperature trend also shows the warmer temperatures this century. Many people believe this temperature change is associate with increases in carbon dioxide. This is because of the greenhouse effect.

Some have criticized the validity of the data showing an increase in global mean temperature because satellite data has shown the opposite trend. However, this opposite trend is focused mainly on the temperatures in the upper atmosphere, whereas the surface temperature trends shown above are only for the surface.

The next questions involve the actual relationship betweengreenhouse gases and temperature increases, as well as whether or not us humans are actually causing the greenhouse gases to increase.

Some believe that climates will change significantly as a result of global warming. Look at a few examples in the Midwest, according to this link, Wisconsin summers in 2095 will be the equivalent of Arkansas summer now. This could lead to adverse conditions for certain species of plants and animals, disrupting the food supply, or in other cases, increase the length of the growing season, adding to the food supply. Many also believe that global warming will lead to more disease being spread from the tropics, sea level rise as a result of melting polar ice caps, more hurricanes, and fires. See early warning signs.

Feedback Loops

There are many theories on Global Warming, some of which involve the ideas of feedback loops.

• A positive feedback loop is one that amplifies changes.

An example of this the world's population. With a fixed birth rate, the population of the globe will continue to grow (until checked). Large populations cause large numbers of births and large numbers of births result in larger population. The change gets amplified each step. These feedback loops are dangerous.

• A negative feedback loop is one that tend to mitigate a change.

An example of this is homeostasis, the maintenance of body temperature. As a person's body gets too hot, (s)he begins to sweat in an attempt to lower the temperature. If their body is too cool,(s)he will begin to shiver in an attempt to increase the temperature.

Global warming is likely to be amplified by a few key positive feedback loops...

• Ice and Snow As the earth warms, the levels of ice and snow decrease, this decreases the surface albedo, allowing for an increase in absorbed solar radiation at Earth's surface. This leads to more warming and less ice and snow cover.

• Water Vapor As the earth warms, so does the atmosphere, this increases the amount of water vapor the atmosphere can hold. Warmer temperatures mean more evaporation, leading to a higher amount of water vapor, the most powerful greenhouse gas in existence, and consequentially even higher temperatures.

Three effects are poorly understood...

1. Changes in cloud cover could dampen the effects, especially if they are low clouds. Most climate models forecast that this will be the phenomenon that eventually brings the earth back to equilibrium.

2. Aerosols may or may not counteract global warming. Some studies have shown aerosols to block out a significant amount of incoming solar radiation, others have not.

3. The ocean circulation may change leading to varying effects in different parts of the world. Although "The Day After Tomorrow" is not a plausible scenario, many scientists believe that although the earth will warm as a whole, some regions, especially western Europe, may cool as a result of weaker ocean circulation.

These effects make global warming scenarios very different.

Facts on the UN Framework Convention on Climate Change

The debate mainly pits environmentalists against economists.

• A majority of environmentalists and scientists believe global warming is occurring and is an issue that needs to be dealt with. Environmentalists say that other species, even the dinosaurs, could have died off in the past as a result of climate change, and we could suffer the same fate.

Read an article from this perspective

• A majority of economists and businesspeople, more concerned with the economy, do not see global warming as an issue. Economists often point to previous claims by scientists that turned out to be untrue or contradictory to the current consensus.

Read an article from this perspective

The Global Warming Debate:

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Points made by Supporters	Points made by Opponents
Rise in CO2 and other Greenhouse gases are anthropogenic. Historical Temperature records show an increase of 0.4-0.8°C in the last 100 years. This is an unusually warm period for the last 1000 years. CO2 is a first order forcing of Climate Change. There will be longterm ramifications, the effects of global warming will be felt centuries in the future. Climate models can only reproduce the current trends if they use Greenhouse gas forcing, these models show that there will be warming and a rise of sea level. IPCC report summerises the state of Climate Science.	IPCC draws conclusions from Climate models with acknowledged weakness in cloud physics schemes. There is a difference between correlation and causation. Just because the temperature were observed to rise around the start of the Industrial Revolution does not mean the Industrial Rev. caused the temperatures to increase. Earth's climate has been both colder and warmer than today, and these periods are not explained by mechanisims that involve human influences. Climate Science can not make a definative prediction yet, the computer climate models are still evolving to include all the feedback mechanisms. Global temperatures are directly correlated with solar (sunspot) activity.