Wednesday, April 03, 2013

Earths Changing Climate

Earths Changing climate discusses climate change from a scientific perspective. The professor tries to be objective, sticking to the scientific facts about climate and change, and for the most part shying away from policy.

The "natural" temperature of the earth is in the freezing range. However, the greenhouse effect is what keeps it warmer. Mars is a little further from the sun, but the lack of atmosphere makes it positively freezing. Venus is closer to the sun; however, it has a greenhouse effect that went into overdrive, making it an oven. The earth has just enough of an atmosphere to keep a comfortable average temperature.

The earth has changed temperature significantly over time. There are plenty of external and internal factors involved. Small changes in the earth's tilt and orbit can have significant impact. The movement of land masses around the planet can also contribute to these. Since water, snow and land all reflect different amounts of light, the rearrangement of these can impact the temperature. If the earth's tilt brings one section closer to the sun, this slight difference can cause a cascading effect.

The primary greenhouse gas on earth is water vapor. However, it has a relatively short "life span", and is often quickly returned to the surface in rain. It may also sit as clouds which reflect heat. Methane is also a significant greenhouse gas, though it is in relatively short supply. Carbon Dioxide is currently persona non grata of the climate change world. It is a natural result of most energy producing activities. It has a relatively short "official" lifespan in the atmosphere, but its impact can live longer (due to the balance of carbon on the planet.)

During the time of dinosaurs, the earth was thought to be much warmer than it is now. Recently, the earth has experienced a few ice ages. The current temperature of the earth works well for humans. However, we appear to be on a path to increase the climate. How much? It is difficult to say. There are increasingly complex models used to calculate temperature changes. However, accurate, detailed records are only available for a little over a century. Other sources, such as ice cores can trace records back further. However, the further you go back, the more difficult it is to obtain data (and the less accurate the data is.) From the available models, it appears there is a significant man-induced increase in Carbon Dioxide and temperature. What will be the result of this is less certain. It is possible that the earth may reach a "cliff", where things suddenly switch out of control. It is also possible that the earth as a whole will be ok, but different areas will suffer (while others will benefit.) While there will likely be some extreme weather and negative impacts, the global warming alarmists have probably overestimated their force.

Fossil fuels are the primary source of atmospheric carbon. However, they represent just a small fraction of the energy available on the earth. The vast majority of the energy available is in the form of sunlight. (Fossil fuels, in fact, represent "sunlight" that had been stored up in the earth millions of years ago.) There are also some other sources, such as the moon (tidal energy) and inside the earth (geothermal). However, these are relatively minor. The sun also produces many secondary power sources, such as wind energy and biomass.

At the end of the lectures, the author presents some ways of dealing with global warming. Some proposals include "whole-earth" projects to reduce the heat level of the earth. These could be extremely dangerous due to the unknown factors. Carbon sequestration could have an impact, however, there is the risk of leakage. Simply producing less carbon may be the easiest. (The US vs. Europe comparison is an example of less production without dampening of lifestyle). Making better use of the sun's energy is also a viable long-term option.

The lectures were simple and straightforward. They attempted to skirt around the policy and political issues. However, in focussing on the "consensus" view they may have avoided some of the interesting work in what is a challenging scientific arena.

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