The Greenhouse Effect.

Документ взят из кэша поисковой машины. Адрес оригинального документа : http://zebu.uoregon.edu/1999/ph161/l13.html
Дата изменения: Sat Feb 6 05:19:01 1999
Дата индексирования: Tue Oct 2 00:39:14 2012
Кодировка:
Поисковые слова: туманность фейерверк

Greenhouse Effect
Is it real or not?

Basic Components to what should be called the Enhanced Greenhouse effect:

The earth has a natural greenhouse effect due to trace amounts of H₂0 and CO₂ that naturally occur. The enhanced greenhouse effect refers to the augmentation of these natural gases by human activities.

The net result is that we are depositing approximately 2 billion extra tons of carbon in an out of equilibrium cycle. Eventually this will be taken up by the land but the timescale for that process is unknown. Hence, the extra carbon, in the form of C0₂ remains in the atmosphere.

The deposition of C0₂ and methane (CH₄) continues to exponentially increase.

Such that we are now at historical all time high concentration:

In principle, CFCS are very bad and will dominate the greenhouse gases in our atmosphere if their terrestrial usage remains high. CFC worldwide production, however, has been significantly reduced because of concern about The Ozone Layer
Methane is more directly related to food production and population growth so it could also dominate in the near future
Methane is also found in the Arctic Ice Caps and in ocean hydrates and will be released due to global warming thus excarerbating the problem

While the US is the worst offender, this is truly a global problem. Are we going to tell China, for instance, not to "contribute"

Bare bones simulator

Manifestations and Predictions of the Greenhouse Effect

Popular Misconception --> Amazon Rain Forest Destruction greatly contributes to the problem. It doesn't, its the total amount of biomass on the planet that contributes to the Carbon Cycle . The real problem with deforestation is the immediate release of methane. However, detailed studies of gas exchange in rain forest systems indicates that rain forests are net producers of greenhouse gases (due to methane emissions) and not net sinks (e.g. they remove CO₂). This point is a bit controversial still and in any event, is not one that the public believes.
Evidence of increased hurricane strength is here: Hurricane Andrew ; Emiliaa in the Pacific ; Hurricane Linda in the Eastern Pacific

Simplest Prediction is increase in global mean temperature.

Role of clouds is crucial --> Net Cooling or Warming? --> There is general consensus that cloud cover will increase as the capacity for the atmosphere to retain water increases with increasing temperature.

What does the actual data look like?

All the Data: Global Warming NCDC Document

Long Term Temperature Trends:

Potential Problems:

Is the pre-1920 data reliable?
Increasing number of recording stations since 1950 means non-uniform data quality
Southern Hemisphere is more ocean to land area than Northern Hemisphere
But, there does appear to be an 0.5 degree Celsius increase per century in the data

Distribution of Temperature trends on the Earth. Where is it getting warmest the fastest:

All the historical data

1953-1973

1973-1993

When positional data is combined with temperature data and timesliced in this way - it seems clear the Global Warming is occurring. This conclusion was reached by a National Academcy of Science panel in Sept. 1995 and is accepted by most.

Previous Lecture Next Lecture Course Page

Greenhouse Effect Is it real or not?

Greenhouse Effect
Is it real or not?