Beverly Said:

help on my gcse science case study!?

We Answered:

Science? That sounds like geography. When I did mine it was things like, examining the relationship between current, voltage and resistance! But as for your question, I'd say it's a bit too broad and hard to determine the answer. After all if anyone actually knew the answer we'd be in a better situation today. Sorry I can't be more help, but my only advice is, answer a question that's already been answered.

Bessie Said:

what are the natural causes of global warming ?

We Answered:

Normally, slight perturbations in the Earth's orbit, axis, ect. start to push the climate warmer, triggering a positive feedback loop.

However, according to the Milankovitch cycles, we should be a cooling stage.

Cassandra Said:

What do you think about the new Met Office study on a global warming worst case scenario?

We Answered:

The difference between the "worst case" scenario and "best case" scenario is time. In the worst case, 4 C warming happens in 40 years. In the best case 4 C warming takes more than 100 years.

The weather is more important than climate for humans because global reserves of food amount to a few months supply. We don't eat the average supply, we eat the last harvest. Therefore, the worst case is not defined by the climate, but the worst year within the new climate. In the pre-industrial climate, a very bad year leading to widespread crop failures might have a probability 2 standard deviations from the mean. In a 4C warmer climate, a very bad year may be less than 1 standard deviation from the mean.

Willie Said:

what do you make of the new study that that suggest a slow down in sea level rise with global warming?

We Answered:

The short answer is that there simply is not enough continental ice mass to support exponential sea level rises (or thermohaline catastrophes) during interglacial periods.

The so called consensus view is that a sea level rise of 6 feet by the year 2100 is somewhat likely. Sea level would have to rise at a rate seven times as fast as it is now for the next 90 years to rise by 6 feet by the year 2100. A seven-fold increase in sea level rise starts sounding just a bit exponential.

<Cut & pasted from another question I just answered>

From 1993-2003 sea level rose at a rate of 3.45 mm/yr. Since 2003 it has been rising at a rate of 2.35 mm/yr...

http://i90.photobucket.com/albums/k247/d…

The satellite data fit very nicely into the long term trend of sea level rise since the end of the Little Ice Age...

http://i90.photobucket.com/albums/k247/d…

Here are the top ten decades of sea level rise (mm/yr) since 1700...


1804-1813 12.75
1803-1812 10.67
1728-1737 10.30
1789-1798 8.38
1842-1851 7.87
1858-1867 7.82
1788-1797 7.72
1861-1870 7.66
1808-1817 7.58
1785-1794 7.18

None of those 10-yr periods has come anywhere close to 22 mm/yr... And all of those periods occurred long before man started pumping CO2 into the atmosphere.


Here are the top ten decades (mm/yr) from 1950-2002...


1989-1998 4.66
1990-1999 3.95
1991-2000 3.86
1956-1965 3.79
1986-1995 3.78
1974-1983 3.71
1952-1961 3.65
1993-2002 3.63
1988-1997 3.44
1975-1984 3.30

Satellite altimetry data from 1993-2010 show that sea level rise has decelerated to less than 3 mm/yr.

Sea level has never risen more than 12.75 mm/yr on a decadal scale since 1700.

Sea level hasn't risen by more than 4.66 mm/yr on a decadal scale since 1950.

Sea level would have to rise at 20 mm/yr to rise by 6 feet by the end of the century.

The observational data support a sea level rise of no more than 11 inches by the year 2100.

<End cut & paste>


Now for some "fun with geology!"

Here is the total Eustatic Sea Level (ESL) change since the Last Glacial Maximum (LGM) compared to the total ESL change since 1700 AD...

http://i90.photobucket.com/albums/k247/d…

Now let's compare the last 300 years of ESL rise with the ESL changes of the last 2 million years (most of the Pleistocene)...

http://i90.photobucket.com/albums/k247/d…

Geologists have a very technical term for this. It's called "perspective."

The alarmists are Chicken Little-ing about a 1 meter rise in sea level over the next 90-100 years.

Could sea level rise another 1, 3 or even 5 meters before the end of the current interglacial? Sure. It rose that high in the previous interglacial.

Could sea level rise another 1 meter over the next 90 to 100 years? No. There is no historical or geological evidence to support such a scenario.

Assuming Earth stays in the warm phase of the 1,500-yr cycle until at least 2100 (not a huge assumption), the maximum possible sea level rise by then will be a bit more than 0.25m above current MSL…

http://i90.photobucket.com/albums/k247/d…

1/4 of a meter… A bit less than 1 foot… That’s it… That’s the worst case scenario that is actually possible in the real world.

Jared Said:

Evidence that humans are to blame for global warming?

We Answered:

If I were you I would rebel a little bit, add a few arguments from the "climate change skeptics" as well as the science debunking their non-sense theories. You can find a lot of info here:
http://www.skepticalscience.com/argument.php
or here http://www.realclimate.org/

Also, I hope you teacher doesn't have a hidden agenda with this project. Remember that there is an international consensus about Climate Change. That only few voices are still denying its existence.