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Science communication is important in today's technologically advanced society. A good part of the adult community is not science saavy and lacks the background to make sense of rapidly changing technology. My blog attempts to help by publishing articles of general interest in an easy to read and understand format without using mathematics. I also give free lectures in community events - you can arrange these by writing to me.

Friday, 6 February 2009

Positive Feedback in Climate Change...

Positive feedback in global warming...

Most studies indicate that global warming is happening quicker than previously thought.Positive feedback is probably responsible for some of it.

An example will explain how this works:Arctic ice is highly reflective and sends a good fraction of sun's energy back into spcae. If the ice melts then it is replaced by darker looking water which reflects less light and absorbs more of the incident energy causing additional warming. This warming then melts more ice that then results in still greater absorption of solar energy. And so the cycle goes on, feeding on itself.
All the evidence is that the amount of arctic ice is shrinking rather rapidly.

Another example of positive feedback may be the oceans that are vast sinks of carbon di-oxide. Water vapour and carbon di-oxide are two main gases in the atmosphere that prevent energy from escaping from the earth. Warmer oceans create more water vapour and also absorb less carbon di-oxide. This then creates more warming etc.Recent studies have found that oceans are absorbing only half the amount of carbon di-oxide from the atmosphere now compared with the amount they soaked up 12 years ago.

This is too rapid a change and a real cause of worry about a run-away situation resulting...
Need to do something positive...!

This post was published previously in Oct 2007

Saturday, 31 January 2009

Flooding due to Sea-level rise...

Global warming is expected to result in sea level rising. Extra water is added by melting ice and increased temperature causes expansion of water. Thermal expansion alone will cause upto 0.7 m rise in sea level by 2100 (IPCC 2007). If all of arctic ice melts then sea levels could rise by 7 metres and far more if antarctic ice melts.

It is interesting to see what areas of the world will be affected by sea levels rising. Low lying areas - of course. The effect can be seen on the maps by clicking on the following links: The links are interactive and you can choose your own values and area.

http://flood.firetree.net/?ll=45.5833,14.6777&z=13&m=0 Europe now
http://flood.firetree.net/?ll=53.3112,4.2407&z=10&m=1 Europe with 1 m rise in sea level
http://flood.firetree.net/?ll=53.0280,4.6472&z=10&m=5 Europe with 5 metres rise is sea level

Notice the vast areas of the Netherland and Denmark being affected even with a 1 m rise. 5 metres rise in sea level will flood a lot of Essex and Yorkshire.

Sunday, 25 January 2009

Topics for Climate Change Talks 3 to 6...

The third talk is on 17th February and will cover the following:

The Atmosphere – structure and composition
The greenhouse effect
Greenhouse gases
Carbon Dioxide, Methane, Nitrous Oxide, Water Vapour
Aerosols, Ozone, CFCs
Global Carbon Cycle
Global Water Cycle

The fourth talk is on 24th February and will cover the following

Clouds and their characteristics
Role of clouds in Climate control
Distribution of Solar energy on the Earth
Air circulation
Jet Streams

The fifth talk is on 3rd March and will cover the following

The Oceans
Ocean currents
The Gulf Stream
Ocean Life
Dead zones in oceans

The sixth talk is on 10th March and will cover the following

Oceans are getting more acidic
pH as a measure of acidity
Destruction of coral reefs

El Nino

Wednesday, 21 January 2009

Topics for Climate Change talks 1 and 2

I am looking forward to the talks on Climate Change in February.

The first talk is on Tuesday 3rd February 2009 and will cover the following:

Weather and climate
Changes in climate – historic data
Ice ages
Forecast scenarios by IPCC
Energy Conservation
Changes in population, carbon dioxide and methane levels
Evidence of adverse effects of Climate Change
Global temperature rise
Reduction in Arctic ice cover
Sea level rise
Disruption of ocean currents
Disappearing fresh water supplies
More frequent heat waves
Increasing desertification
Disease carrying insects moving to colder areas
Frequent and stronger hurricanes
Reduced bio-diversity
Increase in ocean acidity affecting marine life
Increased atmospheric pollutants

The second talk is on 10th February 2009 and will cover the following:

Earth’s energy balance
Sun as the primary source of all energy
Effect of the atmosphere in warming the earth
Earth’s energy budget
Greenhouse effect
Sun spot activity
The seasons
Natural variations in the Earth’s Climate
Milankovitch cycle (100,000 years cycle)
Changes in the Earth’s tilt (41,000 years cycle)
Wobble in the Earth’s axis (22,000 years cycle)

Sunday, 18 January 2009

Curious History of the Leap Year....

Leap years come every four years .. or do they?

A leap year has 366 days with the month of February lasting 29 days. 2008 was a leap year.

We are used to thinking that a leap year happens every fourth year. If the year is divisible by 4 then it would be a leap yaer. Not strictly true!

Actually: Every fourth year is a leap year.  But if the year is divisible by 100 then it must also bedivisible by 400 to be a leap year1600, 2000 were leap years; 1700, 1800, 1900 were not; 2100, 2200, 2300 will also not be leap years.
Every 400 years there are only 97 leap years. WHY???


The idea of the leap year started with Julius Caesar. In 46 BC, Caesar added one extra day to every fourth year to make the avarage year 365.25 days long. This was to take account for the fact that the Earth takes 365.2422 days to complete one orbit of the Sun.
But the fix wasn't exact. In 1267, Roger Bacon noticed that the calendar has slipped by nine days in the intervening 13 centuries.
After a lot of thinking, Pope Gregory XIII in 1582 adjusted the calendar (skipped 10 days – jumped from 4 to 15 October) as used today to correct for the slippage. Dates of 5th to 14th October do not exist in the Gregorian Calendar! Gregorian Calendar also skips three leap years every 400 years to make the year 365.2425 days.
This is still about 26 seconds too long!

Climate Change Talks in February/March 2009....

Free Science Talks for Secondary Pupils & Adults
No Science Background Needed

7:30 pm to 8:30 pm on Tuesdays
3, 10, 17 & 24 February, 3 & 10 March 2009

James Watt Auditorium, E.K. Technology Park
G75 0QD (Ample free parking on site)

In Partnership with: Glasgow University and Scottish Enterprise, Lanarkshire
Further Information:

Climate Change is one of the most important issues facing mankind today. Most scientists and world leaders now accept that the world’s climate is being affected by human activity and urgent action is required to limit the damage not only to our environment but to the way we live.
The talks look at the evidence for climate change and discuss how the Sun, atmosphere, oceans and glaciers affect our climate. Presented in an engaging and informative way, the talks are designed with the express aim to communicate science matters to the local community.
The talks are aimed at the general audience and no prior background in physics or biology is assumed. The talks are also suitable for secondary school pupils who are encouraged to attend. The presentation is visually attractive and highly informative.
Dr. Singhal has taught university level physics for 40 years.

The talks are part of the community education initiative under the Science for All programme.
Talks are free to attend.