The Editor, Sir:

I am at least disturbed, and at most alarmed, as an engineer at the statements being put out in the letter in The Gleaner, (November 22, 2007) titled 'Climate change and the south coast' and the recent presentation by Dr. Witter at the Environmental Foundation of Jamaica's (EFJ) forum. This, because of what was stated without a critical qualification.

The Intergovernmental Panel on Climate Change (IPCC) did say that by the end of this century that the expected sea level rise was being predicted to be 0.18 to 0.59 meter. However, the qualifications (that is, assumptions made to reach this conclusion) were not mentioned.

expansion of seawater

In the November-December issue of MIT's publication Technology Review, page 56, column 1, last paragraph, states "Indeed, the IPCC's sea-level estimates are based on ONLY a few well-understood processes. One is the expansion of seawater as it warms. Another is the melting of mountain glaciers in temperate zones - places like the Alps, Andes, and Himalayas. Third is the melting of the ice sheets' surfaces and the glaciers' seaward migration under the pull of gravity ... The problem is that OTHER processes may actually prove FAR MORE consequential." The capitalised words are my emphasis.

Later in the Technology Review article, unexpected occurrences are mentioned, the increasingly rapid movement of the major glaciers in both Greenland and the West Antarctic Ice Sheet. It must be understood that these alone constitute huge numbers of cubic kilometers of water ON LAND, not in the oceans.

If they were floating in the oceans their melting would make no difference (Archimedes principle) in sea-level rise, but, they are not. Therefore, if even a modest portion of this huge amount of ice melts and flows (or even slides, without melting) into the oceans, the effect would make the IPCC's 0.18 to 0.59 meter sea level rise look like a bad joke.

In New Scientist magazine some time ago, in the Siberian tundra, it was reported that normally frozen (and white) areas of snow melted to form dark coloured lakes which were absorbing more of the sun's heat and, melting more ice and snow. Another consequence of this was that the warmth re-started the decay of the dead plant material in the ground, producing methane (otherwise called 'swamp gas') a more powerful greenhouse gas than carbon dioxide.

absorbed heat

The methane was reportedly being produced so fast that the bubbling up from the lake bottoms PREVENTED THE LAKES FROM FREEZING OVER IN THE WINTER (and turning white to reflect the feat of the sun back into outer space) and absorbed more heat and melted more ice, and absorbed more heat and melted more ice, and so on, and on.

This is what is called a positive feedback loop, and is ALSO NOT INCLUDED in the IPCC's causes of sea level rise. Essentially, in this a positive feedback loop is where a small change causes a bigger change, which makes an even bigger change, etc.

What might be a consequence of much faster sea level rise? Well, look at the Cayman Islands, the highest point I hear is about 10 meters above sea level, and most of it is very close to sea level. So what?

tax-free economic zone

Well, being a person who looks at situations and prefers to take steps accordingly, I would advise the Jamaican Govern-ment to immediately begin preparing an immigration system and income tax-free economic zone (to be later expanded to all of Jamaica) designed to receive Caymanian refugees, as the Cayman Islands sink below the rising Caribbean Sea and is increasingly battered by more powerful hurricanes, etc., etc. (Even without Cayman sinking, this might be a good thing to do.)

When people quote things, beware! The devil is in the details left out.

A sensible engineer tells his client everything, the good and the bad and, investigating and observing carefully, changes course as required.

I am, etc.,

HOWARD CHIN

Member of the Jamaica

Institution of Engineers

(MJIE), P.E., etc.