From: Trinidad & Tobago Express
Troubling concern
Sunday, April 26th 2009


Prof Bhawan Singh agreed with much of what Chu had to say but thought his comments of the Caribbean islands being washed away "somewhat strong".
But he pointed to a troubling finding:
Sea-level rise in the Gulf of Paria appeared to be happening faster than the global average, which indicated that the land was sinking.
Of Chu's summit statement, Singh said:
"The latest (2007) IPCC Report does substantiate his claim of a two-to-four-degree-Celsius rise of global, near-surface temperatures by the end of this century, depending on which forcing of the climate system is used, namely, based on the rate of increase of greenhouse gases globally.
"The link between climate change/global warming and sea-level rise resides in the thermal expansion of oceanic water, the melting of sub-polar ice fields in mountainous areas such as the Andes and the Himalayas and the melting of the polar ice caps in Greenland and Antarctica.
"As an indication of the potential contributions of the polar ice caps to sea-level rise, if the Antarctic ice cap were to melt completely, it would have the potential to raise sea levels by over 60 metres while the Greenland ice cap would have the potential to raise sea levels by close to seven metres.
"But this is not expected to happen by the end of this century.
"Again, using the 2007 IPCC Report as a basis, using a moderate forcing of the climate system, global sea levels are expected to rise by a range of about 0.2 to 0.5 metres by the end of this century. But recent studies claim that these estimates are conservative since the climate/sea-level models inadequately simulate the contribution of land-based ice to sea-level rise. "As for instance, recent satellite and field studies indicate that the Wilkins ice shelf, the size of Connecticut (USA), in Antarctica is carving rapidly and could very soon dislodge itself into the ocean.
"Sea-level changes, especially as driven by the polar ice caps, evolve very slowly...based on proxy records, the last time that the poles were free of permanent ice fields occurred over 200 million years ago.
Furthermore, global sea level rose by 120 metres during several millennia that followed the end of the last glacial period, about 21,000 years ago. But these fluctuations in global sea levels were largely controlled by natural forcings.
"The problem we are facing today is the accelerated rise in global temperatures and sea levels as driven by human activities and the enhanced greenhouse effect since about the mid-18th century.
"For instance, again using IPCC (2007) estimates, global sea levels rose at a rate of about 1.1 mm/year over the period 1961-2003. But if one were to use the more recent period of 1993-2003, the rate goes up to about 2.8 mm/year, clearly an indication of acceleration.
"Also, sea-level changes are expected to vary regionally, based on ocean temperature and salinity changes and oceanic circulation shifts and land movements.
"Based on tide-gauge data we have for the mid-eighties to 2000 for the Gulf of Paria, the rate of sea-level rise is about two to four mm/year, much higher than the global average, and as we demonstrated previously, this may be attributed in large measure to land subsidence.
"And although Trinidad may lie outside the active hurricane belt, it could be subject to storm surges caused by active storm systems in the region, leading to extreme sea levels as occurred recently at Mosquito Creek".
Singh said Chu's claim of Caribbean islands being washed off the map over the next century is somewhat strong, in that "these assessments have been made in reference to low-lying atolls/islands in the Pacific."
On the issue of Trinidad and Tobago's contribution to global greenhouse gas emissions, Singh said the First National Communication to the United Nations Framework Convention on Climate Change (UNFCCC) showed that Trinidad and Tobago was one of the highest emitters of greenhouse gases on a per capita basis.
"Based on the accelerated rate of industrialisation and the explosion of vehicular traffic, this situation may have exacerbated", he said.