Shrinking world due to global warming

By Dhaneshi YATAWARA

As the Intergovernmental Panel on Climate Change reports based on their years of observation on the global climatic changes the earth is losing 0.25 metres of its shorelines every year. This is as an impact of the worldwide phenomenon of climate change or global warming.

As man started using more and more fossil gas, oil and coal for the advancement of their own species, today an irreversible threat - global warming - is imposed on the entire planet. So far this is the only home for humans and all other species.

The Earth is a blue planet - meaning major part of it is covered by water. Thus, the impact on the ocean by global warming changes many environments of the world, directly affecting several industries which we humans heavily rely on. There are many impacts on ocean natural resources from global warming.

Naturally, the surface temperature of the sea would be something around 24C to 28C. So the first 100 to 200 metres it will be around this range. But when you go deeper the temperature is like 3 degrees Celsius. Following today's trend the global temperature is expected to reach higher by 1.4 degrees to 5.8 degrees Celsius, according to scientists.

The sea level rises when the polar ice melts due to global warming. In addition in the high tropical temperatures sea water expands, which commonly happens to seas around our island. "When it comes to Sri Lanka due to sea level rise we expect certain spots of the island will be inundated and Islands in the Jaffna peninsula will be totally covered by sea water," said Prof Ruchira Cumaranatunga of the Department of Fisheries and Aquaculture of the Ruhunu University.

The Department of Fisheries and Aquaculture of the Faculty of Fisheries and Marine Science Technology of the Ruhunu University conducts a continuing research on impacts on Sri Lanka from climatic changes due to global warming. Their observations have lead to a serious situation for one of the country's main economies, fishing.

For our country these coastal areas are very crucial, especially for the fishing industry, Prof. Cumaranatunga added. "The climate change doesn't stop there; it also effects the wave patterns and could raise storms," Prof. Cumaranatunga said, explaining the disasters that global warming could create.

"In the sea, there is a level known as themocline. This is where the temperature drops rapidly. The temperature drops from 22 Celsius to 5 degrees. With global warming this level goes deeper," she added. What is the importance of this water level to fishing industry? According to Prof. Cumaranatunga, this is where the fishermen catch most of the fish harvest that includes the most popular fish for human consumption. "With the temperature rise, tuna like fish tends to go deeper, making it difficult to catch them. Even this may happen to bill fish commonly known in Sri Lanka as 'Thalapath'," she added.

Tuna and bill fish are commonly found 100 - 200 metres deep sea fishermen are aware of this and their techniques, be it old or new, are based on these facts. When the fish goes deeper the fishermen can not catch fish with the available knowledge.

"And in addition, as the temperature in the equatorial region goes higher, the fish most probably will migrate to sub tropical regions. Thus, the fishermen will not be able to find fish in their identified locations and depths," according to the professor.

This is a phenomena where the fish harvest will be lowered drastically affecting the fish industry and the community.

"Islands like ours will be largely affected with these climate changes and not much damage to the large continents," she added. "Sri Lanka is not a small island but of the middle level, yet we will also suffer even though our contribution to global warming is negligible," she said.

"Carbon dioxide dissolves in sea water and it makes the sea acidic. The Ocean absorbed CO2 from a process that helped it maintain a stable pH (8.179) which is not acidic. But as Carbon Dioxide continues to dissolve in sea water and increase in acidity continues the shell forming species, like crabs and lobsters will find it difficult to develop their shells. Their lives are threatened," she explained.

Unprecedented levels of Carbon dioxide are released to the atmosphere due to anthropogenic activities and this has lowered ocean surface pH and made it more acidic. Studies have also shown that such high acidic levels could cause reefs to fall apart.

"Not only do these marine species, but also the microscopic crustaceans get affected.

Then what happens is that the food chain of many sea species gets affected. There are important parts of the food chain. This is the food for small fish and the plankton. Now gradually when these animals go missing there will be cracks in the food chain. This results in the upper levels of the food chain becoming starved," she said, explaining the deterioration of fish species in the sea as a result of global warming. Unless the big fish adopt to eat something else they will die and dietary changes in animals is part of the evolution which takes place over hundreds and thousands of years. As a result the distribution, productivity, and species composition of global fish production would change drastically. It will generate complex and inter-related impacts on oceans, estuaries, coral reefs, mangroves and sea grass beds that provide habitats and nursery areas for fish. Marine living resources have a high economic value and their uses are numerous.

According to the Initial National Communication under the United Nations Framework for Climate Change Conventions Sri Lanka will experience sea level rises, high temperatures, more frequent and prolonged droughts, high intensity of rainfalls and increased thunder activity.

Above all, it will result in a significant threat to the coastal and marine industry as well as to different sectors of the national economy and human health.