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Last week we sailed past a couple of the atolls in the Gilbert
Islands. They were just over 10 miles away, but were so low and
flat, they didn’t look like land at all, just wrinkles in the horizon.
Their fate has been sealed by our addiction to fossil fuels. The
billions of tons of carbon dioxide we pump into the atmosphere every
year are adversely impacting the Pacific.
The Intergovernmental Panel on Climate Change (IPCC) estimates the average global temperature will have increased by 6 degrees by 2100. This may not sound like much but the phrase ‘average global temperature’ conceals a lot.
The average global temperature during the last ice-age, when ice sheets covered most of Scandinavia, reached as far south as northern Germany and covered most of Canada the Upper Midwest and New England in America, was only 6 degrees lower than today’s average global temperature. Even a small change has significant effects on the world’s weather systems, oceans and ecology. Four effects of climate change will have massive impacts on the Pacific.
Sea level rise
One of the most widely publicised effects of climate change is an increase in sea levels. Current estimates predict an increase in sea level of around 1.5 – 3 mm per year. This doesn’t sound so bad, and the IPCC conservatively predict that by 2100, global warming will lead to a sea level rise of 110 to 880 mm.
However, if the ice sheets of Greenland and the Antarctic melt then the sea level is expected to rise by a more drastic 68.3 m. No one knows whether these ice sheets will melt entirely but a 2005 British Antarctic Survey found 87% of the Antarctic Peninsula glaciers have retreated over the past 50 years. In the past five years, the glaciers have lost an average of 50 metres (164 feet) per year. A Greenpeace expedition to Greenland last year found the Arctic to be in a similar situation.
The implications of any sea level rise for the Pacific are enormous. Rising sea levels will smother islands wholesale, drowning mangroves and coral reefs. The Gilbert Islands that we passed last week are part of Kiribati, a country with a population of just over 105,000 people scattered amongst 33 low lying atolls.
The highest point in the country is only 81 metres high and is on the decimated island of Banaba.
The Kiribati people have a good deal compared to their neighbours in Tuvalu. There the population of just under 12,000 people is clustered on 9 atolls. The highest point is 5 metres above sea level. When you add the effect of storms and high tides to the increase in sea level most of the atolls of Tuvalu and Kribati will become uninhabitable. Tuvalu already has a deal with the New Zealand government for all its inhabitants to move there when their homes are drowned.
Mangroves serve as nurseries to juvenile reef and pelagic fish.
Mangroves may just look like muddy swamps but they are of vital importance to island communities and marine ecosystems. They provide communities with food; protect the coastline from the sea, and serve as nurseries for many juvenile reef and open water ocean marine species. The United Nations estimates that 13% of mangroves will be drowned by 2100. Many Pacific Island countries, including Samoa and Fiji, are expected to lose half of their mangroves; this is likely to have a devastating effect on local communities and ocean ecosystems.
Changes in ocean temperatures
Climate change is warming the oceans. Changes in ocean temperature will alter the distribution, migration routes and breeding cycles of marine organisms. For example, Albacore tuna exhibit a strong preference for waters between 16°C and 21°C, whereas Yellowfin tuna only spawn in water above 25.5°C. Other organisms, such as oysters, rely on the temperature of the environment to determine their sex. As temperatures increase these creatures will have to alter their range, adapt or die. Their decreasing population sizes, a result of overfishing, will also reduce their ability to adapt to the rapidly changing environment.
When temperatures increase coral bleaching occurs. What we call coral is actually two co-dependent organisms, a coral polyp and an algae, which live symbiotically. The algae photosynthesise providing the coral polyp with nutrients while the coral provides the algae with a safe and nurturing environment. Temperature increases cause the coral polyp to expel the symbiotic algae, this causes the coral to lose it’s colour (hence the term bleaching). If the coral does not re-establish its relationship with the algae (or another species of algae) it soon dies. A recent report suggests that three quarters of the world’s coral reefs may suffer from climate change related bleaching. Some experts have gone so far as to predict that Australia’s Great Barrier Reef will lose 95% of its living coral by 2050.
Changes in weather patterns
Oceanic currents pump nutrients from the ocean floor to the light sub-surface waters, where they are used by phytoplankon. These are a vital part of ocean ecosystems. Salinity changes in different parts of the ocean, primarily caused by differences in rainfall (e.g. El Nino/El Nina in the Pacific) or melting glaciers (e.g. the Gulf stream in Atlantic) drive these currents. Climate change is altering these patterns of rainfall and glacial melt, and these alterations will inevitably change the magnitude, locations, directions and seasonality of these life-giving currents. A 2005 study, predicted that changes in ocean currents caused by global warming will reduce the supply of nutrients, slashing the oceans’ productivity by a fifth.
Climate modelling suggests that weather patterns will alter, becoming more extreme. This is expected to result in more severe storms, meaning severe weather events, such as hurricane Katrina, which destroyed New Orleans, will become the norm. In addition to floods, changing storm patterns are expected to increase coastal erosion – further exacerbating the effects of sea level rises.
Ocean acidification
A less well known effect of climate change is ocean acidification. Our oceans are, and have been for millions of years, slightly alkaline. Some carbon dioxide from the atmosphere dissolves in the ocean forming a weak acid (carbonic acid). As the volume of carbon dioxide in the atmosphere increases so too does the amount dissolving in the sea. Carbonic acid’s handiwork can be seen in many limestone caves. It is the leeching of carbonic acid through the limestone that results in the formation of the most fantastic stalactites and stalagmites. Its work in the ocean will be much more destructive.
Coral reefs are vulnerable to climate change induced bleaching, ocean acidification and sea level rises.
As the oceans acidify, marine organisms with calcium carbonate in their internal skeletons (bones) and shells will be in trouble. At the moment their skeletons and shells are hard because the upper layers of the oceans are supersaturated with calcium carbonate. As the oceans acidify this concentration will be reduced. This means their shells and skeletons will become softer and, if the level of acidification becomes too high, their shells and skeletons will start to dissolve.
This will have massive impacts all over the marine ecosystem. It will cause huge changes to the species composition of the oceans because key organisms at the bottom of the food web, critically some phytoplanktons and most zooplankton, will no longer be able to survive. Different species of plankton form the basis of nearly all ocean food chains. Further disruptions will occur because the corals that create the structure and provide niches for an array of marine ecosystems will also be unable to survive.
A 2003 study calculated that increasing fossil carbon dioxide in the oceans, could make them more acidic over the next few centuries than they have been for 300 million years, excepting some rare catastrophic events. A 2005 study into such events showed that 55 million years ago, a release of 4500 gigatons of carbon caused the extinction of huge numbers of deep-sea creatures. It took over 100,000 years for the oceans to return to their normal alkalinity. To put that time frame into perspective, Homo Sapiens – us - have been around for between only 200,000 - 400,000 years.
What is to be done?
This is all very depressing both for marine organisms and on a more selfish level, for us. Overfishing and destructive fishing has already impoverished most marine ecosystems, and left them particularly vulnerable to environmental changes. The rapid changes that human induced climate change will bring about will exacerbate the problems we have already caused.
Climate change, overfishing and destructive fishing are more than just personal responsibilities. Their causes are endemic to our economic and social structures. These issues need to be tackled on by every government, industry, corporation and individual. The number of collapsed fisheries around the world are a dire warning to anyone thinking that politicians, self-interested regulatory bodies and corporations are an effective way to make change.
Don’t be overwhelmed by the problems, there are still things we can do.
The Intergovernmental Panel on Climate Change (IPCC) estimates the average global temperature will have increased by 6 degrees by 2100. This may not sound like much but the phrase ‘average global temperature’ conceals a lot.
The average global temperature during the last ice-age, when ice sheets covered most of Scandinavia, reached as far south as northern Germany and covered most of Canada the Upper Midwest and New England in America, was only 6 degrees lower than today’s average global temperature. Even a small change has significant effects on the world’s weather systems, oceans and ecology. Four effects of climate change will have massive impacts on the Pacific.
Sea level rise
One of the most widely publicised effects of climate change is an increase in sea levels. Current estimates predict an increase in sea level of around 1.5 – 3 mm per year. This doesn’t sound so bad, and the IPCC conservatively predict that by 2100, global warming will lead to a sea level rise of 110 to 880 mm.
However, if the ice sheets of Greenland and the Antarctic melt then the sea level is expected to rise by a more drastic 68.3 m. No one knows whether these ice sheets will melt entirely but a 2005 British Antarctic Survey found 87% of the Antarctic Peninsula glaciers have retreated over the past 50 years. In the past five years, the glaciers have lost an average of 50 metres (164 feet) per year. A Greenpeace expedition to Greenland last year found the Arctic to be in a similar situation.
The implications of any sea level rise for the Pacific are enormous. Rising sea levels will smother islands wholesale, drowning mangroves and coral reefs. The Gilbert Islands that we passed last week are part of Kiribati, a country with a population of just over 105,000 people scattered amongst 33 low lying atolls.
The highest point in the country is only 81 metres high and is on the decimated island of Banaba.
The Kiribati people have a good deal compared to their neighbours in Tuvalu. There the population of just under 12,000 people is clustered on 9 atolls. The highest point is 5 metres above sea level. When you add the effect of storms and high tides to the increase in sea level most of the atolls of Tuvalu and Kribati will become uninhabitable. Tuvalu already has a deal with the New Zealand government for all its inhabitants to move there when their homes are drowned.
Mangroves serve as nurseries to juvenile reef and pelagic fish.
Mangroves may just look like muddy swamps but they are of vital importance to island communities and marine ecosystems. They provide communities with food; protect the coastline from the sea, and serve as nurseries for many juvenile reef and open water ocean marine species. The United Nations estimates that 13% of mangroves will be drowned by 2100. Many Pacific Island countries, including Samoa and Fiji, are expected to lose half of their mangroves; this is likely to have a devastating effect on local communities and ocean ecosystems.
Changes in ocean temperatures
Climate change is warming the oceans. Changes in ocean temperature will alter the distribution, migration routes and breeding cycles of marine organisms. For example, Albacore tuna exhibit a strong preference for waters between 16°C and 21°C, whereas Yellowfin tuna only spawn in water above 25.5°C. Other organisms, such as oysters, rely on the temperature of the environment to determine their sex. As temperatures increase these creatures will have to alter their range, adapt or die. Their decreasing population sizes, a result of overfishing, will also reduce their ability to adapt to the rapidly changing environment.
When temperatures increase coral bleaching occurs. What we call coral is actually two co-dependent organisms, a coral polyp and an algae, which live symbiotically. The algae photosynthesise providing the coral polyp with nutrients while the coral provides the algae with a safe and nurturing environment. Temperature increases cause the coral polyp to expel the symbiotic algae, this causes the coral to lose it’s colour (hence the term bleaching). If the coral does not re-establish its relationship with the algae (or another species of algae) it soon dies. A recent report suggests that three quarters of the world’s coral reefs may suffer from climate change related bleaching. Some experts have gone so far as to predict that Australia’s Great Barrier Reef will lose 95% of its living coral by 2050.
Changes in weather patterns
Oceanic currents pump nutrients from the ocean floor to the light sub-surface waters, where they are used by phytoplankon. These are a vital part of ocean ecosystems. Salinity changes in different parts of the ocean, primarily caused by differences in rainfall (e.g. El Nino/El Nina in the Pacific) or melting glaciers (e.g. the Gulf stream in Atlantic) drive these currents. Climate change is altering these patterns of rainfall and glacial melt, and these alterations will inevitably change the magnitude, locations, directions and seasonality of these life-giving currents. A 2005 study, predicted that changes in ocean currents caused by global warming will reduce the supply of nutrients, slashing the oceans’ productivity by a fifth.
Climate modelling suggests that weather patterns will alter, becoming more extreme. This is expected to result in more severe storms, meaning severe weather events, such as hurricane Katrina, which destroyed New Orleans, will become the norm. In addition to floods, changing storm patterns are expected to increase coastal erosion – further exacerbating the effects of sea level rises.
Ocean acidification
A less well known effect of climate change is ocean acidification. Our oceans are, and have been for millions of years, slightly alkaline. Some carbon dioxide from the atmosphere dissolves in the ocean forming a weak acid (carbonic acid). As the volume of carbon dioxide in the atmosphere increases so too does the amount dissolving in the sea. Carbonic acid’s handiwork can be seen in many limestone caves. It is the leeching of carbonic acid through the limestone that results in the formation of the most fantastic stalactites and stalagmites. Its work in the ocean will be much more destructive.
Coral reefs are vulnerable to climate change induced bleaching, ocean acidification and sea level rises.
As the oceans acidify, marine organisms with calcium carbonate in their internal skeletons (bones) and shells will be in trouble. At the moment their skeletons and shells are hard because the upper layers of the oceans are supersaturated with calcium carbonate. As the oceans acidify this concentration will be reduced. This means their shells and skeletons will become softer and, if the level of acidification becomes too high, their shells and skeletons will start to dissolve.
This will have massive impacts all over the marine ecosystem. It will cause huge changes to the species composition of the oceans because key organisms at the bottom of the food web, critically some phytoplanktons and most zooplankton, will no longer be able to survive. Different species of plankton form the basis of nearly all ocean food chains. Further disruptions will occur because the corals that create the structure and provide niches for an array of marine ecosystems will also be unable to survive.
A 2003 study calculated that increasing fossil carbon dioxide in the oceans, could make them more acidic over the next few centuries than they have been for 300 million years, excepting some rare catastrophic events. A 2005 study into such events showed that 55 million years ago, a release of 4500 gigatons of carbon caused the extinction of huge numbers of deep-sea creatures. It took over 100,000 years for the oceans to return to their normal alkalinity. To put that time frame into perspective, Homo Sapiens – us - have been around for between only 200,000 - 400,000 years.
What is to be done?
This is all very depressing both for marine organisms and on a more selfish level, for us. Overfishing and destructive fishing has already impoverished most marine ecosystems, and left them particularly vulnerable to environmental changes. The rapid changes that human induced climate change will bring about will exacerbate the problems we have already caused.
Climate change, overfishing and destructive fishing are more than just personal responsibilities. Their causes are endemic to our economic and social structures. These issues need to be tackled on by every government, industry, corporation and individual. The number of collapsed fisheries around the world are a dire warning to anyone thinking that politicians, self-interested regulatory bodies and corporations are an effective way to make change.
Don’t be overwhelmed by the problems, there are still things we can do.
- Walk, cycle or take public transport
- Only fly when necessary
- Reduce your personal power consumption
- Reduce your consumption of fish and seafood
- Spread the word about over fishing
