In the “The conservation of whales in the 21st century”
In 2001 the third report of the Intergovernmental Panel on Climate Change predicted that average global surface temperatures would increase by 2100 from 1.4 to 5.8 degrees, with accompanying sea level rises of between 9cm and 88cm.
Climate change may cause changes in migratory patterns, destroy habitat (particularly in nutrient-rich polar seas), and drastically change ocean circulation, vertical mixing and overall climate patterns. There may be changes in nutrient availability, biological productivity, and the structure of marine ecosystems from the bottom of the food chain to the top.
Whales may be particularly affected by changing location and abundance of food sources, changed migration patterns and habitat destruction. Endangered whale species may become extinct.
Thinning of the ozone layer in the upper atmosphere over the Poles has affected growth and reproduction of plant plankton – the basis of oceanic and freshwater ecosystems. A short-term 4–23 percent reduction in plant plankton productivity has been measured in areas affected by the ozone hole. Increased intensity of ultraviolet-B radiation damages the larval development of some crab, shrimp and fish species.
Any impacts of such changes on lower levels of the food chain may be expected to affect higher level species, such as large fish and all whales. Light-coloured whale species living in polar regions, such as beluga, may suffer short-term damage to vision and immune systems, and increased risk of disease and reproductive failure. The longterm effects of increased ultraviolet-B are unknown.
Because of their longevity, whales are more vulnerable to the accumulation of marine pollutants. Toxins accumulating in blubber can be passed to infants in their mother’s milk. Whales are known to accumulate heavy metals, organochlorines such as PCBs (polychlorinated biphenyls), DDT, dioxins and polycyclic aromatic hydrocarbons.
Whales are less able than other mammals to metabolise many environmental pollutants. Because of atmospheric circulation patterns, whales living in areas far from industrial centres may contain more environmental pollutants than species near such centres. It is a global problem for whales.
New Zealand believes that problems arising from the effects on whales of persistent organic pollutants, heavy metals, climate change and ozone depletion must be confronted in appropriate international forums. The IWC should work more closely with these forums.