Theme A: Climate change and its impact on the oceans
Twenty-two scientists from around the world–including Silliman University’s Dr. Hilconida Calumpong –submitted to the UN General Assembly their report as the Ad Hoc Working Group on the Regular Process for Global Reporting & Assessment of the State of the Marine Environment, including Socio-economic Aspects.
The First World Ocean Report, approved by the UN General Assembly in December 2015, consists of 10 themes. We wish to share some details of each theme in the Report (verbatim).
Ocean circulation. As a result of changes in the heating of different parts of the ocean, patterns of variation in heat distribution across the ocean are also changing. Those changes in patterns result in significant changes in weather patterns on land Water masses are also moving differently in areas over continental shelves, with consequent effects on the distribution of species.
Storm and other extreme weather events. Increasing seawater temperatures provide more energy for storms that develop at sea. The scientific consensus is that this will lead to fewer but more intense tropical cyclones globally. Evidence exists that the observed expansion of the tropics since approximately 1979 is accompanied by a pronounced poleward migration of the latitude at which the maximum intensities of storms occur. This will certainly affect coastal areas that have not been exposed previously to the dangers caused by tropical cyclones.
Ultraviolet radiation and the ozone layer. UV radiation emitted by the sun in the UV-B range (280-315 nanometres wavelength) has a wide range of potentially harmful effects, including the inhibition of primary production by phytoplankton and cyanobacteria, changes in the structure and function of plankton communities and alterations of the nitrogen cycle.
The ozone layer in the Earth’s stratosphere blocks most UV-B from reaching the ocean’s surface. Consequently, stratospheric ozone depletion since the 1970s has been a concern. International action (under the Montreal Protocol) to address the depletion has been taken and the situation appears to have stabilized, although with some variation from year to year.
Changes in seasonal life cycles in the ocean. It has been predicted under some climate change scenarios that up to 60 per cent of the current biomass in the ocean could be affected, either positively or negatively, resulting in disruptions to many existing ecosystem services. For example, modeling studies of species with strong temperature preferences, such as skipjack and bluefin tuna, predict major changes in range and/or decreases in productivity.
Loss of sea ice in high latitudes and associated ecosystems. The high-latitude ice-covered ecosystems host globally significant arrays of biodiversity, and the size and nature of those ecosystems make them critically important to the biological, chemical and physical balance of the biosphere.
Ice algae are estimated to contribute more than 50 per cent of the primary production in the permanently ice-covered central Arctic. As sea-ice cover declines, this productivity may decline and open water species may increase.
The high-latitude ecosystems are undergoing change at a rate more rapid than in other places on earth. In the past 100 years, average Arctic temperatures have increased at almost twice the average global rate.
Reduced sea ice, especially a shift towards less multi-year sea ice, will affect a wide range of species in those waters. For example, owing to low reproductive rates and long lifetimes, some iconic species (including the polar bear) will be challenged to adapt to the current fast warming of the Arctic and may be extirpated from portions of their range within the next 100 years. (Excerpted by SU REnews)
