Climate Change dramatically affecting Oceans and Coasts
A brief introduction to the “cause and effect” relationship in preparation of CERCA’s Symposium on:
“Expected Impacts of Climate Change on Coastal Communities and Estuaries” (14th of June 2014 at the Vancouver Island University).
Prepared by Dr. Goetz Schuerholz (Chair CERCA)
It is noteworthy that today billions of people are living concentrated in clusters and mega-cities (over 10 Mio inhabitants) along the shorelines of our oceans. As a matter of fact the majority of large- and mega-cities of the world are actually located along the shorelines of oceans and seas which cover more than 70% of the earth’s surface. For millenia mankind has chosen shorelines and estuaries as a preferred living space making use of rich marine food sources, fertile soils, strategic location for international trade, and more recently attractive recreational opportunities. Coasts and islands throughout the world have turned into some of the most frequented tourist destinations contributing significantly to local economies.
It now appears that this key living space is directly threatened by man-caused climate changes, well documented by the fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) to be available by October 2014. The report is composed of contributions by the IPCC’s three working groups providing a clear and up to date view of the current state of scientific knowledge relevant to climate change which is irrefutable.
Key Findings by the International Panel on Climate Change
In its preamble the Synthesis Report of the IPCC states that:
“Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased”.
The world’s leading climate experts agree that green-house gases in the atmosphere have reached a new record high in 2014, continuing an upward and accelerating trend which is driving climate change and will shape the future of our planet for hundreds and thousands of years.
The World Meteorological Organization’s (WMO) annual Greenhouse Gas Bulletin shows that between 1990 and 2012 there was a 32% increase in radiative forcing – the warming effect on our climate – because of carbon dioxide (CO2) and other heat-trapping long-lived gases such as methane and nitrous oxide. Carbon dioxide, mainly from fossil fuel-related emissions, accounted for 80% of this increase. The latest WMO Assessment Report stressed that atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. There is consensus amongst leading climatologists that as a result of this, our climate is changing, our weather is more extreme, ice sheets and glaciers are melting and sea levels are rising.
According to the IPCC report:
“Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010. It is virtually certain that the upper ocean (0−700 m) warmed from 1971 to 2010..
…Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease. The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia.”
What is happening in the atmosphere is only one part of a much wider picture: only about half of the CO2 emitted by human activities remains in the atmosphere, with the rest being absorbed in the biosphere and oceans which have absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification with all its consequences.
Increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, and measurable global warming leave no doubt about human influence on the climate system and it is evident that continued emissions of greenhouse gases will cause further warming with all its dramatic consequences on climate and our habitat.
The IPCC report concludes that:
“The global ocean will continue to warm during the 21st century. Heat will penetrate from the surface to the deep ocean and affect ocean circulation. It is very likely that the Arctic sea ice cover will continue to shrink and thin and that Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises.”
Coastal Communities and Global Economy
The predicted increase in global warming as a result of anthropogenic gas emissions is expected to have most dramatic effects on oceans and coastal zones with significant consequences for coastal communities and their habitat. Expected impacts of rising sea levels are expected to be exacerbated in severity and magnitude by continuing degradation of terrestrial, coastal and marine ecosystems, deforestation, destruction of mangroves, marshes, and corral reefs which loose their critical buffer and filter functions.
There is wide consensus amongst the world’s leading climatologists that global warming will result in:
- Melting of polar ice caps and increase in ocean acidification;
- Changes in oceanic water circulation;
- Rising sea levels as a result of water expansion (temperature increase) and melting icecaps and glaciers;
- Increased frequency and severity of tropical storms;
- Pole-ward changes of biological diversity and ecosystems;
- Overall decrease of biological diversity;
- Flooding and disappearance of thousands of islands and low lying coastal areas;
- Displacement of millions of people living along coastlines;
- Severe impacts and deterioration of sensitive ecosystems such as corral reefs, estuaries and mangrove forests.
Against this background we have to ask ourselves whether oceans and coastal areas will be able to retain their importance as climate regulators, as major contributors to global economy and food supply, or whether they will turn into an unmanageable threat to mankind and climate. Rising sea levels and increasing severity of storms causing disastrous floods in many parts of the world, permanently destroying prime agricultural land and displacing millions of coastal people world-wide have become a common occurrence.
The Food and Agriculture Organizations of the UN has listed Vietnam as one of the countries to be heaviest hit by climate change. Since 1996 one million people had to be re-located already from Vietnam’s Mekong Delta due to rising sea levels. Approximately 20% of the country’s 90 million people live in the Mekong Delta. Conservative simulation models indicate that within the next 50 years possibly all of these people will be displaced by rising sea levels which are expected to cover the entire Mekong Delta with a 70cm of sea water. Even more alarming, the 42 million tons of rice currently produced annually by the delta feeding a large Asian population will be lost forever. It is not the Mekong Delta alone where water tables will rise destroying agricultural livelihoods and coastal cities: The Irrawady River delta of Myanmar, the Chao-Praya-Delta in India and Bangladesh and the Missisipi Delta of the USA will suffer the same fate. The five Deltas currently produce 80% of the world’s rice production. The flooding of these deltas will be a catastrophic threat to global food security.
Apart from their role as climate regulator (i.e., water cycle, absorption of sun energy, temperature regulator, oxygen production, CO2 sequestration) oceans and coastal waters have significant ecological and economic functions, and figure high in terms of employment and world food supply.
It may not be too late to save the world, but we have to act now to slow down climate change. This will require large and sustained reductions of greenhouse gas emissions within this and the coming decade to which we all personally, locally, regionally, nationally and globally can and must contribute in our own way. We need to act now otherwise we will jeopardize the future of our planet.