How is our changing climate affecting the oceans?
I am very conscious about not appearing like 'Mrs Doom and Gloom' or the 'Grime Reaper of Perpetual Bad News' but there is a very important story to tell which affects the 7.6 billion (and counting) people on our planet. Without going into too much detail, here are the key FACTS on exactly how global warming is affecting our oceans today and in the future.
OCEAN HEAT
As climate change warms the Earth, our oceans are responding more slowly than land environments. Global warming caused by human activities that emit heat-trapping carbon dioxide have (to date) raised the average global temperature by about 1°F (0.6°C) over the past century. Three independent analyses show that the amount of heat stored in the ocean has increased substantially since the 1950s. Ocean heat content not only determines sea surface temperature, but also affects sea level and currents. Ultimately the world’s oceans have a two-way relationship with weather and climate. The oceans influence the weather on local to global scales, while changes in climate can fundamentally alter many properties of the oceans.
SEA SURFACE TEMPERATURE
Ocean surface temperatures increased around the world during the 20th century. Even with some year-to-year variation, the overall increase is clear, and sea surface temperatures have been consistently higher during the past three decades than at any other time since reliable observations began in the late 1800s.
SEA LEVEL RISE
When averaged over all of the world’s oceans, sea level has risen at a rate of roughly 1.5 cm or six-tenths of an inch per decade since 1880. The rate of increase has accelerated in recent years to more than an inch or 2.54 cm per decade. As the world's oceans rise, low-lying coastal areas will disappear. Flooding of coastal areas will become more common and more severe as storm surges have easier access to these lower-lying areas. The occurrence of extreme high water events related to storm surges, high tides, surface waves, and flooding rivers will also increase.
LAND LOST AND DROWNING WETLANDS
Flooding and loss of land will have significant impacts on humans, wildlife, and entire ecosystems. As sea level rises, dry land and wetlands can turn into open water. Along many parts of the Atlantic coast, this problem is made worse by low elevations and land that is already sinking. Between 1996 and 2011, the coastline from Florida to New York lost more land than it gained. Wetlands normally grow vertically fast enough to keep up with sea level rise, but recently the sea has been rising too fast for wetlands to keep their blades above water. Coral reefs and sea grass meadows are also in danger of “drowning” since they can only photosynthesize in relatively shallow water.
COASTAL FLOODING
Flooding is becoming more frequent along the US coastline as sea level rises. Nearly every site measured has experienced an increase in coastal flooding since the 1950s. The rate is accelerating in many locations along the East and Gulf coasts. The Mid-Atlantic region suffers the highest number of coastal flood days and has also experienced the largest increases in flooding.
OCEAN ACIDITY
The ocean has absorbed about 30 percent of the carbon dioxide humans have sent into the atmosphere since the start of the Industrial Revolution – some 150 billion tons. Therefore, the ocean has become more acidic because of these increased levels of atmospheric carbon dioxide, which dissolves in the water. This great service, which has substantially slowed global warming, has been accomplished at great cost. Higher acidity affects the balance of minerals in the water, which can make it more difficult for certain marine animals to build their protective skeletons or shells. Ocean acidification also appears to be affecting whole ecosystems, such as coral reefs, which depend on the formation of calcium carbonate to build reef structure, which in turn provides homes for reef organisms.
CORAL BLEACHING
Warmer oceanic temperatures have been identified as the leading cause for coral bleaching worldwide. Mass coral bleaching results in the starvation, shrinkage and death of the corals that support the thousands of species that live on coral reefs. An example of this is the severe coral bleaching that has ravaged two-thirds of the Great Barrier Reef. And the world's largest coral reef system has experienced massive bleaching for the second year in a row.
FISH MIGRATION
Many fish species have moved towards the poles in response to ocean warming. Once a tropical fish species arrives in a new area, it can quickly mow down vegetation and algae and destroy the lush habitat that protects other species. And the loss of vegetation can have a devastating effect the community of species that live there. And scientists are now examining how the migration patterns of fish, a critical food source for millions of people, is likely to exacerbate inequality between the world's poor and rich countries.
DISASTROUS POSITIVE FEEDBACK LOOP
Acidification also appears to be reducing the amount of sulfur flowing out of the ocean into the atmosphere. This reduces reflection of solar radiation back into space, resulting in even more warming. This is the kind of positive feedback loop that could result in 'run-away climate change' and of course, even more disastrous effects on the ocean.
Finally, please understand that even the ocean has limits, and we are bumping up against them, with damaging consequences for the whole world. Think about it.
#thinkaboutit
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