Oceans have become warmer, year on year, in the last 50 years. In the recent decades the rate of ocean warming and heatwaves more than doubled and continues to increase. We have polluted and changed the chemistry of the world’s oceans. The oceans have absorbed 90 per cent of the excess heat from the atmosphere and around 25 per cent of total carbon dioxide emissions generated by humans since the 1980s and by so doing have undergone increased surface acidification.
The warmer surface waters of the seas are absorbing less oxygen and also losing more oxygen. Oxygen normally enters the ocean by interactions between its surface and the atmosphere, and as a photosynthesis by-product from phytoplankton (microscopic marine algae) in the surface layers.
Loss of oxygen is also caused through temperature driven stratification of the ocean which inhibits the production of oxygen from photosynthesis. Ninety-five per cent of the open ocean surface pH is also declining.
This alarming information and much more has been revealed in a recent Special Report by the United Nations Intergovernmental Panel on Climate Change (IPCC) prepared by 104 scientists from 36 countries and based on 6,981 peer reviewed scientific reports.
Ocean stratification (layering) occurs when water with different properties such as salinity, density or temperature forms layers. These layers act as barriers for water to mix. This results in marine life finding it difficult to move up and down the water column.
Water stratification also creates barriers to nutrient mixing between layers. This reduces the presence of phytoplankton in the surface waters – less phytoplankton means less photosynthesis takes place, less photosynthesis means less oxygen. Marine life needs oxygen to live.
Our collective actions have thrown nature out of the particular balance that allows life on earth to thrive. Today’s young generation and future generations (should they exist) will pay the ultimate price for this ecocide.
Acidification, caused by the ocean’s absorption of carbon dioxide, and the loss of oxygen, both a consequence of human activity, are causing severe loss of habitat for marine species – in other words the seas and oceans are losing their ability to sustain life and are slowly but surely being turned into dead zones.
Our chances of survival in this future landscape are low- David Marinelli
Global sea levels are rising, with acceleration in recent decades as a result of increasing rates of ice loss from the Greenland and Antarctic ice sheets and the continued loss of glacier volumes and the warming of the seas and oceans.
Increases in tropical cyclone winds and rainfall, and increases in the height of waves, combined with a rise in sea level, will make already violent sea storms worse and a greater hazard to coastal areas causing more coastal erosion and flooding. Coastal communities are the most exposed and face the greatest risks.
Since about 1950 many marine species across various groups have undergone shifts in geographical range and seasonal activities in response to ocean warming, sea ice change, acidification caused by pollution and oxygen loss. Both land and marine plant and animal species are on the move as they try to escape their historical habitats that no longer support their life. All ecosystems, from the equator to the Poles are compromised and this has placed species in conflict with each other as they invade each other’s territories in a desperate attempt to stay alive.
Altered interactions between species have caused cascading impacts on all ecosystems and their life-sustaining ability. The proximate, and indeed the only ultimate, cause for this catastrophic collapse of the biosphere is human activity. Human infrastructure and our unrelenting interference in all places on earth are the paramount obstacle to any natural recovery or restoration of that temperate and welcoming climate that humanity was born into and that would still be so had we not been around to ruin it.
The oceans are projected to change over the coming decades in ways we cannot fully predict with increased warming, greater upper ocean stratification, further acidification, oxygen decline, and less fish and marine life. Marine heatwaves and extreme weather conditions are projected to become more frequent and more widespread. The ocean’s density, salinity and temperatures are changing. The warm and cold, surface and deep sea currents are changing.
Wildfires are projected to increase significantly for the rest of this century across most tundra and forest regions, and also in some mountain regions. The recent fires in the Australia, Africa and the Amazon forests come to mind.
The global ecosystem processes that ensure that the oceans are continually mixed, and that heat and energy are distributed around the earth, have been altered. The ability of the oceans to contribute to the benign climate we have experienced up to now, has been jeopardised.
These life-threatening events will continue and increase as the global average temperature increase rises to 1.5°C when compared to pre-industrial levels.
At the end of 2019 the increase had reached 1°C. It is expected to reach 1.5°C by 2030 and to go up to 4°C and over by the end of the century, if we do nothing or not enough. All governments have received this United Nations report. The urgency to cut greenhouse gas emissions to zero cannot be overstated.
Human activity has significantly disturbed the proper functioning of the earth’s ecosystems. These ecosystems need to be life supporting, stable and predictable for life on earth as we know it to exist. Our chances of survival in this future landscape are low.