The global ocean has warmed up more and more, year on year, in the last 50 years. Since 1993, the rate of ocean warming has more than doubled. Marine heatwaves have also doubled in frequency since 1982 and are getting hotter. We have polluted and changed the chemistry and temperature of the world’s oceans. This has caused severe stress to marine ecosystems and life. The Oceans have absorbed 90% of the excess heat from the atmosphere and between 20–30% of total carbon dioxide emissions generated by humans since the 1980s and by so doing have undergone increased surface acidification.
Loss of oxygen in the top 1,000 meters of the water column is another problem. The warmer surface waters of the seas are absorbing less oxygen and also releasing 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.
95% of the open ocean surface pH is also declining. Marine life forms survive within a pH range. Changes in the pH (acid/alkaline) balance is a matter of life and death.
This alarming information and much more has been revealed in a recent Special Report by the United Nations Intergovernmental Panel on Climate Change (IPCC) called ‘The Ocean and Cryosphere in a Changing Climate’ prepared by 104 scientists from 36 countries and based on 6981 peer reviewed scientific reports.
Ocean stratification (layering) occurs when water with different properties such as salinity, density or temperature forms layers, which act as barriers for water to mix. This results in marine life finding it difficult to move through these barriers in the upper water levels as the different strata present extreme characteristics. 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, less photosynthesis means less oxygen. Marine life needs oxygen to live, draw your own conclusions as to where this takes us.
It is clear that all life is a balance. 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 will now pay the ultimate price.
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.
There is more. 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, continued loss of glacier volumes and the warming of the seas and oceans. Loss of ice volumes in the last decade has doubled in Greenland and trebled in Antarctica, from the previous decade.
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.
Global warming has impacted land and freshwater species and ecosystems in high-mountain and polar regions, through the appearance of land previously covered by ice, changes in snow cover, and thawing permafrost. This has disturbed the existing ecological balance which is not a matter to be taken lightly. The previously existing ecological balance supported life as we know it, with the seasonal activities, abundance and distribution of ecologically, culturally, and economically important plant and animal species that we are familiar with.
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 strive 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 is 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.
Marine mammals and seabirds in both polar regions have experienced habitat contraction linked to sea ice changes. Reduction of habitat directly reduces the ability to forage for food or hunt for prey – this is a brutal and unforgiving equation – without food and habitat the animals die.
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 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.
Marine heatwaves are projected to further increase in frequency (by 20 to 50 times), duration, area and heat intensity (by 10 times) in the next 50 years when compared to pre-industrial times, 1850-1900. 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 Australia and the Amazon forest come to mind.
This 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 jeopardized.
These life threatening events will come to pass at a temperature increase of 1.5°C over pre-industrial levels. At the end of 2019 the temperature increase was at 1.1°C. This 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. All governments have received the United Nations report that is the subject of this article. Wherever you live, be certain that your government is well informed and that its inaction is therefore inexcusable and unacceptable. 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. The resulting ecosystems and the eventual balance that they will reach will not be welcoming to the life forms we are familiar with. Our own chances of survival in this future landscape are low. This is Ecocide. #ACTNOW
This article was published in the Times of Malta on the 28th April 2020