The World May Become Unfit for Human Life

World May Lose Suitability for Human Life Prof. Dr. Güray Salihoğlu stated that with the transgression of nine planetary boundaries established by scientists, it is unknown whether the world can continue to provide conditions suitable for human life. The concept of planetary boundaries was first introduced in a 2009 study conducted by a group of 28 scientists led by Johan Rockström from the Stockholm Resilience Centre. The concept, which expresses the habitability level of the world for humans, encompasses nine thresholds: climate change, chemical substances, stratospheric ozone depletion, atmospheric aerosol loading, ocean acidification, biogeochemical flows, freshwater change, land system change, and biosphere integrity. While transgression of one planetary boundary creates risk for other thresholds, exceeding climate change or biosphere integrity boundaries can push other thresholds into a more risky dimension, accelerating their transgression. In an article published in Science Advances, attention was drawn to the fact that of the nine established thresholds, climate change, chemical substances, freshwater change, land system change, biosphere integrity, and biogeochemical flows have exceeded safe boundaries and reached dangerous levels.

"We are trying to determine how far we have exceeded the planet's boundaries"

Salihoğlu noted that a comparison framework was used in determining the planet's boundaries, stating: "These boundaries refer to the Holocene period, meaning the period 11,000 to 11,650 years ago, after the last ice age, when habitable conditions existed for humans, the climate was temperate, and human communities had begun to establish civilizations. We know that conditions in those times were suitable for human life, and by comparing today's conditions with those times, we are trying to determine how far we have exceeded the planet's boundaries." Noting that beyond the loss of biodiversity, the abundance of freshwater and forests on the planet has also declined due to human impact, Salihoğlu stated that humanity has initiated the Anthropocene epoch, which it dominates, through greenhouse gas emissions, ozone-depleting chemical substances, toxic chemicals, aerosols, and nitrogen-phosphorus loads into the planet.

Emphasizing that the continuity of human life depends on the functioning of ecosystems, Salihoğlu continued:

"There is a decline in plant and animal populations, ecosystems are deteriorating, genetic diversity is being lost. The services we receive from ecosystems are being damaged. Given that within biosphere integrity, approximately one million of eight million plant and animal species face extinction, it means we will no longer receive the services they provide. This will continue in a chain reaction. In terms of biosphere integrity system boundaries, we are in a dangerous zone." With the Ice Age behind us, a suitable environment was created for human life, but Salihoğlu stated that with global warming and greenhouse gas emissions, it is unknown whether suitable conditions will exist in the future to ensure the continuity of human life. He warned that the level of carbon dioxide, known as the safe boundary in the Holocene epoch at 350 ppm (parts per million), has today reached 417 ppm, this figure may continue to increase, and we are in a dangerous zone regarding climate change. Also commenting on the decline in forest resources worldwide, Salihoğlu said: "Scientists say that the number of trees has declined by 50 percent from the advent of agriculture to today. To remain in a safe zone, we need to protect 85 percent of our tropical forests, yet we continuously lose them and ecosystem services are at risk. Changes in our land use continue. In this respect, we are in a dangerous zone." Noting that freshwater faces many pressures, primarily from agriculture, industry, and population, and that shifts in weather patterns linked to climate change result in both droughts and floods occurring simultaneously, Salihoğlu stated: "When the Holocene epoch is compared with today, chemical substances did not exist 12,000 years ago. Today, we are discussing plastics that have become microplastics, organic pollutants, nuclear waste, nuclear weapons, and genetically modified organisms. It is not fully known how these substances will affect the world. We continue to produce hundreds of thousands of chemical substances daily and release them into the environment. Boundaries have long been exceeded; in short, we are in a dangerous zone and period."

Loss of coral reefs triggers biodiversity loss in oceans

Noting that a portion of the carbon dioxide released into nature reaches the atmosphere while the remaining portion is absorbed by the oceans, and that ocean waters, particularly surface waters, are becoming acidic, Salihoğlu stated: "When comparing the pH value of oceans in the 18th century with today, today's acidity is 30 percent higher. When seawater becomes acidic, coral reefs and shellfish begin to dissolve. These reefs host 25 percent of marine life. Loss of coral reefs means catastrophic loss of biodiversity in the oceans. For now, we are in a safe zone, but it could be exceeded at any moment." Comparing the transgression of planetary boundaries to elevated blood pressure in humans and drawing a parallel between rising blood pressure and the likelihood of a heart attack, Salihoğlu concluded: "Even if a heart attack does not occur, efforts must be made to lower blood pressure. In particular, to prevent loss of biodiversity and reverse the effects of the climate crisis, greenhouse gas emissions should be eliminated and a carbon-neutral lifestyle should be adopted." Source