The age of humans

Dr Anjani Ganase looks at the planetary boundaries that humans have impacted, moving the earth to a state that may no longer be hospitable for our species.

The Holocene Epoch marks 11,700 years of recorded human history in which we thrived in a stable environment and ecology. This allowed significant human evolution and in the last 100 years, saw the advance of technology and industry. In that short time, humans have drastically altered the global environment through resource extraction and pollution of our air and waterways. Some of these conditions have become destabilized resulting in the sudden loss of biodiversity, habitats, resources and even shifting climate. Scientists have collated such environmental changes between 1950 to now, to identify the most important boundaries that should not be crossed for the sake of human survival.

The planetary boundaries framework is a science-based analysis that observes the risk associated with human activities in destabilizing the earth’s system. Metrics are used to identify the boundaries, which are conservatively estimated for circumstances of transgressions with some leeway for human remediation before reaching that tipping point. There are nine major planetary boundaries that must not be exceeded for the planet to remain hospitable to life as we know it and sustain thriving human societies. Three major zones are defined: (1) the safe zone of operation; (2) the zone of uncertainty – approaching the boundary with increasing risk of destabilizing the earth systems; and (3) the zone beyond uncertainty with a high risk of destabilization. The aim of identifying such planetary boundaries and measurable targets to be maintained as sustainable development goals is a safe and stable earth and a just system for human wellbeing.

Here are the nine planetary boundaries that have been considered:

– Biosphere integrity is measured by the diversity (functional and genetic) of the planet’s natural world given the understanding that such evolutionary diversity is directly connected to the environment and our survival. Over the last fifty years, human activities have resulted in more biodiversity loss with current global extinction rates ranging from 100 to 1000 extinctions per million species per year (the baseline extinction rate is one species in every one million per year). We have pushed passed the planetary boundary with respect to the rate of biodiversity loss.

– Biogeochemical flows refer to chemical pollution that exists in our waterways and oceans with a specific focus on nutrient pollution (nitrogen and phosphorus) that leaches from pastoral and agricultural lands. Other chemicals have not been investigated in such detail. Considering the concentrations of nutrients to create eutrophication and anoxic waterways, the current annual rate of nutrient input far exceeds this threshold.

– Land change system refers to changes in all terrestrial biomes – forests, savannas, etc. - across the tropical, temperate and boreal regions, that regulate climate, water and energy resources. Tropical forests have a significant consequence on the water cycle and biodiversity. We are in an area of increasing uncertainty as we near our planetary boundary of 75 % loss.

– Climate change measured by our carbon emission is dangerously close to our planetary boundary of 350 -450 parts per million (ppm) carbon dioxide (we’re currently at 413 ppm). Heat waves (land and sea), wildfires, sea ice loss, and droughts are already being observed as the new normal.

– Freshwater use refers to how we consume/ impact the freshwater from rivers, lakes, reservoirs and groundwater. While the current global freshwater use continues to occur within livable boundaries, there are specific regions in the world where water use is beyond the boundary (Southern Europe, Middle East). The water stored in our soils (green water) has not been considered; in fact, most of the soil moisture globally has been depleted resulting in degraded ecosystems and might therefore be considered to have exceeded the planetary capacity.

– Ocean acidification refers to the shift in the chemical condition of the ocean known to absorb up to 30 per cent of global carbon dioxide emissions. This results in impairments in the marine environment. While the current concentrations are still functioning within relatively safe limits, regional ocean acidification is having visible impacts on marine ecosystems and associated industries.

– Stratospheric ozone depletion refers to the loss of the ozone layer because of ozone-depleting chemicals - chlorofluorocarbons (CFCs). After the banning of this chemical, the hole in the ozone has been repaired and therefore this action occurs safely within the planetary boundary.

For the last two boundaries – atmospheric aerosol loading and novel entities – there is not enough information to define the boundary levels.

Atmospheric aerosol loading refers to air pollution through the release of chemicals and particles such as sulfates, carbon, and nitrates from fossil fuel combustions. Such emissions have direct impacts on human health and monsoonal rainfall activities; they can affect atmospheric conditions such as dim sunlight, and shift rainfall patterns. Both the increase and decrease in rainfall may be based on the aerosol, as is observed in South Asia and the Atlantic Ocean.

Novel entities refer to any novel substance (material, chemical or life form) or natural substance mobilized by human activities that are likely to negatively affect humans or ecosystems whereby the impact is based on its persistence in the environment and ease of transmission. Examples of this include chlorofluorocarbons which were thought to be harmless but rapidly degrade the ozone. Consider microplastics and associated chemicals dispersed in a similar manner, that are likely to shift ecosystems and environments. There is yet no global standard for measuring these entities or defining a boundary.

How are we doing?

All nine boundaries have been incorporated into our sustainable development goals established by the United Nations, including freshwater (SDG 6), climate (SDG 13), biodiversity (SDG 15), oceans (SDG 14), and sustainable cities (SDG 11). However, when we look at how businesses are incorporating these boundaries into their models, the targets and actions continue to be too slow.

A study done on six nature targets (aligned with planetary boundaries) undertaken by Fortune Global 500 companies showed that most companies (85 %) had climate-related targets. However, few (25 per cent) consider freshwater consumption; only 20 per cent have chemical and plastic pollution targets; fewer still had biodiversity loss reduction targets (five per cent) and less than one per cent consider nutrient pollution. No company had targets to combat six of the main targets. Of those with set targets, most of the targets were one-dimensional. There is a general lack of comprehension among the companies of their relationship with nature – both the benefits and impacts. The sectors with the highest number of businesses with no targets include construction. Agriculture had the most multidimensional targets to protect nature considering the direct impact on land, freshwater systems, and climate change.

While change is happening slowly, it is crucial to sustainable development that socioeconomic well-being should not mean environmental degradation. Socio-economic transformation must include consideration of these planetary boundaries. One of the myths to be dismissed might be that of continuous economic growth. Or rather, what does a well-being economy look like?

References

https://www.mckinsey.com/capabilities/sustainability/our-insights/where-the-worlds-largest-companies-stand-on-nature

Rockström, Johan, et al. “Identifying a safe and just corridor for people and the planet.” Earth’s Future 9.4 (2021): e2020EF001866.

Rockstrum, J. (2021) Protecting planetary boundaries: aligning the SDGs to ensure humankind’s future.

Steffen, Will, et al. “Planetary boundaries: Guiding human development on a changing planet.” science 347.6223 (2015): 1259855.

Wang-Erlandsson, L., Tobian, A., van der Ent, R.J. et al. A planetary boundary for green water. Nat Rev Earth Environ 3, 380–392 (2022). https://doi.org/10.1038/s43017-022-00287-8