Johan Rockström | Planetary boundaries: scientific advances | Frontiers Forum Live 2023

Key Concepts

Anthropocene, Planetary Boundaries, Holocene, Tipping Elements, Climate Crisis, Ecological Crisis, Polycrisis, Decarbonization, Resilience, Science-Based Targets, Global Commons, Carbon Law, Nature Positive Agenda, Net Primary Production, Montreal Protocol Moment.

The Anthropocene and Planetary Boundaries

The speaker emphasizes that we have entered a new geological epoch, the Anthropocene, where humanity is the dominant force of change on Earth. This is supported by the work of scientists like Will Stefan, who argued that we are hitting the ceiling of hard-wired processes regulating the Earth system. Evidence suggests we are deep into the Anthropocene, witnessing a loss of resilience, challenging the assumption that the Earth system will automatically recover if emissions cease.

The Anthropocene's scale, pace, and connectivity contribute to global turbulence, manifesting as geopolitical, climate, and ecological crises. The ecological crisis involves a 70% loss in vertebrate populations in the last 70 years and a risk of extinction for one million out of eight million known species. This loss impacts moisture recycling, carbon sequestration, and food production, linking to zoonotic disease outbreaks and pandemics caused by unsustainable exploitation of natural habitats. These crises can interact and reinforce each other, leading to a polycrisis.

Climate Change and the 1.5°C Limit

Currently, the world is at 1.2 degrees Celsius of warming. Despite three years of La Niña, 2022 was the fifth warmest year on record and the most expensive in terms of climate-related loss and damage, with the Pakistan floods costing an estimated $20 billion. Projections indicate a likely breach of the 1.5°C threshold by 2024, raising questions about its viability as a target.

The IPCC's AR6 report highlights three key insights: the climate crisis is impacting human well-being globally, we are threatening the stability of the planet, and there is no safe landing at 1.5°C without phasing out fossil fuels. The IPCC also emphasizes the need to keep up to 50% of intact nature on land for carbon sinks, aligning with the planetary boundary for land use.

A climate model from the Potsdam Institute, led by Andrei Ganopolsky and Mateo Willett, recreates Earth's temperature journey over the past three million years. This model shows that the Earth's temperature has remained within a corridor of life, never exceeding 2°C, until now. The current trajectory leads to a potential 2.7°C warming in 70 years, which the speaker unequivocally labels a catastrophe.

The Holocene, with a stable temperature of 14°C plus or minus 0.5°C, serves as a reference point for a desired planetary state. A healthy biosphere maintained this stability, with oceans and intact nature absorbing 50% of emissions. However, there are signs of cracks in this system, with the Amazon rainforest and temperate forests shifting from carbon sinks to sources.

Tipping Elements and Global Commons

The speaker emphasizes that 1.5°C is a physical limit due to climate tipping elements. Sixteen climate tipping element systems have been identified, distributed across the planet, and considered the new Global Commons. These systems have negative feedbacks that cool and dampen climate change pressures.

At 1.5°C, four of these systems are likely to cross their tipping points: the Greenland ice sheet, the West Antarctic ice sheet, tropical coral reef systems, and abrupt thawing of permafrost. The two ice sheets alone hold 10 meters of potential sea level rise. The IPCC's risk assessment for large-scale singular events has decreased from 3°C in AR5 to between 1.5°C and 2°C in AR6, indicating increased sensitivity to climate forcing.

Security Implications and Cascading Effects

Research from Mexico and Exeter University highlights the security implications of climate change. Regions with average temperatures exceeding 29°C face health threats and potential social instability. By 2070, large parts of Brazil, West Africa, the Horn of Africa, the Middle East, and India could experience these conditions, affecting 3.5 billion people.

Tipping element systems are interconnected through cascades. For example, melting of the Greenland ice sheet slows down the North Atlantic overturning, pushing the monsoon further south and causing dieback in the Amazon rainforest. Slowing the overturning also traps warm water in the Southern Ocean, accelerating the melting of the West Antarctic ice sheet.

The Planetary Boundaries Framework

The planetary boundaries framework defines a safe operating space for humanity based on biophysical processes regulating the planet. It identifies nine boundaries, four of which were transgressed in the 2015 assessment: climate, biodiversity, land system change, and overloading of nitrogen and phosphorus. The stratospheric ozone layer is a success story, moving back into the safe space due to the Montreal Protocol, which banned chlorofluorocarbons.

The speaker argues that we have reached a Montreal Protocol moment for climate, with settled science, policy (Paris Agreement), and solutions (scalable technologies). The journey requires a global sustainability transition, not just decarbonization. This involves transforming the food system, scaling negative emission technologies, and investing in the resilience of intact nature and land.

The Carbon Law and Nature Positive Agenda

The Carbon Law calls for cutting emissions by half every decade, inspired by Moore's Law. There is a positive trend with 70 countries and regions having a price on carbon, and the EU adopting the ETS2 and CBAM. Renewable energy is doubling every 5.5 years, potentially reaching 50% of global electricity by 2030. The transition in the mobility sector, with end dates for combustion engines, is also promising.

The Kunming-Montreal meeting established the nature positive agenda, equivalent to the 1.5°C target for nature. This requires stopping the loss of ecosystem functions from 2020 onwards, regenerating nature, and achieving a net positive point by 2030. The Earth Commission and Global Commons Alliance are translating this into science-based targets for businesses and cities.

Conclusion

While the Anthropocene presents a major challenge, it is currently a pressure, not a new state. There is still a window to keep the planet in a Holocene-like state. The question is whether we can act fast enough to maintain resilience. The journey requires equity, innovation, and transformation, with science playing a fundamental role. The speaker urges spreading the scientific story and understanding the urgency of the situation.