A Plausible Scenario for Environmental Optimism in the 21st Century

1. Power: Cost Declines Are Driving the Energy Transition 

The strongest empirical foundation for optimism lies in energy. 

Solar power costs have followed a consistent learning curve, declining by roughly 20% for every doubling of installed capacity, and in many regions now fall below $0.10 per kWh. This has made solar the cheapest new source of electricity across most of the globe. In real dollar terms in these places, it is the cheapest source of electricity in human history. 

As a result, renewables are no longer dependent solely on policy support. In fact, recent data shows that renewables are now outpacing coal in new electricity generation, marking a structural turning point in global energy systems. 

Levitt also pointed to forward-looking scenarios where solar paired with battery storage could meet up to ~90% of electricity demand in large markets such as India at low cost, highlighting how quickly energy systems are likely to evolve as economics align. 

2. Population: Slowing Growth Reduces Systemic Pressure 

Demographic trends provide a second pillar of optimism. 

Global fertility rates have declined sharply across both developed and emerging markets, with projections indicating that the global population is likely to peak this century and decline thereafter. 

This shift reduces long-term pressure on key environmental systems: particularly energy demand, land use, and food production. Importantly, these trends are closely linked to improvements in education and gender equality, suggesting that social progress and environmental outcomes are mutually reinforcing. 

3. Protein: The Environmental Cost of Food Can Be Reduced 

Food production, especially livestock, remains one of the most resource-intensive sectors of the global economy. 

Empirical comparisons presented during the talk showed that beef production has among the highest greenhouse gas emissions per kilogram of food, significantly exceeding plant-based alternatives now available. 

Emerging technologies offer a new and compelling alternative. Novel approaches such as fermentation-based protein and so-called “air protein” fundamentally rethink how food is produced. Instead of relying on land-intensive agriculture or livestock, air protein uses microorganisms that convert inputs such as carbon dioxide, water, and renewable electricity into edible, versatile protein products, now being market tested, that could largely decouple protein production from traditional resource constraints. 

This shift has significant environmental implications. Early-stage systems suggest that protein can be produced using a tiny fraction of the land and water required for conventional livestock, while also avoiding methane emissions associated with ruminants. Unlike conventional agriculture, production can occur in controlled, industrial environments, making it less vulnerable to climate variability such as droughts or soil degradation. 

If these technologies scale, they can meaningfully reduce pressure on global land use. In turn, this creates the possibility of reallocating land toward reforestation, biodiversity restoration, and other natural climate solutions, amplifying environmental benefits beyond the food system itself. 

In effect, these innovations could fundamentally reshape the environmental impact of global food systems. 

4. Pollution Control: Measurement Is Changing What Is Enforceable 

One of the more underappreciated trends is the rapid improvement in environmental monitoring. 

Satellite-based systems can now detect methane emissions with high precision, enabling identification of specific sources such as coal mines and oil infrastructure. This is particularly important given that methane has roughly 30 times the warming impact of CO₂ over shorter time horizons. 

Empirical evidence also shows that improved monitoring, combined with policy enforcement, can lead to rapid improvements. For example, stricter environmental regulations have already contributed to measurable declines in air pollution levels in countries such as China over the past decade. 

The broader implication is that environmental challenges are increasingly becoming measurable, trackable, and therefore solvable. 

5. Productivity & Innovation: Expanding the Energy Frontier 

Technological innovation continues to unlock new sources of clean energy.

Emerging geothermal technologies, including advanced drilling techniques, could enable access to heat resources deep within the earth, creating the potential for large-scale, continuous clean power generation. 

Early projects suggest that geothermal systems can operate at utility scale (e.g., gigawatt-level potential), offering a complement to intermittent renewable sources such as solar and wind. 

This reflects a broader pattern: improvements in productivity and technology do not just reduce costs, they expand what is physically possible within the energy system. 

6. Protecting Land & Water: Scaling Natural Climate Solutions 

Finally, Levitt emphasized the importance of restoring natural systems, based on pioneering research done by Yale School of the Environment professor Oswald Schmitz in conjunction with colleagues around the world. 

Reductions in inefficient livestock production and improvements in agricultural productivity, paired with the careful reintroduction across selected large landscapes of native species such as American bison, could significantly improve the carbon sequestration capacity of the land. Leveraging this finding can create impressive positive feedback loops, offering enhanced opportunities for reforestation, biodiversity recovery, and enhanced carbon sequestration. 

Natural systems, forests, soils, and oceans, play a central role in regulating the carbon cycle. When restored at scale, they can deliver disproportionately large environmental benefits linked to incremental emissions reductions.