Climate Solutions: The Science and Economics of Stabilising the Climate

Stabilising Earth's climate at any specific temperature target requires reaching net zero greenhouse gas emissions globally — the point where remaining emissions are balanced by carbon dioxide removals. The IPCC's Sixth Assessment Report concluded that limiting warming to 1.5°C requires reaching net zero CO₂ emissions by approximately 2050; limiting to 2°C by approximately 2070. The gap between current trajectories and any net zero scenario is enormous: global CO₂ emissions reached a record 40.9 billion tonnes in 2023, and current national commitments would produce approximately 2.5-3°C of warming by 2100 if fully implemented. Closing this gap requires deployment of climate solutions at a scale and speed that is technically feasible — the technologies exist — but historically unprecedented in the pace of global economic transformation required.

The Energy Transition

Decarbonising the global energy system — transitioning from fossil fuels to zero-carbon electricity and using that electricity to power transport, heating, and industry — is the most important climate solution available. The economic case has been transformed by extraordinary cost reductions: solar photovoltaic costs have fallen approximately 90% since 2010, making solar the cheapest source of new electricity in most of the world. Wind power costs have fallen 70%. By 2023, solar and wind together were generating approximately 12% of global electricity and adding capacity faster than any energy technology in history. The economic competitiveness of clean energy means the transition is accelerating — but not fast enough. Annual clean energy investment reached approximately $1.8 trillion in 2023 — but needs to approximately double to reach net zero trajectories.

Nature-Based Solutions

Nature-based climate solutions — protecting and restoring ecosystems that store carbon — can contribute meaningfully to mitigation while simultaneously delivering biodiversity, water, and livelihood co-benefits. Tropical forest protection and restoration is the largest single nature-based opportunity: halting tropical deforestation alone could contribute 3-4 billion tonnes of CO₂ reduction per year. Peatland restoration, sustainable agriculture, and blue carbon (mangrove, seagrass, and salt marsh restoration) add further potential. A global analysis by The Nature Conservancy found that nature-based solutions could provide approximately one-third of the emissions reductions needed by 2030 to maintain a 1.5°C pathway — at a cost typically well below $100 per tonne of CO₂, making them among the most cost-effective options available.

Methane Reduction — The Fast Climate Fix

While CO₂ receives the most attention in climate discussions, methane — with a global warming potential 86 times that of CO₂ over 20 years — represents a significant near-term climate opportunity. Methane's shorter atmospheric lifetime (approximately 12 years versus centuries for CO₂) means that methane emission reductions translate to reduced warming much faster than equivalent CO₂ reductions, making methane mitigation one of the most effective tools available for limiting near-term warming below 1.5°C. Major methane sources include livestock agriculture (enteric fermentation in ruminants — cattle produce approximately 250-500 litres of methane per day — and manure management), fossil fuel extraction (leakage from gas wells, pipelines, and coal mines), and landfills (anaerobic decomposition of organic waste). The Global Methane Pledge — signed by over 100 countries at COP26 in 2021 — commits to reducing methane emissions by 30% by 2030 relative to 2020 levels, which the IPCC estimates could reduce warming by approximately 0.2°C by 2050.

Carbon Pricing — The Economist's Solution

Carbon pricing — placing an explicit monetary cost on greenhouse gas emissions through carbon taxes or cap-and-trade systems — is widely supported by economists as the most efficient mechanism for reducing emissions across an entire economy. By internalising the external costs of carbon emissions into market prices, carbon pricing creates incentives for emissions reductions at every point in the economy simultaneously: businesses that can reduce emissions cheaply do so; those for whom reduction is expensive pay the carbon price and contribute to a collective fund that can be invested in clean energy, efficiency, or returned to citizens as a dividend. The economic theory is straightforward and well-supported by empirical evidence from the systems that have been implemented: British Columbia's revenue-neutral carbon tax introduced in 2008 reduced fuel consumption by 15% relative to the rest of Canada while maintaining equivalent economic growth; the EU Emissions Trading System has driven significant emissions reductions in covered sectors at costs well below early predictions.