雅思阅读

📖 Reading Passage

The concept of 'tipping points' in climate science refers to critical thresholds that, once crossed, lead to significant and often irreversible changes in the Earth's systems. For instance, the melting of the Greenland ice sheet is not a gradual process but could accelerate dramatically once a certain temperature is sustained. Similarly, the Amazon rainforest, which acts as a major carbon sink, may undergo a dieback process if deforestation and drought exceed a certain level, converting it from a carbon absorber to a carbon emitter. These thresholds are characterized by nonlinear responses, meaning that small perturbations can trigger disproportionately large effects. Understanding tipping points is crucial for policymakers, as they imply that mitigation efforts must be proactive rather than reactive, because waiting for visible signs of damage may leave insufficient time to avert catastrophic outcomes. However, the exact location of these thresholds remains uncertain, complicating decisions on emissions reduction targets.