Jisung Park, assistant professor of public policy and environmental health sciences, spoke with Marketplace about the impact of climate change on economic productivity. The International Labor Organization predicts that heat stress linked to global warming could drain more than $2 trillion from the world’s gross domestic product. In hot weather, people work more slowly, need more breaks and make errors, studies have found. “If you work outdoors, it’s much harder to protect yourself from either the productivity or the health impacts from extreme heat,” said Park, who has conducted research showing that student test scores decline in hot weather. The effect of rising global temperatures on cognitive development is particularly acute in low-income areas where air conditioning is not available, Park has found.