Final answer:
Climate change negatively impacts coral reefs primarily through ocean warming, which leads to bleaching, and ocean acidification, which affects coral calcification.
Step-by-step explanation:
The two primary factors negatively affecting coral reefs due to climate change are ocean warming and ocean acidification. Global warming from fossil fuel emissions increases sea temperatures, leading to coral bleaching, wherein the corals expel their symbiotic algae and lose their vibrant colors, resulting in weakened and dying coral. Higher levels of atmospheric CO₂ dissolve in the ocean, which reduces the pH and increases acidity. This hampers the corals' ability to build their calcium carbonate structures in a process known as calcification and, consequently, impacts the entire local ecosystem that relies on the coral reefs for food and shelter.