evidence: Corals and tiny fossilised marine organisms buried in the seabed act as natural recorders of past ocean temperatures. Along with tree rings and ice cores, which offer a window into land temperatures throughout Earth’s history, these are all examples of "climate proxies". Adding in the information from the proxies extends the instrumental temperature record in today’s study back in time to 1500AD. It is different from previous studies that use climate proxies because it uses a brand new temperature reconstruction for the tropical oceans.