Climate Change and the Oceans

Our Changing Climate

We can see changes in our climate in a variety of ways. Atmospheric Warming IPCC report This record shows that, over the past millennium, temperatures in the atmosphere have risen significantly. While we don't have records of actual temperature from 1000 years ago, scientists use "proxy" measurements including growth patterns in tree rings and coral, and analyses of layering and gas concentrations in ice cores, to deduce temperature. In order to establish their reliability, these proxy records are validated against measured temperature over the last ~140 years.

This figure shows warming over the recent past. This record goes back to about the earliest time when temperatures were measured adequately to compute global surface temperature values. IPCC report Oceanic Warming The oceans are warming too. This plot shows the changes in heat content of the oceans (down to 3000 m) over the past 45 years. It is based on historical data examined by Levitus et al (Science, 1999). The oceans are capable of storing much, much more heat than the atmosphere, so a small temperature change represents a large heat gain. This plots shows that the oceans are storing an ever-increasing amount of heat. There are regional differences in ocean warming, although nowhere is there a long-term cooling trend. This warming is largely responsible for an ongoing sea level increase. Levitus et al. (Science, 1999).