Changes in temperature and sea-levels based on man made actions are harder to convince people of than other factors. My go-to in cases like this is ocean acidification. The following is a straightforward introduction to this part of climate change:

http://www.nationalgeographic.com/environment/oceans/critica...

The process seems fairly simple. Oceans absorb a high proportion of the carbon dioxide released into the atmosphere from burning fossil fuels. This changes the pH levels of oceans, which then alters the environment that marine animals live in, causing a necessity to adapt. You could perform water pH experiments to prove the effects on marine life if you needed to convince yourself (though I wouldn't want to promote animal testing if there was another way to reach clarity on this).