 One of the most concerning consequences and an indicator of global warming is sea level rise. Sea level rise has the potential to displace coastal populations throughout the globe and consequently allows storm surges from tropical storm systems to penetrate further inland. This causes damage to places previously untouched by the sea. Sea level rise is not uniform and some areas will see significantly more rise than others. One reason sea level is rising is from the thermal expansion of sea water as the oceans warm. When water gets warmer, it expands. As a result, warmer water takes up more space than colder water. This effect alone has been responsible for a lot of the sea level rise we have observed so far. Thermal expansion is pretty straightforward, just basic physics. Another reason sea levels are rising is due to the melting of ice that sits on land, such as glaciers and the two ice sheets, Greenland and Antarctica. When sea ice melts, it doesn't add to sea level rise, just like melting ice cubes in a cup doesn't make the water level go up. So as far as sea level rise is concerned, it's melting land ice that matters. We have some awesome satellite technology and other observations to keep track of ice loss, but predicting future ice loss is what gives our model projections of sea level rise the most uncertainty. This rate of melt of glaciers and ice sheets is complex and changes happen quite quickly. What sea level rise have we observed in the past? Well, by stitching together the tide gauge record with the recent satellite record, we have found sea levels have already risen about 20 centimeters since 1880. We have also observed that the rate of sea level rise is increasing. In other words, sea level is rising more quickly now than we've seen over the past century. We expect global temperatures to continue to warm, so we expect thermal expansion's contribution to sea level rise to continue. This also means we expect land ice to continue to melt. It's very likely that the rate of sea level rise will increase more and more over the 21st century, although how quickly sea level rise speeds up depends on how much carbon dioxide we emit. For a middle of the road emission scenario, the IPCC report projects a rise of about a half a meter or one and a half feet by the end of the century. Other studies predict as much sea level rise is twice that amount. The answer will depend on how much ice melt takes place on the ice sheets. So that is what we know about sea level rise, but some myths distort the observations of sea level rise. One myth related to sea level rise is that it is exaggerated and it is actually slowing down. This myth uses the technique of cherry picking. This means it picks out a short-term change in sea level and exploits it while ignoring the long-term trend. For example, look at this graph of sea level rise. Notice the dip around 2010 when sea level actually went down temporarily. One of the reasons for the dip was an incredible amount of rainfall and flooding that year in Australia and South America. You might remember hearing about the devastating Queensland flooding that year. If the water cycle produces flooding rains over land and the water doesn't drain back into the ocean right away, this can temporarily affect sea levels. But eventually the water did drain back into the ocean. Sea level rebounded and continued increasing along the trend line as expected. So in summary, we've seen that all scenarios point to continued increasing sea level rise. We expect more sea level rise in the 21st century than we did in the 20th century despite the myth that distorts the science of sea level rise.