Climate change inevitable

Even if no more greenhouse gases were added to the atmosphere, globally averaged surface air temperatures would rise about a half degree Celsius (one degree Fahrenheit) and global sea levels would rise another 11 centimetres (4 inches) from thermal expansion alone by 2100, according to a new study by a team of climate modellers at the US National Center for Atmospheric Research (

).

“Many people don’t realize we are committed right now to a significant amount of global warming and sea level rise because of the greenhouse gases we have already put into the atmosphere,” said NCAR’ s Gerald Meehl.

“Even if we stabilize greenhouse gas concentrations, the climate will continue to warm, and there will be proportionately even more sea level rise. The longer we wait, the more climate change we are committed to in the future.”

The half-degree temperature rise is similar to that observed at the end of the 20th century, but the projected sea level rise is more than twice the 3-inch (5-centimetre) rise that occurred during the latter half of the previous century. These numbers do not take into account fresh water from melting ice sheets and glaciers, which could at least double the sea level rise caused by thermal expansion alone.