Climate change may cause 11-inch rise in sea levels by 2100
Rhett A. Butler,
January 26, 2006

Global warming will cause sea levels to rise up to 34 centimeters (11 inches) by the end of the century, causing increased flooding, worsening the impact of storms, damaging low-lying ecosystems, and accelerating coastal erosion, according to a new study by Australian researchers.

The study — published in this month's issue of the journal Geophysical Research Letters — said climate change was expected warm oceans and cause glaciers in the Himalayas to retreat and ice sheets in Greenland to melt.

"What we found is that sea levels are rising and increasing with time," said John Church, a co-author of the study by the Commonwealth Scientific and Industrial Research Organization (CSIRO), a research arm of the Australian government.

"It means there will be increased flooding of low-lying areas when there are storm surges," he said. "It means increased coastal erosion on sandy beaches. We're going to see increased flooding on island nations."

The study supports research published last October by scientists at the Max Planck Institute for Meteorology in Hamburg, Germany who calculated that sea levels could rise on average by as many as 30 centimeters based on a four degree rise in global temperatures by 2100. Another study published in late November 2005 using core samples of sediments along the New Jersey coast found that rates of sea level change have doubled in the past 150 years, coinciding with the beginning of the industrial revolution when carbon dioxide emissions began to dramatically increase. Carbon dioxide is the principal greenhouse gas believed to contribute to global warming.

Intergovernmental Panel on Climate Change (IPCC) graph showing that CO2 concentration, temperature, and sea level continue to rise long after emissions are reduced. Image courtesy of the IPCC.
The new CSIRO-led research looked at historical tidal data, instead of climate change models and projections. The team found that sea levels rose by 19.5 centimeters (7.7 inches) between 1870 and 2004, with annual increases accelerated with time, averaging 1.7 millimeters (0.07 inches) a year in the 20th century and 1.8 millimeters in the past 50 years.

Rising levels are of great concern territories with low-lying areas, especially nations in the South Pacific and Indian Ocean. Last month, a small community living in the Pacific island chain of Vanuatu became the first to be formally evacuated as a result of climate change. The UN-backed relocation project involved over 100 villagers, but more permanent evacuations in other areas are expected over the next few years. The low-lying Pacific island state of Tuvalu has struck an agreement with New Zealand to accept its 11,600 citizens in the event rising sea levels inundate the country. By one rough estimate provided by the UN, as many as 100 million people worldwide live in areas below sea level and are subject to storm surge.

While containing greenhouse gas emissions could help stem increases, Church added that sea levels would rise nonetheless due to the capacity of oceans to store heat.

"We do have to reduce our emissions but we also have to recognize climate change is happening, and we have to adapt as well," Church said.

The IPCC explains what causes the sea level to change. Image courtesy of the IPCC.

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This article is based on a news releases from CSIRO, the UN, the Max Planck Institute, and Rutgers.

Rhett A. Butler, (January 26, 2006).

Global warming may cause 11-inch rise in sea levels by 2100.