How much has ocean risen

The two major causes of global sea level rise are thermal expansion caused by warming of the ocean since water expands as it warms and increased melting of land-based ice, such as glaciers and ice sheets. The oceans are absorbing more than 90 percent of the increased atmospheric heat associated with emissions from human activity. Sea level rise at specific locations may be more or less than the global average due to local factors such as land subsidence from natural processes and withdrawal of groundwater and fossil fuels, changes in regional ocean currents, and whether the land is still rebounding from the compressive weight of Ice Age glaciers.

In urban settings, rising seas threaten infrastructure necessary for local jobs and regional industries. Roads, bridges, subways, water supplies, oil and gas wells, power plants, sewage treatment plants, landfills—virtually all human infrastructure—is at risk from sea level rise. Home Ocean Facts Is sea level rising? Over the past years, global temperatures have risen about 1 degree C 1. And the current rate of sea level rise is unprecedented over the past several millennia.

How fast it will rise depends mostly on the rate of glacier and ice sheet melting. The pace of sea level rise accelerated beginning in the s, coinciding with acceleration in glacier and ice sheet melting. In , at the request of the U. Their experts concluded that even with lowest possible greenhouse gas emission pathways, global mean sea level would rise at least 8 inches 0. With high rates of emissions, sea level rise would be much higher, but was unlikely to exceed 6.

Interagency Sea Level Rise Taskforce. Based on their new scenarios, global sea level is very likely to rise at least 12 inches 0. On future pathways with the highest greenhouse gas emissions, sea level rise could be as high as 8. Observed sea level from tide gauges dark gray and satellites light gray from , with future sea level through under six possible future scenarios colored lines.

The scenarios differ based on potential future rates of greenhouse gas emissions and differences in the plausible rates of glacier and ice sheet loss. Since the report report, new research has emerged showing that some of the more extreme estimates of how quickly those ice sheets could melt were more plausible than they previously seemed. Along almost all U. For the densely populated Atlantic seaboard north of Virginia and the western Gulf of Mexico, sea level rise will likely be higher than the global average for all pathways.

On the bright side, if future energy choices keep us on one the three lowest pathways, Alaska and the Pacific Northwest are likely to experience local sea level rise that is less than the global average. In all cases, however, rising sea levels are increasing coastal flood risk. High-tide flooding is already a serious problem in many coastal communities, and it is only expected to get much worse in the future with continued rising seas. These data are for education and communication purposes only.

They are documented in Church and White It is based on a weighted average of global tide gauge records collected by the U. The weights for each gauge in the global mean are determined by a cluster analysis that groups gauges from locations where sea level tends to vary in the same way. This prevents over-emphasizing regions where there are many tide gauges located in close proximity.

The most recent year of data should be considered preliminary. Cassotta, S. Chapter 3: Polar regions. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, M. Nicolai, A. Okem, J. Petzold, B. Rama, N. Weyer eds. In press. Church, J. Clark, A. Cazenave, J. This finding, reached after the team improved their own ice model, is much closer to projections made by other glaciologists.

It is a reassuring constraint placed on one of the most alarming scientific hypotheses advanced this decade. Yet their work—and the work of other sea-level-rise scientists—still warns of potential catastrophe for our children and grandchildren. If every country meets its current commitment under the Paris Agreement, the Earth will warm about 2. Read: A radical new scheme to prevent catastrophic sea-level rise.

Their new research also raises the marginal risk of disaster. Officially, the Paris Agreement aims to keep global warming from exceeding 2 degrees Celsius, though many experts consider that goal fanciful. And even in that extremely optimistic scenario, West Antarctica still switches into unavoidable collapse about 10 percent of the time, according to the new research.

Their short-term revisions also barely change their long-term forecast of West Antarctic disintegration. If emissions keep rising, they warn that global sea level could rise by more than 26 feet by These new results have not yet been peer-reviewed. DeConto, a professor at the University of Massachusetts at Amherst, presented them to other scientists last month at the fall meeting of the American Geophysical Union, the largest annual conference of Earth scientists in the world.

He and his colleagues declined to comment for this story in keeping with an academic custom not to discuss new work with the press before its publication. The new results inform one of the biggest outstanding questions—and most fervent debates—concerning how climate change will reshape our world: How much will the seas rise, and how fast will that upheaval occur?