Category: NEWS_ARCHIVE Water_SLR_KEY

Coastal communities in three locations along the Atlantic and Pacific coasts saw record high tide flooding last year — a trend that is expected to continue into 2023 and beyond without improved flood defenses, according to NOAA.

As relative sea level rises, it no longer takes a strong storm or a hurricane to cause coastal flooding. High tide flooding occurs when sea level rise combines with local factors to push water levels above the normal high tide mark. Changes in prevailing winds, shifts in ocean currents, and strong tidal forces (which occur during full or new moon) can all cause high tide flooding, inundating streets even on sunny days.

Sea level rise is caused primarily by two factors related to global warming: the added water from melting ice sheets and glaciers and the expansion of seawater as it warms. The first graph tracks the change in sea level since 1993 as observed by satellites.

The phrases “climate change” and “sea level rise” nearly go hand in hand, particularly when discussed in coastal communities like Martha’s Vineyard. Many of the cliché images of global warming often involve the seas, whether it be a polar bear stranded on a melting iceberg or dramatic artistic depictions of seas consuming cities. There is quite a bit of misunderstanding and misinformation on how, how much, and how fast the seas will rise as our climate warms. Many people don’t have a great sense of how much the seas will rise in the future and if you ask around, you often can get wildly different answers or no answers at all. Contributing to this confusion is the fact that the future rate of climate change is somewhat uncertain mostly due to the uncertainty in how much society acts now to reduce future carbon emissions.

The sea level trends measured by tide gauges that are presented here are local relative sea level (RSL) trends as opposed to the global sea level trend. Tide gauge measurements are made with respect to a local fixed reference on land. RSL is a combination of the sea level rise and the local vertical land motion. The global sea level trend has been recorded by satellite altimeters since 1992 and the latest global trend can be obtained from NOAA’s Laboratory for Satellite Altimetry, with maps of the regional variation in the trend. The University of Colorado’s Sea Level Research Group compares global sea level rates calculated by different research organizations and discusses some of the issues involved.

Global sea level has risen between 6 and 8 inches (15-20 cm) over the last 100 years. About one third of the increase is due to the thermal expansion of ocean water as it has gotten warmer, and about two-thirds is due to meltwater flowing back to the ocean as glaciers and ice sheets on land melt.

Greta is known for her famous speeches before world leaders. She recently spoke at COP 26 where delegates from around the world are charged with fulfilling goals of the Paris Agreement and the UN Framework Convention on Climate Change. Greta’s quote perfectly captures the gravity of the climate crisis and the need for immediate action.

This animation shows how global sea levels have risen more than 80 millimeters (3.15 inches) over the past three decades, which is like covering the U.S. in about 4 meters (about 13 feet) of water over that period. The video breaks down total sea level rise (gray and red lines) and its two main causes:

Sea level rise is caused primarily by two factors related to global warming: the added water from melting ice sheets and glaciers and the expansion of seawater as it warms. The first graph tracks the change in sea level since 1993 as observed by satellites.

A new Climate Central sea-level-rise analysis identifies the assisted living and nursing homes at risk in five states. Experts say waiting to evacuate during storms is not the answer.