Sea levels on the West Coast of the United States are rising at a faster rate than the global average – and that trend is likely to continue for at least a few years, with likely effects for people living in the region.
The height of the sea surface in the western and eastern tropical Pacific Ocean seesaws over time – when one is higher, the other is lower. This is driven on shorter timescales by two natural climate patterns: the El Niño-Southern Oscillation and the Pacific Decadal Oscillation.
Every few years, the El Niño Southern Oscillation (ENSO) pattern produces either an El Niño or a La Niña event. El Niños can increase West Coast sea level; while La Niñas can decrease it.
On a longer timescale, every 5 to 20 years the Pacific Decadal Oscillation (PDO) brings warmer or cooler waters to the West Coast. These shifts can impact sea level rise and global climate.
In the 1990s and 2000s, the Pacific Decadal Oscillation suppressed the effects of sea level rise on the West Coast, but that’s likely changing. As the PDO changes phase, the region is seeing about a centimeter of sea level rise a year. Visualization showing diffe...
That means that understanding exactly when the seesaw will swing the other way is critical. @NASA's Sea Level Change Science Team is using satellite data, tide gauges, and computer models to understand what drives elevated sea level rates and what the West Coast can expect.

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More from @NASAEarth

10 Nov
We know that as human activity warms the planet, global sea level is rising. We know that about 2/3 of sea level rise so far has come from melting ice. But how do we know this? We can measure it from space.
#SeeingTheSeas Visualization of sea level ...
Sea level isn’t uniform around the planet. Tides and currents, the density and temperature of water, and landforms can affect where the ocean piles up. We know this because we measure the shape of the ocean using radar altimetry. Graph of sea level rise mea...
Altimetry works by bouncing radio waves off the ocean surface and timing how quickly they return. Then comes the next challenge: Calculating the natural and seasonal changes in ocean height to determine how much more global warming has made seas rise.
Read 8 tweets
9 Nov
The effects of sea level rise come in many forms. During tropical storms, higher sea levels drive intense storm surges — water level much higher than normal tides. But with sea level rise, the tides themselves can cause flooding.

During high-tide floods, water can make its way from the ocean onto land and bubble up from storm drains. In cities like Miami & Annapolis, high-tide flooding can close down streets & businesses, and damage infrastructure like pipes & wastewater systems.
Between 2000-2015, days with high-tide flooding doubled along the U.S. Northeast Atlantic coast, & that will likely keep climbing. Some locations could see high-tide flooding 180 days a year by 2050. From May '19 to April '20, Annapolis had a record 18 days of high-tide flooding.
Read 4 tweets
13 Oct
#HurricaneDelta was the 25th named Atlantic storm of the 2020 hurricane season. After exhausting a list of prepared names, @WMO turns to the Greek alphabet to name storms.
Hurricanes typically get a massive boost of energy when they pass over warm waters. #HurricaneDelta rapidly intensified to a Category 4 storm. #HurricaneLaura also underwent rapid intensification in the Gulf of Mexico. Natural color satellite image of Hurricane Delta making landImage of Hurricane Delta making landfall with ocean colored
As it made landfall, #HurricaneDelta was generating heavy rainfall. Combining data from @NASARain’s satellites with computer models helps track precipitation to help those living in the storm’s path.
Read 4 tweets
21 Sep
Arctic sea ice reached its second-lowest minimum extent on record on Sept. 15, 2020. This year’s extent was larger only than 2012’s extent. @NASA and @NSIDC track sea ice through the year.
Sea ice plays an important role in keeping our planet cool. Light-colored ice reflects heat from the Sun back into the atmosphere, while darker ocean water absorbs it, so warming accelerates as sea ice extent declines.
Sea ice extent grows and shrinks with the seasons, with the colder northern winter temperatures freezing sea water and the warmer summer temperatures melting it. Over the last decades, sea ice extent has been trending smaller — a direct result of warmer global temperatures. ImageSea ice seen from a planeImageImage
Read 5 tweets
6 May
318 gigatons.
That’s how much ice is lost every year from Antarctica and Greenland’s ice sheets, according to new science from @NASA_Ice's #ICESat2.

But… how much ice is that, really? 🤔
Let's say 🧊= a gigaton of ice.

🧊 would be enough to cover NYC’s Central Park in ice past the top of the Chrysler Building. When melted, it would fill 400,000 Olympic-sized swimming pools.

Each year from 2003 to 2019, Greenland lost 200 🧊s. Antarctica lost 118 🧊s.
From 2003-2019, Greenland lost: 🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊🧊
Read 40 tweets
15 Jan
2019 was the second hottest 🌡 year and the last decade was the warmest decade on record. The global average temperature was more than 2°F warmer than during the late 19th century.
Scientists at @NASA and @NOAA separately analyze temperature measurements taken at thousands of weather stations, ships and ocean buoys around the globe. Although the records differ slightly due to data processing, they both show a long-term pattern 📈 of increasing temperature.
The global temperature 🌎 is an average, so not every place on Earth had its second-warmest year. For instance, the continental U.S. had a cold October, but Alaska set records for high temperatures. The U.S. was still warmer than average over the year.
Read 6 tweets

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