Drip, drip, drip – head for higher ground
Home › Forums › Archives › The Crash Course › Chapter 18: Environmental Data › The Definitive Global Climate Change (aka Global Warming) Thread — General Discussion and Questions › Drip, drip, drip – head for higher ground
In addition to the stock market (apparently) there are two things that are going up continuously, one is global temperatures and the other is global sea level. Unlike the stock market though these two real trends aren't going to reverse in our lifetimes.
Having sea levels rising is bad enough but having them continue to rise at faster and faster rates is truly worrisome. For millennia sea level has been relatively stable, rising a little for a century or two and then falling again when it was cooler. That changed dramatically in the 20th century (link, based on Kopp et al. 2016)…
In case you are wondering, this century isn't looking so great for beach front property either. NOAA (2012) reviewed all the literature and data and concluded that there was a 90% chance that sea level would rise by at least 8 inches and no more than 6.6 ft (0.2 – 2.0 m) by 2100. However, since sea level is already rising by 3.4mm/yr, that means that even if the rate doesn't rise any further that we will be looking at 13 inches (33cm) of sea level rise by 2100. Given that more than 1 billion people live in low lying coastal areas, this is a serious problem. Some 39% of the US population lives in coastal counties. The problem isn't when everyone's homes go under the water for good, it is when the rate of flooding gets to be too frequent to put up with, 75% of large cities are located on the coast.
In addition to megaflooding episodes from major storms, cities and properties are being hit with an increasing amount of nuisance flooding during high tides. How many times a decade or year does somewhere need to flood before a city should just abandon it and build on higher ground? What if there is no higher ground? When do we abandon a city like Miami?
Wilmington, NC used to average 14 nuisance flood days a decade between 1955-64, that increased to 38, 63, 78 days in the following three decades. However, between 1995 and 2004 the nuisance flooding rates jumped to 224 days, from 2005 to 2014 it increased again to 376 days! Do you see a pattern. If parts of the city flood more than 30 days a year is it really inhabitable land anymore? It's going to get worse year after year. When do we retreat?
Sea level rise used to be equal parts thermal expansion of the water and melted ice from the land (plus a little from aquifer pumping) but something changed in the last decade. Now 2/3 of the sea level rise is coming from melting ice in places like Greenland and Antarctica.
Now we learn that Greenland has been losing ice at an average rate of 269 gigatons a year since 2011 (McMillan et al 2016). Put another way, over the last century Greenland has lost 9 trillion tons of ice, it lost 1 trillion of those tons in just the last 4 years between 2011 and 2014. In sea level terms, Greenland is now contributing 0.74 mm/yr, which is twice the amount is was giving off between 1992-2011.
Thank of that next time you go to the beach.