A new report by the UN’s Intergovernmental Panel on Climate Change says sea levels are rising twice as fast as they used to. They’re also warming up and losing oxygen, meaning climate change will increasingly impact everything from coastal flooding to hurricanes to the number of fish in the sea.
According to the report, about 680 million people (10% of the global population) live in coastal regions less than 30 feet above sea level, and face increasing risks caused by sea level rise, storm intensification, and a host of other issues. Large swaths of coastal Louisiana and the Gulf Coast fall squarely into that category.
To better understand what the report suggests about the future of the Gulf Coast, WWNO’s Travis Lux spoke with Dr. Lisa Levin, an oceanographer at UC San Diego and one of the authors of the report.
The following transcript has been edited for length and clarity:
Q:This report was a really big one. There were more than 100 researchers that worked on it. You looked at how climate change is causing ocean warming, acidification, sea level rise, that kind of thing. I want to start with sea level rise. What do we know about sea level rise right now?
Levin:We know that sea level is rising and has been for some time. We know that the rate of rise has been accelerating since the mid-1990s. And that is because the rate of ocean warming has accelerated. This has led to greater volume of ocean water and also melting of ice sheets in glaciers. This has caused sea level to rise and is projected to rise significantly more into the future toward the end of the century.
Q:The report also lays out what are basically predictions of what could happen to the oceans under different emissions scenarios. It’s going to have effects on everything from hurricanes to sea levels to fisheries. In your mind, what’s the biggest concern for people living near the Gulf Coast?
Levin:I would say it’s probably a combination of consequences of warming. Sea level rise is one of those consequences. But warming increases the intensity of hurricanes. Warming also is going to increase the incidence of hypoxia -- or oxygen loss. And the Gulf of Mexico has a large dead zone [an area where the oxygen is so low that aquatic species cannot live].
So I would say all of those things, put together, are going to create enormous pressure on the coastlines in the Gulf of Mexico -- leading to the potential loss of wetlands and damage to inshore communities.
Q:The Gulf Coast is also known for its seafood -- shrimp, oysters, red snapper and all kinds of things. The report says commercial fisheries are expected to decline by about 20%. Why?
Levin:It’s a combination of factors. Warmer waters lead to loss of oxygen, and this combination of warming and low oxygen leads to smaller fish. The fish are also going to move around and so there’s a combined effect of lower surface productivity. As the waters warm they stratify and there are fewer nutrients mixed into the surface waters. Those nutrients fuel the phytoplankton that are at the base of the food web. So with fewer nutrients we’ll have less phytoplankton production, and that will trickle down and mean less fish production.
Q:Climate reports can be very overwhelming, with lots of heavy-sounding news. Are there any bits of good news that you would like to draw people’s attention to in this report?
Levin:I would say the best news is that we have a choice now. We are committed to some climate change, but we can control the severity of that and its consequences. So, the good news is that if we act now -- at least keep the level of warming to near 1.5 to 2.0 degrees Centigrade -- we have the option of experiencing changes that we can probably cope with or adapt to. At least in many parts of the world. If we don’t act now, the future looks much more chaotic and catastrophic.
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Here are a few highlights from the report, relevant to the Gulf Coast:
- Sea levels are rising about twice as fast as they used to be. The current rate is 3.6 millimeters (0.14 inches) per year.
- Seas will continue to rise. Sea levels could rise another 3.6 feet by 2100 if greenhouse gas emissions continue to increase strongly, but could be kept down to about 1 foot if emissions are strongly reduced.
- Extreme sea level events will increase. Super high tides and storm surges that used to happen once every 100 years are likely to occur once or twice a year by 2100.
- The ocean is changing in several ways. Oceans are becoming warmer, more acidic, and are losing oxygen. This is already having a negative impact on marine species and commercial fisheries. Warm waters also intensify hurricanes.
- Marine heatwaves -- actual heat waves of ocean water -- are projected to increase in frequency, duration, and intensity.
- Climate patterns will shift. Extreme El Niño and La Niña events are expected to increase and intensify existing climate events -- like dry spells and wet spells. That could mean fewer named hurricanes in the Atlantic (and Gulf Coast).
- The number of hurricanes might decrease, but their intensity will increase. More extreme El Niño events could mean fewer storms in the Atlantic (including the Gulf of Mexico). However, if global temperatures rise 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels, the number and intensity of Category 4 and 5 storms will increase. Similarly, areas just inland from the coast will see more intense rainstorms.
- Sea critters will decline. Under a high emissions scenario, marine animals are projected to decline by 15%, and commercial fisheries (shrimp, finfish, etc.) are expected to decline 21-24% by 2100.
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