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Three Effects of Climate Change

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This post will focus on a few articles published recently that highlight effects that climate change is already having around the world. Though the phenomena studied in them occurred far away, they will have important consequences for us here in the USA, and even in Missouri.

Climate Change Causes Migration

Human migration into Europe has become a large political and humanitarian problem. European countries have been struggling to provide the basic services that the migrants need, and to find ways to integrate them into society. The problem of immigration has been one of the forces leading to Brexit, and to the upsurge in right-wing populism around the world (including here in America).

Missirian and Schlenker (2017) studied European asylum applications from 103 source countries, and found that the number of migrants from each country related to the weather in that country. In colder countries, when the temperature decreased, asylum applications increased. Conversely, in hot countries, when the temperature increased, asylum applications increased, and they did so in a non-linear fashion – small increases in temperature could lead to large increases in applications. Far more migrants have come to the EU from hot countries (Africa, the Middle East) than from cold countries, thus the temperature increase is the more important effect.

Figure 1. Predicted Change in Asylum Applications by Change in Temperature. Source: Missirian and Schlenker 2017.

Holding everything else constant, Figure 1 shows the predicted increase in asylum applications by change in temperature. The red line shows the predicted increase, the shaded areas show the 90% and 99% confidence intervals. The blue line at the top should be read against the right vertical axis, and it represents the probability that asylum applications will increase. The more temperature increases, the more asylum applications are predicted to increase. Under the high emissions scenario, by the end of the century, applications are predicted to increase by 188%.

The study didn’t include migration into the USA from countries south of our border, but I suspect that the basic findings would apply here, as well. In fact, I already reported (here) that in 2014 the CNA Military Advisory Board concluded that climate change would become one of the most significant threats to national security faced by our nation. Climate change would lead to increased migration around the world, which would lead to political instability, which would cause conflicts to break out. Given the difficulty that Europe is having coping with the current problem, and that the problem could nearly triple in size by the end of the century, the Military Advisory Board’s conclusion doesn’t seem too far off. (May, 2014)

The Shrimp Are Gone From Maine

Figure 2. Source: Atlantic States Marine Fisheries Commission 2017.

Northern Shrimp are a species of shrimp that require cold water in order to spawn. Maine has been the southern limit of their historical habitat, and they have represented a small but valuable fishery for New England states. Since 2012, the total biomass of shrimp estimated by the Gulf of Maine Summer Shrimp Survey have been the lowest on record. (Figure 2) Managers have closed the waters to shrimp fishing from 2014-2018 in an attempt to prevent shrimp from being completely eliminated from Maine waters. (Atlantic States Marine Fisheries Commission, 2017)

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The primary cause of the decline is climate change. Ocean temperatures in the Gulf of Main have increased at a rate of about 0.5°F per year – that is incredibly fast, almost 8 times faster than the global rate. Figure 3 shows the data. The blue lines show the 15-day average water temperature anomaly in the Gulf of Maine from 1980 to 2015. The black dots show the average annual temperature anomaly, and the dashed line shows the trend over the whole time period. The red line shows the trend for the decade from 2005 to 2015.

It is easy to see that the ocean has been warming. The shrimp don’t spawn well in the warmer water, so they are dying out. (Evans-Brown, 2014)

The warmer temperatures have affected more than shrimp. As temperature has increased, cod have also declined, to the point that they are now commercially extinct in the New England fishery. With the cod, a failure to recognize the effect of global warming caused fishery regulators to keep the permitted catch at a high level that could not be sustained, and they were basically fished out out existence. The moratorium on shrimp fishing is an attempt to prevent a similar occurrence. (Pershing et al 2015)

Fishing, especially off New England, was the first colonial industry when Europeans came to America. Over the past century, several species have collapsed and no longer support viable commercial fishing: Atlantic halibut, ocean perch, haddock, and yellowtail flounder. These once fed millions of Americans. No more. Even the venerable Atlantic cod, once so numerous that it was said you could walk from America to England stepping on their backs, are commercially extinct. We are killing the oceans. More below. (NOAA Fisheries Service, 2017)

Global Warming Is Ravaging Coral Reefs

To live, coral requires a symbiotic relationship with certain species of algae. Coral bleaching occurs when stressful conditions cause the algae to be expelled from the coral, which then turns white. If algae don’t reenter the coral quickly enough, the coral will starve to death.

Figure 4. Temporal Patterns of Coral Bleaching. Source: Hughes et al., 2018.

Before global warming, bleaching events were relatively rare, and reefs had enough time to recover between them. Scientists looked at 100 reefs globally and found that the average interval between bleaching events is now less than half of what it was previously. It is now only 6 years, which is not enough time for recovery. Figure 4 shows the findings. Chart A in the figure shows the number of locations experiencing bleaching events in a given year. You can see that the trend increases left to right, and that the worst years have all occurred in the most recent 2 decades. Chart B in the figure shows the cumulative number of locations that have remained free of bleaching over the time period in blue, and the total cumulative number of bleaching events in red. You can see that, over time, none of the locations have escaped bleaching, and that the number of bleaching events has topped 600. Chart C shows the frequency of bleaching events at individual locations. Almost 30 locations have experienced 3 severe bleaching events, and a similar number have experienced 8 or more bleaching events in total. Chart D counts intervals between bleaching events, and how many times each interval occurred. It used to be (1980-1999) that the most common interval was 10-12 years. Recently, however (2000-2016), an interval of 4-6 years was the most common. (Hughes et al 2018, Pols 2017) Thus, the data show that bleaching has spread to the point that none of the locations escaped it altogether, almost 1/3 of them have experienced 8 bleaching events of some kind, almost 1/3 have experienced 3 severe events, and the most common interval between events has shrunk to half of what it was previously.

The main culprit is global warming. Coral survives only in a relatively narrow temperature band, and if the water temperature rises too high, bleaching occurs. Temperatures have, indeed, risen. As noted above in the section on the Gulf of Maine, in some places they have increased incredibly quickly.

Coral reefs are like oases. In the desert, oases are separated by vast distances where life is scarce. Similarly, coral reefs are often separated by vast distances where life is scarce. Reefs, however, support thousands of species in great abundance. Though the reefs occupy less than 0.1% of the ocean’s surface, they support at least 25% of all marine species. (NOAA Fisheries Service 2018)

These phenomena, though occurring far away, are all signs that the basic systems that support life on this planet as we know it are in danger. If we think that they could not collapse, we are seriously kidding ourselves. They may be collapsing already. If we dream that we will somehow escape being affected, we need to wake up.

Sources:

Atlantic States Marine Fisheries Commission. 2017. Northern Shrimp Species Profile. Viewed online 2/6/2018 at http://www.asmfc.org/species/northern-shrimp.

Evans-Brown, Sam. “Gulf of Maine Is Warming Faster Than Most of World’s Oceans.” New Hampshire Public Radio. Viewed online 2/6/2018 at http://nhpr.org/post/gulf-maine-warming-faster-most-worlds-oceans.

Hughes, Terry P., Kristen D. Anderson, Sean R. Connolly, Scott F. Heron, James T. Kerry, Janice M. Lough, Andrew H. Baird, Julia K. Baum, Michael L. Berumen, Tom C. Bridge, Danielle C. Claar, C. Mark Eakin, James P. Gilmour, Nicholas A. J. Graham Hugo Harrison, Jean-Paul A. Hobbs, Andrew S. Hoey, Mia Hoogenboom, Ryan J. Lowe, Malcolm T. McCulloch, John M. Pandolfi, Morgan Pratchett. Verena Schoepf, Gergely Torda, Shaun K. Wilson. 2018. “Spatial and Temporal Patterns of Mass Bleaching of Corals in the Anthropocene. Science 359 (6371), 80-83.

Missirian, Anouch, and Wolfram Schlenker. (2017). “Asylum Applications Respond to Temperature Fluctuations.” Science 358 (6370), 1610-1614.

Pershing, Andrew. Michael Alexander, Christina Hernandez, Lisa Kerr, Arnault Le Bris, Katherine Mills, Janet Nye, Nicholas Record, Hillary Scanell, James Scott, Graham Sherwood, and Andrew Thomas. 2015. “Slow Adaptation in the Face of Rapid Warming Leads to Coillapse of the Gulf of Maine Cod Fishery.” Science, 350 (6262), 809-812.

NOAA Fisheries Service. 2017. Brief History of the Groundfishing Industry of New England. Viewed online 2/6/2018 at https://www.nefsc.noaa.gov/history/stories/groundfish/grndfsh1.html.

Pols, Mary. 2018. “It’s Maine Shrimp Season, Without the Shrimp.” New York Times, 12/26/2017. Downloaded 2/6/2018 from https://www.nytimes.com/2017/12/26/dining/maine-shrimp-fishery-climate-change.html.


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