Home » Columns »Sustainable Planet » Currently Reading:

The State of Corals

November 20, 2016 by Tony Noerpel filed under Columns, Sustainable Planet No Comments
Figure 3 close up view of healthy coral polyps. [9]

(Presented to the Board of Supervisors December 6, 2016)

“Events as severe as the 1998 event, the worst on record, are likely to become commonplace within 20 years.” – Ove Hoegh-Guldberg, 1999 [4]

Tony Noerpel

In Figure 1, I’ve updated the global temperature anomaly using the NASA/GISS data set through September, 2016. It remains a stark reminder that global warming did not stop in 1998 as many pundits insisted. Misinformed by such pronouncements, it is difficult for us to appreciate the impact of a few degrees of global warming. Many of the anticipated consequences which are discussed by scientists such as sea level rise occur too gradually to be observed and appreciated. Though it means more nuisance flooding in coastal communities such as Norfolk and more flooding during extreme storms such as super storm Sandy, there are no daily reminders for most of us. Mass coral mortality however has been dramatic, well reported and consequential. Coral reefs are the rain forests of the oceans and harbor about 26% of all marine species. And coral reefs are dying before our eyes as shown in Figure 2.

A mutualistic symbiotic relationship exists between corals and small marine algae which live inside their tissue [2] shown in Figure 3. The algae use photosynthesis to capture sun light to create organic molecules from carbon dioxide and water as well as trace minerals provided by the host corals. In turn the algae provide most of the energy corals need to grow. When temperatures get too hot, corals expel the algae. Without the algae, the corals turn white which is why this process is called bleaching. The coral can survive in this state for a few weeks. But, if temperatures do not decrease they will die from starvation and disease.

There were no observed or recorded mass coral bleaching events until the 1980s [3]. The first multi-year event on record occurred during 1982-83. Since then we have experienced repeated regional mass bleaching events and in 1997-1998 we experienced the first global coral bleaching event which prompted coral biologist Ove Hoegh-Guldberg to forecast in 1999 that these events would become commonplace and they have. I’ve therefore added a new feature to the temperature anomaly chart I produce each month. The dotted orange line in Figure 1 indicates the surface temperature threshold corresponding to the start of mass bleaching events, about 1 degree Fahrenheit (0.6 Kelvin) above pre-industrial climate.

Coral reef bleaching is not only dependent on surface temperature but also on other stresses such as ocean acidification, pollution, particularly agricultural runoff, disease, invasive species and over fishing. However only atmospheric carbon and its consequences, increased warming and ocean acidification, are global. Since all of these stresses are correlated human activity, it isn’t surprising that coral mortality is correlated to surface temperature. Human activities emit about 11 billion tons of carbon dioxide per year. If this rate were ten to hundred times slower as would be the case if the sources were natural, then the temperature would rise slowly and the oceans would not become acidic because at that slower rate the ocean could chemically buffer the carbon dioxide. In the past corals and other species have easily adapt to the slowly rising temperature. At the rate of human emissions, the oceans become too acidic and the temperature rises too quickly for species to adapt.

I’ve also shown a dotted red line corresponding to a surface temperature of 1.6 F or 0.9 K, the threshold consistent with more server global mass bleaching such as the one occurring during the El Nino of 1997-98 [4]. The latter event killed off 16% of all corals [5]. During the first decade of the twenty-first century the Earth was in a continuous state of mass coral bleaching. In 2006 a local mass bleaching event occurred in the Keppel Islands on the southern end of the Great Barrier Reef which resulted in 30 to 40% coral mortality. In 2010 the second global mass bleaching event occurred and in 2014, a third global bleaching event began, which is still ongoing [6]. Biogeochemist Andrea Grottoli told me that such events were not expected to happen before 2030.

In a 2015 presentation to the Loudoun County Board of Supervisors I had forecast a La Nina event occurring in 2017 and 2018 during which we might have expected corals to get some relief as the surface temperature cooled down. However, NOAA is now expecting the La Nina to be weak [7] and therefore temperature may remain closer to the climate trend line which as can be seen in Figure 1 is now above the global beaching threshold given by the dotted red line in the figure.

For anyone looking for a consequence of human-caused climate change, corals may be the canaries in our global coal mine. Coral reefs are the rain forests of the ocean comprising much of the ocean’s marine diversity. If they go extinct we will have initiated a fairly major marine mass extinction event.

Figure 1 NASA GISS global temperature anomaly [1]

Figure 1 NASA GISS global temperature anomaly [1]

Figure 2 bleaching on the Great Barrier Reef [8]

Figure 2 bleaching on the Great Barrier Reef [8]

Figure 3 close up view of healthy coral polyps. [9]

Figure 3 close up view of healthy coral polyps. [9]

[1] http://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts+dSST.txt

[2] https://theconversation.com/great-barrier-reef-disaster-is-the-latest-harbinger-of-a-global-mass-extinction-57327

[3] https://theconversation.com/coral-bleaching-comes-to-the-great-barrier-reef-as-record-breaking-global-temperatures-continue-56570

[4] https://theconversation.com/as-the-earth-enters-its-third-mass-bleaching-event-will-corals-survive-50740

[5] http://www.publish.csiro.au/MF/pdf/MF99078

[6] Bob Henson, Weather Underground blog, 3:30 PM GMT on March 28, 2016. Longest Coral Bleaching Event on Record Continues to Hammer Reefs. https://www.wunderground.com/blog/JeffMasters/archive.html?year=2016&month=03

[7] Bob Henson, 5:06 PM GMT on November 11, 2016, Weak La Niña Expected to Persist into 2017, https://www.wunderground.com/blog/JeffMasters/weak-la-nia-expected-to-persist-into-2017

[8] https://theconversation.com/coral-bleaching-taskforce-more-than-1-000-km-of-the-great-barrier-reef-has-bleached-57282

[9] https://theconversation.com/as-the-earth-enters-its-third-mass-bleaching-event-will-corals-survive-50740

Comment on this article

By commenting, you agree to abide by our Terms of Service.







The Holocene Climate


(Public Input Loudoun County Board of Supervisors, 7 March, 2017) Figure 1 shows the climate variation over the last million years. The low points on the curve correspond to ice ages when glaciers up to a mile thick covered New …

Choosing To Forgive


By Samuel Moore-Sobel “Truly forgiving is the ability to say, ‘Thank you for giving me that experience.’” James Arthur Ray vaulted into fame on the Oprah Winfrey Show back in the mid-2000’s. Stunned hearing these words while watching The Rise and …

Five Key Retirement Questions


Beyond asking yourself where you see yourself and even what your lifelong goal are, effective retirement and longevity planning begs some very big questions. Review the points below and consider how housing, transportation and health considerations all play a role …

Work Woes


By Michael Oberschneider, Psy.D. Dr. Mike, I’m a manager at a large tech company and my boss has directed me to fire someone on my team, but as a Christian, I just can’t do it. It’s true that the employee …

Joy or Suffering

Lunde new

By Mary Rose Lunde No one likes to suffer. When given the chance, many people would choose to laugh rather than cry, to sit in silence with their friends rather than talk through their feelings, because not even their friends …

Wage Radio


I will always remember – very fondly – the first time I ever set foot on the property at 711 Wage Drive Southwest in Leesburg, Virginia. It was a warm, sunny July morning in 1997, and I’d driven all the …

Speaking Truth to Power


“With public sentiment nothing can fail. Without it nothing can succeed.” Abraham Lincoln On Thursday evening, February 23, I requested the Board of Supervisors pass a proclamation resolving to support the March for Science on Earth Day, April 22 [1]. …

Student News

Congratulations, Class of 2016

6 Jul 2016


Woodgrove High School’s Class Of 2016 Graduation – By Amanda Clark On June 16, Woodgrove’s Class of 2016 was the 5th graduating class to walk the stage and accept their diploma. The ceremony was filled with anticipation as the chorus, …

(Be the first to comment)

Buckland Earns Degree In Medicine

6 Jul 2016


Molly Buckland, D.O., graduated from the West Virginia School of Osteopathic Medicine with a degree of Doctor of Osteopathic Medicine on May 28. While at WVSOM, Dr. Buckland received the Dr. Roland P. Sharp President’s Award and the James R. …

(Be the first to comment)

Adams Promoted To Lieutenant

6 Jul 2016


Lt. James Adams, from Sterling and a Potomac Falls Halls Graduate, earned the promotion to the rank of Lieutenant. Adams is a Navy Week and Executive Outreach Planner for the Navy Office of Community Outreach in Millington, Tennessee. U.S. Navy …

(Be the first to comment)


March 2017
Monday Tuesday Wednesday Thursday Friday Saturday Sunday
February 27, 2017 February 28, 2017 March 1, 2017 March 2, 2017 March 3, 2017


March 4, 2017

Notaviva Vineyards - Bluegrass Jam - FREE event

Notaviva Vineyards - Bluegrass Jam - FREE event
March 5, 2017
March 6, 2017 March 7, 2017 March 8, 2017 March 9, 2017 March 10, 2017 March 11, 2017 March 12, 2017
March 13, 2017 March 14, 2017 March 15, 2017 March 16, 2017 March 17, 2017 March 18, 2017

Wine & Chili Weekend

Wine & Chili Weekend
March 19, 2017

Joshua Carr River Safety Foundation Rummage Sale

Joshua Carr River Safety Foundation Rummage Sale
March 20, 2017 March 21, 2017 March 22, 2017 March 23, 2017 March 24, 2017

March Fourth Friday

March Fourth Friday
March 25, 2017 March 26, 2017

Spring Brunch

Spring Brunch

Spring Brunch

Spring Brunch
March 27, 2017 March 28, 2017 March 29, 2017 March 30, 2017 March 31, 2017 April 1, 2017

”Homage to Mother Earth”

”Homage to Mother Earth”

Nebbiolo Vertical Tasting

Nebbiolo Vertical Tasting

Notaviva Vineyards - Bluegrass Jam - FREE event

Notaviva Vineyards - Bluegrass Jam - FREE event

Old Time Country Ham and Turkey Dinner

Old Time Country Ham and Turkey Dinner
April 2, 2017

”Homage to Mother Earth”

”Homage to Mother Earth”

GALLERY COFFEEHOUSE: Readers Theater, “One Slight Hitch”

GALLERY COFFEEHOUSE: Readers Theater, “One Slight Hitch”
Current Print Issue:
Sign up for our email newsletter:

Recent Comments

  • David on Protecting Free Speech: Constitutionally protected speech is exactly what it sounds like, protected. We all have the legal right to utter nonsensical and...
  • Martha on Protecting Free Speech: Free speech is not a cherished right at the not-quite accredited Patrick Henry College, a religious school that Del. LaRock...
  • Martha Polkey on First Look at Envision Loudoun Results: It remains to be seen whether the direction citizens have provided to the Envision process is actually incorporated into the...
  • David on Protecting Free Speech: Mr. LaRock, I assume that the only reason you weren’t at every School Board meeting in 2005 passionately defending the...
  • LongTimePville on Purcellville Emergency Meeting Postponed to March 10: I bet Kelli Grim flip flops on her conflicts of interest and transparency campaign she ran on and does not...

Steady and NoBull


Sterling Library Moving To New Location

25 Mar 2017


Sterling Library’s current location, 120 Enterprise St., Sterling, will close beginning Saturday, March 25, to prepare for the opening of the new Sterling Library on Saturday, April 15. Patrons can return library materials using the drop box at the new location, 22330 S. Sterling Boulevard. Printer-friendly Related

(Be the first to comment)

Middleburg Gallery Presents Country Pursuits Exhibit

25 Mar 2017

Mr and Mrs Andrews 24x35 59 2016 whelan

The Gallery on Madison in Middleburg is presenting an exhibit of Brian Whelan’s (a London Irish painter now settled in Waterford) ) transcriptions of a gallery of paintings by Thomas Gainsborough, ‘Mr. and Mrs. Andrews’ through April 2. The exhibit includes 23 paintings, two masks, two graphics, and nine preparatory drawings. Printer-friendly Related

(Be the first to comment)

Loudoun Workforce Resource Center Presents STEM Career Fair March 28

16 Mar 2017

Illustration of STEM education word typography design in orange theme with icon ornament elements

Anyone interested in a career in the rapidly growing field of STEM (Science, Technology, Engineering and Math) is encouraged to attend an upcoming STEM Career Fair in Loudoun. The Loudoun Workforce Resource Center, in partnership with Northern Virginia Community College (NVCC)’s Loudoun campus and NOVA SySTEMic Solutions, is holding a STEM Career Fair Tuesday, March 28, from 1:00 to 4:00 …

(Be the first to comment)

Around Virginia

McAuliffe Vetoes LaRock’s Public Assistance Eligibility Legislation  


On March 28, Governor Terry McAuliffe vetoed Del. Dave LaRock’s (R-33) House Bill 2092, which would have required any applicant for public assistance to undergo a full review of death records, incarceration status, employment status, lottery winnings, and all income. Recently, an Arlington woman was arrested on four counts of welfare fraud for …

(Be the first to comment)

Virginia Schools Kick Off Statewide Campaign To Encourage Safe Teen Driving


More teen drivers in Virginia will be involved in traffic crashes between the months of May and August than any other time of the year, statistics show. To help save lives and prevent such crashes during the high-risk warm weather months, Virginia schools are kicking off a statewide teen safety …

(Be the first to comment)

Protecting Free Speech


By Dave LaRock (R-33) As elected officials and members of the legislature, our most fundamental responsibility is to protect God-given constitutionally protected rights. The First Amendment of the United States Constitution prohibits the government, including governmental public colleges and universities, from infringing on free speech and the free exercise of …



Vikings Runner-Up at the State Championship 

8 Mar 2017


The Loudoun Valley Vikings are the boy’s runner-up at the VHSL 4A State Indoor Track and Field Championships at Roanoke College.  During the 2015-2016 school year, the Loudoun County School Board approved Indoor Track and Field as a Tier 2 (self-funded) sport.  The seven boys competing scored 48 points, second …

(Be the first to comment)

WLVBC U14 Boys Finish 3rd at VA Beach Event

23 Feb 2017


The Western Loudoun Volleyball Club’s U14 Boys Team garnered 3rd place in their first travel tournament of 2017, the Virginia Beach Invitational. This event was held Feb. 18-19 and featured more than 24 teams from the U14 to U18 age group. The team was second on their net on day …

(Be the first to comment)


  • +2017
  • +2016
  • +2015
  • +2014
  • +2013
  • +2012
  • +2011
  • +2010
  • +2009