From the Poles to the Equator, High Sea Surface Temperatures are Taking a Toll

The National Oceanic and Atmospheric Administration (NOAA) reported yesterday (State of the Climate, Global Analysis, August 2010, 15 September 2010) that sea surface temperatures (SSTs) thus far in 2010 are the second warmest on record.  Both NOAA and NASA data indicate that 2010 overall (including both global land and ocean surface temperatures) has been the warmest on record.  As the NASA figure below indicates, the warming has been most pronounced in the Northern Hemisphere, where sea surface temperatures for the year-to-date are the warmest on record. 

SSTs have been especially elevated in the northern latitudes including the Arctic Ocean.  Other areas where SSTs have been most elevated include the central and southern Atlantic Ocean, the Indian Ocean, and parts of the western and southern Pacific Ocean.  Temperatures also have been anomalously warmer around the Antarctic Peninsula.

Above: January through August, 2010 and 1998: Mean Surface Temperatures Anomalies (oC) (relative to mean period 1951-1980).  Source: NASA.

As the figure below indicates, the warm SSTs are part of a longer-term trend of rising SSTs (and surface air temperatures over land) driven by rising atmospheric concentrations of greenhouse gases.

Above: Jan-Aug Global Mean Temperature Anomalies, 1880-2010.  Source: NOAA.

We have written extensively on the impacts of rising surface temperatures on the Arctic, most notably on the consequences for Arctic sea ice and the wildlife (such as walruses) that depends on it (see Arctic Sea Ice Decline and its Impacts: Online Resources).  Among the other major consequences of elevated SSTs are their impacts on hurricanes and on coral reefs.

Record  High Sea Surface Temperatures in Atlantic's Main Development Region for hurricanes 

We've reported in recent months on the elevated sea surface temperatures in the tropical Atlantic, their connection to rising greenhouse gas concentrations and their impacts on hurricane intensities.  See Online Resources section below for some of our coverage. 

Just yesterday (15 Sept 2010), Environment 360 published an interview with Kerry Emanuel of the Massachusetts Institute of Technology, Exploring the Links Between Ocean Warming and Hurricanes.  Emanuel, an expert on the connection between climate change and hurricanes, says that "when you look at hurricane power, it really has been going up a lot in the last 20 years or so in the Atlantic in sync with the temperature of the tropical Atlantic, which by the way is at an all-time record high right now."

 Dr. Jeff Masters reported in his WunderBlog on 10 September 2010 (92L still a threat to develop; record SSTs continue in the tropical Atlantic) that "Sea Surface Temperatures (SSTs) in the Atlantic's Main Development Region for hurricanes [10°N to 20°N and 20°W to 80°W] had their warmest August on record."  He added that "August 2010 was the 7th straight record warm month in the tropical Atlantic. The five warmest months in history for the tropical Atlantic have all occurred this year; June 2005 comes in sixth place, and August 2010 in seventh."

Masters said that forecasted atmospheric conditions in the region indicate that "Atlantic SST anomalies will continue to stay at record warm levels during September, significantly increasing the odds of major hurricanes in the Atlantic."

Then on 15 September, he reported in Karl hits the Yucatan; two simultaneous Cat 4s in the Atlantic for 2nd time in history:

"This morning's unexpected intensification of Hurricane Julia into a Category 4 storm with 135 mph winds has set a new record--Julia is now the strongest hurricane on record so far east. When one considers that earlier this year, Hurricane Earl became the fourth strongest hurricane so far north, it appears that this year's record SSTs have significantly expanded the area over which major hurricanes can exist over the Atlantic. This morning is just the second time in recorded history that two simultaneous Category 4 or stronger storms have occurred in the Atlantic...Julia's ascension to Category 4 status makes it the 4th Category 4 storm of the year. Only two other seasons have had as many as five Category 4 or stronger storms (2005 and 1999), so 2010 ranks in 3rd place in this statistic. This year is also the earliest a fourth Category 4 or stronger storm has formed (though the fourth Category 4 of 1999, Hurricane Gert, formed just 3 hours later on today's date in 1999.) We've also had four Cat 4+ storms in just twenty days, which beats the previous record for shortest time span for four Cat 4+ storms to appear."

Finally, Masters reports at 1547 hrs EST today on A rare triple threat: three simultaneous Atlantic hurricanes: "For the first time in twelve years, we have a rare triple threat in the Atlantic--three simultaneous hurricanes. Hurricane Karl joined Hurricanes Igor and Julia in the steadily expanding Hurricanes of 2010 club this morning, becoming the sixth hurricane of the season. The last time we had three simultaneous hurricanes in the Atlantic was in 1998."  See the satellite image below. 

Trio of hurricanes in the Atlantic on 16 Sep 2010: Karl, Igor and Julia.  Source: National Hurricane Center.

Widespread Coral Bleaching

Meanwhile, elevated sea-surface temperatures are having an adverse impact on coral reefs in some regions.  NOAA reported yesterday in State of the Climate, Global Analysis, August 2010:

"Coral reefs, sometimes called `rainforests of the seas,' are found throughout the world's oceans. Not only do reefs provide food and habitat for many species to grow, live, and reproduce, but they also are essential for supporting fisheries, coastal protection, and tourism. Today, many coral reefs are threatened by overfishing and pollution, as well as ocean acidification, disease, and warmer ocean temperatures. Warmer-than-average temperatures cause corals to become stressed. This can lead to mass bleaching (indicated by a white or pale color) of coral colonies and reefs. If ocean temperatures increase just 1°-2°C (1.8°-3.6°F) above average and persist for a month or more, this frequently leads to severe damage or death of corals. Even if corals survive a mass bleaching event, their vulnerability to infectious disease increases and their ability to reproduce decreases. Experts have estimated that bleaching and disease from high ocean temperatures have destroyed nearly one-third of the world's coral reefs.

In 2005, warmer-than-average ocean temperatures in the Caribbean contributed to record-breaking mass coral bleaching, with 50-95% of coral colonies being severely affected. This was the worst bleaching event ever seen in many Caribbean countries. Unfortunately, Caribbean corals are at risk from warming ocean temperatures again this year. Warming in 2010 already has caused mass coral bleaching and mortality in Southeast Asia and the Coral Triangle." [emphasis added]

The journal Science reported in Hard Summer for Corals Kindles Fears for Survival of Reefs (27 August 2010):

"The most recent massive worldwide bleaching incident occurred in 1998, when El Niño conditions in the South Pacific caused sea surface temperatures to soar across the globe. This year, too, the hand of El Niño was at work. According to Coral Reef Watch, warming started in early summer in the Indian Ocean and persisted until cooling monsoon rains arrived. High temperatures later hit Southeast Asia and the Coral Triangle, which stretches from central Indonesia east to the Solomon Islands and north through the Philippines. In recent weeks, sea surface temperatures have risen in the Western Pacific in a band from Micronesia to Guam and the Northern Mariana Islands, and in the southern Caribbean. In some areas, says Eakin [C. Mark Eakin, a NOAA coral reef ecologist in charge of the agency's Coral Reef Watch], temperatures ^`are worse than in '98.'

Scientists are still surveying the damage. Early data are grim. Reefs on both sides of the Thai Peninsula were hit, with up to 100% of some coral species bleached, says James True, a coral biologist at Prince of Songkla University in Hat Yai, Thailand. He expects at least 80% of the most sensitive species to die. `A few inshore reefs got so badly damaged they probably won't ever come back to the way they were,' he says. Among surviving corals, `disease is rampant,' True says, with two to three times the usual incidence of necrotic lesions and growth anomalies. Similar reports of `quite extensive bleaching' have come from Vietnam and through the heart of the Coral Triangle in Indonesia and the Philippines, says [Clive] Wilkinson [a coral reef ecologist at Australia's Reef and Rainforest Research Centre in Townsville], who coordinates the Global Coral Reef Monitoring Network, which tracks reef status and promotes conservation

... Global warming is pushing baseline sea temperatures upward, says Eakin, causing localized bleaching even in years without an El Niño. `Unless there is concerted action to reduce greenhouse gases,' he warns, `bleaching will become increasingly common and not just during extraordinary weather events.'

Online Resources:

Arctic Sea Ice and related wildlife:

Arctic Sea Ice Decline and its Impacts: Online Resources.  WWF Climate Change blog.

Hurricanes:

• Exploring the Links Between Ocean Warming and Hurricanes. Environment 360, 15 Sep 2010.
• For Sixth Consecutive Month, Record High Sea Surface Temperatures in Tropical Atlantic (9 Aug 2010)
• As Atlantic Hurricane Season Ramps Up, Radio Audiences Hear About Hurricanes and Climate Change (2 Aug 2010)
• Rising Greenhouse Gas Concentrations Driving Up Sea Surface Temperatures that Fuel More Intense Hurricanes (12 July 2010)
• NOAA Sees Potential for "Hyperactive" Hurricane Season; Record High Sea Surface Temperatures Among Contributing Factors (1 June 2010) 

Coral Reefs:

• National Oceanic and Atmospheric Administration's Coral Reef Watch.
• Hard Summer for Corals Kindles Fears for Survival of Reefs.  By Dennis Normile, Science, Vol. 329. no. 5995, p. 1001 (27 August 2010).
   
• Mass coral bleaching closes dive sites, threatens future of world’s most diverse marine region.  WWF International Press Release, 29 July 2010.
• Coral reefs suffer mass bleaching.   Telegraph, 18 July 2010.
•  WWF Study Says Climate Change Could Displace Millions in Asia’s Coral Triangle , WWF Climate Blog, 13 May 2010.
• Coral Triangle and Climate Change: Ecosystems, People and Societies at Risk (PDF, 4.51MB) May 2009.