Until recently, global maps of coral reefs had not changed much since the days of Charles Darwin.
The British scientist created some of the first maps in the 1840s, including observations from his ocean expeditions.
French scientist Louis Joubin updated those maps in 1912, adding information from letters he received from people living near reefs around the world.
But it was not until the beginning of the 21st century that coral
reef mapping caught up with modern technology.
It took the arrival of a
high-quality satellite camera—the Enhanced Thematic Mapper Plus
on Landsat 7—and a convincing argument.
The Landsat series of
satellites was originally created to observe landforms, so imagers on
Landsat 1 through 5 were typically turned off while flying over large
oceans in order to conserve power or limited data storage.
Ocean
researchers eventually made the case to turn the instrument on over
coastal waters and, occasionally, the open ocean.
From 2000 to 2003, scientists participating in the Millennium Global Coral Reef Mapping project collected and analyzed 1,724 Landsat 7 satellite images in order to create a uniform, global map
of coral reefs.
The map has since been distributed openly on the
Internet and has been adopted by researchers and coral reef managers
around the world.
Now the next generation of Earth-observing satellites
is poised to significantly improve and update coral reef mapping.
The
sensors aboard Landsat 8 were designed to have higher sensitivity to
brightness and color than Landsat 7 (12-bit data versus 8-bit). Most
significantly, the satellite can observe Earth in wavelengths that
allows scientists to adjust for the distortions caused by the atmosphere
near the coast (a new shortwave, ultra-blue band at 0.43-0.45
micrometers supplements the blue band at 0.45-0.51 micrometers). This extra sensitivity
has made it easier to spot coral reefs and to quantify their area and
depth.
Scientists now have a tool for monitoring the health of coral
reefs even in the most remote regions.
“The Operational Land Imager on Landsat 8 is allowing us to outline
the reefs around the world and measure area and estimate depth in ways
never possible before,” said Frank Muller-Karger, a professor of
oceanography at the University of South Florida and a leader of the
Landsat-coral mapping efforts.
Muller-Karger has been funded by NASA’s
Applied Sciences to work together with the NOAA Coral Reef Watch program to develop new products for a coral reef alert program.
The large image and close-up above were acquired on May 10, 2015, by
the OLI instrument on Landsat 8.
The images show the extensive coral
reefs on the north shore of Vanua Levu, Fiji’s second largest island.
In addition to Landsat, Muller-Karger and colleagues can turn to
several other satellites to measure conditions around reefs.
Satellite
sensors like the Moderate-Resolution Imaging Spectroradiometer (MODIS)
instruments aboard NASA’s Terra and Aqua satellites can sense ocean
temperatures, a key variable in the healthy development of corals.
Similar readings are being collected by the Visible Infrared Imaging
Radiometer Suite (VIIRS) instrument on Suomi NPP and the Advanced Very
High Resolution Radiometer (AVHRR) instruments on NOAA’s Geostationary
Operational Environmental Satellites.
The next big leap in coral studies may come from hyperspectral
imaging.
New instruments tested on satellites, the International Space
Station, and research aircraft have shown the potential to observe at
more wavelengths and much better spatial resolution.
Such sensors might
someday be able to spot minor variations in coral reef color—a sign of
coral bleaching due to warming waters and changing ocean chemistry.
“You need Earth-observing cameras with small pixel sizes that allow a
closer look at the corals. The scale needed is much less than 100
meters,” said Nima Pahlevan, a scientist at NASA’s Goddard Space Flight
Center.
“With VIIRS and MODIS, for example, the best achievable spatial
resolution is 250-500 meters We need instruments capable of resolving
reefs at scales ranging from 1 to 40 meters.”
A truly amazing sight is the arrival of a billion indian oil sardines, amassing to over three miles long they can confuse their predators but one of them is unavoidable...
Business-as-usual carbon emissions would cause global warming that brings serious ocean acidification, death of corals and mangroves, scientists say
Time is rapidly running out for the world’s oceans and the creatures that live in them as the Earth’s climate continues to warm, say scientists.
Only “immediate and substantial” reductions in greenhouse gas emissions can hope to prevent “massive” impacts on marine ecosystems, warn the experts.
Researchers compared the fate of the oceans under two scenarios, one a “business-as-usual” approach and the other involving drastic cuts in emissions.
Their analysis showed that business-as-usual would have an enormous and “effectively irreversible” impact on ocean ecosystems and the services they provide, such as fisheries, by 2100.
Even after curbing emissions of carbon dioxide (CO2) enough to prevent temperatures rising by more than 2C compared with pre-industrial levels, many marine ecosystems would still suffer significantly, they said.
The international team led by Dr Jean-Pierre Gattuso, from the Laboratoire d’Océanographie de Villefranche in France, wrote in the journal Science: “Impacts on key marine and coastal organisms, ecosystems, and services from anthropogenic (man-made) CO2 emissions are already detectable, and several will face high risk of impacts well before 2100, even with the stringent CO2 emissions scenario.
“These impacts are occurring across all latitudes and have become a global concern that spans the traditional north/south divide.”
Any new global climate agreement that fails to minimise the impact on oceans will be “incomplete and inadequate”, stressed the scientists.
Changes in ocean physics and chemistry and impacts on organisms and ecosystem services according to stringent (RCP2.6) and high business-as-usual (RCP8.5) CO2 emissions scenarios.
The findings are intended to inform the forthcoming 2015 United Nations climate change conference in Paris.
By 2050, the loss of critical habitats such as coral reefs and mangroves was expected to contribute to “substantial declines” for tropical fisheries, on which many human communities depended, said the researchers.
This was the case even under the 2C emission cutting scenario.
While Arctic fisheries may benefit from warmer temperatures at first, the scientists pointed out that this region was a “hot spot” of ocean acidification.
It also contained communities that were highly reliant on the sea.
Acidification, warmer oceans, sea level rise threaten the all marine ecosystems...in that video, the Ocean Initiative 2015 Project provides straightforward answers to this issue.
A new paper just published in Science summarizes the projected impacts of climate change on the world’s oceans, and consequently on humans and our economy.
The study concludes that global warming beyond the international limit of 2°C above pre-industrial temperatures would pose serious threats to marine ecosystems and their millions of human dependents.
It builds on the consensus science published by the Intergovernmental Panel on Climate Change last year.
The study concludes, Ocean changes associated with a 2°C warming of global surface temperature carries high risks of impacts and should not be exceeded.
The oceans have absorbed over 90% of the excess heat and 28% of the carbon pollution generated by human consumption of fossil fuels.
As the authors of the paper note, in many regions, the ocean plays an important role in the livelihood and food supply of human populations.
The ocean represents more than 90% of the Earth’s habitable space, hosts 25% of eukaryotic species, provides 11% of global animal protein consumed by humans, protects coastlines, and more.
‘Irreversible change’ to sea life from CO2 A major report warns that life in the seas will be irreversibly changed unless CO2 emissions from industrial society are drastically cut. Twenty-two experts in the journal Science say the oceans are heating, losing oxygen and becoming more acidic - all in response to our carbon dioxide. The scientists in Germany have been studying an event five million years ago that could throw light on today's challenges.
The study considers human impacts on the world’s oceans under two different scenarios.
The first is a business-as-usual high fossil fuel consumption scenario (called RCP8.5 in the latest IPCC report), and the second is a scenario in which humans take immediate serious steps to curb fossil fuel consumption (called RCP2.6).
Between now and 2100, RCP8.5 involves 6 times more global carbon pollution emitted by humans than RCP2.6.
The societal effort involved in reducing fossil fuel consumption and carbon emissions to meet RCP2.6 is obviously much greater than the effort involved in the do-nothing scenario, but this study finds that the outcomes are also starkly different for the world’s oceans.
In the business-as-usual scenario, by 2100 the oceans would be about 30 cm higher, oxygen content nearly 2% lower, ocean acidity 70% higher, and sea surface temperatures about 2°C hotter than in RCP2.6.
The authors write,
In summary, the carbon that we emit today will change the Earth System irreversibly for many generations to come. The ocean’s content of carbon, acidity, and heat as well as sea level will continue to increase long after atmospheric CO2 is stabilized. These irreversible changes increase with increasing emissions, underscoring the urgency of near-term carbon emission reduction if ocean warming and acidification are to be kept at moderate levels.
"Oceans - The sinks of our World": gives an example of how public engagement can make a significant contribution to scientific investigations of the effects of global warming and ocean acidification on marine life.
The film introduces us to a man who has been recording the temperature of the sea in his region of the Mediterranean Sea for forty years.
Now he is also collecting water samples to support scientific investigations on ocean acidification.
His work is of great importance to scientists who are studying the impacts of increasing emission of CO2, driven by human fossil fuel combustion, on the temperature and chemical make- up of our oceans.
Questions about the impact ocean acidification may have already caused to the health and diversity of marine life need to be answered.
However, questions about how the conditions for marine organisms may change in the future also matter greatly.
After all, experimental research in the laboratory and observations of marine life close to undersea volcanic vents have already shown that that calcifying organisms, such as chorals, are greatly affected by an increase of acidity in the water.
The film invites the viewer to observe scientific investigations in the laboratory but more so to join scientists as they conduct their investigations at under water sites.
As an example of one consequence of these changes, many marine species are shifting to different geographic regions as the oceans warm.
These shifts can pose serious challenges for fisheries. Recent studies strongly reiterate that many species—including various invertebrates, commercially important fish species and marine mammals—are undergoing phenological and geographical shifts of up to 400 km per decade as a result of warming.
These geographical species shifts are projected to occur about 65% faster in the business-as-usual scenario than under RCP2.6.
Coral reefs are particularly sensitive to human-caused ocean changes.
They provide habitat for almost a quarter of the species in the oceans.
Hundreds of millions of people rely on the coastal protection, tourism, and food provided by coral reef ecosystems.
However, the authors of this study note that the dual threats of global warming and ocean acidification pose a serious threat to coral reefs.
Reef-building corals are extremely vulnerable to warming.
Warming causes mass mortality of warm-water corals through bleaching as well as through biotic diseases, resulting in declines in coral abundance and biodiversity.
Coral reefs can recover from bleaching events when thermal stress is minimal and of short duration.
However, ocean warming and acidification are expected to act synergistically to push corals and coral reefs into conditions that are unfavorable for coral reef ecosystems.
There is limited agreement and low confidence on the potential for corals to adapt to rapid warming.
The study also estimates some of the economic impacts of ocean changes in the business-as-usual scenario.
For example, lost coastal habitats and sea level rise could combine to expose 0.2 to 4.6% of the global population to inundation annually at a cost of 0.3 to 9.3% to global GDP.
In terms of tourism dollars, the difference between the two scenarios amounts to about $10 billion per year, hitting Australia and the USA particularly hard. Loss of coral reefs to tourism under the RCP2.6 and RCP8.5 scenarios could cost between US$1.9 billion and US$12 billion per year, respectively.
Coral reef losses due to ocean warming and acidification on the Great Barrier Reef place up to $5.7 billion and 69,000 jobs in Australia at risk.
In addition, ocean acidification may cause an annual loss of reef ecosystem services that are valued up to US$1 trillion by 2100.
For about a quarter of countries with reef-related tourism, mainly less developed countries, this kind of tourism accounts for more than 15% of gross domestic product and is more sustainable than extractive livelihoods.
The study also makes a critical and often-overlooked point.
Some people believe geoengineering is a better or more practical solution than curbing our carbon pollution.
Geoengineering proposals often involve slowing global warming by reducing the amount of sunlight absorbed by the Earth, for example by pumping sulfur high into the atmosphere, or putting large mirrors into orbit.
However, these proposals wouldn’t curb human carbon emissions, and hence wouldn’t slow the accumulation of carbon in the oceans, or the resulting ocean acidification.
Ultimately, the authors warn that immediate action to cut carbon pollution is critical if we want to curb the rapid and dangerous impacts already being observed in the world’s oceans. …immediate and substantial reduction of CO2 emissions is required in order to prevent the massive and effectively irreversible impacts on ocean ecosystems and their services that are projected with emissions scenarios more severe than RCP2.6. Limiting emissions to below this level is necessary to meet UNFCCC’s stated objectives. Policy options that overlook CO2, such as solar radiation management and control of methane emission, will only minimize impacts of ocean warming and not those of ocean acidification.
History repeats itself, and according to a new report, the same patterns that affected species extinction on land could be happening in the global oceans.
Despite this trend, however, we can help shape the future of ocean life by advocating for more marine protected areas and being an informed consumer.
Sea Technology spoke with Douglas McCauley, a University of California, Santa Barbara scientist who worked on the report, about what terrestrial species extinction means for marine life and the industrialization of the oceans.
Marine defaunation: Animal loss in the global ocean
How many land-based species have gone extinct?
In the last 500 years, there have been about 500 species of terrestrial animals that have gone extinct. There are many more that have gone extinct prior to 500 years, but some of the record keeping gets harder to do when you move back thousands of years.
What we are trying to do is focus on extinctions that are driven by people.
It's easier to concentrate on the past five centuries, where we know much more about what has happened to the environment.
In the ocean, in the same time period, 15 animals have been lost.
Why is the trend of species extinction on land important when looking at marine life?
It is a way for us to get a sense of how history can inform the future.
Things are basically behind in the oceans, in terms of our impact on wildlife communities, relative to our impacts on land.
It seems that we run through a couple of different transitions in the way that we influence wildlife.
When we look back at what happened on land, we can see how these transitions took form and what the consequences were.
We started hunting animals directly.
Then, we switched over to using the resources and space that animals use, hunting their homes and degrading their habitats.
That transition toward moving from hunting directly to hunting the land they use happened about the time, in a serious way, of the Industrial Revolution.
It was during that period where we were degrading habitats more rapidly that we also saw a major elevation in rates of terrestrial animal extinction.
In the oceans, the clock is turned back.
We're still hunting animals directly.
What we report is that there may be early signs of going toward this same shift in the ocean.
If we look at a wide range of data sources from marine industry, it seems there is a lot of new growth in development in the oceans.
We are now beginning to use space in the oceans at unprecedented rates.
That may be pushing us toward a period where we begin to industrialize our use of space in the oceans.
You mention a marine industrial revolution. Is this shift what that refers to?
Exactly.
The terrestrial Industrial Revolution was about building out our cities and factories and using resources from wild spaces.
That seems to be what we are seeing early signs of in the ocean.
We are building power plants in the oceans.
We're beginning to set ourselves up to start mining in the oceans.
There are more than 1 million square kilometers of seabed that have been set aside for future mining. We're beginning to farm in an almost industrial-strength way.
It seems like some of the signs in these data remind us of the early days of the terrestrial Industrial Revolution.
As an ecologist, that's where we get a bit worried, because we saw this explosion of growth go hand-in-hand with major extinction rates.
We don’t want that to happen in the oceans.
We need to be careful about where we put this industry and what rates we let it develop.
In your research, how do you correlate human actions and species extinction?
The nice thing is, with only 15 animal extinctions in the oceans, there is not a lot of ambiguity.
You take an animal like the Caribbean monk seal, one of the more charismatic marine animals that was driven extinct.
It was just hunting.
We can look at historical records.
We arrive, and we start directly hunting the seals.
Future extinctions get a bit more complicated.
The major shift is that climate change is going to be a challenge in the oceans.
We are making the oceans more acidic and warmer, and that's a new source of stress that these animals have to cope with.
So, if their populations are getting low, they have to work though the process of adaption to a new environment.
So much of the ocean is unexplored. How does that play into your research?
The oceans are incredibly difficult places to study and understand.
This is the reason why a report like this is new.
We have been talking about these extinctions that are taking place on land, and the science is so much easier to document on land.
Doing it in the ocean is a lot harder.
First of all, this report is coming out a little late because of the challenges describing these patterns of change in the ocean.
They can only be incomplete views.
This is the best distillation of information from so many different sources, yet it remains a pretty incomplete view of what's happening out there with marine wildlife.
What can we do to help preserve marine species?
There are some big things and some small things.
Put more parks in the ocean.
Everybody knows that protected areas, parks on land, are the places you go to see wildlife.
Marine wildlife also thrives in parks.
We have far fewer protected areas in the oceans than we have on land.
We simply need more.
We need to address climate change.
It doesn't help us to set aside space for wildlife if we are heating up that space and acidifying it.
You don't think about a connection between what kind of miles-per-hour rating your car gets and oysters or tropical fish, but there is in fact a connection.
Everything that we do in our daily lives to reduce carbon emissions is going to buy marine animals time.
Use less plastic.
There are five trillion pieces of plastic in the oceans.
The last thing I'd say is don't eat endangered wildlife.
Use one of the smartphone applications to sort through your seafood section to figure out which are the rhinos of the sea.
Links :
NYTimes : Ocean Life Faces Mass Extinction, Broad Study Says
