Tag Archives: Climate Change

Climate change affecting fish hearing

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ABC News, 9th March 2007

Marine scientists have found that once fish hatch they use sound to find a home on a coral reef.

But the scientists say warming sea temperatures are affecting the hearing of fish and making them lose their way home.

Dr Steve Simpson from the University of Edinburgh recorded sounds on a reef in Oman and played it to a group recently hatched fish in traps.

He says as coral reef fish move very little after they’ve settled on a reef, finding a good home is crucial to their survival.

“If you’re a centimetre long and you are trying to pick a home, a reef is a pretty dangerous place to arrive at,” Dr Simpson said.

“We’ve described it as having the wall of mouths waiting to receive you. So, you don’t want to get it wrong and have to visit several reefs.

“So, we think that in the same way as say when you are choosing a house, you’d go walking around local areas.

“This gives fish the ability to preview different reefs and make a decision based on those previews. So, they only actually have to take on one wall of mouths.”

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Are the impacts of climate change on coral reefs exaggerated? Questions and Answers (Part 1)

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For a long time the New Scientist has waged an ongoing battle with the climate change “skeptics”, and have produced some thorough articles such as “Climate change: a guide for the perplexed“, a round-up of the 26 most common climate myths and misconceptions. Time and time again I see people use similar myths and misconceptions regarding corals and coral reefs that are used as an argument as to why global warming is clearly a hoax, how warm water is good for corals (and the list goes on). In response to recent debates, below is the first part of a series called “Are the impacts of climate change on coral reefs exaggerated? Questions and Answers” in which I hope to address these misconceptions following the scientific evidence. Over the coming weeks I will aim to add more in the series: please feel free to add or ask any further questions in the comments below or email me at climateshifts @ gmail.com


1. “Warm water is good for corals”

Corals are locally adapted to the water temperature that they live in. This has taken many hundreds if not thousands of years to occur. It does not happen over decades, which would be the requirement if corals were to tolerate and survive the very rapid changes in sea temperature that we are currently facing.

The statements that “corals calcify faster in warmer waters” and “hotspots of coral diversity are found in warm waters close to the equator” are indeed true, but these conditions are only good for those corals that have adapted to these warmer conditions. For example, if you take corals from the southern end of the Great Barrier Reef and put them at the northern end of the Great Barrier Reef, these corals will suffer from being exposed to warmer than normal conditions and will die.

Although corals thrive within the upper limits of their thermal tolerance (within 1-2ºC), coral bleaching occurs when this tolerance is exceeded, resulting in loss of photosynthetic function, expulsion of symbiotic algae, and ultimately death of the coral. Clearly warm water is beneficial to those corals that are adapted to these warmer temperatures, although exceeding these thresholds results in mortality – a precarious balance.

With respect to the statement “corals in Moreton Bay are regularly stressed as the water is too cold” – it is well-known that corals in Moreton Bay (and other high latitude regions) where conditions that drop below 18°C in the winter lead to coral death. Just like they are sensitive to being too hot, they are also sensitive to becoming too cold. This is called the physiological range or tolerance of species. Conditions at places like Moreton Bay are marginal and therefore an outlier in global coral reefs and are restricted by their latitudes by cold winters.

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“Climate change could be the next subprime meltdown”

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Financial Post, 14th February 2008

Another subprime-mortgage-meltdown-sized risk could be looming for investors: global warming. That alarm was sounded Thursday at an investor summit at the United Nations headquarters, at which 480 investors, pension fund leaders and corporate executives from around the globe were warned that the vast majority of companies are ill-prepared for the Earth’s changing climate.

Many oil producers, utilities and manufacturing plants have yet to factor in the added expense if the United States – as is expected in the next few years – imposes caps on carbon-dioxide emissions. Similarly, many companies with big real-estate holdings in U.S. coastal regions haven’t calculated their exposure to increased tropical storms and rising seas.

Most of the financial institutions that lend to these companies and the insurance companies that protect them also have yet to adequately consider how they might get burned.

"It’s like subprime mortgages…one of longest kept secrets of uncalculated risk," said Mindy Lubber, president of Ceres, a coalition of investors and environmental groups, which co-hosted yesterday’s event. "By not acting on climate change…we face the same kind of [risks] with what we’re seeing in subprime."

Former U.S. vice president Al Gore, who was awarded the Nobel Peace Prize last year for bringing attention to the issue of climate change, echoed that theme as keynote speaker, urging investors to dump any assets they hold in businesses that are heavily reliant on carbon-intensive energy – or risk losing a ton of money down the road.

"You need to really scrub your investment portfolios, because I guarantee you…that if you really take a fine-tooth comb and go through your portfolios, many of you are going to find them chock-full of "subprime" carbon assets," Mr. Gore said according to an Associated Press report of the speech, which was closed to the press.

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Further calls for dramatic reductions in carbon emissions in the news

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Climate report calls for 2008 commitment to target
The Age, 21st February 2008

Greens leader Bob Brown has described a report that urges action on global warming as “spot on” but says he is worried the Federal Government will back away from adopting its recommendations.

Economist Ross Garnaut’s interim report on climate change, released today after being commissioned by Kevin Rudd and his colleagues while in opposition last year, has recommended Australia commit to a 2020 greenhouse target this year.

So far the Rudd Government has only adopted a long-term goal of cutting greenhouse emissions by 60% by 2050, but Professor Garnaut’s report says action needs to be taken immediately because recent scientific data indicates the global climate is changing faster than expected. (Read More)

Adaptation ‘key to climate deal‘
BBC News, 20th February 2008

The UK’s former top diplomat has called for a massive increase in the amount of money available to help developing countries to adapt to climate change.Lord Jay was speaking in Brazil, ahead of a two-day meeting of lawmakers from 13 key countries. The Global Legislators’ Organisation for a Balanced Environment conference will discuss the shape of a long-term deal to tackle global warming.

The discussions will not determine policy but they may influence it. The aim is to show what kind of future agreement would have enough support to be politically viable.

The Globe meeting brings together 100 leading politicians from the group of eight richest economies (G8) and five key developing countries: Brazil, China, India, Mexico and South Africa.On the table is a document drawn up by the former head of the UK Foreign Office, Lord Jay, sketching out the key principles of a global deal on climate change which the world’s leaders have pledged to negotiate by 2009, the timetable agreed at December’s UN climate meeting in Bali. (Read more)

First map of threats to marine ecosystems shows all the world’s oceans are affected

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EurekAlert, 14th February 2008

As vast and far-reaching as the world’s oceans are, every square kilometer is affected by human activities, according to a study in the journal Science by researchers at the University of North Carolina at Chapel Hill and others.

The international team of scientists integrated global data from 17 aspects of global change – from overfishing to global warming – that threaten 20 different marine ecosystems, such as coral reefs and continental shelves. Similar to an online satellite map that lets you add layers of highways, retail stores, schools, parks, etc., to find the most congested areas or the highest concentration of fast food restaurants, the global threat map highlights areas in the ocean where threats overlap.

The researchers scored the potential threats – from having very-low to very-high impacts – and found that affects were ubiquitous, and more than 40 percent of the oceans experience medium- to very high-impact threats.

“For the first time we can see where some of the most threatened marine ecosystems are and what might be degrading them,” said Elizabeth Selig, an author on the study and a doctoral student in UNC’s curriculum in ecology in the College of Arts and Sciences.

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More on sunscreen and coral bleaching

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Here is an excerpt from a recent news article (click below for full story):

Sunscreen may be killing corals

Cosmos, Monday 4th October

Some experts are yet to be persuaded by the findings, however.

“Any contaminant can experimentally damage a coral under artificially high concentrations. The amount [in the wild] must be tiny due to dilution,” commented Terry Hughes, director of the Australian Research Council’s Centre of Excellence for Coral Reef Studies at James Cook University in Queensland.

“Imagine how much water a tourist wearing one teaspoon of sunscreen swims through in an hour-long snorkel. Compared to real threats like global warming, runoff and overfishing, any impact of sunscreen is unproven and undoubtedly trivial,” he said.

However, Pusceddu argued that the coral response to sunscreen exposure was not dose dependent, “The mechanism appears to be on-off: thus once the virus has been switched on by [the chemicals in] sunscreen, toxicity is irrelevant.”

Ove Hoegh-Guldberg, director of marine studies at the University of Queensland in Brisbane, said the study is interesting, but notes that many factors are likely to be responsible. “Bleaching is like a runny nose: there are lots of things that could cause it.”

Though sunscreens may contribute to coral death, virus-caused bleaching is only a small part of the big picture, he said: “Climate related bleaching is a direct consequence of heat stress and does not involve viruses or bacteria.”

Coral reefs and climate change

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A colleague of mine, Dr John Bruno forwarded me an excellent article that he wrote for The Encyclopedia of the Earth, titled “Coral Reefs and Climate Change”

“A healthy reef ecosystem literally buzzes with sounds, activity and colors and is populated by incredibly dense aggregations of fish and invertebrates. In this respect, tropical reefs are more reminiscent of the African Serengeti than of the tropical rainforest they are often compared to, where the resident birds and mammals can be secretive and difficult to see. A coral reef can contain tens of thousands of species and some of the world’s most dense and diverse communities of vertebrate animals. Unfortunately, very few remaining coral reefs resemble this pristine condition; on most, corals and fishes are much less abundant than they were only a few decades ago”

John’s expert write-up and summary of threats to coral reefs related to climate change (coral bleaching, disease, ocean acidification) provides an excellent background of the literature and current threats, and is a worthy read for scientists, managers and the general public alike.

Healthy Great Barrier Reef reefscape A recovering Jamaican coral reef Bleached corals off Puerto Rico in 2005

 

2005 a deadly year for Caribbean coral

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Following close on the heels of IUCN report …

PARIS (AFP, Jan 28 2008) — The Caribbean’s fragile coral reefs were devastated in 2005 by a doubly whammy of record-high temperatures and 13 full-on hurricanes, according to a UN-sponsored report released Monday.During the last 50 years many Caribbean reefs have lost up to 80 percent of their coralacp-palmata.jpg cover, damaging or destroying the main source of livelihood for hundreds of thousands of people, said the report, prepared by a team of scientists and experts at the Global Coral Reef Monitoring Network.

The study was jointly sponsored by UNESCO and the Intergovernmental Oceanographic Commission.

Coral-based ecosystems are extremely sensitive to temperature increases, which have led over the last 50 years to massive bleaching — affecting up to 95 percent of the reefs around some islands, including the Cayman Islands, Jamaica, Cuba, and the French West Indies.

2005 was the warmest year since records were first kept in 1880, and global warming is likely to increase in years to come, climate scientists have warned.

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Sunscreens trigger VLPs that cause mass coral bleaching? The case of the blunt razor.

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I was rung up today by a journalist who wanted me to comment on whether sunscreens could cause coral bleaching. Her question was triggered by an article published this month in Environmental health Perspectives by Danovaro, R. et al. (doi:10.1289/ehp.10966.) which shows that very small amounts of sunscreen can cause corals to bleach. This is potentially interesting given the often close association of tourists and coral reefs.Nature News

Looking closely at the paper, however, I think there may be a few problems. Whereas the article talks about ‘bleaching’ (which involves the specific movement of symbiotic dinoflagellates out of the coral tissue, which remains behind), the photo that accompanies the article shows a white coral which looks as if it has lost all of its host tissue. That is, the coral looks dead in my opinion rather than bleached.

Danovaro et al. (2008) also discuss the mechanism behind the putative bleaching caused by the sun screens. The authors saw a proliferation of viral like particles or VLPs in their ‘bleached’ specimens and concluded that the VLPs were responsible. Why did Danovaro and his team conclude this? Well, there are earlier pieces of work out of Willy Wilson’s laboartory, supposedly showing that mass coral bleaching is triggered by latent VLPs are triggered by elevated water temperatures (Lohr et al. 2007). Willy is pretty straight up about it. “I’m pretty convinced that viruses are instrumental in the whole bleaching process,” says William Wilson from the Bigelow Laboratory for Ocean Sciences Sciences in Boothbay Harbor, Maine (Nature News). Continue reading →