Coral and chatting climate: Tougher than they seem

University of British Columbia's Professor Simon Donner

University of British Columbia's Professor Simon Donner

Simon Donner says that in 30 to 50 years, if they do not adapt, we will see corals bleaching and starving dangerously frequently as the oceans warm up. “Corals, the stationary animals that build reefs, get most of their food from colourful algae which live in the coral tissue,” the University of British Columbia professor explained. “When the surrounding waters gets too hot, the corals expel the algae and lose pigmentation. If the heat stress persists, the corals can essentially starve to death.”

Donner points out that the levels of greenhouse gases already in the atmosphere today will create enough warming for this to happen by themselves – a situation he calls “committed warming”. “Even if we froze the greenhouse gas concentrations in the atmosphere today, the climate is going to keep warming for several decades,” he says. However, talking at a conference back in February, he also looked at how corals will adapt to temperature, citing some studies showing that they can increase their temperature tolerances by as much as 1.5°C.

“That’s not guaranteed to happen, it is simply possible under the right circumstances,” Donner said. He found that if all corals could adapt by this much, and humanity could stabilise total atmospheric greenhouse gas concentrations at the equivalent of 550 parts per million of CO2, bleaching events would not be dangerously frequent by 2100. “In other words, adaptation could buy us time,” he said. “We might avoid the worst for coral reefs, but it may come with other consequences like reduced productivity and species diversity. Coral reefs would not continue looking the way they do now.”

Coral reef in Karimunjawa, Java, Indonesia. Reef building corals provide the source of calcium carbonate which builds the frameworks of coral reef ecosystems. Without this framework, it is estimated that over a million species would have nowhere to live. Image courtesy of Science/AAAS

Coral reef in Karimunjawa, Java, Indonesia. Reef building corals provide the source of calcium carbonate which builds the frameworks of coral reef ecosystems. Without this framework, it is estimated that over a million species would have nowhere to live. Image courtesy of Science/AAAS

Coral reef bleachings have already been happening in the tropical areas of the world for the past three decades. “You can’t look at any individual bleaching event, nor any individual weather event, and absolutely, definitively blame climate change,” Donner warns. “But we can look at the likelihood of a bleaching event happening with and without human influence on the climate. The best example is probably our work on the 2005 Caribbean bleaching: we found that the event was roughly ten times more likely to happen in today’s climate than in a pre-industrial climate.”

Tough Job

Critics of climate change researchers often accuse them of making up results for money, or to advance their career. Donner’s work involves him taking field trips to places like the Pacific islands of Kiribati for three weeks to dive and study reefs: What does he make of those who say he might do anything to get that job? “I’d say it is a ridiculous criticism, but understandable given the state of communications today,” he counters. “The internet provides easy access to scientific data and results, but not to the life of a scientist. You can’t publish just anything. It needs to be of sufficient accuracy, importance and quality, be based on accepted method and be replicable in order to pass peer review, and also in order to get and keep a job at a university. The fact that your research is constantly being evaluated by the community and that promotion at universities depends on people’s assessment of the quality of your work ensures that blatant distortions are rare and/or go unrewarded.”

Field-work is also high pressure, requires months of planning, and is far from glamorous, Donner points out. “You are cleaning oil out of compressors in the back of airports, sitting at the end of an exhausting day in the dark recharging tanks, eating unfamiliar local food,” he says. “You are working the whole time. No one would call our recent field project in Kiribati a holiday – I wanted a holiday when I got home.”

Tough audience

Yet despite the effort his research takes, Donner plays down the importance of explaining his results in detail. “The mistake we make in communicating about climate change is loading the audience with facts and figures without thinking about how they might receive them,” he says. “I think it’s important to first say: here’s where I am coming from, here’s where you might be coming from, before launching into the radiative properties of carbon dioxide. The basic science of climate change is simple. The perception of climate change, and the reason people continue to believe refuted ‘skeptic’ arguments, is not simple. By failing to first address how different people perceive information, we end up in pointless shouting matches.”

Bleached corals on the southern Great Barrier Reef in January 2002. Coral bleaching primarily affects reef building corals when conditions get too warm. Increasingly, corals are dying after bleaching events affecting their role as a habitat. Image courtesy of Science/AAAS

Bleached corals on the southern Great Barrier Reef in January 2002. Coral bleaching primarily affects reef building corals when conditions get too warm. Increasingly, corals are dying after bleaching events affecting their role as a habitat. Image courtesy of Science/AAAS

It can be hard to believe that people can change the climate, Donner says. “For thousands of years, we’ve assumed that only powers greater than us could possibly influence something as vast as the atmosphere,” he says. “That’s enshrined in most cultural and religious traditions. But today, there are so many people on the planet, and we consume so much energy every year, that we generate enough waste products – greenhouse gases – to alter the climate.”

While science tells us that human activity is changing the climate, Donner says, how you want the world to respond to that information is more related to politics, and people’s individual values. “As a scientist working on this subject for a number of years, I can provide you with a reasonably informed opinion on the costs and benefits of different responses,” he says, “but the choice is not mine alone.” Only once he has made these points clear, Donner says, would he go on to explain the scientific evidence – if his listener is “still awake and interested”.

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2 Responses to “Coral and chatting climate: Tougher than they seem”

  1. Simple Climate poll part 3: Getting personal « Simple Climate Says:

    […] Simon Donner, climatologist, The University of British Columbia, Vancouver, Canada: […]

  2. Temperature cuts swathe through Australian seaweed « Simple Climate Says:

    […] much farther south than usual to stay in comfortable temperatures. Coral reefs became bleached, which happens when colourful algae that live in the coral tissue die. In fact, it looks like the heatwave affected all levels of the area’s ecosystem, Thomas told me. […]


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