Marine scientists have been meeting in Cairns, Australia this week to look at the world's coral reefs. This is a depressed group of people, for these desperate scientists have been privileged to watch their living subjects of study disappear right before their very eyes. These scientists issued a statement to highlight the problem.
The international Coral Reef Science Community calls on all governments to ensure the future of coral reefs, through global action to reduce the emissions of carbon dioxide and other greenhouse gases, and via improved local protection of coral reefs. Coral reefs are important ecosystems of ecological, economic and cultural value yet they are in decline worldwide due to human activities. Land-based sources of pollution, sedimentation, overfishing and climate change are the major threats, and all of them are expected to increase in severity. Changes already observed over the last century:
- Approximately 25-30% of the world's coral reefs are already severely degraded by local impacts from land and by over-harvesting.
- The surface of the world's oceans has warmed by 0.7 °C, resulting in unprecedented coral bleaching and mortality events.
- The acidity of the ocean's surface has increased due to increased atmospheric CO2.
- Sea-level has risen on average by 18cm.
By the end of this century:
- CO2 emissions at the current rate will warm sea surface temperatures by at least 2-3 °C, raise sea-level by as much as 1.7 meters, reduce ocean pH from 8.1 to less than 7.9, and increase storm frequency and/or intensity. This combined change in temperature and ocean chemistry has not occurred since the last reef crisis 55 million years ago.
Other stresses faced by corals and reefs:
- Coral reef death also occurs because of a set of local problems including excess sedimentation, pollution, habitat destruction, and overfishing.
- These problems reduce coral growth and vitality, making it more difficult for corals to survive climate changes.
Future impacts on coral reefs:
- Most corals will face water temperatures above their current tolerance.
- Most reefs will experience higher acidification, impairing calcification of corals and reef growth
- Rising sea levels will be accompanied by disruption of human communities, increased sedimentation impacts and increased levels of wave damage.
- Together, this combination of climate-related stressors represents an unprecedented challenge for the future of coral reefs and to the services they provide to people.
Corals threatened by acidification near Ishigaki island in Okinawa, Japan. Image from Pace of Ocean Acidification Has No Parallel in 300 Million Years, Paper Says. A new scientific paper suggests that the ocean is acidifying at a rate that is many times faster than at any time in the last 300 million years. The change is occurring so rapidly that it raises “the possibility that we are entering an unknown territory of marine ecosystem change,” said the paper, published this week in the journal Science.
An unprecedented challenge for the future of coral reefs. Unprecedented, that is, since the Paleocene-Eocene Thermal Maximum 55 million years ago, "in which a pulse of carbon dioxide from an unknown source entered the atmosphere over several thousand years. That event produced immense environmental changes and some extinctions of life in the sea, but research suggests it did not lead to mass extinctions on land."
I don't really need to add anything here, do I? I will remind you that when we talk about the 6th Mass Extinction of the Phanerozoic Eon, i.e. in the 543 million years after the pre-Cambrian, the rich marine life supported by coral reefs will almost certainly be among the many "losers" in this high-stakes lottery we've created. If your species loses, your species dies off—completely. Extinction is forever. You might also look at my previous post on the coral reefs called Our Dying Planet — Coral Reefs.
And now I hear James Carville talking about the disappearing middle class on National Propaganda Radio. I grant you that preserving the doomed middle class is important—there is endless talk about it, but not much preserving. I grant you that many Americans are going to suffer in the coming years.
But we're talking about an ongoing Mass Extinction here.
Makes you think, doesn't it? About what's truly important, and what is not.