Title: Carbon Dioxide, Global Warming and Coral Reefs: Prospects for the Future
1Carbon Dioxide, Global Warming and Coral Reefs
Prospects for the Future
Dr. Craig D. Idso, Chairman Center for the Study
of Carbon Dioxide and Global Change
2Concerns About Global Warmingand Coral Reefs
- Magnify the intensity, frequency and duration of
environmental stresses - Leading to more cases of coral disease, bleaching
and death - Alter ocean water chemistry, ultimately leading
to reduced rates of coral calcification - Leads to slower-growing and weaker corals, and
possibly death
3How Do We Proceed?
- Must first have a correct understanding of the
scientific basis for the problems that are
predicted - We have been reviewing papers on CO2 and coral
reefs for more than a decade, recently releasing
a major report
4Coral Bleaching in Guam
5Noted Causes of Coral Bleaching
- Anomalously high water temperature
- Anomalously low water temperature
- High levels of solar irradiance
- Combined solar radiation-temperature stress
- Reduced salinity
- Bacterial infections
- Increased sedimentation
- Exposure to toxicants
6The Power of Adaptation
- Responding to the stress of high solar irradiance
- Corals exhibit a zonation of their symbiont taxa
with depth, with less tolerant species in corals
at greater depths - Zooxanthellae possess light quenching mechanisms
- Both produce amino acids that act as natural
sunscreens
7The Power of Adaptation
- Responding to the thermal stress
- Coral bleaching event in 2002 was 30-100 lower
than a bleaching event in 1998 even though the
thermal stress was more than double that in 1998 - The two corals most susceptible to bleaching in
1998 exhibited the least amount of bleaching in
2002 - Findings are consistent with other literature
examining bleaching events across the globe
8The Power of Adaptation
- Responding to the thermal stress
- on the basis of the present knowledge of genetic
variation in performance traits and species
capacity for evolutionary response, it can be
concluded that evolutionary change will often
occur concomitantly with changes in climate as
well as other environmental changes - (Skelly et al., 2007, Conservation
Biology 21 1353-1355)
9The Power of Adaptation
- Symbiont Shuffling
- Replace the zooxanthellae expelled during the
stress event with varieties more tolerant of the
stress - Produce heat shock proteins
- Bacterial Shuffling
- Rearranging bacterial populations in a process
akin to symbiont shuffling
10Corals have successfully adapted for the past 450
million years
11Ocean Acidification Hypothesis
- Higher atmospheric CO2 concentrations will lead
to - More CO2 dissolved into surface waters of the
worlds oceans, which leads to - Lower oceanic pH, which leads to
- Reduced calcification rates, which leads to
- Slower, weaker growing corals and perhaps even
coral death - Is there any real-world evidence to support such
claims?
12Calcification Observations
13Calcification Observations(1903-1922 vs
1979-1998)
141C SST rise 0.45 g cm-2 yr-1rise in
calcification
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17Why has Coral Calcification Increased?
- observed increases in coral reef calcification
with ocean warming are most likely due to an
enhancement in coral metabolism and/or increases
in photosynthetic rates of their symbiotic algae - Coral calcification is a biologically-driven
process that can overcome physical-chemical
limitations, which in the absence of life would
appear to be insurmountable
18Photosynthesis increases the pH of marine waters
making them less acidic
19The 20th Century Impact on Corals
- Rising CO2 and rising temperatures
- have not been anywhere near as catastrophically
disruptive as alarmists suggest they should have
been - actually appear to have been helpful
- But what about other calcifying marine organisms?
Have they been harmed in any way?
20The 20th Century Impact on Other Calcifying
Marine Life
- Determined particulate organic and inorganic
carbon produced for a coccolithophore at 750 ppm
CO2 - Also examined historic growth trends in this
species over the 90 ppm rise in CO2 over the past
two centuries
Emiliania huxleyi
21The 20th Century Impact on Emiliania huxleyi
- A doubling of both particulate organic and
inorganic carbon was observed for an approximate
doubling of atmospheric CO2 - Field evidence revealed a 40 increase in average
coccolith mass over the past 220 years as
temperatures and CO2 rose
22Similar Results Obtained by Other Researchers for
Emiliania huxleyi
Low-Light Environment
Elevated Temp. CO2
Elevated Temp.
Elevated CO2
Ambient
23Similar Results Obtained by Other Researchers for
Emiliania huxleyi
High-Light Environment
Elevated Temp. CO2
Elevated Temp.
Elevated CO2
Ambient
24Concluding Comments
www.co2science.org
25Concluding Comments
- Neither increases in temperature, nor increases
in atmospheric CO2 concentration, nor increases
in both of them together, have had any lasting
ill effects on the important processes of
calcification and growth in marine organisms - Out in the real world of nature, these processes
have actually been enhanced
26Carbon Dioxide, Global Warming and Coral Reefs
Prospects for the Future
Dr. Craig D. Idso, Chairman Center for the Study
of Carbon Dioxide and Global Change