Information

Global Acidification or Warming


Which poses the greater threat to ecology Global Ocean Acidification or Warming?


The issues of global ocean acidification and global warming are two symptoms of the same disease, too much carbon in the atmosphere. And they have 1 solution, put less carbon into the atmosphere. It doesn't really matter which aspect is the more harmful one, you can't treat one without treating the other.

If reducing carbon output were simple, we would have done it by now. However, it will most likely require radical changes to our energy infrastructure, with moves away from coal, oil, and natural gas and towards solar, wind, and nuclear power. It will probably require changes to our agricultural practices, and you should really watch Allan Savory's TED Talk for how those changes should be implemented.

People are very slow to change their habits, and short term profit is a powerful motivator against change, but I believe these we can and must solve these problems if humanity is to continue to thrive on Earth.


Biological responses of two marine organisms of ecological relevance to on-going ocean acidification and global warming

Recently, there has been a growing concern that climate change may rapidly and extensively alter global ecosystems with unknown consequences for terrestrial and aquatic life. While considerable emphasis has been placed on terrestrial ecology consequences, aquatic environments have received relatively little attention. Limited knowledge is available on the biological effects of increments of seawater temperature and pH decrements on key ecological species, i.e., primary producers and/or organisms representative of the basis of the trophic web. In the present study, we addressed the biological effects of global warming and ocean acidification on two model organisms, the microbenthic marine ciliate Euplotes crassus and the green alga Dunaliella tertiocleta using a suite of high level ecological endpoint tests and sub-lethal stress measures. Organisms were exposed to combinations of pH and temperature (TR1: 7.9[pH], 25.5 °C and TR2: 7.8[pH], 27,0 °C) simulating two possible environmental scenarios predicted to occur in the habitats of the selected species before the end of this century. The outcomes of the present study showed that the tested scenarios did not induce a significant increment of mortality on protozoa. Under the most severe exposure conditions, sub-lethal stress indices show that pH homeostatic mechanisms have energetic costs that divert energy from essential cellular processes and functions. The marine protozoan exhibited significant impairment of the lysosomal compartment and early signs of oxidative stress under these conditions. Similarly, significant impairment of photosynthetic efficiency and an increment in lipid peroxidation were observed in the autotroph model organism held under the most extreme exposure condition tested.

Keywords: Biological effects Ciliated protozoa Global warming Green algae Ocean acidification.


Ocean acidification amplifies global warming (Update)

Figure 1 : Observations of reduced DMS concentration with decreasing seawater pH from different mesocosm experiments.

Scientists at the Max Planck Institute for Meteorology (MPI-M), Dr. Katharina Six, Dr. Silvia Kloster, Dr. Tatiana Ilyina, the late Dr. Ernst Maier-Reimer and two co-authors from the US, demonstrate that ocean acidification may amplify global warming through the biogenic production of the marine sulfur component dimethylsulphide (DMS).

It is common knowledge that fossil fuel emissions of CO2 lead to global warming. The ocean, by taking up significant amounts of CO2, lessens the effect of this anthropogenic disturbance. The "price" for storing CO2 is an ongoing decrease of seawater pH (ocean acidification), a process that is likely to have diverse and harmful impacts on marine biota, food webs, and ecosystems. Until now, however, climate change and ocean acidification have been widely considered as uncoupled consequences of the anthropogenic CO2 perturbation.

Recently, ocean biologists measured in experiments using seawater enclosures (mesocosms) that DMS concentrations were markedly lower in a low-pH environment (Figure 1). When DMS is emitted to the atmosphere it oxidizes to gas phase sulfuric acid, which can form new aerosol particles that impact cloud albedo and, hence, cool the Earth's surface. As marine DMS emissions are the largest natural source for atmospheric sulfur, changes in their strength have the potential to notably alter the Earth's radiation budget.

Figure 2 : Zonal averaged changes in radiative forcing (a) caused by the projected changes in DMS emission (b) for three sensitivity experiments (high, medium and low) based on the relationship shown in Fig.1 (same color coding) and a reference run (Ref).

Based on the results from the mesocosm studies the researchers from the MPI-M have established relationships between pH changes and DMS concentrations in seawater. They projected changes in DMS emissions into the atmosphere in a future climate with enhanced ocean acidification using the MPI-M Earth system model4. In the journal Nature Climate Change it is demonstrated, that modeled DMS emissions decrease by about 18 (±3)% in 2100 compared to preindustrial times as a result of the combined effects of ocean acidification and climate change. The reduced DMS emissions induce a significant positive radiative forcing of which 83% (0.4 W/m2) can, in the model, be attributed to the impact of ocean acidification alone (Figure 2). Compared to the Earth system response to a doubling of atmospheric CO2 this is tantamount to an equilibrium temperature increase between 0.23 and 0.48 K. Simply put, their research shows that ocean acidification has the potential to speed up global warming considerably.


Oceans were stressed preceding abrupt, prehistoric global warming

Scanning electron microscopy images of foraminifera from different angles. Credit: Northwestern University

Microscopic fossilized shells are helping geologists reconstruct Earth's climate during the Paleocene-Eocene Thermal Maximum (PETM), a period of abrupt global warming and ocean acidification that occurred 56 million years ago. Clues from these ancient shells can help scientists better predict future warming and ocean acidification driven by human-caused carbon dioxide emissions.

Led by Northwestern University, the researchers analyzed shells from foraminifera, an ocean-dwelling unicellular organism with an external shell made of calcium carbonate. After analyzing the calcium isotope composition of the fossils, the researchers concluded that massive volcanic activity injected large amounts of carbon dioxide into the Earth system, causing global warming and ocean acidification.

They also found that global warming and ocean acidification did not just passively affect foraminifera. The organisms also actively responded by reducing calcification rates when building their shells. As calcification slowed, the foraminifera consumed less alkalinity from seawater, which helped buffer increasing ocean acidity.

"The formation and dissolution of calcium carbonate help regulate the acidity and alkalinity of seawater," said Northwestern's Andrew Jacobson, a senior author of the study. "Our calcium isotope data indicate that reduced foraminiferal calcification worked to dampen ocean acidification before and across the PETM."

"This is a pretty new concept in the field," added Gabriella Kitch, the study's first author. "Previously, people thought that only the dissolution of carbonates at the sea floor could increase alkalinity of the ocean and buffer the effects of ocean acidification. But we are adding to existing studies that show decreased carbonate production has the same buffering effect."

The research was published online last week (March 4) in the journal Geology. This is the first study to examine the calcium isotope composition of foraminifera to reconstruct conditions before and across the PETM and the third recent Northwestern study to find that ocean acidification—due to volcanic carbon dioxide emissions—preceded major prehistoric environmental catastrophes, such as mass extinctions, oceanic anoxic events and periods of intense global warming.

Jacobson is a professor of Earth and planetary sciences at Northwestern's Weinberg College of Arts and Sciences. Kitch is a Ph.D. candidate and National Science Foundation Graduate Research Fellow in Jacobson's laboratory. Northwestern Earth science professors Bradley Sageman and Matthew Hurtgen, as well as collaborators from the University of California-Santa Cruz (UCSC) and the University of Kansas, coauthored the paper with Jacobson and Kitch.

Sorting microscopic shells

To study oceanic conditions during the PETM, the researchers examined the calcium isotope composition of foraminiferal fossils collected from two sites—one in the southeast Atlantic Ocean and one in the Pacific Ocean—by the Ocean Drilling Program.

Because each fossilized shell is about the size of a single grain of sand, UCSC researchers physically collected the tiny specimens by first identifying them under a microscope. After sorting the shells from bulk sediments, the Northwestern team dissolved the samples and analyzed their calcium isotope composition using a thermal ionization mass spectrometer.

"The work is very challenging," Jacobson said. "To manipulate these tiny materials, you have to pick them up, one by one, with a wet paintbrush tip under a microscope."

Scanning electron microscopy images of foraminifera from different angles Credit: Northwestern University

As the shells formed more than 56 million years ago, they responded to oceanic conditions. By examining these shells, the Northwestern team found that calcium isotope ratios increased prior to the onset of the PETM.

"We are looking at one group of organisms that built their shells in one part of the ocean, recording the seawater chemistry surrounding them," Kitch said. "We think the calcium isotope data reveal potential stress prior to the well-known boundary."

Other archives indicate that the atmosphere-ocean system experienced a massive carbon dioxide release immediately before the PETM. When atmospheric carbon dioxide dissolves in seawater, it forms a weak acid that can inhibit calcium carbonate formation. Although it is still undetermined, Earth scientists believe the carbon release most likely came from volcanic activity or cascading effects, such as a release of methane hydrates from the seafloor as a result of ocean warming.

"My suspicion is that it's both of these factors or some sort of combination," Sageman said. "Most big events in Earth's history represent a confluence of many actors coming together at the same time."

Consistent pattern emerges

This is the third study led by Jacobson to find that ocean acidification precedes major environmental catastrophes that correlate with large igneous province eruptions. Last month, Jacobson's team published results finding that volcanic activity triggered a biocalcification crisis prior to an ocean anoxic event that occurred 120 million years ago. Just over a year ago, Jacobson's team published another study finding ocean acidification preceded the asteroid impact leading to the Cretaceous-Paleogene mass extinction event 66 million years ago, which included the demise of dinosaurs.

In all three studies, Jacobson's team used sophisticated tools in his laboratory to analyze the calcium isotope composition of calcium carbonate fossils and sediment. Jacobson said a clear pattern is emerging. Influxes of carbon dioxide led to global warming and ocean acidification and, ultimately, to massive environmental changes.

"In all of our studies, we consistently see an increase in calcium isotope ratios before the onset of major events or extinction horizons," Jacobson said. "This seems to point to similar drivers and common responses."

"Perhaps the calcium isotope system has a sensitivity to the earliest phases of these events," Sageman added.

Predictor for future ocean stress

Many researchers study the PETM because it provides the best analog for current-day, human-caused global warming. The carbon influx during the PETM is similar to the amount of carbon released during the past two centuries. The timescales, however, differ significantly. Temperatures during the PETM increased by 5 to 8 degrees Celsius over 170,000 years. With human-caused climate change, the same level of warming is projected to occur in less than 200 years, if carbon dioxide emissions remain unabated.

Frighteningly, terrestrial and ocean stress, including a major decrease in foraminiferal calcification, accompanied the PETM.

"The PETM is a model for what happens during major large carbon cycle perturbations," Jacobson said. "A lot of predictions for Earth's future climate rely on understanding what happened during the PETM."


Northwestern Now

Shelled organisms helped buffer ocean acidification by consuming less alkalinity from seawater

Gabriella Kitch works with samples from an ocean sediment core.

Microscopic fossilized shells are helping geologists reconstruct Earth’s climate during the Paleocene-Eocene Thermal Maximum (PETM), a period of abrupt global warming and ocean acidification that occurred 56 million years ago. Clues from these ancient shells can help scientists better predict future warming and ocean acidification driven by human-caused carbon dioxide emissions.

Led by Northwestern University, the researchers analyzed shells from foraminifera, an ocean-dwelling unicellular organism with an external shell made of calcium carbonate. After analyzing the calcium isotope composition of the fossils, the researchers concluded that massive volcanic activity injected large amounts of carbon dioxide into the Earth system, causing global warming and ocean acidification.

They also found that global warming and ocean acidification did not just passively affect foraminifera. The organisms also actively responded by reducing calcification rates when building their shells. As calcification slowed, the foraminifera consumed less alkalinity from seawater, which helped buffer increasing ocean acidity.

Andrew Jacobson

“The formation and dissolution of calcium carbonate help regulate the acidity and alkalinity of seawater,” said Northwestern’s Andrew Jacobson, a senior author of the study. “Our calcium isotope data indicate that reduced foraminiferal calcification worked to dampen ocean acidification before and across the PETM.”

“This is a pretty new concept in the field,” added Gabriella Kitch, the study’s first author. “Previously, people thought that only the dissolution of carbonates at the sea floor could increase alkalinity of the ocean and buffer the effects of ocean acidification. But we are adding to existing studies that show decreased carbonate production has the same buffering effect.”

The research was published online March 4 in the journal Geology. This is the first study to examine the calcium isotope composition of foraminifera to reconstruct conditions before and across the PETM and the third recent Northwestern study to find that ocean acidification — due to volcanic carbon dioxide emissions — preceded major prehistoric environmental catastrophes, such as mass extinctions, oceanic anoxic events and periods of intense global warming.

Jacobson is a professor of Earth and planetary sciences at Northwestern’s Weinberg College of Arts and Sciences. Kitch is a Ph.D. candidate and National Science Foundation Graduate Research Fellow in Jacobson’s laboratory. Northwestern Earth science professors Bradley Sageman and Matthew Hurtgen, as well as collaborators from the University of California-Santa Cruz (UCSC) and the University of Kansas, coauthored the paper with Jacobson and Kitch.

Sorting microscopic shells

To study oceanic conditions during the PETM, the researchers examined the calcium isotope composition of foraminiferal fossils collected from two sites — one in the southeast Atlantic Ocean and one in the Pacific Ocean — by the Ocean Drilling Program.

Because each fossilized shell is about the size of a single grain of sand, UCSC researchers physically collected the tiny specimens by first identifying them under a microscope. After sorting the shells from bulk sediments, the Northwestern team dissolved the samples and analyzed their calcium isotope composition using a thermal ionization mass spectrometer.

“The work is very challenging,” Jacobson said. “To manipulate these tiny materials, you have to pick them up, one by one, with a wet paintbrush tip under a microscope.”

Stress prior to PETM

As the shells formed more than 56 million years ago, they responded to oceanic conditions. By examining these shells, the Northwestern team found that calcium isotope ratios increased prior to the onset of the PETM.

“We are looking at one group of organisms that built their shells in one part of the ocean, recording the seawater chemistry surrounding them,” Kitch said. “We think the calcium isotope data reveal potential stress prior to the well-known boundary.”

56 million years Age of the sediment samples

Other archives indicate that the atmosphere-ocean system experienced a massive carbon dioxide release immediately before the PETM. When atmospheric carbon dioxide dissolves in seawater, it forms a weak acid that can inhibit calcium carbonate formation. Although it is still undetermined, Earth scientists believe the carbon release most likely came from volcanic activity or cascading effects, such as a release of methane hydrates from the seafloor as a result of ocean warming.

“My suspicion is that it’s both of these factors or some sort of combination,” Sageman said. “Most big events in Earth’s history represent a confluence of many actors coming together at the same time.”

Consistent pattern emerges

This is the third study led by Jacobson to find that ocean acidification precedes major environmental catastrophes that correlate with large igneous province eruptions. Last month, Jacobson’s team published results finding that volcanic activity triggered a biocalcification crisis prior to an ocean anoxic event that occurred 120 million years ago. Just over a year ago, Jacobson’s team published another study finding ocean acidification preceded the asteroid impact leading to the Cretaceous-Paleogene mass extinction event 66 million years ago, which included the demise of dinosaurs.

In all three studies, Jacobson’s team used sophisticated tools in his laboratory to analyze the calcium isotope composition of calcium carbonate fossils and sediment. Jacobson said a clear pattern is emerging. Influxes of carbon dioxide led to global warming and ocean acidification and, ultimately, to massive environmental changes.

In all of our studies, we consistently see an increase in calcium isotope ratios before the onset of major events or extinction horizons. ”

Andrew Jacobson
Earth scientist

“In all of our studies, we consistently see an increase in calcium isotope ratios before the onset of major events or extinction horizons,” Jacobson said. “This seems to point to similar drivers and common responses.”

“Perhaps the calcium isotope system has a sensitivity to the earliest phases of these events,” Sageman added.

Predictor for future ocean stress

Many researchers study the PETM because it provides the best analog for current-day, human-caused global warming. The carbon influx during the PETM is similar to the amount of carbon released during the past two centuries. The timescales, however, differ significantly. Temperatures during the PETM increased by 5 to 8 degrees Celsius over 170,000 years. With human-caused climate change, the same level of warming is projected to occur in less than 200 years, if carbon dioxide emissions remain unabated.

Frighteningly, terrestrial and ocean stress, including a major decrease in foraminiferal calcification, accompanied the PETM.

“The PETM is a model for what happens during major large carbon cycle perturbations,” Jacobson said. “A lot of predictions for Earth’s future climate rely on understanding what happened during the PETM.”

The study, “Calcium isotope composition of Morozovella over the Late Paleocene-early Eocene,” was supported by a David and Lucile Packard Fellowship (award number 2007-31757) and the National Science Foundation (award numbers NSF-EAR 0723151 and DGE-1842165).


Ocean warming and acidification effects on calcareous phytoplankton communities

A new study led by researchers from the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB) warns that the negative effects of rapid ocean warming on planktonic communities will be exacerbated by ocean acidification.

The research, recently published in the journal Scientific Reports of Nature, shows that some of the major environmental changes projected for this century in the Mediterranean Sea (e.g., ocean acidification, ocean warming, and the increasingly frequent marine heatwaves in summer) can have adverse effects on the productivity of calcifying phytoplankton communities (coccolithophores).

Carbon dioxide (CO2) emissions by human activities have alarmingly increased in the past decades. A quarter of this anthropogenic CO2 has been absorbed by the ocean, changing the chemistry and ultimately lowering the pH of the seawater, a phenomenon known as ocean acidification.

The extra heat trapped in the atmosphere due to greenhouse gases is also causing the warming of the seawater (which annually absorbs up to 90% of this heat). The process hampers the supply of nutrients to the upper ocean layers, due to a sharp stratification of the surface water column.

"Atmospheric warming is expected to evolve in the Mediterranean area 20% faster than the global average, and marine heatwaves will occur with increasing frequency by the end of the 21st century, with serious consequences for marine biodiversity and production", says Dr Patrizia Ziveri, ICREA Research Professor at the ICTA-UAB.


Discussion

The principle environmental variable affecting Pacific herring embryos and larvae in this study was elevated temperature. This finding is congruent with the understanding of temperature’s effect on developing Pacific herring, in which development was accelerated along with a greater embryo mortality and reduced hatching success (Alderdice and Velsen, 1971 Alderdice and Hourston, 1985 Pepin, 1991 Dinnel et al., 2007 Kawakami et al., 2011). Given that the mean temperature measured at Cherry Point during spawning season is already within 1 degree of the high temperature investigated here (DNR), and that further increases of between 1.5 and 4ଌ can be expected (Khangaonkar et al., 2018), temperature stress may become critical for larval herring at Cherry Point and in the Salish Sea. Elevated pCO2 as a single stressor did not elicit a discernable effect on the metrics of Pacific herring fitness surveyed here. Pacific herring in this region may be desensitized to the elevated pCO2 level used in this study. The carbonate system in coastal oceans is dynamic and in the Salish Sea daily and seasonal pCO2 variability can be extreme, due to freshwater inputs, respiratory activity from biological communities, and the intrusion of pCO2-rich deep water into the Salish Sea basin (Feely et al., 2010 Hoffman et al., 2011 Moore-Maley et al., 2016).

These environmental conditions may influence the relative sensitivity of species-specific responses to ocean acidification. For example, Leo et al. (2018) suggest that the differing responses to high pCO2 observed in Atlantic herring, a congener species to Pacific herring, may be explained by environmental acclimation. High pCO2 is regularly observed in the Kiel Fjord, and little to no effect of highly elevated pCO2 was observed in Atlantic herring larvae from this location (Franke and Clemmesen, 2011), compared to significant effects in larvae from populations spawning in relatively low pCO2 in the Oslo Fjord (Frommel et al., 2011 Leo et al., 2018). Diel and tidal cycles in coastal environments may also contribute to a lack of embryo sensitivity to elevated pCO2 (Cross et al., 2019). Coastal species, such as the Pacific herring, that experience short-term pCO2 fluctuations could produce offspring that are tolerant of these conditions, as the cost of acid-base regulation decreased during diel pCO2 cycles in several teleost species (Jarrold et al., 2017 Cross et al., 2019). The possibility for parental acclimation to elevated pCO2 on larval survival is a fundamental parameter for population recruitment. A recent study on Atlantic cod (Gadus morhua) found that parental acclimation, along with high food availability, alleviated some negative effects of high pCO2 on larval mortality (Stiasny et al., 2018). Atlantic silverside offspring were more susceptible to acidified conditions early in the spawning season, compared to later in the season, perhaps because of better parental conditioning later in the season when these conditions are more common (Murray et al., 2014).

While our study solely focused on the early life stages, until hatch, of Pacific herring embryos from one spawning event under static conditions, the results are suggestive that effects may be present under more fully realized simulations including variable conditions and with more widely sampled individuals. The potential for parental acclimation in this species, or varying adaption between populations is another area of research that could yield valuable information about potential responses to ocean acidification in Pacific herring populations. Below we discuss how the synergy of these climate variables affected the various aspects of Pacific herring early life stages in this study.

Hatching Success and Mortality

As an individual stressor, high pCO2 did not affect hatching success, which is a congruent finding with a previous study on Atlantic herring. Franke and Clemmesen (2011) found no linear relationship between high pCO2 and negative effects on Atlantic herring larval total length, dry weight, yolk sac and otolith area. While temperature has clear effects on Pacific herring embryo mortality and hatching success (Alderdice and Velsen, 1971 Alderdice and Hourston, 1985), this study demonstrates that high pCO2 when combined with temperature stress, may further increase mortality. The increased mortality at combined high temperature and pCO2 observed here calls for further investigation.

The broad temperature effects measured in this study are similar to those observed in other investigations (Alderdice and Velsen, 1971 Johnston et al., 1998, 2001 Dinnel et al., 2007). For instance, Pacific herring hatching success at a salinity of 30 PSU is predicted to be 80% and 36% at 10ଌ and 16ଌ, respectively by Alderdice and Velsen (1971), compared to measured values of 70% and 32% is this study. Predicted mortality rates are also similar to our observed values (Alderdice and Velsen, 1971). Mechanisms for increased mortality in the high temperature treatment may be related to oxygen supply, respiratory activity and metabolic activity, as suggested by heart rate and yolk sac data combined with results of previous studies (Alderdice and Hourston, 1985 Rombough, 2011 Dahlke et al., 2017). The interaction of pCO2 and temperature was not significant for hatching success. This metric is closely related to mortality, but includes larvae that hatch, yet are not likely to survive due to malformations.

Size and Development

While the effects of increased embryo mortality on Pacific herring populations are obvious, subtle effects on elevated heart rates and changes in size and development at hatch can have important survival impacts at later life stages, and can provide insight into mechanisms that may be driving the changes in embryo mortality. We found that Pacific herring incubated at higher temperatures hatched earlier and were smaller in length than those incubated at lower temperatures, which is consistent with patterns found in Atlantic herring, including length association with age (Geffen, 2002 Leo et al., 2018). Larval lengths at hatch may have an indirect effect on swimming performance. Shorter lengths (∼ 7 mm total length difference) decreased swimming velocity (m s 𠄱 ) by 24% of Atlantic herring larvae (Johnston et al., 2001). Energetic tradeoffs may also continue into later life stages. For example, elevated temperature was associated with increased swimming ability, but decreased growth and survival in Atlantic herring larvae (Sswat et al., 2018).

Pacific herring larval dry weights did not statistically differ between treatments and an examination of embryo yolk sacs may provide an explanation. Yolk conversion efficiency reaches a maximum within the thermal tolerance range of a given species, and tends to decrease near the upper and lower boundaries of tolerated temperatures (Galloway et al., 1998). For example, Atlantic cod embryos incubated at a low temperature (1ଌ) produced smaller larvae with larger yolk sacs, than embryos incubated at 5ଌ or 8ଌ (Galloway et al., 1998) suggesting that the reduced larval length obtained at the low temperatures may be a sub-lethal response an unfavorable environment. Conversely, under increased temperature (12ଌ) and pCO2 (1100 㯊tm), Atlantic cod embryos experienced higher metabolic rates and reduced larval length at hatch, while the consumption of yolk reserves remained unaffected indicating embryos were not able to convert yolk energy to other physiological functions (Dahlke et al., 2017).

In this study, Pacific herring embryos reared in the 1200 㯊tm:16ଌ treatment had the largest yolk area. Greater yolk areas in Pacific herring embryos reared at increased temperature and pCO2 indicate less energy was used for other developmental processes, such as growth. This may explain why no differences were detected in larval dry weights, with mass either remaining within the yolk sac for larvae under the high temperature or converted into growth for larvae in the ambient temperature treatment.

Metabolism

The effects of increased temperature on metabolism are well known and have been widely studied on marine fish, while the pCO2 effects on metabolic rates and processes are only now beginning to be explored. The increase in heart rate in both 16ଌ treatments observed in this study could be caused by increased oxygen demand at higher temperature, and appears to be exacerbated by high pCO2. The effect of temperature on oxygen availability may help to explain these results. Thermally regulated limits to oxygen supply can be a major driver in determining the thermal window through both limited circulatory capacity and solubility driven reductions in O2 availability (Pörtner and Knust, 2007). While elevated pCO2 conditions can impose additional metabolic demands through acid-base regulation, basal oxygen demand and standard metabolic rate have not been found to increase in marine fish under existing and projected globally relevant pCO2 levels (Lefevre, 2016 Esbaugh, 2018).

While oxygen consumption rates appear to respond to increased temperature in Atlantic herring larvae (Leo et al., 2018), enzyme activity – which indicates overall aerobic capacity – did not exhibit a strong temperature response (Overnell and Batty, 2000). Increased oxygen uptake in Atlantic herring appears to be partially linked to a reduction in the efficiency of mitochondrial ATP production as temperature increases (Leo et al., 2018). When efficiency in energy conversion decreases, both oxygen uptake and respiration must increase, potentially reallocating energy resources away from growth and development when energy becomes limiting. A similar mechanism for reduced metabolic scope with increased temperature was detected in Atlantic cod, and in this case, elevated pCO2 caused an earlier onset of the thermal stress to metabolic rates (Dahlke et al., 2017). This pairing of increased respiration with impaired energy conversion fits with the elevated heart rates and slower yolk utilization observed in the Pacific herring embryos exposed to high temperature and elevated pCO2 in this study. Direct oxygen uptake measurements were not successful here, but future investigation of mitochondrial oxygen uptake could determine if the interaction effects of temperature and pCO2 on Pacific herring heart rates are driven by this mechanism as well.

Resilience to pCO2 stress may result from acclimation to the dynamic environment in the Salish Sea, where the pH and pCO2 regularly fluctuate to extreme values on diurnal and tidal cycles during early to mid-summer months in nearshore eelgrass meadows where Pacific herring regularly spawn. These fluctuations often exceed the magnitude of predicted climate change related shifts for the end of the century in both temperature and pH. However, as climate changes progresses and the additional inputs from upwelling events, freshwater inputs, and other natural processes within the Salish Sea further reduces environmental pH, Pacific herring embryos may exhibit a reduced tolerance to elevated pCO2, particularly with the co-occurrence of warmer temperatures. The high temperature and high pCO2 conditions tested in this study are present currently, at least during some periods of the diurnal and tidal cycles for late spawning Cherry Point population. They may become increasingly common during those cycles at this location, and for earlier spawning populations in the coming decades, perhaps bringing increased metabolic stress and mortality as thresholds for harmful temperature and pCO2 are more frequently crossed.


How is Today&rsquos Warming Different from the Past?

Earth has experienced climate change in the past without help from humanity. We know about past climates because of evidence left in tree rings, layers of ice in glaciers, ocean sediments, coral reefs, and layers of sedimentary rocks. For example, bubbles of air in glacial ice trap tiny samples of Earth&rsquos atmosphere, giving scientists a history of greenhouse gases that stretches back more than 800,000 years. The chemical make-up of the ice provides clues to the average global temperature.

See the Earth Observatory&rsquos series Paleoclimatology for details about how scientists study past climates.

Glacial ice and air bubbles trapped in it (top) preserve an 800,000-year record of temperature & carbon dioxide. Earth has cycled between ice ages (low points, large negative anomalies) and warm interglacials (peaks). (Photograph courtesy National Snow & Ice Data Center. NASA graph by Robert Simmon, based on data from Jouzel et al., 2007.)

Using this ancient evidence, scientists have built a record of Earth&rsquos past climates, or &ldquopaleoclimates.&rdquo The paleoclimate record combined with global models shows past ice ages as well as periods even warmer than today. But the paleoclimate record also reveals that the current climatic warming is occurring much more rapidly than past warming events.

As the Earth moved out of ice ages over the past million years, the global temperature rose a total of 4 to 7 degrees Celsius over about 5,000 years. In the past century alone, the temperature has climbed 0.7 degrees Celsius, roughly ten times faster than the average rate of ice-age-recovery warming.

Temperature histories from paleoclimate data (green line) compared to the history based on modern instruments (blue line) suggest that global temperature is warmer now than it has been in the past 1,000 years, and possibly longer. (Graph adapted from Mann et al., 2008.)

Models predict that Earth will warm between 2 and 6 degrees Celsius in the next century. When global warming has happened at various times in the past two million years, it has taken the planet about 5,000 years to warm 5 degrees. The predicted rate of warming for the next century is at least 20 times faster. This rate of change is extremely unusual.


Ocean Acidification Will Make Climate Change Worse

Bleaches corals off the coast of Indonesia. Ocean acidification could have disastrous impacts on sealife—and the climate

Given that they cover 70% of the Earth’s surface—and provide about 90% of the planet’s habitable space by volume—the oceans tend to get short shrift when it comes to climate change. The leaked draft of the forthcoming coming new report from the Intergovernmental Panel on Climate Change highlighted the atmospheric warming we’re likely to see, the rate of ice loss in the Arctic and the unprecedented (at least within the last 22,000 years) rate of increase of concentrations of greenhouse gases like carbon dioxide and methane. But when it came to the oceans, press reports only focused on how warming would cause sea levels to rise, severely inconveniencing those of us who live on land.

Some of that ignorance is due to the out of sight, out of mind nature of the underwater world—a place human beings have only seen about 5% of. But it has more to do with the relative paucity of data on how climate change might impact the ocean. It’s not that scientists don’t think it matters—the reaction of the oceans to increased levels of CO2 will have an enormous effect on how global warming impacts the rest of us—it’s that there’s still a fair amount of uncertainty around the subject.

But here’s one thing they do know: oceans are absorbing a large portion of the CO2 emitted into the atmosphere—in fact, oceans are the largest single carbon sink in the world, dwarfing the absorbing abilities of the Amazon rainforest. But the more CO2 the oceans absorb, the more acidic they become on a relative scale, because some of the carbon reacts within the water to form carbonic acid. This is a slow-moving process—it’s not as if the oceans are suddenly going to become made of hydrochloric acid. But as two new studies published yesterday in the journal Nature Climate Change shows, acidification will make the oceans much less hospitable to many forms of marine life—and acidification may actually to serve to amplify overall warming.

The first study, by the German researchers Astrid Wittmann and Hans-O. Portner, is a meta-analysis looking at the specific effects rising acid levels are likely to have on specific categories of ocean life: corals, echinoderms, molluscs, crustaceans and fishes. Every category is projected to respond poorly to acidification, which isn’t that surprising—pH, which describes the relative acidity of a material, is about as basic a function of the underlying chemistry of life as you can get. (Lower pH indicates more acidity.) Rapid changes—and the ocean is acidifying rapidly, at least on a geological time scale—will be difficult for many species to adapt to.

Corals are likely to have the toughest time. The invertebrate species secretes calcium carbonate to make the rocky coastal reefs that form the basis of the most productive—and beautiful—ecosystems in the oceans. More acidic oceans will interfere with the ability of corals to form those reefs. Some coral have already shown the ability to adapt to lower pH levels, but combined with direct ocean warming—which can lead to coral bleaching, killing off whole reefs—many scientists believe that corals could become virtually extinct by the end of the century if we don’t reduce carbon emissions.

The Nature Climate Change study found that mollusks like oysters and squids will also struggle to adapt to acidification, though crustaceans like lobsters and crabs—which build lighter exoskeletons—seem likely to fare better. With fish it’s harder to know, though those species that live among coral reefs could be in trouble should the coral disappear. But ultimately, as the authors point out, “all considered groups are impacted negatively, albeit differently, even by moderate ocean acidification.” No one gets out untouched.

The other Nature Climate Change study—by American, German and British researchers—looked at the effects that ocean acidification could have on atmospheric warming. It turns out there may be some feedback—the researchers found that as the pH of the oceans dropped, it would result in lower concentrations of the biogenic sulfur compound dimethylsulphide (DMS). Why does that matter? Marine emissions of DMS are the largest natural source of atmospheric sulfur. (Manmade sources of sulfur include the burning of coal.)

Sulfur, in the form of sulfur dioxide, isn’t a greenhouse gas. But higher levels of sulfur in the atmosphere can reduce the amount of solar energy reaching the Earth’s surface, causing a cooling effect. (In the aftermath of the eruption of Mt. Pinatubo in the Philippines in 1991, which threw millions of tons of sulfur dioxide into the atmosphere, average global temperatures the two years fell by about 0.5 C.) If acidification decreases marine emissions of sulfur, it could cause an increase in the amount of solar energy reaching the Earth’s surface, speeding up warming—which is exactly what the Nature Climate Change study predicts. It’s one more surprise that the oceans have in store for us.


The Biggest Climate Change Lie of All: 'Ocean Acidification'

Throughout the history of claims about global warming, aka “climate change,” we’ve been served some real whoppers. Of course there’s Michael Mann’s “hockey stick” of temperatures, which was coddled together from bad data, bad computer code, and even “hiding the decline” by truncating data that didn’t agree with the warming narrative and splicing different data on top of it that did.

Then there’s Al Gore’s claims of polar bears disappearing when in fact their numbers are increasing, and the melting ice cap of Mount Kilimanjaro, which was supposedly a victim of climate change but turned out to be a result of deforestation. And who can forget the “children won’t know what snow is” claim by British climatologist David Viner which was so laughably over-the-top and wrong that it was finally shoved down the memory hole by the newspaper that published it.

All these climate claims have been shredded for the abuse of science that they are.

But it turns out that the biggest whopper of them all is still being used today by the media and some scientists to push a doomsday scenario: the dreadful-sounding “ocean acidification.” The phrase conjures up images of sea life dissolving in acidic seawater.

It’s completely untrue. The ocean is not acidic at all, and not even close. In fact, the phrase “ocean acidification” is a complete lie. Media outlets and science claim the ocean is “acidifying” because of increased carbon dioxide in the atmosphere. They claim ocean acidification is dissolving the shells of marine creatures.

While media claims run wild about dissolving sea creatures in an “acidic” ocean, real world data shows the ocean is far from acidic.

Have a look at this figure showing where seawater currently is on the pH scale. The reality shown in the figure is that with an average pH of 8.1, the oceans are a long way from turning acidic. Using the word “acidic” instead of more neutral phrasing in media reports sounds scarier for the cause of climate alarmism.

Figure: Comparison of the pH of common substances.
Data source: U.S. Environmental Protection Agency website.

The acidity or alkalinity of sea water is described by its pH level. Water is acidic at a pH less than 7 and alkaline if pH is greater than 7. Seawater is naturally alkaline at 8.2.

Although climate models suggest the ocean’s surface pH has dropped from pH 8.2 to 8.1 since 1750, that change was never actually measured. The pH drop is merely a modeled conjecture that is, unfortunately, constantly repeated as fact. The concept of pH was first introduced in 1909, and the pH concept was not modernized in chemistry until the 1920s.

Despite our sophisticated global fleet of 3,800 Argo floats that measure ocean temperature and salinity, only 10 percent also measure ocean carbon dioxide chemistry, and just 40 floats measure ocean pH, suggesting the researchers don’t think it is a really big problem. Measured trends in ocean pH only began in the 1990s, which is far too short a time to allow a robust analysis.

A new white paper from the CO2 Coalition, Ocean Health—Is There an ‘Acidification’ Problem?,” outlines the issue in scientific detail. The principal researcher for the paper is biologist Jim Steele, a member of the CO2 Coalition and recently retired director of San Francisco State University’s Sierra Nevada field campus, a position he held for more than 25 years.

Steele reports a scientific consensus that even if atmospheric CO2 concentrations were to rise from today’s 0.4 percent to .10 percent (over about 250 years at current rates), ocean pH would fall only to 7.8, still well above neutral for all ocean surface waters, and stabilize there.

The paper reveals that the term “ocean acidification” was invented to scare citizens into opposing the use of fossil fuels, which power 80 percent of the U.S. and world economies. It also shows that carbon dioxide is a vital part of ocean health and the ocean food web, because additional CO2 input allows marine life to thrive. The foundation of the ocean food web is phytoplankton, which includes organisms such as microscopic plants and bacteria. These organisms require CO2 to make their food through photosynthesis.

CO2 Coalition chair Patrick Moore, a noted ecologist and a former top-ranking Greenpeace official, said, “This paper details the powerful cycle that takes surface carbon down to the depths for lengthy periods, before upwelling to enrich surface life again. Shells and marine species thrive in widely varying pH levels, making the so-called acidification crisis yet another cynical example of propaganda masquerading as science. As with fears of polar bear extinction, frequencies of hurricanes, length of droughts, and ‘accelerating’ sea-level rise, the specter of ‘ocean acidification’ has no basis in the scientific data.”

—Guest essayist Anthony Watts is a senior fellow at The Heartland Institute and the founder and publisher of Watts Up With That, the world's most-viewed site on global warming and climate change.

IN THIS ISSUE …

NO ‘HOCKEY STICK’ FOR THE NORTHERN HEMISPHERE … LAND USE HAS BIGGER IMPACT ON CLIMATE THAN GREENHOUSE GASES … WELFARE INCREASES WILL DOMINATE CLIMATE COSTS

NO ‘HOCKEY STICK’ FOR THE NORTHERN HEMISPHERE

Guest essay by Jim Lakely

More bad news for Michael Mann and his hockey stick. (Can someone let him know? He has blocked us on Twitter.)

According to a post by Kenneth Richard at NoTricksZone, “new paleoclimate records from Europe, Scandinavia-Russia, China, and the northeastern USA indicate there has been no unusual modern warming. Instead, these newly published reconstructions show warmer periods and more rapid centennial-scale warming events occurred in past centuries, or when CO2 concentrations were much lower than they are now.”

Those facts, of course, fly right in the face of Mann’s hockey stick graph, in which he used tree-ring evidence in North America to construct the stubborn myth that the Earth's climate was relatively quiet and stable (and cool) for nearly 1,000 years and then suddenly rocketed up faster than SpaceX at the start of the Industrial Revolution. That is proof, Mann says, that human CO2 emissions have caused catastrophic, runaway global warming.

Well, two can play the tree-ring game. A study published in Quaternary Science Reviews by Jessie K. Pearl et. al. looked at tree-ring records (as well as "sub-fossil trees”) of Atlantic white cedar going back 2,500 years, from 411 B.C. to 2016 A.D. When they did this, the hockey stick disappeared.

NoTricksZone’s post cites another study of tree-ring data from Northern Eurasia, this one in the journal Climate Dynamics (Feng Shi et. al.). That study shows the region warmed “three to six times faster during the 4th, 15th, and 19th centuries than during the 1900s-2000s”—the time of Mann’s hockey stick. And what do you know, the researchers also found “regional temperatures were warmer during the first millennium than during the last century.”

But hold on, there’s more. Scientists reported in a new paper in the Journal of Geographical Sciences (Zhixin Hao et. al.) that their study of ice cores, tree rings, lake sediments, and stalagmites throughout the “whole country” of China found the “longest warm period on the centennial scale” happened between the 10th and 13th centuries. NoTricksZone also reports the study confirmed that “the two warmest 30-year periods during the Medieval Warm Period are also ‘comparable’ to the warmth of recent decades.”

Someone tell Michael Mann they found his missing Medieval Warm Period. It was all over the Northern Hemisphere. How did he miss it?

LAND USE HAS BIGGER IMPACT ON CLIMATE THAN GREENHOUSE GASES

Guest essay by Jim Lakely

A recent study published by the International Journal of Climatology (Mi Yan et. al.) looks at the temperature record of the 20th century and examines not only the effect of greenhouse gases (GHG) but also the role historical land use/land cover change (LUCC) has played in the equation. Their conclusion: “Globally, the biogeophysical effect of historical LUCC can offset the warming induced by increased GHG.”

The scientists note the vast majority of their peers have focused primarily on trying to determine the way human GHG emissions have affected the composition of the atmosphere, and that they consider it “a primary cause of present-day global warming.” The role of land use in climate change “remains under debate” and an open field pardon the pun) for further study, the scientists state.

For instance, not all forest clearing is equal. The authors write:

The authors are more certain, however, about their conclusion that the “statistically significant biogeophysical impact of historical LUCC is comparable in overall magnitude to that of historical GHGC, especially over high latitudes.” They urge scientists to “pay more attention to the interactions between external forcings and internal variabilities when investigating the climate effects of external forcings either for the past or for the future projection.”

Good advice. Who knows where it may lead?

LOMBORG: POOR BETTER OFF IF WE IGNORE PARIS

Guest essay by Jim Lakely

Everyone’s favorite telegenic, lukewarm non-alarmist, Bjorn Lomborg, has a new paper in the journal Technological Forecasting and Social Change. Lomborg takes another lap on a topic that has become his specialty: pointing out that the enormous costs of “fighting climate change” would be better spent on things the world’s poorest people actually need, such as clean water and the vaccines that have eradicated most dread diseases in the developed world.

In his abstract, Lomborg does a little throat clearing that keeps him in the good graces of climate realists. There is no evidence that extreme weather is increasing in a warming world even the IPCC finds no trend in global hurricane frequency the global risk from extreme weather has declined by an astounding 99 percent over the last 100 years and by 28 percent since 1992, he notes. Even if hurricanes do get stronger if less frequent, our increasingly wealthy societies (the wealth of which is driven by the use of fossil fuels, though Lomborg doesn’t mention that) will weather the storms more effectively and rebuild more quickly.

Lomborg brings up the oft-ignored fact that the unrealistic climate policies pushed by global planners “also have costs that often vastly outweigh their climate benefits.” If the world embraces the Paris Climate Accord fully and actually implements it, it will cost the global economy between $819 billion and $1.9 trillion per year starting in 2030, Lomborg notes. And for what? To “reduce emissions by just 1% of what is needed to limit average global temperature rise to 1.5°C,” Lomborg writes. By Lomborg’s math, “each dollar spent on Paris will likely produce climate benefits worth 11¢.”

Given the choice between two of the IPCC’s scenarios for the future—the “sustainable” SSP1 and the “fossil-fuel driven” SSP5—Lomborg says the decision is easy: go for the fossil-fuel driven option. “After adjusting for climate damages, SSP5 will on average leave grandchildren of today's poor $48,000 better off every year. It will reduce poverty by 26 million each year until 2050, inequality will be lower, and more than 80 million premature deaths will be avoided.”

Yes, Lomborg advocates imposing “carbon taxes” and cares about trying to reduce the rate of warming over the next 80 years. He also pushes “investment in green R&D to make future decarbonization much cheaper.” Although those instincts may annoy climate realists, it’s a certainty that Lomborg annoys the alarmists at the IPCC even more.


Watch the video: What Is Ocean Acidification? NowThis (December 2021).