Ocean acidification is the ongoing decrease in the pH of the Earth‘s oceans, caused by the uptake of carbon dioxide (CO2) from the atmosphere. Seawater is slightly basic (meaning pH > 7), and the process in question is a shift towards pH-neutral conditions rather than a transition to acidic conditions (pH < 7). Ocean alkalinity is not changed by the process, or may increase over long time periods due to carbonate dissolution. An estimated 30–40% of the carbon dioxide from human activity released into the atmosphere dissolves into oceans, rivers and lakes. To achieve chemical equilibrium, some of it reacts with the water to form carbonic acid. Some of these extra carbonic acid molecules react with a water molecule to give a bicarbonate ion and a hydronium ion, thus increasing ocean acidity (H+ ion concentration). Between 1751 and 1994 surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14, representing an increase of almost 30% in H+ion concentration in the world’s oceans. Earth System Models project that within the last decade ocean acidity exceeded historical analogs and in combination with other ocean biogeochemical changes could undermine the functioning of marine ecosystems and disrupt the provision of many goods and services associated with the ocean.
Increasing acidity is thought to have a range of potentially harmful consequences for marine organisms, such as depressing metabolic rates and immune responses in some organisms, and causing coral bleaching. By increasing the presence of free hydrogen ions, each molecule of carbonic acid that forms in the oceans ultimately results in the conversion of two carbonate ions into bicarbonate ions. This net decrease in the amount of carbonate ions available makes it more difficult for marine calcifying organisms, such as coral and some plankton, to form biogenic calcium carbonate, and such structures become vulnerable to dissolution. Ongoing acidification of the oceans threatens food chains connected with the oceans. As members of theInterAcademy Panel, 105 science academies have issued a statement on ocean acidification recommending that by 2050, global CO2emissions be reduced by at least 50% compared to the 1990 level.
While ongoing ocean acidification is anthropogenic in origin, it has occurred previously in Earth’s history. The most notable example is the Paleocene-Eocene Thermal Maximum (PETM), which occurred approximately 56 million years ago. For reasons that are currently uncertain, massive amounts of carbon entered the ocean and atmosphere, and led to the dissolution of carbonate sediments in all ocean basins.
Climate deniers try to distort or obfuscate the evidence about the changing atmosphere, and it’s not always easy to give overwhelmingly conclusive data that would convince them. In some cases the data are tricky to analyze, or do not have well-documented long-term histories necessary to answer every concern about whether recent weather events are truly unprecedented. The atmospheric system is very complicated, with many different processes operating on short-term, medium-term, and long-term time scales, and not all of it is as well understood as we would like. Thus, the arguments over changes in earth’s atmosphere often reach an impasse.
Not so for the oceans. Although oceans are an even larger system than the atmosphere, we understand them much better. More importantly, we have an excellent long-term record of how the oceans have changed over millions of years from thousands of deep-sea cores, and from the paleontological record of marine fossils that goes back over 700 million years. And unlike the atmospheres, oceans change very slowly over time, since the thermal inertia of water makes the seas very resistant to change except on long-term time scales. In addition, most ocean currents move slowly compared to atmospheric currents. So no matter what you want to make of the data showing atmospheric change, the changes in the oceans are more alarming, since oceans require immense stimuli to cause such change.
CO2 is plant food
Earth’s current atmospheric CO2 concentration is almost 390 parts per million (ppm). Adding another 300 ppm of CO2 to the air has been shown by literally thousands of experiments to greatly increase the growth or biomass production of nearly all plants. This growth stimulation occurs because CO2 is one of the two raw materials (the other being water) that are required for photosynthesis. Hence, CO2 is actually the “food” that sustains essentially all plants on the face of the earth, as well as those in the sea. And the more CO2 they “eat” (absorb from the air or water), the bigger and better they grow. (source: Plants Need CO2)
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can be later releasedto fuel the organisms’ activities (energy transformation). This chemical energy is stored in carbohydrate molecules, such as sugars, which are synthesized from carbon dioxide and water – hence the name photosynthesis, from the Greek φῶς, phōs, “light”, and σύνθεσις,synthesis, “putting together”. In most cases, oxygen is also released as a waste product. Most plants, most algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis maintains atmospheric oxygen levels and supplies all of the organic compounds and most of the energy necessary for life on Earth.
Although photosynthesis is performed differently by different species, the process always begins when energy from light is absorbed byproteins called reaction centres that contain green chlorophyll pigments. In plants, these proteins are held inside organelles calledchloroplasts, which are most abundant in leaf cells, while in bacteria they are embedded in the plasma membrane. In these light-dependent reactions, some energy is used to strip electrons from suitable substances, such as water, producing oxygen gas. The hydrogen freed by water splitting is used in the creation of two further compounds that act as an immediate energy storage means: reduced nicotinamide adenine dinucleotide phosphate (NADPH) and adenosine triphosphate (ATP), the “energy currency” of cells.
In plants, algae and cyanobacteria, long term energy storage in the form of sugars are produced by a subsequent sequence of light-independent reactions called the Calvin cycle, but some bacteria use different mechanisms, such as the reverse Krebs cycle. In the Calvin cycle, atmospheric carbon dioxide is incorporated into already existing organic carbon compounds, such as ribulose bisphosphate(RuBP). Using the ATP and NADPH produced by the light-dependent reactions, the resulting compounds are then reduced and removed to form further carbohydrates, such as glucose.
The first photosynthetic organisms probably evolved early in the evolutionary history of life and most likely used reducing agents such as hydrogen or hydrogen sulfide, rather than water, as sources of electrons.Cyanobacteria appeared later; the excess oxygen they produced contributed to the oxygen catastrophe,which rendered the evolution of complex life possible. Today, the average rate of energy capture by photosynthesis globally is approximately 130 terawatts, which is about three times the current power consumption of human civilization. Photosynthetic organisms also convert around 100–115 thousand million metric tonnes of carbon into biomass per year.
What are the implications of observations above 400pm? Water supply, sea level rising, increase of precipitation intensity, food production, heat waves, health threat, biodiversity collapse, etc. IPCC report consist more than 1500 pages of science-based information about causes and implications.
Existing climate changes will go faster and more extreme & unpredictable. We know about a lot of difficult and interconnected issues like ocean acidification or new type of more intensive forest fires (has already taken place in Canada, Russia, Australia) and record existing changes there.
The Keeling Curve record from the NOAA-operated Mauna Loa Observatory shows that the atmospheric carbon dioxide concentration hovers around 400 ppm, a level not seen in more than 3 million years when sea levels were as much as 80 feet higher than today. Virtually every media outlet reported the passage of this climate milestone, but we suspect there’s more to the story. Oceans at MIT’s Genevieve Wanucha interviewed Ron Prinn, Professor of Atmospheric Science in MIT’s Department of Earth, Atmospheric and Planetary Sciences. Prinn is the Director of MIT’s Center for Global Change Science (CGCS) and Co-Director of MIT’s Joint Program on the Science and Policy of Global Change (JPSPGC). Prinn leads the Advanced Global Atmospheric Gases Experiment (AGAGE), an international project that continually measures the rates of change of the air concentrations of 50 trace gases involved in the greenhouse effect. He also works with the Integrated Global System Model, which couples economics, climate physics and chemistry, and land and ocean ecosystems, to estimate uncertainty in climate predictions and analyze proposed climate policies.
02 November 2015
A volunteer registration of insects for 18 consecutive years on the roof of the Natural History Museum of Denmark has revealed local insect community turnover due to climate change. The research suggests a pattern of specialised species being more sensitive to climate change.
1543 different species of moths and beetles and more than 250.000 individuals have been registered on a single urban rooftop in Copenhagen over 18 years of monitoring. That corresponds to 42 % of all the species of moths in Denmark and 12 % of the beetles. More interestingly, the insect community has changed significantly during that period. The results are published today in the Journal of Animal Ecology led by researchers from the Center for GeoGenetics and the Center for Macroecology, Evolution and Climate at the Natural History Museum of Denmark at the University of Copenhagen.
“We are likely to lose some specialist species as they retreat north, but more new specialist species will arrive from the south. This trend is theoretically expected but extremely rare to confirm with observations across this many species. Insects are often over-looked and under prioritised for long term studies” says the other lead authorPeter Søgaard Jørgensen, PhD from the Center for Macroecology, Evolution and Climate.
The linkage between faunal change and climate change really has to do with a very basic observation, which is that organisms are fundamentally linked to the resource availability of a given landscape. As the energetics of the landscape, the utility of the landscape changes, the fauna have a series of options that that they can either adapt or become extinct.
Those grasslands didn’t come into being until almost two million years ago. Actually, the first appearance of that really open dry, arid, vegetation coincided in time almost exactly with this Acheulian tool kit, this very sophisticated bi-facial rock blade.
The lesson that we take home from the study of how climate change may have changed early human evolution is a recognition of the larger truth, which is actually echoed throughout the geologic record of the co-evolution of life on the planet and climate change — is that there are many, many examples of extinctions linked to events of massive environmental change.