Oceanerne forsures - hvad er konsekvensen

The world's oceans are likely to become more acidic than at any time in the past 14 million years, scientists have found.

New research led by Cardiff University has shown that under a 'business-as-usual' scenario of carbon dioxide (CO2) emissions, ocean acidification is likely to hit unprecedented levels.

Ocean acidification occurs when CO2 from the atmosphere is absorbed by seawater, resulting in more acidic water with a lower pH.

Around a third of the CO2 released by burning coal, oil and gas gets dissolved into the oceans. Since the beginning of the industrial era, the ocean has absorbed around 525 billion tons of CO2, equivalent to around 22 million tons per day.

The rapid influx of CO2 in to the oceans is severely threatening marine life, with the shells of some animals already dissolving in the more acidic seawater.

In their new study, published in the journal Earth and Planetary Science Letters, the researchers set out to reconstruct levels of ocean acidity and atmospheric CO2 levels over the past 22 million years.

They did so by studying the fossils of tiny marine creatures that once lived near the ocean surface, specifically using the chemistry of their shells to monitor the acidity of the seawater in which the creatures lived.

Based on this information, the researchers were able to put their new records of pH and CO2 levels in context of the range of future carbon emission scenarios that are recognised by the Intergovernmental Panel on Climate Change (IPCC).

Under a 'business-as-usual' future scenario where we continue to emit CO2 at the same rate as we do today, atmospheric CO2 would be near 930 parts per million in the year 2100, compared to around 400 parts per million today.

Similarly, the pH of the oceans would be less than 7.8 in 2100 compared to a pH of around 8.1 today. This is very significant as the pH scale is logarithmic, meaning a drop of just 0.1 pH units represents a 25% increase in acidity.

These levels of atmospheric CO2 and ocean acidity have not been since the Middle Miocene Climatic Optimum period around 14 million years ago, when global temperatures were around 3°C warmer than today as a result of the Earth's natural geological cycle.

Lead author of the study Dr Sindia Sosdian, from Cardiff University's School of Earth and Ocean Sciences, said: "Our new geological record of ocean acidification shows us that on our current 'business as usual' emission trajectory, oceanic conditions will be unlike marine ecosystems have experienced for the last 14 million years."

Professor Carrie Lear, co-author of the study, added: "The current pH is already probably lower than any time in the last 2 million years. Understanding exactly what this means for marine ecosystems requires long-term laboratory and field studies as well as additional observations from the fossil record."

The study was funded by the UK's Natural Environmental Research Council (NERC) and also included researchers from the University of Southampton, University of St Andrews and the University of California.

Ny undersøgelse viser:

Oceans absorb a substantial proportion of the CO2 emitted into the atmosphere by human activities, with potentially negative effects on shell-forming organisms.

Increasing CO2 in the atmosphere due to human activities not only affects the climate; it also has direct, chemical effects on ocean waters.
The oceans have absorbed between a third and a half of the CO2 humans have released into the atmosphere since about 1850. This has slowed the rate of climate change.
When CO2 dissolves in seawater, the water becomes more acidic. The acidity of the oceans has increased by 26 % since about 1850, a rate of change roughly 10 times faster than any time in the last 55 million years.
Associated chemical reactions can make it difficult for marine calcifying organisms, such as coral and some plankton, to form shells and skeletons, and existing shells become vulnerable to dissolution.
The extent to which calcifying organisms are already being affected by acidification is unclear, as this is a very new area of study. Limited evidence suggests that some organisms are more sensitive than others.
The rate at which acidification occurs is a determining factor in the extent to which calcifying organisms will be able to adapt.
The impacts of acidification will extend up the food chain to affect economic activities such as fisheries, aquaculture and tourism. Wherever there are marine calcifying organisms, there are risks from ocean acidification.

Niels K Sørensen skrev:
Det en kendt sag, at oceanernes bliver mindre basiske og mere syreholding i og med, at der udledes enorme mængder af CO2 fra afbrænding af olie, kul og gas til atmosfæren, og at en del af dette CO2 optages i oceanerne med forsuring til følge.

Frank Lansner skrev:
Niels K du skriver:

"Det faktuelle er, at pH falder fra 8,2 til 7,8 i dette århundrede."

Nej. Det er fakta at den artikel du omtaler skriver at dette vil ske ca 82 år ude i fremtiden.

Det er fakta, at videnskaben mener, gennem mange rapporter, at pH falder til 7,8 i dette århundrede, med mindre der gøres en enorm indsats for at få standset de uhyre mængder CO2, der udledes af mennesket til atmosfæren.

Niels K Sørensen skrev:
Den øgede mænge CO2 i atmosfæren, hvoraf en del medvirker til forsuring af oceanerne, skyldes alene menneskelig aktivitet som afbrænding af kul, olie og gas.
Mvh Niels

Jørgen Petersen skrev:
Så kan argumentet om forsuring af havene ikke bruges længere.

Niels K Sørensen skrev:
Efter hvad jeg har læst mig frem til, så vil oceanernes evne til at absorbere CO2 falde over tid pga opvarmningen.
Herved vil CO2 indholdet i atmosfæren øges hurtigere, hvilket blot øger opvarmningen.

Mvh Niels

Jørgen Petersen skrev:
@ Niels K Sørensen

Du kan ikke argumentere for opvarmning af verdenshavene og forsuring af den samtidigt. Disse to ting er hinandens direkte modsætninger. Ved at argumentere for disse to ting samtidig, afslører man sin uvidenhed.

Tidligere blev der argumenteret meget for, at verdenshavene bliver opvarmet og at de som følge heraf frigiver CO2, da varmt vand ikke kan holde på CO2, som koldt vand kan. En sådan CO2-afgasning gør verdenshavene mere basiske og ikke sure. Denne CO2-afgasning af verdenshavene skulle så angiveligt bevirke en selvforstærkende global opvarmning. Man er nu så godt som ophørt med at tale om denne CO2-afgasning som følge af at temperaturen i verdenshavene kun stiger ekstremt langsomt.

Jørgen Petersen skrev:
@ Niels K Sørensen

Det er åbenlyst for enhver, at man ikke kan ikke argumentere for opvarmning af verdenshavene og forsuring af dem g. p. a. CO2 samtidigt. Disse to ting er hinandens direkte modsætninger.

Fordi, havet , Jordens oceaner under ét , rummer idag ca 160.000 Gt tilgængelig CO2.

Mennesket tilfører ca 8 Gt pr år hvis vi fortsætter som nu.

Dvs vi får pr år 2100 en opgang i mængden af CO2 fra
160.000 Gt idag til ca ca ca
160.576 Gt år 2100.

Unexpected acidification of deep waters in the Sea of Japan due to global warming.

Oceans worldwide are warming up, and thermohaline circulation is expected to slow down. At the same time, ocean acidity is increasing due to the influx of anthropogenic carbon dioxide (CO2) from the atmosphere, a phenomenon called ocean acidification that has primarily been documented in shallow waters. In general, deeper waters contain less anthropogenic CO2, but predicted reductions in ventilation of deep waters may impact deep ocean chemistry, as described in a recent study in Nature Climate Change.

The Sea of Japan is a marginal sea with its own deep- and bottom-water formation that maintains relatively elevated oxygen levels. However, time-series data from 1965-2015 (the longest time-series available) reveal that oxygen concentrations in these deep waters are declining, indicating a reduction in ventilation that increases their residence time. As organic matter decomposition in these waters continues to accumulate more CO2, the pH decreases. As a result, the acidification rate near the bottom of the Sea of Japan is 27% higher than at the surface. As a miniature ocean with its own deep- and bottom-water formation, the Sea of Japan provides insight into how future warming might alter deep-ocean ventilation and chemistry.

Niels K Sørensen skrev:
De seneste år har stigningen nærmet sig 3 ppm pr år.
Lad os så sige 4 ppm middel over 82 år, så 330ppm ekstra.
Vi er så på 740ppm i 2100.
Ved 5ppm middel nås 820ppm i 2100.
Der er intet urealistisk i, at fortsat afbrænding af kul, olie og gas kan bringes os på 900 ppm i 2100.
Hvis alle politikere var som Trump, så var det en realitet.
Heldigvis er der andre og mere intelligente individer ombord.


Ny undersøgelse om forsuring af dybhavet:

Unexpected acidification of deep waters in the Sea of Japan due to global warming.

Oceans worldwide are warming up, and thermohaline circulation is expected to slow down. At the same time, ocean acidity is increasing due to the influx of anthropogenic carbon dioxide (CO2) from the atmosphere, a phenomenon called ocean acidification that has primarily been documented in shallow waters. In general, deeper waters contain less anthropogenic CO2, but predicted reductions in ventilation of deep waters may impact deep ocean chemistry, as described in a recent study in Nature Climate Change.

The Sea of Japan is a marginal sea with its own deep- and bottom-water formation that maintains relatively elevated oxygen levels. However, time-series data from 1965-2015 (the longest time-series available) reveal that oxygen concentrations in these deep waters are declining, indicating a reduction in ventilation that increases their residence time. As organic matter decomposition in these waters continues to accumulate more CO2, the pH decreases. As a result, the acidification rate near the bottom of the Sea of Japan is 27% higher than at the surface. As a miniature ocean with its own deep- and bottom-water formation, the Sea of Japan provides insight into how future warming might alter deep-ocean ventilation and chemistry.

Så fint med de mange forklaringer, FL,, jeg savner lidt erkendelse af, at vi faktisk ikke rigtigt har styr på, hvad konsekvenserne egentligt ender op med at blive.
Det er ikke i dette forum, der er viden til at analysere i dybden.[img][/img]
Mvh Niels

Niels K Sørensen skrev:
Kan du udtrykke dig klart, Kjeld Jul?
Det er helt umuligt at gætte hvad du mener?
Mvh Niels

Jørgen Petersen skrev:
Niels K Sørensen godtager og videregiver ukritisk de mest alarmistiske budskaber, som han kan finde. Herefter kan han ikke forstå, at vi andre ikke er enige i disse forhold.

Jørgen Petersen skrev:
Dommedagsprædikanter kan i sagens natur ikke lide at blive kaldt dommedagsprædikanter. Men jeg foretrækker nu at kalde en skovl for en skovl og en spade for en spade.

Kjeld Jul skrev:

Niels K Sørensen skrev:
Kan du udtrykke dig klart, Kjeld Jul?
Det er helt umuligt at gætte hvad du mener?
Mvh Niels

Hvis alle politikere var som Trump,var det en realitet.
Dæmrer det Niels?

De seneste år har stigningen nærmet sig 3 ppm pr år.
Lad os så sige 4 ppm middel over 82 år, så 330ppm ekstra.
Vi er så på 740ppm i 2100.
Ved 5ppm middel nås 820ppm i 2100.
Der er intet urealistisk i, at fortsat afbrænding af kul, olie og gas kan bringes os på 900 ppm i 2100.
Hvis alle politikere var som Trump, så var det en realitet.
Heldigvis er der andre og mere intelligente individer ombord.

Hvis nu vi på mirakuløs vis nåede f.eks. 6,5 ppm/år i år 2060, så skulle stigningen fortsætte op til 12 ppm/år i 2100 for at nå et GENNEMSNIT på 6,5 ppm/år 2018-2100.