Skip to comments.Volcanoes Helped Slow Ocean Warming Trend, Researchers Find
Posted on 02/13/2006 10:34:10 AM PST by cogitator
Ocean temperatures might have risen even higher during the last century if it weren't for volcanoes that spewed ashes and aerosols into the upper atmosphere, researchers have found. The eruptions also offset a large percentage of sea level rise caused by human activity.
Using 12 new state-of-the-art climate models, the researchers found that ocean warming and sea level rise in the 20th century were substantially reduced by the 1883 eruption of the Krakatoa volcano in Indonesia. Volcanic aerosols blocked sunlight and caused the ocean surface to cool.
"That cooling penetrated into deeper layers of the ocean, where it remained for decades after the event," said Peter Gleckler, an atmospheric scientist at Lawrence Livermore National Laboratory (LLNL). "We found that volcanic effects on sea level can persist for many decades."
Gleckler, along with LLNL colleagues Ben Santer, Karl Taylor and Krishna AchutaRao and collaborators from the National Center for Atmospheric Research, the University of Reading and the Hadley Centre, tested the effects of volcanic eruptions on recent climate models. They examined model simulations of the climate from 1880 to 2000, comparing them with available observations.
External "forcings," such as changes in greenhouse gases, solar irradiance, sulphate and volcanic aerosols, were included in the models.
Oceans expand and contract depending on the ocean temperature. This causes sea level to increase when the water is warmer and to recede in cooler temperatures.
The volume average temperature of oceans (down to 300 meters) worldwide has warmed by roughly .037 degrees Celsius in recent decades due to increasing atmospheric greenhouse gases. While seemingly small, this corresponds to a sea level rise of several centimeters and does not include the effect of other factors such as melting glaciers. That sea level jump, however, would have been even greater if it weren't for volcanic eruptions over the last century, Gleckler said.
"The ocean warming suddenly drops," he said. "Volcanoes have a big impact. The ocean warming and sea level would have risen much more if it weren't for volcanoes."
Volcanic aerosols scatter sunlight and cause the ocean surface temperature to cool, an anomaly that is gradually subducted into deeper layers, where it remains for decades.
The experiments studied by Glecklers team also included the more recent 1991 Mt. Pinatubo eruption in the Philippines, which was comparable to Krakatoa in terms of its size and intensity. While similar ocean surface cooling resulted from both eruptions, the heat-content recovery occurred much more quickly in the case of Pinatubo.
"The heat content effects of Pinatubo and other eruptions in the late 20th century are offset by the observed warming of the upper ocean, which is primarily due to human influences," Gleckler said.
The research appears in the Feb. 9 issue of the journal Nature.
Founded in 1952, Lawrence Livermore National Laboratory has a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy's National Nuclear Security Administration.
The so-called "Year Without A Summer" after Krakatau blew up in the 1800s stands testament to this. So, fire up the coal-fired powerplants and save the planet, lol.
Where is a good volcano rock man when you need him...
Krakatau did cool things off, but "The Year Without a Summer" was in the 18-teens, after Tambora (not quite as explosive, but a lot more ash into the atmosphere).
Another batch of scientists that are wrong, Why cant they realise that humans are effecting the earth, not small thing like cyclical earth changes ,or volcanoes, or earthquakes. After all didnt George Bush just cause a big hurricane?. The natural changes of the earth are all the fault of humans.
That is one of the main problems with Environmental "Science" why "new" models and why "12 models"? This raises questions as to how the results of the models were combined, or which models were accepted and which models were rejected.
It would seem that "Scientists" might be able to pick and choose results that confirmed their prejudices.
Quite a few of them blew their tops...
Popocatepetl in Mexico.
Thanks. I shoulda recognized El Popo...
Here's what Wikipedia has to say about it, FWIW. Year Without a Summer.
Not exactly. They have an effect, but it's short-term. This paper was interesting in that it identified a longer-term aspect of volcanic influence, but not one that will have a major effect on climate change.
Or, are volcanoes part of the natural events which help the planet in self-regulating its weather? If that's the case, global warming and global cooling are manisfestations of that self-regulating planetary activitiy.
Volcanoes are certainly part of the Earth climate system, and at times an important part, but their effects are still integrated with the changing atmospheric composition, and changes in greenhouse gas concentrations (because GHGs are more long-lived in the atmosphere) have a more "persistent" effect on climate.
... was caused by the eruption of Tambora.
So it says.
Global warming (teehee) caused by a core of magma....
The eruption of the Toba Volcano some 75,000 YA came pretty near to wiping Homo Sapiens off the face of the entire earth. Blasting several thousand cubic kilometers of ash and gas into the atmosphere can have a devastating effect on the planet's inhabitants.
Yeah, I read that. I've posted this picture a couple of times:
Now this is a real crater lake: