Showing posts with label volcanic. Show all posts
Showing posts with label volcanic. Show all posts

Monday, April 6, 2009

Atlantic Ocean Warming Dust Driven

This is a little unexpected. It is not unexpected that dust is a contributor but the magnitude certainly is. It appears that two thirds of the regional temperature gain can be attributed to dust and volcanic ash.

This also clarifies the feedback mechanism. We forget the heat gathering capacity of ocean water as compared to land because is attenuated through a thick upper layer. Land either absorbs and uses the energy chemically or reflects it back into the atmosphere. Thus the ocean has a stable temperature regime whose variation is minor as remarked on here. However a one degree rise represents a major jump in heat content in the water that will discharge into the atmosphere producing storms.

A modest amount of dust in the atmosphere generated major reduction in the driving heat engine.

The clear lesson is that a major volcanic interlude will be felt strongly in terms of climate change.

This returns me to contemplation on the possible causes of the worst climate experiences of the little ice age.
Assuming that we were on the low end of the normal Holocene climate variation, the injection of volcanic dust would have been rather damaging. And it need not be a overly big event. I recall that Fuji erupted in a timely manner and its position is such as to possibly affect European climate through high level aerosols and dust.

Thus provided that we already had a modest reduction is temperature due to a very slightly cooler sun, an inconvenient volcano could easily wreck a years climate while not even been noticed.

Dust Responsible for Most of Atlantic Warming

posted: 26 March 2009 02:15 pm ET

The warming of Atlantic Ocean waters in recent decades is largely due to declines in airborne dust from African deserts and lower volcanic emissions, a new study suggests.

Since 1980, the tropical North Atlantic has been warming by an average of a half-degree Fahrenheit (a quarter-degree Celsius) per decade.

While that number may sound small, it can translate to big impacts on hurricanes, which are
fueled by warm surface waters, said study team member Amato Evan of the University of Wisconsin-Madison. For example, the ocean temperature difference between 1994, a quiet hurricane year, and 2005's record-breaking year of storms (including Hurricane Katrina), was just 1 degree Fahrenheit.

Evan and his colleagues had previously shown that African dust and other airborne particles can suppress hurricane activity by reducing how much sunlight reaches the ocean and keeping the sea surface cool. Dusty years predict mild hurricane seasons, while years with low dust activity — including 2004 and 2005 — have been linked to stronger and more frequent storms.

In the new study, the researchers investigated the exact effect of dust and volcanic emissions on ocean temperatures. They combined satellite data of dust and other particles with existing climate models and calculated how much of the Atlantic warming observed during the last 26 years could be accounted for by simultaneous changes in African dust storms and tropical volcanic activity, primarily the eruptions of El Chichón in Mexico in 1982 and
Mount Pinatubo in the Philippines in 1991.

The results: More than two-thirds of this upward trend in recent decades can be attributed to changes in African dust storm and tropical volcano activity during that time.

This was a surprisingly large amount, Evan said.

The results, detailed in the March 27 issue of the journal Science, suggest that only about 30 percent of the observed Atlantic temperature increases are due to other factors, such as
a warming climate.

"This makes sense, because we don't really expect global warming to make the ocean [temperature] increase that fast," Evan said.

This adjustment brings the estimate of global warming's impact on the Atlantic more in line with the smaller degree of ocean warming seen elsewhere, such as the Pacific.

Of course, this doesn't discount the importance of global warming, Evan said, but indicates that newer climate models will need to include dust storms as a factor to accurately predict how ocean temperatures will change.

Satellite research of dust-storm activity is relatively young, and no one yet understands what drives dust variability from year to year. And volcanic eruptions are still relatively unpredictable.

"We don't really understand how dust is going to change in these climate projections, and changes in dust could have a really good effect or a really bad effect," Evan said.

More research and observations of the impact of dust will help answer that question.

Friday, April 4, 2008

Dust and Soot

This article is a timely reminder that dust and soot impact hugely, although both are actually been progressively tackled as global industrialization advances. The richer our economy becomes, the less willing we are to tolerate having smoke blowing in our faces. China and India are no different. The yelling has already started and the polluters are slowly responding.

Cleaning up our own house is the easy part. Even converting all of humanity into manufacturers of terra preta is also easy. It can even happen rather quickly and certainly within a lifespan, thanks to the communication revolution.

What is not so easy is cleaning up nature’s house. The global desert needs to be covered in vegetation in order to end the constant mobilization of dust into the atmosphere. This will take technology and sustained investment. Again I have described some of the how, but as yet there is little will.

The other monkey on the global back is the constant threat of a massive volcanic eruption. This is an event that at best wreaks growing seasons for at least two seasons by filling the atmosphere with volcanic dust and gases.
A globally unified reserve system needs to be in place in which long lasting staples maintain a long inventory train. It would entail a global treaty in which designated food stuffs must be warehoused for two years before sale.

This pushes the cost out onto the market, yet ensures a very long train if a major disaster occurs. It goes without saying that this also cushions localized disasters. A drought in the Midwest would be countered by a drawdown of warehoused stocks, to be quietly rebuilt over the succeeding years as fresh crops come in.

It also must be a global decision because the real costs of sustaining inventory must be bourn by all.

Dust plays huge role in climate change

Tiny particles heat up the atmosphere faster than scientist once believed. The good news is this dust can be cleaned up fairly quickly.

By Robert C. Cowen Columnist
from the April 3, 2008 edition Christian Science monitor

Science columnist Robert Cowen talks about atmospheric dust and its effect on climate.

Scientists know that dust affects climate. Tiny particles create veils that reflect sunlight and cool the atmosphere. Dark particles absorb sunshine and warm things up. But as scientists look deeper into the dust-climate connection, they find that they have underestimated its importance.

Research published April 3 in Nature reveals the tight linkage between atmospheric dust flows and Antarctic temperatures during ice ages over the past 800,000 years. A research review published March 23 in Nature Geoscience online shows that black carbon particles in the atmosphere have a more powerful global-warming effect than any of the greenhouse gases except carbon dioxide. And these particles are 60 percent as effective as CO2 itself. That's far more powerful than the estimate in last year's report of the UN-sponsored Intergovernmental Panel on Climate Change (IPCC).

The good news is that black carbon particles such as diesel soot or wood-stove smoke only stay airborne for weeks. (It takes a century to get rid of today's CO2 emissions.) This fact offers an opportunity for instant payback, say study authors V. Ramanathan at Scripps Institution of Oceanography in San Diego and Gregory Carmichael at the University of Iowa in Iowa City. In an announcement from Scripps, the authors note that commercially available technologies exist to cut back soot emissions substantially. Using them would rapidly reduce black-carbon warming.

Dr. Ramanathan explains that the difference between the study estimate of the sooty warming and that of the IPCC is the difference between inadequate computer modeling and actual observation. The Carmichael-Ramanathan estimate integrated data from satellite, aircraft, and ground instrumentation. This shows a black-particle warming of 0.9 watts per square meter. The IPCC estimate was between 0.2 and 0.4 watts per square meter.

In China and India, home cooking with wood and cow dung in addition to home heating with coal contribute 25 to 35 percent of the global atmosphere's black particle burden. Areas that use a lot of diesel fuel contribute comparable amounts. Ramanathan says the next phase of this research is "to examine if black carbon is also having a large role in the retreat of arctic sea ice and Himalayan glaciers."

Meanwhile, Fabrice Lambert at the University of Bern in Switzerland and colleagues are taking advantage of an unbroken 800,000-year climate record in an Antarctic ice core to track dust flows into the region. They find what they call "a significant correlation" between dust coming into the region and Antarctic cooling. They suggest that the 25-fold increase in dust inflow they see during glacial times relates to stronger South American dust sources. Also, less rainfall during those times allows dust to stay airborne longer than when more abundant rain washed it out. It's what the research team calls "a progressive coupling of the climates of Antarctic and lower latitudes" during glacial times.

Such results show that climate modelers need to take careful account of dust in their climate change scenarios. So, too, should the delegates from 163 countries now meeting in Bangkok, Thailand, as they schedule the drafting of a new global-warming mitigation agreement. They might find the prospect of a quick payback from curbing black-particle emissions attractive.