Upper Paleolithic and Epipaleolithic vegetation and climate of NW Iberia

Just a brief mention of an important palaeoclimatic paper (in Spanish language):

Pablo Ramil Rego, Cambio climático y dinámica del paisaje en Galicia (Climate change and environmental dynamics in Galicia). Recursos Rurais, 2009. (Direct PDF link).

Most informative is maybe figure 12, that I reproduce here:

Click to expand

It is pretty evident that in the Last Glacial Maximum (first map), the region was dominated by grass and mountain dwarf shrubs, but with importance of forest in the south (Northern Portugal) and even in Asturias (something I was not clearly aware of and that should be general for all the Cantabrian strip).

Forests gradually expanded in the Late Upper Paleolithic, as climate warmed gradually, becoming clearly dominant in the Epipaleolithic (last map), when climate was already pretty much like today's. Epipaleolithic would anyhow last for some three millennia after the period covered here.

Later deforestation is apparent (fig. 15) but mild at some locations since c. 5000 calBP (beginnings of Neolithic), in the Iron Age, but specially since the Roman and Medieval periods.

Found at Arquêociencias[por].

Ice sheet fragmenting near the North Pole

We still haven't really got out of the deepest solar minimum in a century (solar minimums correlate with colder years) and the Arctic ice sheet is again heading towards the extreme disintegration of 2007, one of the warmest years on record, when the NW passage along the arctic coast of Canada became navigable for the first time ever.

That's what the Italian blog Crisis? What Crisis? has found looking at NASA data (Spanish language version at Rebelión), as it's evident in this image of ice fragmenting at just a little further than 200km from the North Pole:



Which is part of a much larger composite satellite image of the Arctic Sea, where you can see many other cracks as well. The image is dated to June 19th: a month ago.

And something that is also evident in this graph:



It is important to realize that 2007 and 2010 are at the edges of a severe Solar minimum and therefore should not be particularly warm years, rather cold ones. Still the ice sheet is fragmenting like never before. This is of course caused by global warming but also to the accumulative effect produced by it: thinning the ice more and more and reducing the albedo by exposing more water and old bluish ice (we all know that white clothes or walls reduce heating, while black ones increase it). This causes that, while the overall global temperature has only risen by less than one degree Celsius, the change is almost fourfold in the Arctic, which in turn is the cooling central of the planet.

It's a case of positive feedback out of control.

Again this September, most likely, the NW passage will be navigable and we are just beginning the new solar cycle, whose maximum is expected for 2013 (seems it will be a short and mild cycle, or so believes NASA).

But even if the Sun is giving us a hand, the evidence from 2007 and 2010 shows that even with low solar activity and the corresponding relatively "cold" years, the Arctic Sea is melting.

Ashes can dry up the sky

This is the conclusion of Israeli scientists studying storm formation in the Amazon basin. While some particulates (ashes, aerosols) do promote rain formation, a well known fact for several decades now, their excess actually does the opposite: preventing rain and restricting the formation of clouds.

This may affect the ongoing process of global warming in several ways: restricting rain in wildfire and highly polluted areas and reducing the overall cloud cover of Earth and hence its albedo, allowing for more solar radiation to reach the surface.

More details at Science Daily.

Ref. O. Almaratz et al., Lightning response to smoke from Amazonian fires. Geophysical Research Letters, 2010. Pay per view.

Bering strait closure caused the end of last Ice Age in the long run

A very interesting new climate theory the one mentioned today at Science Daily: while the cooling of Earth was caused by orbit perturbations, leading to the closure of Bering Strait and the formation of the Beringia isthmus, this last caused such perturbation in global oceanic currents that in the long run sentenced the Ice Age to its end.

The Atlantic Ocean is saltier than the Pacific, what leads to water flowing from this latter to the former. This circulation can only go through the south or via the Arctic Ocean. With Bering Strait closed, Atlantic salinity grew and the North Atlantic Conveyor (Gulf Stream) was enhanced leading to a gradual meltdown of the North Atlantic Ice sheets (in North America and Northern Europe), which in turn lead to higher sea levels and eventually to the reopening of the Bering Strait and the stabilization of climate in the Holocene.

It took many many thousand years though.

Arctic will be ice free in three decades

This is the conclussion drawn by two independent researchers from Washington state on a selection of the best models for the effects of ongoing climatic change in the Arctic. Climatlogist Muyin Wang and oceanographer James Overland selected the six best performing models on this matter (out of 23), picking only those that had been able to make good predictions for the recent past, and concluded that this (bottom half, top two are from now) is the most likely picture for March and September 2040:

Source: Science Daily.
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After the storm

Just a quick snap from Plentzia. When an unprecedented storm like this hit your homeland, you cannot just ignore it. Though we did try.

More, often impressive, pics at EITB.
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Global warming de-stabilizing North Atlantic climate

Researchers from Woods Hole Oceanographic Institution have used coral as direct reference for climatic oscilations within the North Atlantic ocean. The results show that atmospheric global warming does not directly just warm up the ocean but that it rather de-stabilizes it causing much more intense oscilations in its natural tension between the Azores high and Icelandic low pressure nodes. This means that, as global warming increases, both storms and droughts are becoming and will become more extreme and insidious in the affected areas (Europe, Eastern North America, North Africa).

More at Science Daily.
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Sharp warm spikes at the end of the Ice Age.

A University of Colorado team researching the Greenland ice sheet has found that two sudden warm epysodes happened just before the definitive end of the Ice Age some 10,000 years ago.

The first one was c. 14,700 BP and lasted till c. 12,900 BP. Then deep freeze conditions were back agains for some 1200 years until the second sudden warming (11,700 BP) that preluded the definitive end of the Ice Age.

But the most important finding is that the warming happened in such a brief period as 50 years, with the reorganization of atmospheric circulation being as quick as only one or two years!

We have analyzed the transition from the last glacial period until our present warm interglacial period, and the climate shifts are happening suddenly, as if someone had pushed a button.

The origin of the sudden changes seems to be in the tropical belt but it doesn't seem like the researchers can pinpoint the ultimate trigger of such a climatic change.

While these abrupt climate changes could really alter radically the life of Paleolithic hunter-gatherers, for the case of Europe, the first one seems to imply some continuity: Magdalenian was dominant in the SW and expanded to Central Europe about that date. The second one preludes the Paleolithic, with the gradual diversification of Magdalenian culture but it doesn't show lack of continuity either. Fully diversified Epipaleolithic cultures (Azilian, Sauveterrean, etc.) are only found since c. 10,000 BP, some time after the second peak, when the Ice Age had already become history.

(Via Science Daily)

Australia about to collapse

Economy?, nuclear war?, class struggle?, ethnic tensions?

Nope. Mere and simple imminent ecological disaster caused, probably, by global warming.

Timeline? A century or two ahead?, several decades?, an undefined future?

Nope. By October this year.

While the USA and China are succumbing to brutal massive floods, Australia is facing the worst of the worst drought ever. It's been nicknamed the Big Dry and it's been going on for many years now, since 2003, sending many farmers into bankrupticy and becoming one of the factors behind increased food prices worldwide (as Australia used to be one of the main food exporters of the World).

Drought affected croplands

Now an expert panel has warned that the most important river system of Australia, the Murray-Darling basin, the Australian breadbasket, will be beyond the point of recovery unless it gets enough water by October. In practical terms it means that the whole ecology of the single most important agricultural and economical region of Australia will take at least a decade to recover or will not recover at all in any foreseable future.

The Murray-Darling basin

The reaction of the government? Wait until November. Incredible but true. The report has been leaked to the press anyhow sparkling great concern and political scandal in the island-continent.

Human-made carbon emissions 100 times what Earth can manage

It may sound ultra-hippy but it's hardcore science: for at least 610,000 years Earth has managed to keep a very tight balance of atmospheric carbon, with a variance of just 1-2%. Now we are challenging that finely tuned balance with releases that ammount to 100 times what Earth has ever been confronted with, so it is virtually impossible that our mother planet will be able to correct our wrongdoings.

This finding, already suspected, was made by K. Cladeira of Carnegie Institution for Science and R. Zeebe of the University of Havaii.

When carbon dioxide levels in the atmosphere rise, the chemical reactions that break down silicate minerals in soils are accelerated. Among the products of these reactions are calcium ions, which dissolve in water and are washed to the ocean by rivers. Marine organisms such as mollusks combine the calcium ions with dissolved carbon dioxide to make their shells (calcium carbonate), which removes both calcium and carbon dioxide from the ocean, restoring the balance.

The researchers found that over hundreds of thousands of years the equilibrium between carbon dioxide input and removal was never more than one to two percent out of balance, a strong indication of a natural feedback system. This natural feedback acts as a thermostat which is critical for the long-term stability of climate. During Earth's history it has probably helped to prevent runaway greenhouse and icehouse conditions over time scales of millions to billions of years — a prerequisite for sustaining liquid water on Earth's surface.

The Carnegie Institution's press release concludes with a most alarming remark by Caldeira:

We are emitting CO2 far too fast to expect mother nature to mop up our mess anytime soon. Continued burning of coal, oil and gas will result in long-term changes to our climate and to ocean chemistry, lasting many thousands of years.

As a chain smoker, I know well that slow stupid suicidal is a very human possibility. No kidding.

Glaciers melting a lot faster!

World glaciers melted at an already suspicious rate of 30 cm per year in the 80s and 90s, they reached 50 cm in 2005 and (and that's the striking news) 140 cm. in 2006, almost triple than the previous year (source). The figures for 2007 are not available yet but I can only think of horrible figures considering it was the year that the Northwestern passage melted for the first time ever.

Since 1980 our average glacier has lost some 11.5 meters of thickness and the process tends to behave as a positive feedback, because deeper compactated layers of ice are less white and therefore absorb more heat and melt faster.

Of course we can take consolation in the fact that the Earth of the dinosaurs was much warmer, with no ice at the poles and wide deserts and semideserts... but one thing is living since "always" in such conditions and another very different is to face the critical transition, with all the ecological imbalances and the more or less severe extinctions, further aggravated by our destructive "economic" practices on land and in the seas.

The prospect is really gloomy.