CLIMATE CHANGE

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

Since it will soon be summer, I thought I’d talk a little bit about global warming. And you know climate change isn’t just about warming up. Several months ago, I talked about how a storm in Alaska had caused a giant iceberg to break up off the coast of Antarctica, literally on the other side of the planet.

Well, researchers at the University of Wisconsin have discovered something really interesting about a couple of freak events that happened in the continental U.S. Three years ago in May of 2010, the state of Tennessee experienced a torrential rainfall of over 20 inches. And in April of 2011, there was a historic outbreak of tornadoes centered on Alabama.

Both events are apparently linked to a rare coupling of the polar jet stream and the subtropical jet stream. But here’s the fascinating part. These researchers think that these unprecedented storms were caused by events that happened in a place that we’re all familiar with; the western Pacific which is about 9,000 miles away from the U.S. midsection.

The mechanism that caused the storms originates during spring or fall when organized complexes of tropical thunderstorms over Indonesia push the subtropical jet stream north, causing it to merge with the polar jet stream. The researchers call the resulting band of wind a “superjet”.

A superjet and its circulating winds carry roughly twice as much energy as a typical jet stream and when the normally separate jet streams sit stacked up, it causes very strong vertical circulation, which produces clouds, heavy rain and tornadoes under the right conditions.

The scientists think that a warmer climate may be triggering the overlap of the jet streams and that the high impact weather it causes may become more frequent. The next step, the researchers say, will be to examine historic weather data to see if these jet stream interactions have happened in the past and whether they triggered violent weather. This, they hope, will lead to more accurate long term weather forecasts.

Of course, the biggest news as far as climate change goes is what’s happening to the ice caps at the poles. Well, Alan Werner, professor of geology at Mount Holyoke College, says that melting Arctic ice is no longer just evidence of a rapidly warming planet: it’s also part of the problem. That’s because the loss of snow and ice makes Earth’s surface less reflective, and the Sun’s heat is absorbed in greater amounts by the exposed dark ocean or tundra.

This means that the high latitudes are warming at a much faster rate than the other latitudes. Werner made his observations after the announcement by the National Snow and Ice Data Center that the surface area of Arctic sea ice reached a new low in 2012, breaking a previous record reached in 2007.

So . . . . do we believe them? I went to London last fall and took a non-stop flight out of Tokyo. If you look at a globe, you can trace my great circle flight path and you’ll see that virtually the entire trip took place over Siberia, that vast snow and ice-covered plain in the far north. I’ve flown over Siberia in the past and it was always covered with snow.

Except that in the last week of September last year on the outbound flight and the first week of October on the return flight, I saw no snow. That’s right. NO. SNOW. The entire flight was over endless empty vistas of brown, treeless dirt. NO snow.

Global warming? I’ve seen it with my own eyes, boys and girls, and I believe. I believe.

WATER WATER EVERYWHERE

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

I’ve been talking about doomsday scenarios for the last two weeks or so and it turns out that the one that many people are trying to deny is getting worse: much worse. I’m talking, of course, about global warming.

Researchers from the Potsdam Institute for Climate Impact Research have recently published a paper stating that the Greenland ice sheet is much more vulnerable to global warming than previously thought. The best estimate of the temperature threshold for melting the ice sheet completely is 1.6 degrees C. above pre-industrial levels. Since temperatures have already risen 0.8 C. above pre-industrial levels this is a little scary.

The scientists achieved their insights by using a computer simulation of the Greenland ice sheet and the regional climate. The model performs calculations using data from many physical systems, like climate feedback associated with changes in snowfall and melting rates. The simulation correctly calculated both the observed ice sheet of today and its evolution over previous glacial cycles, thus increasing the confidence that it can properly assess the future. All this makes the new estimate of Greenland temperature threshold more reliable than previous ones.

And on the other side of the planet, a new study that examined nearly 40 years of satellite imagery has revealed that the floating ice shelves of West Antarctica are steadily losing their grip on adjacent bay walls, potentially amplifying an already accelerating loss of ice to the sea.

The most extensive record yet of the evolution of the floating ice shelves in West Antarctica shows that their margins, where they grip onto rocky bay walls or slower ice masses, are fracturing and retreating inland. As that grip continues to loosen, these already-thinning ice shelves will be even less able to hold back grounded ice upstream, according to researchers at The University of Texas at Austin’s Institute for Geophysics (UTIG).

The UTIG team found that the extent of ice shelves in the Amundsen Sea Embayment changed substantially between the beginning of the Landsat satellite record in 1972 and late 2011. These changes were especially rapid during the past decade.

The shear margins that bound these ice shelves to the land are now heavily rifted and they look like a cracked mirror in satellite imagery. Eventually the cracks widen entirely and the ice shelves calve massive icebergs that drift north and melt.

Rifts along the northern shear margin of Pine Island Glacier (Credit: Michael Studinger, NASA’s Operation IceBridge.)

So . . . .what does this all mean for us? We live about as far away as it’s possible to get from either Greenland or Antarctica. Well, according to a study by scientists at Rutgers University, even if we manage to limit global warming to 2 degrees C (3.6 degrees F), future generations will have to deal with sea levels 40 to 70 feet higher than present levels.

The scientists studied rock and soil cores taken from Virginia, Eniwetok Atoll and New Zealand and looked at the late Pliocene epoch, 2.7 million to 3.2 million years ago. That was the last time atmospheric carbon dioxide was current levels, and temperatures were 2 degrees C higher than they are now.

The difference in water volume between then and today is the equivalent of melting the entire Greenland and West Antarctic Ice Sheets, as well as some of the marine margin of the East Antarctic Ice Sheet. The sea level rise would swamp the world’s coasts and affect as much as 70 percent of the world’s population.

Releasing this much water won’t happen overnight, but when I lived in Ipan, I always said that my house was on the bottom of what had once been a beautiful half moon bay below Talofofo. Ladies and gentlemen, it looks like it will be a beautiful half moon bay again in the not so distant future!

FOSSILS OLD AND NEW

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

There’s no question that fossils can teach us about the past but a recent discovery in Australia has proved remarkable. A team of researchers from the University of New South Wales has found a 15-million-year-old fossil limestone cave packed with even older animal bones. The bones have revealed the entire life cycle of a large prehistoric marsupial, from babies still in their mother’s pouch to elderly adults.

The scientists uncovered hundreds of beautifully preserved fossils of an extinct browsing wombat-like marsupial they named Nimbadon lavarackorum, along with the remains of galloping kangaroos, primitive bandicoots, a fox-sized thylacine (also called Tasmanian tigers) and forest bats.

By comparing the bones of 26 different Nimbadon individuals that died in the cave at varying stages of life, the team has been able to show that the babies developed in much the same way as marsupials today, probably being born after only a month’s gestation and crawling to the mother’s pouch to complete their development.

The animals appear to have plunged to their deaths through a vertical cave entrance that was probably hidden by plants and acted as a natural pit-fall trap. The animals either unwittingly fell to their deaths or survived the fall only to become trapped.

The site is also scientifically important because it documents a critical time in the evolution of Australia’s flora and fauna when lush greenhouse conditions were giving way to a long, slow drying out that fundamentally reshaped the continent’s cargo of life as rainforests retreated.

A skull of the sheep-sized Nimbadon lavarackorum from the middle Miocene cave deposit, AL90. (Credit: Karen Black, UNSW)

That climate change caused by the global warming that we all know isn’t happening (tongue firmly planted in cheek) will probably have a great effect on many animals because as the next story shows us, it isn’t only Australia that was affected by warming trends.

We’ll fast-forward several million years to a more recent global warming. We’re headed for Africa where genetic investigators are examining the beginnings of the partnership between humans and the ancestors of today’s donkeys. Apparently nomads recruited the animals to help them survive the increasingly harsh Saharan landscape more than 5,000 years ago.

The domestication of wild animals is quite an intellectual breakthrough for humans (although we’re not quite sure what it says about the donkeys) and the researchers provided solid evidence that donkey domestication happened first in northern Africa and happened there more than once.

The researchers used the most comprehensive sampling of mitochondrial DNA ever assembled from ancient, historic and living specimens and determined that the critically endangered African wild ass, which exists today only in small numbers in eastern Africa, zoos and wildlife preserves, is the living ancestor of the modern donkey.

Knowing when and where donkeys were first tamed is important, because there are always cultural ramifications from being first. Having animals at your disposal that you can use as food or transport or as work aids can make you more successful than your neighbors. After all, the horse and donkey were also used in war.

A small herd of wild donkeys. (Credit: iStockphoto)

Wombats and donkeys. We share our planet with some astounding creatures. Here’s hoping we don’t destroy ourselves and all of them in the process.

HOT AND DRY

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

I thought we’d continue our discussion of global warming this week with a couple of new stories. Some of you may have seen the first item on the news feeds although there wasn’t a whole lot of attention paid to it as far as I could see. In addition to an ozone hole forming over the warming Arctic, the region experienced its second largest ice loss in history last summer.

According to a NASA press release, satellite data show that the sea ice cover in the Arctic narrowly avoided surpassing the record low set in 2007. The near-record ice-melt followed higher-than-average summer temperatures, but without the unusual weather conditions that contributed to the extreme melt of 2007. The release said that older, thicker ice is melting faster than the new ice that forms each winter which jeopardizes the entire ice cover.

This summer’s low ice extent continued the downward trend seen over the last 30 years, which scientists attribute largely to warming temperatures caused by climate change. Data show that Arctic sea ice has been declining both in extent and thickness. Since 1979, September Arctic sea ice extent has declined by 12 percent per decade. Climate models have suggested that the Arctic could lose almost all of its summer ice cover by 2100, but in recent years, ice extent has declined faster than the models predicted.

So . . . the ice is melting, but it turns out that’s not all that’s going on. The human-created pollution that’s causing ozone holes to develop, is also causing carbon dioxide levels in the atmosphere to rise. Rising CO₂ levels are the main cause of the general warming trend. But new research shows that although rising CO₂ levels are causing one kind of hole to develop, they’re causing another kind to disappear.

Most of us learned in grade school science that we breathe in oxygen and breathe out carbon dioxide and that plants breathe in carbon dioxide and breathe out oxygen. It’s a win-win situation.

But researchers in Indiana and the Netherlands have recently shown that as carbon dioxide levels have risen during the last 150 years, the density of pores that allow plants to breathe has dwindled by 34 percent. Hey, if there’s lots more CO₂ out there, you don’t need as many holes to take it in. Unfortunately, fewer holes also means less water release.

The scientists gathered their data from many different plant species in Florida, and they included living plants and samples taken from herbarium collections and peat formations that were 100 to 150 years old.

Plant pores are called stomata and the CO₂ increase has had a profound effect on the number and size of stomata found on the plant leaves the scientists examined. This has caused a huge reduction in the release of water to the atmosphere. It’s well known that long-lived plants like trees can seasonally adjust their number of stomata depending on growing conditions, but little is known about the long-term structural changes in stomata number or size over periods of decades or centuries.

The authors conclude that a doubling of today’s carbon dioxide levels — from 390 parts per million to 800 ppm — will halve the amount of water lost to the air. They conclude that plant adaptation to rising CO₂ is currently altering the hydrological cycle and climate and will continue to do so throughout this century.

So . . . rising temperatures AND less water. Looks like the desert is coming to planet Earth!

Stomata are structures that allow plants to exchange gases with the air. Contemporary plants in Florida have fewer stomata than their ancestors did a few decades ago. (Credit: Emmy Lammertsma)

DIGGING A HOLE

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

Most of you realize that I typically limit myself to the interesting but obscure science stories. Unless you’re a science geek like I am, my column is usually the only place you’ll read about whales tracking longliners and eating the fish or Mad Hatter disease or growing a blue hibiscus. But a story that was published online last Sunday in the journal Nature may actually make some news somewhere else other than this column and goodness knows it should.

So what is this story? A NASA-led study documented an unprecedented depletion of Earth’s protective ozone layer above the Arctic last winter and spring caused by an unusually prolonged period of extremely low temperatures in the stratosphere.

Well, hey, ozone holes aren’t new, we’ve known about them since the ‘80’s. So why is this news? Read the preceding paragraph again. Notice that it says “Arctic” and NOT “Antarctic”. And that, boys and girls is why it’s BIG news.

Ozone holes form in winter when it gets really cold over the poles. Since there’s a continent parked at the South Pole, it typically gets a lot colder there than it does over the North Pole where there’s only water. Ozone has always been destroyed above the North Pole in winter, but the hole has typically been much smaller than the one that forms over the South Pole.

Scientists from 19 institutions in nine countries (United States, Germany, The Netherlands, Canada, Russia, Finland, Denmark, Japan and Spain) monitored the ozone loss over the Arctic last winter. They used NASA spacecraft to monitor polar cloud cover, balloons to measure ozone and they gathered weather data from many other sources. They discovered that at some altitudes, the cold period in the Arctic lasted more than 30 days longer in 2011 than in any previously studied Arctic winter and this led to the unprecedented ozone loss. This implies that if winter Arctic stratospheric temperatures drop just slightly in the future as a result of climate change, then severe Arctic ozone loss may occur more frequently.

So why do we care if there’s an ozone hole over the Arctic? Especially since the report says that it’s much smaller than the one that forms over the South Pole.

Well, the Arctic polar vortex, which is a persistent large-scale cyclone where the ozone loss takes place, is smaller and shorter-lived than its Antarctic counterpart, but it’s much more mobile and it moves around. Over Canada and Russia and . . . the northern United States and Europe.

And you should remember from school and the national news just why ozone holes are a problem to begin with. The ozone blocks a large part of the ultraviolet radiation that the Sun puts out in prodigious quantities. And when the ozone is gone, animals and crops and people fry.

So what are we going to do about it? And the answer is: Nothing. Not because those horrible governments won’t act but because it’s already too late. There’s enough chlorine in the stratosphere to fuel ozone holes at both poles for the rest of your life and the lives of your grandchildren.

I’ve said it before and I’ll say it again. We’re messing with things we do NOT understand and cannot control. What should you do about it? Don’t move to Sweden (or London or New York City or Seattle).