Lab report

Was The Day After Tomorrow right after all? New data from Germany suggests that global temperatures could plummet within a single year. Plus, how vitamin C can destroy tumours
September 27, 2008
The day after tomorrow won't come

I am no climate change sceptic, but I recommend caution about the idea that the world could be plunged into Arctic conditions within a year. This idea formed the plot of the rather silly 2004 Hollywood blockbuster The Day After Tomorrow, and has now been given apparent support by scientists studying a climate record imprinted in sediments of a west German lake. They claim to find evidence of such abrupt cooling about 12,700 years ago.

It's long been known that the world got at least 3 degrees Celsius colder at this time—a sharp reversal of the warming that ended the last ice age. This cold snap is known as the Younger Dryas, and it returned the world to glacial conditions for over 1,000 years. Understanding why the Younger Dryas happened helps to evaluate the likelihood of rapid temperature shifts on today's warming planet.

The most popular theory is that the Younger Dryas was triggered by a sudden influx of meltwater into the north Atlantic as the great ice sheets of the glacial period broke up. This water was fresh and therefore less dense than seawater. A large injection could have slowed or even stopped the conveyor-like circulation of water in the Atlantic, which redistributes heat from the tropics to higher latitudes. A warming of the polar regions today could have a similar effect—the scenario behind The Day After Tomorrow.

The movie sought justification from geological climate records showing that fluctuations like the Younger Dryas are both common and rapid, perhaps happening in just a few decades. But the German data paint an even more dramatic picture. The lake sediments contain layers that record the annual growth cycle of a type of algae called diatoms, whose hard mineral shells sink to the lake bed when they die. The mineral layers are thinner when winds stir up the water and mix in oxygen, inhibiting diatom growth. So the sediments give a yearly record of wind and storms dating back thousands of years.

The scientists found that there was an abrupt increase in storminess precisely 12,679 years ago, which heralded the start of the Younger Dryas. The scientists link the rise in wind strength to a reorganisation in atmospheric flow patterns that could in turn have shifted north Atlantic ocean currents. In other words, changes in ocean circulation may be an effect and not a cause of cooling.

But higher winds over a German lake don't tell us much about global climate. There's no sign yet that temperatures can became glacial again within a single season. And in any case, ice sheets grow very slowly—however cold it is.

Prepare for vitamin C injections

Linus Pauling was the greatest chemist of the 20th century. His reputation just about survived his conviction, near the end of his career, that massive doses of vitamin C could cure cancer, but it was seen as the kind of crankiness to which elderly Nobel laureates seem prone. Now there are new claims for the vitamin's anti-cancer powers. They don't exactly vindicate Pauling—in science you have to be right for the right reasons—but they do invoke a sense of déjà vu.

There's little point in munching handfuls of vitamin C pills, as Pauling advocated, when the intestine can only absorb limited amounts. But at the US National Institute of Diabetes and Digestive Kidney Diseases, Mark Levine and his team have been testing intravenous injection as a means of getting high amounts of vitamin C directly to tumours. They report this can halve the growth rate of ovarian, pancreatic and brain tumours in mice. Vitamin C, they say, may help cancers with "poor prognosis and limited therapeutic options"—that is, as a last resort.

Yet Pauling was well served by his intuition. He suspected that vitamin C might destroy tumours by reacting with oxygen to create toxic chemicals called reactive oxygen species, such as hydrogen peroxide. Normal cells have enzymes for mopping up substances like this, since they're a persistent hazard for oxygen-breathers. But cancer cells seem to have poorer defences. These latest results suggest that hydrogen peroxide is indeed the anti-tumour agent induced by vitamin C.

While there's no firm evidence that this will work for humans, the results are worth pursuing, particularly as high intravenous doses seem to pose no serious health risks. But one concern is that patients might seize on this as a miracle cure and start injecting vitamin C themselves without medical supervision.

The Tevatron's parting shot

The first particle collisions at the Large Hadron Collider at Cern, near Geneva, should occur later this year. Once the LHC comes online, it will eclipse the previous highest-energy collider, the Tevatron at Fermilab in Illinois. But as a parting shot, the Tevatron team recently announced that they have placed new constraints on the possible mass of the Higgs particle, the LHC's main quarry.

The Tevatron's results show that the Higgs mass must exceed the middle of the possible range identified by earlier experiments. With particles this elusive, finding out where they aren't is an important part of the quest. So it seems the LHC will need its hefty punch to reach the high energies needed to make a massive Higgs.