The joker who brought climate science out of the cold

Wally Broecker, when he registered for the Columbia University geology department in 1953. Credit: Department of Earth and Environmental Engineering Archives, Columbia University

Wally Broecker, when he registered for the Columbia University geology department in 1953. Credit: Department of Earth and Environmental Engineering Archives, Columbia University

In Los Angeles on September 1 1955, the day temperatures reached a new record of 43°C, Wally Broecker stood, sweating, giving the first scientific talk of his life. He could scarcely have guessed where the new method he was telling an audience of sleepy archaeologists about, called radiocarbon dating, would send him. But thanks in part to its messages from history he would help spawn the phrase ‘global warming’ and warn of its effects, which have today pushed temperatures even higher.

Wally grew up and started college on the outskirts of Chicago, Illinois, good at maths, but largely uninterested in science. But college-mate Paul Gast steered his career sciencewards by helping get him a summer job at the new Lamont Geological Observatory that Paul had recently started working at. On June 15, 1952 Wally and pregnant wife Grace drove 800 miles to the Palisades, New York mansion Columbia University had inherited, and set up the observatory in. There, in the basement, Wally worked in and soon practically ran Laurence Kulp’s radiocarbon lab. Rather than lose him at the end of the summer Laurence organised for Wally to transfer to Columbia and stay working at Lamont, where he has remained ever since.

Taking advantage of the slow decay of a rare, radioactive form of carbon – carbon-14 – radiocarbon dating was in its infancy. The balance between carbon-14 and the usual form, carbon-12, is quite steady in CO2 in the air, and also in living plants that take up the gas as they grow. But when plants die, the carbon-14 they contain slowly decays to nitrogen. Measuring the ratio between the two forms of carbon, scientists can tell when the plants had died. But in 1952, Laurence’s lab was getting inconsistent readings, with carbon-14 counts sometimes coming out too high, even after Wally had fixed a problem with the equipment. Then Wally realised the problem came from outside the lab. The extra counts were coming from nuclear tests that had recently started over Nevada.

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Projected warming set to exceed civilisation’s experience

Oregon State University's Shaun Marcott has built a climate record reaching back 11,300 years, showing that today's temperatures are warmer than at least 70% of that period. Credit: Shaun Marcott

Oregon State University’s Shaun Marcott has built a climate record reaching back 11,300 years, showing that today’s temperatures are warmer than at least 70% of that period. Credit: Shaun Marcott

The world is headed for average surface temperatures warmer than it has seen in at least 11,300 years. That’s one conclusion US researchers have reached after bringing together 73 studies of ancient climate from across the world into a single global record. Their work supports previous records for the past 2,000 years built mainly from tree ring data, explained Shaun Marcott from Oregon State University, and gives a much broader view.

“We can put today’s global temperature into context against the entire Holocene period,” Shaun told me. “That’s when human civilisation was born, developed and progressed to today.” Modern temperatures are higher than in around three-quarters of that period, which reaches back to the end of the last ice age. And their comparison against forecasts for 2100 made in models used by the Intergovernmental Panel on Climate Change (IPCC) is even starker. “If those scenarios come to fruition, we’ll be well outside anything human civilisation has seen,” Shaun warned. “We won’t have even have been close.”

Knowing climate’s history helps understand its present, and so researchers have puzzled out temperatures on the Earth’s surface from proxy, or indirect, records for the last 2,000 years. In particular, bringing together measurements from tree rings, ice and coral has showed a sharp recent temperature rise often referred to as the ‘hockey stick’. Meanwhile, studies scattered across the world had reached back across the 11,300 years since the beginning of the Holocene. But they can be influenced by regional effects, and no one had pieced them into a global view that would overcome that. Read the rest of this entry »

More turtles could become fish supper with warming

University of Queensland's David Booth and Andrew Evans have tested the effect of temperature on the swimming ability of the endangered green turtle. Credit: Nick Holmes

University of Queensland's David Booth and Andrew Evans have tested the effect of temperature on the swimming ability of the endangered green turtle. Credit: Nick Holmes

The moment they break open the shells their mother laid them in, baby green turtles face arguably the most dangerous journey of their lives. Despite spending most of their time out in the open sea, these endangered creatures are born from clutches of eggs in deep nests in coastal and island sand dunes. Though it may take them several weeks to dig their way out of the sand, once they emerge, they rapidly plunge into the sea, and then swim continuously for about another 24 hours. On that voyage, they must run the gauntlet of hungry fish, who are thought to eat three in ten hatchling green turtles on average.

Last week, the University of Queensland’s David Booth and Andrew Evans showed that a hotter climate would harm the baby green turtles’ ability to swim away from this early death. That’s despite warmer seas improving their swimming ability. “We also found that hatchlings that emerged from cooler nests had a better swimming performance,” Booth told Simple Climate. “However the effect of nest temperature was greater than the effect of the change in water temperature. We predicted that if there were both a 2ºC rise in nest temperature and water temperature, there would be a net decrease in green turtle hatchling swimming performance, thus increasing the chances that hatchlings would be eaten by predatory fish.” Read the rest of this entry »

A picture of climate change is worth 1,000 words

As a science writer, I’m constantly battling against those occasions on which words fail me. Perhaps I don’t explain an idea clearly enough, or maybe I just can’t figure out what to say. Well, over 100 blog entries into Simple Climate, I’m actually going to (kind of) shut up for once. Throughout the year there I’ve been able to include some great illustrations explaining climate change, from how it works to the temperature changes we’ve gone through. This week I’m rounding some of them up here, along with some other diagrams I thought were powerful that I haven’t included before. Have a look – I hope they get your thought processes going as much as the normal entries do.

This is my attempt for a simple diagrammatic explanation of climate change. Greenhouse gases in the atmosphere trap heat from the sun in our atmosphere. We need this: if it didn't happen it would be too cold to live on earth. However, because we're pumping so much greenhouse gas into the atmosphere - mainly CO2 from burning fossil fuels - it's warming up more than it would normally.

This is my attempt for a simple diagrammatic explanation of climate change. Greenhouse gases in the atmosphere trap heat from the sun in our atmosphere. We need this: if it didn’t happen it would be too cold to live on earth. However, because we’re pumping so much greenhouse gas into the atmosphere – mainly CO2 from burning fossil fuels – it’s warming up more than it would normally.

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Simple Climate poll part 4: The effects of change

A cloud forest habitat in southern Peru where lizard species are found. Certain lizards in these habitats are at risk of extinction due to climate warming. Credit: Ignacio De la Riva.

A cloud forest habitat in southern Peru where lizard species are found. Certain lizards in these habitats are at risk of extinction due to climate warming. Credit: Ignacio De la Riva.

The impact that climate change will have on the world is what makes it such a crucial issue, and makes it important to understand. Consequently, when I have asked scientists what the situation is with climate change this year, some have given me an explanation based on the effects that they’ve seen or expect.

I’ve gathered these answers together as the last group of explanations that I’m summarizing in the Simple Climate end of year polls. These polls are a way for you to help me with one of the aims of my blog – producing a single, simple explanation of climate change. Please read them and then vote for your favourite and/or comment at the end. Also, if you haven’t already voted in them, the first three polls are still ongoing. The first includes direct explanations of the physics underlying climate change, the second one-line and metaphorical explanations, and the third includes attempts to explain it at a personal level. The winner from each poll will then go into a final poll-to-end-all-polls at the end of the year. Happy voting! Read the rest of this entry »

Coral and chatting climate: Tougher than they seem

University of British Columbia's Professor Simon Donner

University of British Columbia's Professor Simon Donner

Simon Donner says that in 30 to 50 years, if they do not adapt, we will see corals bleaching and starving dangerously frequently as the oceans warm up. “Corals, the stationary animals that build reefs, get most of their food from colourful algae which live in the coral tissue,” the University of British Columbia professor explained. “When the surrounding waters gets too hot, the corals expel the algae and lose pigmentation. If the heat stress persists, the corals can essentially starve to death.”

Donner points out that the levels of greenhouse gases already in the atmosphere today will create enough warming for this to happen by themselves – a situation he calls “committed warming”. “Even if we froze the greenhouse gas concentrations in the atmosphere today, the climate is going to keep warming for several decades,” he says. However, talking at a conference back in February, he also looked at how corals will adapt to temperature, citing some studies showing that they can increase their temperature tolerances by as much as 1.5°C. Read the rest of this entry »

Researchers fight for OK coral

Penn State University's Nick Polato. Credit: Penn State University.

Penn State University's Nick Polato. Credit: Penn State University.

“Unfortunately for corals the outlook is grim.” So says Nick Polato, a graduate student at Penn State University. “While some reefs will certainly endure, we are facing drastic declines both in the number and diversity of reefs as they deal with a host of man-made impacts, such as development and pollution, which aggravate effects of climate change.” Polato is a member of the team led by Iliana Baums, which last month had its research into the effect of temperature on young corals published in the journal PloS One. Polato points out that corals can’t move into more favourable environments except when they are in their young forms, known as larvae. “Our study showed high temperatures can really mess up the development of young corals,” he says, “so the ability of coral larvae to endure stress will be critical to the survival and recovery of affected reefs.”

Because corals don’t feature obviously in most people’s lives, it’s easy to underestimate their importance, Polato says. “Reefs matter because they protect shorelines from erosion, provide habitats for many species that we rely on for food, and that contain unique chemical compounds that we might be able to use to develop new drugs,” he explains. While he and his fellow researchers have looked at exactly how coral larvae respond to higher temperature, Polato emphasises that the loss of colour and death of mature coral has been well studied. “It is proven beyond reasonable doubt that corals bleach and eventually die in response to persistent warm water temperatures,” he says. Read the rest of this entry »