Heat drives Pakistani migration

Shahdadpur, Sanghar district, Pakistan: Residents collecting their belongings on a higher ground outside village during floods. Though they may be displaced temporarily, Valerie Mueller from the International Food Policy Research Institute (IFPRI) in Washington DC and her team find high temperatures are more likely to drive permanent migration. Image credit: Oxfam International

Shahdadpur, Sanghar district, Pakistan: Residents collecting their belongings on a higher ground outside village during floods. Though they may be displaced temporarily, Valerie Mueller from the International Food Policy Research Institute (IFPRI) in Washington DC and her team find high temperatures are more likely to drive permanent migration. Image credit: Oxfam International

Excessive rainfall rarely drives Pakistanis to permanently leave their villages, even when it causes hardship like the flooding that hit around a fifth of the country in 2010. Yet they do consistently move in response to extreme temperatures, Valerie Mueller from the International Food Policy Research Institute (IFPRI) in Washington DC and her colleagues have found. She says the finding is a first stage in establishing if, how, and why people’s choices are affected by climate and climate change. “This is a useful step in order to be able to predict migration flows and inform local governments how might they better prepare in terms of the delivery of resources and investing in infrastructure given the occurrence of extreme weather events,” she told me.

There are few efforts collecting information about who has migrated and why over long periods of time, especially in areas where extreme weather occurs. But IFPRI has a long history of evaluating questions linked to food security in countries across the world, including Pakistan. From 1986-1991 its Pakistan Rural Household Survey questioned 800 households about how they lived and farmed, and it has tracked those households ever since. “Local collaborators found the original households in 2001 and 2012 and asked the head of household or an otherwise knowledgeable person what happened to each household member who resided with them in 1991,” Valerie said. “Our study is one of the first to quantify long-term migration patterns over a long period of time.”

The follow-ups recorded the long-term movements and fortunes of 4,428 people from 583 households. The researchers combined these answers with temperature and rainfall data in one ‘logit’ and one ‘multinomial logit’ model designed to let them measure the odds that people moved. “The first model allows us to answer: What are the odds of a person moving out of the household in response to extreme temperature or rainfall?” Valerie explained. “The second model allows us to distinguish moves by location and allows us to answer the following questions: What are the odds of a person moving out of the household but within the village in response to extreme temperature or rainfall? What are the odds of a person moving out of the household but out of the village in response to extreme temperature or rainfall?” Read the rest of this entry »

The man who got the world to agree on climate

  • This is part two of a two-part post. Read part one here.
When not tackling climate science or negotiations Bert Bolin liked nothing more than a little choir singing. Credit: KVA

When not tackling climate science or negotiations Bert Bolin liked nothing more than a little choir singing. Credit: KVA

In 1975, advised by Bert Bolin, the Swedish government drafted a bill on future energy policy containing a conclusion that elsewhere might be controversial even today. “It is likely that climatic concerns will limit the burning of fossil fuels rather than the size of the natural resources,” it foresaw. Produced thanks to Bert’s early role tackling environmental issues, it was one of the first times humans’ effect on climate and the risk it poses us was noted officially. For more than two decades afterward the Stockholm University researcher would further strengthen that case, both through his research and by putting climate science firmly on the political agenda. And those tireless efforts would help the United Nations’ Intergovernmental Panel on Climate Change (UN IPCC) to consistently achieve what otherwise might have been impossible agreements.

The Swedish bill was a bold statement, given that average air temperatures were only just about to reverse a slight cooling that had gone on since 1940. Bert and scientists like Dave Keeling had shown that CO2 levels in the atmosphere were rising. Basic science established by Svante Arrhenius 80 years before had showed this should warm Earth’s surface. So why was it cooling? The way scientists found the answer was typical of the progress in climate science Bert was overseeing. They would use the latest tools, including computers and satellites, bringing theory and measurement together to improve our understanding.

Climate models in the early 1970s were still simple by today’s standards, but had advanced from the early computerised weather predictions Bert had previously pioneered. And when Columbia University’s Stephen Schneider and S. Ichtiaque Rasool added aerosols of floating dust to CO2 in a model for the first time, they found a possible explanation for the temperature drop. The aerosols, particularly human pollution, created a cooling effect that swamped the warming – so much so they warned it could trigger an ice age. Though Stephen and Ichtiaque soon realised that their model overestimated the cooling, aerosols obviously deserved a closer look.

To clear up such murky problems, the Global Atmospheric Research Programme (GARP) that Bert jointly set up would bring together scientists from around the world, despite the cold war. As GARP’s first experiments, looking at heat and moisture flow between the atmosphere and ocean, started in 1974, Bert organised a meeting in Stockholm on climate physics and modelling. GARP had two goals – improving 6-10 day weather forecasts first, and climate change predictions second. As it gradually became clear how hard the first was, climate forecasting became more important.

Diplomacy was needed among the gathered scientists as arguments flared over how ambitious they should be. Should they strive for satellites that could collect the high resolution data scientists and models needed, even though that was beyond their capabilities at the time? And significantly for later climate work – should they seek to produce results so society could respond to change, even when results were uncertain? Bert was clear on that one: scientists had to answer socially important questions, though he was in a very small minority prepared to say so openly. Read the rest of this entry »

The underprepared figurehead that led climate science from calculation to negotiation

Bert Bolin discussing weather maps in Stockholm circa 1955. Image copyright Tellus B, used via Creative Commons license, see Rodhe paper referenced below.

Bert Bolin discussing weather maps in Stockholm circa 1955. Image copyright Tellus B, used via Creative Commons license, see Rodhe paper referenced below.

In 1957, at the young age of 32 and just one year after completing his PhD, Bert Bolin officially gained a new skill: leadership. Taking over the International Meteorological Institute (IMI) in Stockholm, Sweden, after his mentor Carl-Gustaf Rossby’s sudden death must have been a huge shock. But Bert gained responsibility after responsibility over the next 40 years, ultimately becoming the first chairman of the United Nations’ Intergovernmental Panel on Climate Change (UN IPCC). And though it’s hard to beat setting up a Nobel-prize winning organisation, Bert was not just an administrator – his research helped build the foundations of climate science too.

Growing up in Nyköping, south of Stockholm, Bert recorded the weather with encouragement from a schoolteacher father who had studied meteorology at university. After the pair met the Swedish Meteorological and Hydrological Institute’s deputy director when Bert was 17, he moved north to study maths, physics and meteorology at the University of Uppsala. Immediately after graduating in 1946 he went to Stockholm to do military service, where he first saw Carl-Gustaf giving a series of lectures.

By that time Carl-Gustaf had been living in the US for 21 years, pioneering mathematical and physical analysis of the atmosphere, becoming the country’s foremost meteorologist. He had set up meteorology departments at Massachusetts Institute of Technology in the 1930s, and the University of Chicago, Illinois, in the 1940s. He had also modernised the US Weather bureau and by 1946 wanted to help improve meteorology’s status in his native Sweden. As Carl-Gustaf’s renowned organisational prowess gradually pulled together the IMI, Bert came to study with him, gaining his Master’s degree in 1950.

Carl-Gustaf was collaborating with leading scientists of his time, and through some of these links Bert spent a year working in the US after his Master’s. Perhaps the most notable such relationship was with John von Neumann at Princeton University in New Jersey, who had helped develop the hydrogen bomb. John and his team had made history using arguably the world’s first computer, ENIAC, to predict weather mathematically. But when errors emerged, Carl-Gustaf asked Bert to help analyse why, using his understanding of the atmosphere to prevent such forecasts being ‘mathematical fantasy’. Read the rest of this entry »

Tundra plants show modern temperatures unmatched in over 44,000 years

Gifford Miller collects vegetation samples on Baffin Island. Credit: University of Colorado, Boulder.

Gifford Miller collects vegetation samples on Baffin Island. Credit: University of Colorado, Boulder.

Tiny plants in Arctic Canada have shown that average summer temperatures there over the last 100 years are higher than those during any century for over 44,000 years. Gifford Miller from the University of Colorado, Boulder, and his teammates collected plants perfectly preserved but recently revealed by rapidly retreating ice sheets. The temperature findings are especially surprising as around 10% more energy from the sun fell on the Northern half of the planet 5,000 years ago than today.  And by looking at other scientists’ historical temperature records, they think the last time temperatures were as warm as today was likely around 120,000 years ago. “This adds to the growing consensus that the greenhouse gases we’ve added to the atmosphere have made a very large difference to the planet’s energy balance,” Gifford told me.

Scientists have known receding glaciers on Baffin Island are revealing well-preserved moss and lichen for almost 50 years. Gifford first read about it during his PhD, which he completed in 1975, in a paper written by a Canadian Department of Mines and Technical Surveys employee in 1966. “I had been to that site in 1981, found where he’d built a camp at the ice edge, measured how far the ice had disappeared and found plants coming out,” he recalled. “I’d repeated what he had done, but hadn’t done anything else with it. But as the ice is melting a lot right now we hypothesised that this wasn’t an isolated case.”

Glaciers don’t usually preserve what’s underneath them. “It’s almost counterintuitive to some people – you think of ice doing some damage to the landscape,” Gifford said. “But ice doesn’t move on its own, it’s driven by gravity. Where it’s flat, there’s not a whole lot of gravity pushing it, and if the ice is fairly thin and cold it’s an exquisite preservation agent. They’re frozen solid when they’re under the ice, which is very cold, like -14°C.” Sites like that can be hard to get to, as many are on plateaus high above Baffin Island. “You could mount climbing expeditions and spend a week getting to one site, so really there’s no practical way to get up there, except to have very good weather and a helicopter,” the scientist added. Read the rest of this entry »

Braving African piracy reveals abrupt rainfall shifts

Woods Hole Oceanographic Institution's Jessica Tierney has patiently produced a record of rainfall in East Africa reaching back 40,000 years, from sediment collected from pirate- and extremist-infested waters. Image copyright: Tom Kleindinst, Woods Hole Oceanographic Institution

Woods Hole Oceanographic Institution’s Jessica Tierney has patiently produced a record of rainfall in East Africa reaching back 40,000 years, from sediment collected from pirate- and extremist-infested waters. Image copyright: Tom Kleindinst, Woods Hole Oceanographic Institution

Having dodged pirates and extremists, and slogged for two years to interpret the record collected, US scientists have shown how abruptly rainy climates in East Africa come and go. Jessica Tierney puzzled out a rainfall record back to the last ice age from mud collected in one of the last research cruises to brave the Horn of Africa. “The region goes from being pretty humid to very arid in hundreds of years,” Jessica, who works at Woods Hole Oceanographic Institution (WHOI) in Massachusetts, told me. “That’s important because there’s a threshold behaviour in its rainfall. We need to better understand what drives those thresholds, and when we’d expect to be pushed over one, as it has huge implications for predicting drought and famine in the region.”

Long interested in ancient East African climate, Jessica wanted to study the Horn of Africa area, which includes Ethiopia and Somalia, because the climate there is very sensitive and variable. But its dry conditions rule out many options scientists use to build historical records from ice, cave deposits, sediments from lake beds or tree rings. So in 2010, she started working with Peter deMenocal at Lamont-Doherty Earth Observatory in New York, who collected sea bed sediments from the area in April and May 2001.

“We boarded ship in Dar Es Salaam in Tanzania and our cruise was to end in Port Said, in Egypt,” Peter told me. That took the team down the Somali coast and into the Gulf of Aden, where a few months earlier suicide bombers killed 17 sailors aboard the USS Cole. Though the scientists were worried, the captain of their Dutch research ship, R/V Pelagia was vigilant. “He had ordered radio silence, and we actually turned off all our lights on the ship at night, even navigation lights,” Peter recalled. “He had also put in orders for us to train on what to do in case we were boarded.”

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If we pass safe climate limits, it’s a long way back

University of Victoria's Andrew MacDougall in Canada's Kluane National Park Credit: Nicolas Roux

University of Victoria’s Andrew MacDougall in Canada’s Kluane National Park Credit: Nicolas Roux

If CO2 levels in the air pass the ‘safe’ limit, we’d have to take out up to four-fifths more than we originally emitted to get back under it. That’s the result from seemingly the first study to look at climate change’s reversibility with plausible scenarios, done by Andrew MacDougall from the University of Victoria (UVic), Canada. “With monumental effort and political will climate change is reversible within the millennium,” Andrew told me. “However, more carbon will need to be extracted from the atmosphere than was originally emitted to it. Meanwhile, changes in sea-level are effectively irreversible on the millennial time-scale.”

Andrew started looking at whether climate change could be undone in autumn 2012, after publishing a study showing that melting permafrost will speed up global warming. “The results were pretty grim,” Andrew said. “Combined with the failure of the political classes to implement controls on carbon emissions I began to wonder if there was a way to undo what humanity will do to the climate if we greatly exceeded the 450 parts per million (ppm) target.” That target comes because scientists say temperatures 2°C higher than the ‘pre-industrial’ average from 1850-1899 could become dangerous, and governments have agreed to keep warming below this level. Scientists also calculate that 450 CO2 molecules are allowable in every million air molecules to give us better than a 3/5 chance of temperature rises below 2°C.

After human emissions cease, current evidence suggests that natural processes would take tens of thousands of years to remove all of the fossil carbon from the atmosphere. Most of the warming will remain, even 10,000 years into the future. This sentence could be reduced by taking CO2 directly from the atmosphere, though this would be a huge effort, on the same scale as today’s fossil fuel industry according to one estimate. One method for doing that involves generating electricity by burning plants or trees that grew by absorbing CO2, and capturing and storing the CO2 from the burning. The other, known as air capture, uses machines to scrub CO2 right out of the air. However, this would need to be powered by clean energy and arguments over its cost are holding back research. Read the rest of this entry »

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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Enhanced fingerprinting strengthens evidence for human warming role

Microwave sounding units, like the AMSU units on the Aqua satellite, shown here, can be used to take temperature measurements from different layers in the atmosphere. Ben Santer and his colleagues use this information to find a 'fingerprint' of human impact on recent climate changes. Credit: NASA

Microwave sounding units, like the AMSU units on the Aqua satellite, shown here, can be used to take temperature measurements from different layers in the atmosphere. Ben Santer and his colleagues use this information to find a ‘fingerprint’ of human impact on recent climate changes. Credit: NASA

We have left a clear climate change ‘fingerprint’ in the atmosphere, through CO2 emissions that have made air near the Earth’s surface warmer and caused cooling higher up. That’s according to Ben Santer from Lawrence Livermore National Laboratory (LLNL) in California, who started studying this fingerprint in the mid-1990s, and his expert team. They have strengthened the case by comparing satellite-recorded temperature data against the latest climate models including natural variations within Earth’s climate system, and from the sun and volcanic eruptions. Ben hopes that in the process their results will finally answer ill-tempered criticism his earlier work attracted, and lingering doubts over what causes global warming.

“There are folks out there even today that posit that the entire observed surface warming since 1950 is due to a slight uptick in the Sun’s energy output,” Ben told me. “That’s a testable hypothesis.  In this paper we look at whether changes in the sun plausibly explain the observed changes that we’ve monitored from space since 1979. The very clear answer is that they cannot. Natural influences alone, the sun, volcanoes, internal variability, either individually or in combination, cannot explain this very distinctive pattern of warming.”

That pattern emerged when scientists in the 1960s did some of the first computer modelling experiments looking at what would happen on an Earth with higher CO2 levels in the air. “They got back this very curious warming in the lower atmosphere and cooling of the upper levels of the atmosphere,” Ben explained. The effect happens because most of the gas molecules in the atmosphere, including CO2, sit relatively near to Earth’s surface. CO2’s greenhouse effect lets heat energy from the Sun reach the Earth, but interrupts some of it getting back to the upper atmosphere and outer space. Adding more CO2 by burning fossil fuels therefore warms the lower atmosphere, or troposphere, and cools the stratosphere, 6-30 miles above the Earth’s surface.  Read the rest of this entry »

Climate change can make us more violent

Civil wars, like the one in Somalia that destroyed this tank, could become more common as the world warms. Image taken by Charles Roffey, used via Flickr CreativeCommons license.

Civil wars, like the one in Somalia that destroyed this tank, could become more common as the world warms. Image taken by Charles Roffey, used via Flickr CreativeCommons license.

US economists have drawn together 45 sets of evidence spanning 10,000 years to show that warmer temperatures and more extreme rainfall can cause greater human conflict. University of California, Berkeley’s Ted Miguel says this “could have critical implications for understanding the impact of future climate change on human societies”.

“Many global climate models project global temperature increases of at least 2°C over the next half century,” Ted told me. “Our findings suggest that global temperature rise of 2°C could increase the rate of intergroup conflicts, such as civil wars, by over 50% in many parts of the world, especially in tropical regions where such conflicts are most common.”

Scientists have long puzzled over whether data backs climate as a cause of violent events such as the fall of the Roman empire. Global warming has brought an ‘explosion’ of interest from researchers, from archaeologists to psychologists, in climate-linked violence. And the types of conflict vary from fights between two people to civil wars and collapse of whole civilisations. But some studies see political, economic and geographical factors as more important than climate.

How researchers assess their data in these studies could introduce problems. For example, it can often be argued that ‘correlation does not imply causation’, meaning that links between two data sets might be caused by other factors. For example, reading ability might seem to improve as shoe size does, but one doesn’t cause the other – getting older causes both. To find any real, bizarre, link between shoe size and reading ability, you would need to look at people with the same age – or ‘control for’ age.

So Ted and his Berkeley teammates only brought together data that could be used to find causal links, although not all the original studies they started from had done this. Bringing together data from many different studies, collected all over the world, considering different types of violence, gives their findings stronger backing than each lone study. They called on records collected in many places that had taken measurements repeatedly in each place, and analysed them from scratch to reach their own conclusions. Read the rest of this entry »

How a beer bottle helped reveal rapid past climate change

According to Willi Dansgaard "A sophisticated experimental set-up on the lawn became the beginning of a new field in geophysics." Credit: Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen.

According to Willi Dansgaard “A sophisticated experimental set-up on the lawn became the beginning of a new field in geophysics.” Credit: Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen.

On Saturday June 21, 1952, in a garden in Copenhagen, Denmark, raindrops fell through the slim neck of a beer bottle, splattering and splashing as they hit its bottom. But the bottle wasn’t carelessly left behind – Willi Dansgaard had inserted a funnel into its neck so he could use it for an experiment. He was watching it closely, collecting rain to later measure in his lab. Each drop brought Willi closer to revealing the secrets of Earth’s history, by giving scientists a way to work out temperature from ancient ice. In doing so, he would help show how climate can change much faster than experts had thought possible.

Willi was born in Copenhagen in 1922, living and studying physics and biology there until going to work for the Danish Meteorological Institute (DMI) in 1947. The DMI sent Willi and his wife Inge to Greenland, first to study the Earth’s magnetic fields, and then to help improve the reliability of weather forecasts. Their time there left the pair with ‘deep impressions of the course of Greenland nature, its forces, its bounty, its cruelty, and above all its beauty,’ Willi wrote in his autobiography. ‘We were both bitten with Greenland for life, but after a year the need for further education forced us to turn homeward.’

So in 1951, Willi took a job at the biophysics research lab at the University of Copenhagen, where his first job was to install a mass spectrometer. Able to distinguish between chemicals using weight differences, mass spectrometers are often described as atomic-level weighing scales. But they actually measure molecules’ weight by firing them through an electromagnetic field at a detector, similarly to how bulky old TVs fire electrons at their screens. Though mass spectrometers existed since the early 20th century, Second World War US efforts to produce uranium for an atomic bomb had boosted their power. Willi set up the type of machine that had been invented in the course of that work, so his department could detect tracers used in medicine and biology.

By 1952, Willi knew that his mass spectrometer could separate forms of the same chemical elements – or isotopes – that could differ in weight by as little as a single neutron. And faced with a wet weekend in June, he wondered whether the amount of these isotopes in rainwater could change from one shower to the next. ‘Now when I had an instrument that ought to be able to measure it, there was no harm in trying,’ he writes. ‘I placed an empty beer bottle with a funnel on the lawn and let it rain.’

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