Climate cycles drive civil wars

A child in a rebel camp in the north-eastern Central African Republic, one of the countries where internal conflict has been shown to be twice as likely to occur during a year when the El Niño weather pattern occurs than in La Niña years. Credit: Pierre Holtz/UNICEF CAR/Flickr

Civil war is much more likely during the warmer phase of a global climate cycle, seemingly as political tensions get literally overheated. That’s according to researchers from Columbia University, New York, who say that conflicts within a single country are twice as likely to occur during warmer El Niño years as cooler La Niña years. This is the first indication that modern societies’ stability relates strongly to climate, though the scientists warn that their findings might not be applicable to human-caused climate change. However some of the more dramatic changes in climate and society during humanity’s history have successfully been tied together. Columbia’s Mark Cane says his team’s latest findings build on those results. “What it shows beyond any doubt is that even in this modern world, climate variations have an impact on the number of civil conflicts,” Cane said Tuesday. “It’s frankly difficult to see why that won’t carry over to a world that is disrupted by global warming.”

Previous studies on whether modern climate has influenced war found only weak links between temperature over long periods, while studies on year-to-year local changes have disagreed and been criticised for having too narrow a focus. Consequently, together with Solomon Hsiang and Kyle Meng, Cane turned to the El Niño-Southern Oscillation, or ENSO, that affects weather patterns where half the world’s people live. El Niño originates from around 1°C warming in the tropical Pacific every three to seven years, bringing hotter, drier weather to the tropics. That alternates with cooler La Niña phases that provide more tropical rain, but can dry out more northern areas, as in East Africa and the southwest US this year. Consequently, the Columbia scientists were working with changes between two states on a worldwide scale that happened relatively regularly. This comes close to the “ideal but impossible” experiment of studying two Earths with different climates, they write in top science journal Nature.

Climate change gets nature moving

An Amblychia moltrechti moth, a member of the Geometridae family that Chris Thomas, I-Ching Chen and their colleagues discovered had on average moved 67 metres uphill on Mount Kinabalu in Borneo in 42 years in response to higher temperatures. Credit Bettaman/Flickr

Life on Earth is creeping to cooler locations up to three times more quickly than previously thought as it strives to survive the warming climate. That’s what Chris Thomas from the University of York, UK, and colleagues have found after updating a prior study with measurements published over the last eight years. “We estimated that, on average, species have been moving away from the Equator towards the poles at 17.6 kilometres per decade,” Thomas told Simple Climate. “Because there are differences among studies, we can conclude that the true rate lies between 11.8 and 23.4 kilometres per decade. Even the lower value is considerably larger than the previously-published best estimate.” Thomas noted that this is equivalent to animals and plants shifting away from the Equator at around 20 cm per hour, every hour of the day, every day of the year. “This has been going on for the last 40 years and is set to continue for at least the rest of this century,” he said.

Following changes in where a species can be found over time takes a lot of measuring, meaning that most studies just look at a few different plants, insects or animals. However, in 2003, Camille Parmesan, a lead author for the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), and Gary Yohe analysed previously recorded range data on 99 species. They found shifts averaging 6.1 km per decade towards the poles. Writing in a paper to be published in top research journal Science on Friday, Thomas’ team has brought that work up to date. “We were aware that a considerable amount of literature had been published since,” Thomas said. “We also thought that there was an opportunity to establish a stronger link between the level of climate warming and the responses.”

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

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.”

Climate controls must cover gases other than CO2

Agriculture is one of the main sources for the greenhouse gas nitrous oxide (N2O) which results from the use of fertilisers. Credit: André Künzelmann/UFZ

Cutting emissions of other greenhouse gases would slam the brakes on short-term climate change faster than controlling CO2 alone. But rather than offering an easy way out, warns Jim Butler, director of the Global Monitoring Division at the US National Oceanic and Atmospheric Administration (NOAA), they present both an opportunity and a challenge. “Addressing them can help us see earlier results than we would see with CO2, which poses a problem today but a much bigger one in the future,” he told Simple Climate. “CO2 must be addressed, but ignoring these other gases too could take us to places where we don’t want to go.”

Butler’s division has tracked the levels of different gases in the atmosphere for decades. Among them he says, CO2 rightfully gains most attention. That’s because it traps so much of the sun’s energy, it currently accounts for almost two-thirds of the warming power known as “climate forcing”. “It is responsible for well over 80 per cent of the increase in climate forcing from long-lived gases each year,” Butler said. “It is also very long lived, with around one-fifth of what is emitted hanging around for at least 1,000 years.” Yet as burning oil, natural gas and coal, which produces CO2, propels modern life, cutting the amount we use enough will take some time. “In the meantime there are other gases that could and probably should receive attention,” Butler underlined.

Stephen Montzka of NOAA, along with colleagues Butler and Ed Dlugokencky, looked at exactly how these gases have been affecting climate in top scientific journal Nature this week. Monitoring and evaluating these gases helps show how humans are affecting their levels in the atmosphere. It also serves as a check on the results of claimed emissions. Unfortunately, the amount countries say they produce and levels recorded at observatories across the world disagree. However, Butler noted that no approach is perfect, and that at least comparing the two gave them some idea how far out they were. “The beauty of comparing the two is that each relies on completely different measurements, procedures and assumptions,” he said.