Climate provides weak power to predict African violence

Two boys from the Local Defence Unit (LDU) in Kitgum, Northern Uganda, whose job is to protect the people at a refugee camp from attacks and kidnappings by the Lord’s Resistance Army, which has been responsible for much violence in East Africa in recent years. Credit: John & Mel Kots/Flickr

Rainfall and temperature changes are linked to conflict in East Africa, but have less power to predict violence than links to political, economic and geographical factors. That’s according to one of the most detailed studies into climate-violence relationships yet, done by John O’Loughlin from the University of Colorado, Boulder, and his team-mates. “Fears of climate wars across Africa are exaggerated,” John told me. “Any effect of climate change will likely be localized and subject to other conditions.”

One political argument made about our changing climate is that it will bring more violence, particularly in Africa. For example, in 2009, US President Barack Obama told the United Nations that a warming world represents an “urgent, serious, and growing threat” because “more frequent drought and crop failures breed hunger and conflict”. But, with a background of looking in detail at where violence happens and having studied African conflicts before the 1990s, John was concerned that the evidence didn’t back such statements. That’s even though other researchers have reported statistical links between climate and conflict. “I believe that previous studies were limited by data problems and also that the policy discussions were not connected to the research findings,” John explained.

John’s team described how they fixed this in a paper published in the research journal Proceedings of the National Academy of Sciences of the USA on Monday. Previous attempts to study climate-violence have either lacked detail, looking at data per country, per year, or have been too narrowly focussed to allow generalisations, they wrote. John added that this type of work needs detailed data on both conflicts and all the factors that might predict it. Collecting the information needed on conflicts as well as political, health, location and other possibly predictive data was the biggest challenge in the work, he said.

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Cause vagueness hinders climate extinction action

Stony Brook University’s John Wiens and Abigail Cahill were among a team who looked at what existing research said about how climate change causes extinctions. Credit: Stony Brook University

Though human-caused climate change is making organisms extinct, we know worryingly little about how it’s happening. That’s what John Wiens and PhD students from Stony Brook University in New York State found after looking at existing research into the subject.  Among 136 studies into our changing climate’s effects on life around the world, the 11-strong team found that just seven mentioned a direct – or proximate – cause of extinction. “Understanding the proximate causes of extinction from climate change should be an urgent priority for future research,” they write in a paper published on Wednesday. “For example, it is hard to imagine truly effective strategies for species conservation that ignore these proximate causes.”

Currently, the International Union for Conservation of Nature lists 20 species as extinct worldwide or extinct in the wild potentially because of climate change. And while John’s team found there typically isn’t strong evidence for these links, there is evidence that climate has pushed many other organisms into local extinction. But while climate is the ultimate, driving, force behind their downfall, there can be direct, or proximate, causes of extinction that are less obvious. That means looking beyond overheating and rainfall changes, to include issues like disease and food availability. Change in population of other species is another common proximate cause. That could include population increases of predators or competitors that are harmful to an organism, or declines in beneficial species like prey, pollinators, and hosts for parasites.

John became interested in such causes through his personal interest in biodiversity and climate change’s threat to it. Building on that, he led a class last year for PhD students at his university on whether and how species can adapt to such changes.  “As we read papers related to this topic, the students and I realized that it was not really clear what species would need to adapt to in order to survive in a changed climate,” he told me. “Initially, we assumed that they would need to evolve to not overheat.  But, as we read and thought more about the topic, we realized that the story was much more complicated.”

Focus on uncertain climate cliff-edge invites disaster

Scott Barrett from the Earth Institute at Columbia University says existing climate negotiation strategies have failed. Credit: Earth Institute

Countries trying to agree climate deals based on avoiding dangerous ‘cliff-edge’ limits will not work. That’s according to Scott Barrett and Astrid Dannenberg from the Earth Institute at Columbia University in New York, who’ve modelled the negotiations in a simple game. They found that uncertainty about the threshold at which their actions hurt everyone made players ignore the deals they made almost every time.  “We found that if the threshold for catastrophic climate change were certain, Mother Nature would essentially enforce an agreement to avoid the threshold,” Scott told me. “The fear of falling off of a cliff disciplined everyone to do what was needed, collectively, to avoid falling off. When the threshold was uncertain, this effect collapsed. Uncertainty about the impact made no difference at all.” And with science unable to be completely certain where the limit is, Scott and Astrid think that how climate deals are put together must change.

Scott got the idea that knowing where the cliff-edge is important because of the two different ways climate can affect the world. The first is ‘gradual’, where small emissions add a little to greenhouse gas levels in the air and raise global temperatures slightly. The second is ‘abrupt and catastrophic’, where small emissions push part of the world’s climate over a limit into a new state. “The second kinds of change are more important to welfare,” he said. “The effects tend to be uniformly negative – think of 5 meters of sea level rise, or the possibility of warm temperatures releasing methane stored in tundra, causing a rapid rise in temperature. The effects also occur quickly, meaning that adaptation will be harder. For both reasons it seemed to me that countries would have a stronger reason to prevent this kind of climate change than the gradual kind.”

Warming weakens deep freeze on Arctic islands

Pictures from William D'Andrea's August 2012 expedition to Svalbard. There are 24 slides in this series - apologies for the poor formatting. Credit: The Earth Institute/Columbia University

Normally 6°C wouldn’t be very warm – but in the Norwegian islands of Svalbard it’s a sultry modern summer, unlike anything seen for at least 1,800 years. That’s what sediments taken from an Arctic lake have told William D’Andrea from Columbia University in New York and a US team. It’s even warmer than a medieval warm period when parts of the northern half of the planet were as hot as, or hotter, than today. And while the record they’ve made reflects just this one site, it adds to the picture showing how unique today’s climate is. It’s also another step towards understanding how climate has changed through history, William told me.

Climate dynamics are extremely complex, and cooling in some locations can happen at the same time as warming in others, or increased precipitation in some places along with drought in other places,” he said. “These are the fingerprints we are trying to map and understand by generating such reconstructions.”

The fingerprints slowly become clearer as scientists collect more historical records, often as tubes of ice drilled from glaciers, or of mud and rock drilled from sea and lake beds. The tubes, or cores, cut through layers of mud or ice built up year after year. Scientists can then use fossils and chemicals to date and work out what conditions were like when they were laid down.