Baking sands worsen leatherback turtle survival crisis

Baby leatherback turtles face many threats, and climate change looks set to add to them. Credit: Juanma Carillo/Flickr

Baby leatherback turtles face many threats, and climate change looks set to add to them. Credit: Juanma Carillo/Flickr

As the world warms in upcoming decades less than half the current number of Costa Rican leatherback turtles will succeed in their first, vital, journey from sandy nest to sea. That’s according to a team of US researchers who have closely monitored how regular climate fluctuations affect egg and hatchling survival. That’s allowed them to show a clear relationship that they can use to predict the turtles’ future prospects, explained James Spotila from Drexel University in Philadelphia, Pennsylvania. “With the projected warming that’s going to happen in this century, these eggs and hatchlings are going to have a serious problem,” Spotila told Simple Climate. “We’ll have to do some kind of mitigation to keep these animals alive.”

James, who is also chairman of the Leatherback Trust, has been studying nesting turtles, considered “critically endangered”, at Las Baulas Park in Costa Rica for 22 years. Over that time, he and his fellow scientists had noticed more hatchlings in some years than others, and wanted to know the cause. The close watch they keep on the turtles gave them the first clues that climate played a role. “We noted that as the season would progress, and got hotter and drier, you had a reduction in hatching success of the eggs,” James said.

To find a detailed link, the scientists focused on one important nesting area in the Las Baulas Park – Playa Grande – over 6 seasons, from 2004-2010. Over that time they tracked temperature and rainfall measurements recorded at a nearby airport. But the hardest part – much of which was done by James’ Drexel colleague Pilar Santidrian Tomillo – came after the nests hatched.

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Climate will thwart some mammals’ quest for new homes

University of Washington's Carrie Schloss. Credit: University of Washington

University of Washington’s Carrie Schloss. Credit: University of Washington

The speed of climate change means that one in ten mammal species in North and South America face a stark challenge: evolve or die out. “As the climate changes, the conditions where a species currently exists may no longer be suitable for it,” explained Carrie Schloss from the University of Washington. “This species can evolve, die, or move.” But some mammals can’t move fast enough to get to areas they’re adapted to, leaving them with just two of those options, Carrie and her fellow scientists have found.

Scientists have already shown that where plants and animals can be found has moved in response to a changing climate. And while many studies have projected species range shifts in the future, they don’t usually consider whether species can get to areas it’s suited to. In part that’s because there isn’t much information on how quickly they can disperse from their homes, Carrie told Simple Climate. But Carrie called on a known relationship between species’ body size and diet and the distance mammals can disperse before their first mating. “In general, larger animals disperse further than smaller animals,” Carrie said. Meat-eating animals also disperse further than same-sized animals eating just plants or plants and meat.

Together with fellow Washington ecologists Josh Lawler and Tristan Nuñez, Carrie combined this dispersal distance with time between each generation for 493 different species in North and South America. The team then worked out how many generations there would be between 1990 and 2100. “Some mammals, like some small mice, may reproduce and the next generation may mature and disperse and reproduce several times within a year,” Carrie explained. “With other mammals, such as primates, the juveniles may not be reproductively mature for a few years.” By combining the number of generations with the pre-mating dispersal distance, Josh, Tristan and Carrie could get an overall figure for how far the mammals could migrate. Read the rest of this entry »

Economy-CO2 link reveals GDP weakness

The key US National Oceanic and Atmospheric Administration (NOAA) site where CO2 concentrations in the air are monitored, at Mauna Loa, Hawaii. Unlike CO2 emissions, these CO2 concentrations can be readily measured directly, so Edward Ionides, José Tapia Granados, and Óscar Carpintero used them to study their link with global GDP. Credit NOAA

The key US National Oceanic and Atmospheric Administration (NOAA) site where CO2 concentrations in the air are monitored, at Mauna Loa, Hawaii. Unlike CO2 emissions, these CO2 concentrations can be readily measured directly, so Edward Ionides, José Tapia Granados, and Óscar Carpintero used them to study their link with global GDP. Credit NOAA

Researchers have confirmed a relationship that is making climate change tough to fight: economic growth and atmospheric CO2 concentrations have been tightly linked for the past 50 years. That’s what the University of Michigan‘s Edward Ionides and co-workers found by looking at levels of the greenhouse gas and gross domestic product (GDP), an important measure of countries’ financial performance, at a worldwide level. “GDP growth is like a proxy for CO2 concentration growth,” Edward told Simple Climate. “Under business-as-usual conditions, these two quantities are measuring essentially the same thing. This highlights a problem with using GDP as a measure of progress.”

Until now, much research on the link between CO2 and economic growth has looked at figures for each country. Some think using each country’s CO2 emissions separately “should be more informative”, Edward said. But there are problems with recording emissions accurately, plus goods or services used in one country often result in CO2 emissions in another. So, with Michigan colleague José Tapia Granados, and Óscar Carpintero from the University of Valladolid, Spain, Ionides went to the worldwide level for “a new and simpler perspective”.

As well as the total of all countries’ GDP, they used precisely measured atmospheric CO2 levels, rather than the more uncertain emission figures. “In addition, concentration of CO2, rather than the level of emissions, is the variable directly determining the global climate,” Óscar said. “Change in the atmospheric concentration is the result of emissions – mainly from burning fossil fuels, since natural emissions from volcanoes are estimated as a tiny fraction of man-made emissions – minus removals by natural sinks.”

Atmospheric CO2 (monthly average) as measured in air samples collected at Mauna Loa, Hawaii from Feburary 1958 to Februrary 2012. Units are parts per million by volume. Estimated preindustrial concentrations, at levels between 200 and 300 ppm, would be far out of the graph. The graph is often known as the Keeling curve. Credit: University of Michigan

Atmospheric CO2 (monthly average) as measured in air samples collected at Mauna Loa, Hawaii from Feburary 1958 to Februrary 2012. Units are parts per million by volume. Estimated preindustrial concentrations, at levels between 200 and 300 ppm, would be far out of the graph. The graph is often known as the Keeling curve. Credit: University of Michigan

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Water’s climate risks show high temperature sensitivity

Like having a fleet of miniature research vessels, the global flotilla of more than 3,000 robotic profiling floats provides crucial information on upper layers of the world's ocean currents. Credit: CSIRO/Alicia Navidad

Like having a fleet of miniature research vessels, the global flotilla of more than 3,000 robotic profiling floats provides crucial information on upper layers of the world’s ocean currents. Credit: CSIRO/Alicia Navidad

Climate change is strengthening the cycle of rain falling and evaporating by twice as much as models predict. That’s what data collected by Susan Wijffels from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Hobart, Australia, and her co-workers suggest. They’ve studied how rainfall has changed the sea’s surface salinity – or ‘saltiness’ – over the past 50 years, and compared that against current climate models. Wet areas have become wetter and dry areas drier as the water cycle strengthened by 4 per cent over this time. The scientists’ findings suggest the cycle will get 8 per cent stronger for every 1°C warming at the world’s surface, with 2-3°C warming expected by the end of the century. “As a mother I’m hoping that we’re wrong, but if this high sensitivity holds up then it could potentially be quite a significant impact to the future,” Susan told Simple Climate.

Climate change strengthens the water cycle because a warmer atmosphere can
hold and transport more moisture as water vapour. Scientists had expected this to enhance worldwide patterns of rainfall and evaporation. But understanding how rainfall is changing across the world is hard, as around four-fifths of it falls on oceans, where we have little monitoring equipment. So together with Paul Durack, who is currently at the Lawrence Livermore National Laboratory in Livermore, California, Susan had previously used salinity to get round this. As oceans lose water to the atmosphere, the sea gets saltier, and as it then returns to the sea as rain or snow it freshens again. Using salinity measurements reaching back 60 years, including from the Argo network of floating data recorders since 1995, Susan and Paul showed that the water cycle had strengthened. But they didn’t show by exactly how much, even though they wanted to. One other group of scientists had tried, but they had assumed they knew how salinity and the water cycle are linked, something Susan and Paul wanted to avoid. “We actually asked the question: How is salinity and the water cycle related and how is it related to the observed increase in temperature?”

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