18/02/2020

Study: One-Third Of Plant And Animal Species Could Be Gone In 50 Years

University of Arizona - Daniel Stolte

University of Arizona researchers studied recent extinctions from climate change to estimate the loss of plant and animal species by 2070. Their results suggest that as many as one in three species could face extinction unless warming is reduced.
The common giant tree frog from Madagascar is one of many species impacted by recent climate change. (Photo: John J. Wiens)

Accurately predicting biodiversity loss from climate change requires a detailed understanding of what aspects of climate change cause extinctions, and what mechanisms may allow species to survive.
A new study by University of Arizona researchers presents detailed estimates of global extinction from climate change by 2070. By combining information on recent extinctions from climate change, rates of species movement and different projections of future climate, they estimate that one in three species of plants and animals may face extinction. Their results are based on data from hundreds of plant and animal species surveyed around the globe.
A dead Alligator Juniper from Arizona. Unable to cope with rising temperature extremes, repeated surveys have shown that this species is literally being pushed up the mountain slopes under the impact of climate change. (Photo: Ramona Walls)
Published in the Proceedings of the National Academy of Sciences, the study likely is the first to estimate broad-scale extinction patterns from climate change by incorporating data from recent climate-related extinctions and from rates of species movements.
To estimate the rates of future extinctions from climate change, Cristian Román-Palacios and John J. Wiens, both in the Department of Ecology and Evolutionary Biology at the University of Arizona, looked to the recent past. Specifically, they examined local extinctions that have already happened, based on studies of repeated surveys of plants and animals over time.
Román-Palacios and Wiens analyzed data from 538 species and 581 sites around the world. They focused on plant and animal species that were surveyed at the same sites over time, at least 10 years apart. They generated climate data from the time of the earliest survey of each site and the more recent survey. They found that 44% of the 538 species had already gone extinct at one or more sites.
"By analyzing the change in 19 climatic variables at each site, we could determine which variables drive local extinctions and how much change a population can tolerate without going extinct," Román-Palacios said. "We also estimated how quickly populations can move to try and escape rising temperatures. When we put all of these pieces of information together for each species, we can come up with detailed estimates of global extinction rates for hundreds of plant and animal species."
The study identified maximum annual temperatures — the hottest daily highs in summer — as the key variable that best explains whether a population will go extinct. Surprisingly, the researchers found that average yearly temperatures showed smaller changes at sites with local extinction, even though average temperatures are widely used as a proxy for overall climate change. 
"This means that using changes in mean annual temperatures to predict extinction from climate change might be positively misleading," Wiens said.
Previous studies have focused on dispersal — or migration to cooler habitats — as a means for species to "escape" from warming climates. However, the authors of the current study found that most species will not be able to disperse quickly enough to avoid extinction, based on their past rates of movement. Instead, they found that many species were able to tolerate some increases in maximum temperatures, but only up to a point. They found that about 50% of the species had local extinctions if maximum temperatures increased by more than 0.5 degrees Celsius, and 95% if temperatures increase by more than 2.9 degrees Celsius.
Projections of species loss depend on how much climate will warm in the future.
"In a way, it's a 'choose your own adventure,'" Wiens said. "If we stick to the Paris Agreement to combat climate change, we may lose fewer than two out of every 10 plant and animal species on Earth by 2070. But if humans cause larger temperature increases, we could lose more than a third or even half of all animal and plant species, based on our results."
The paper's projections of species loss are similar for plants and animals, but extinctions are projected to be two to four times more common in the tropics than in temperate regions.
"This is a big problem, because the majority of plant and animal species occur in the tropics," Román-Palacios said.

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(AU) Mammal That Mates Itself To Death Will Struggle Under Climate Change, Scientists Say

Newsweek - 



A small Australian mammal that mates itself to death will struggle under climate change, scientist have said.
For a study published in the journal Frontiers in Physiology, a team of researchers investigated how climate change may affect the yellow-footed antechinus, or Antechinus flavipes—a marsupial that has a rare and unusual mating behavior known as "male semelparity." This is where a whole generation of males die in their first mating season.
In the case of the yellow-footed antechinus, the mating season may last two to three weeks and takes place in the Australian winter and spring months, depending on where in the country a given population is located. In this time the males succumb to stress and exhaustion after having copulated with so many female partners.In the latest paper, the scientists found that if this marsupial experiences warmer temperatures during the early stages of its life, it may be less capable of adapting to and surviving the winter. The marsupials are born between September and November and so they spend their first months in the Australian summer and autumn, which are expected to become hotter under climate change. This could mean that many males will be unable to survive the winter in future, so would be incapable of mating.
The scientists, led by Clare Stawski from the University of New England and the Norwegian University of Science and Technology, exposed captive-bred juveniles to either "cold" or "warm" temperatures—17 and 25 degrees Celsius (63 to 77 degrees Fahrenheit.) The mammals were about 100 days old at the beginning of this experiment, and had just finished being weaned by their mothers.
Stawski and colleagues then monitored various factors such as body mass and the activity levels of the animals.
Once the juveniles had reached adult size, at around 220 days of age, the scientists conducted a series of temperature tests and measured the basal metabolic rate—the number of calories required to keep the body functioning at the most basic level while it is resting—of the animals.
In one test, the mammals were placed in a chamber where the temperature was 18 degrees Celsius. This was then increased by 4 degree Celsius increments every two hours, until the temperature reached 30 degrees.
In the second test, the initial temperature in the chamber began at 14 degrees Celsius and was reduced to 10 degrees after three hours.
The results showed that temperatures experienced by juvenile yellow-footed antechinuses during development can impact the behavior and physiology of the animal.
Juveniles placed in the "cold" group just after being weaned were able to adapt their metabolic rate as the temperature around them changed. But the metabolic rate of those juveniles that had initially been placed in the warm group did not change when exposed to colder temperatures.
Stock photo: A yellow-footed antechinus. iStock
According to the researchers, this indicates that the juveniles raised in warm conditions may have less "phenotypic plasticity"—the ability of an organism to adapt to environmental influences.
This has significant implications for the yellow-footed antechinus given temperatures in Australia are expected to rise with climate change, according to the Commonwealth Scientific and Industrial Research Organisation (CSIRO)—an Australian government agency.
"We hypothesize that as individuals raised in warm conditions appear to have less phenotypic flexibility, they may not be able to respond effectively to prolonged increases in temperature and therefore struggle throughout winter," Stawski told ABC News.
This lack of phenotypic plasticity in juveniles raised in warm conditions does not bode well for a species that is dependent on a single breeding event and experiences "a complete population turnover," the authors wrote in the study.
This makes the species particularly vulnerable to potentially deadly environmental events, such as heatwaves, which are expected to become more common under climate change, according to CSIRO.
If these events occur in the periods when there are no males, and only pregnant or lactating females, there is a chance that significant numbers of females could die, meaning fewer offspring, leading to a subsequent reduction in the population.
While the latest study focused only on the yellow-footed antechinus, which has a relatively wide distribution across Australia, other species in the same genus (group of species) with smaller ranges may be even more severely affected by climate change, Andrew Baker from the Queensland University of Technology, Australia, who was not involved in the paper, told ABC.
Scientists only know about a handful of species that display male semelparity. Most of these are invertebrates, or animals without a backbone, making Antechinus an unusual case.
The Frontiers in Physiology paper is not the only recent piece of research to highlight the plight of animals in Australia under climate change.
One study published in the journal Biological Conservation found that populations of the iconic platypus were at risk in the face of increasingly dry conditions. The researchers found that under current climate projections, platypus numbers could decline by up to 73 percent by 2070.

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Landing A Blow Against Climate Change

Project Syndicate - 

For the last decade, bioenergy has been confined to the sidelines of climate-policy debates, owing to the environmental problems associated with its production. But recent innovations have made this option for supplying sustainable, renewable energy not just viable, but necessary.
Kambou Sia/AFP via Getty Images
BONN – In the face of climate change, providing reliable supplies of renewable energy to all who need it has become one of the biggest development challenges of our time. Meeting the international community’s commitment to keep global warming below 1.5-2°C, relative to preindustrial levels, will require expanded use of bioenergy, carbon storage and capture, land-based mitigation strategies like reforestation, and other measures.
The problem is that these potential solutions tend to be discussed only at the margins of international policy circles, if at all. And yet experts estimate that the global carbon budget – the amount of additional carbon dioxide we can still emit without triggering potentially catastrophic climate change – will run out in a mere ten years. That means there is an urgent need to ramp up bioenergy and land-based mitigation options. We already have the science to do so, and the longer we delay, the greater the possibility that these methods will no longer be viable.
Renewable energy is the best option for averting the most destructive effects of climate change. For six of the last seven years, the global growth of renewable-energy capacity has outpaced that of non-renewables. But while solar and wind are blazing new trails, they still are not meeting global demand.
A decade ago, bioenergy was seen as the most likely candidate to close or at least reduce the supply gap. But its development has stalled for two major reasons. First, efforts to promote it had negative unintended consequences. The incentives used to scale it up led to the rapid conversion of invaluable virgin land. Tropical forests and other vital ecosystems were transformed into biofuel production zones, creating new threats of food insecurity, water scarcity, biodiversity loss, land degradation, and desertification.
In its Special Report on Climate Change and Land last August, the Intergovernmental Panel on Climate Change showed that scale and context are the two most important factors to consider when assessing the costs and benefits of biofuel production. Large monocultural biofuel farms simply are not viable. But biofuel farms that are appropriately placed and fully integrated with other activities in the landscape can be sustained ecologically.
Equally important is the context in which biofuels are being produced – meaning the type of land being used, the variety of biofuel crops being grown, and the climate-management regimes that are in place. The costs associated with biofuel production are significantly reduced when it occurs on previously degraded land, or on land that has been freed up through improved agriculture or livestock management.
Under the 1.5°C warming scenario, an estimated 700 million hectares of land will be needed for bioenergy feedstocks. There are multiple ways to achieve this level of bioenergy production sustainably. For example, policies to reduce food waste could free up to 140 million additional hectares. And some portion of the two billion hectares of land that have been degraded in past decades could be restored.
The second reason that bioenergy stalled is that it, too, emits carbon. This challenge persists, because the process of carbon capture remains contentious. We simply do not know what long-term effects might follow from capturing carbon and compressing it into hard rock for storage underground. But academic researchers and the private sector are working on innovations to make the technology viable. Compressed carbon, for example, could be used as a building material, which would be a game changer if scaled up to industrial-level use.
Moreover, whereas traditional bioenergy feedstocks such as acacia, sugarcane, sweet sorghum, managed forests, and animal waste pose sustainability challenges, researchers at the University of Oxford are now experimenting with the more water-efficient succulent plants. Again, succulents could be a game changer, particularly for dryland populations who have a lot of arid degraded land suitable for cultivation. Many of these communities desperately need energy, but would struggle to maintain solar and wind facilities, owing to the constant threat posed by dust and sandstorms.
In Garalo commune, Mali, for example, small-scale farmers are using 600 hectares previously allocated to water-guzzling cotton crops to supply jatropha oil to a hybrid power plant. And in Sweden, the total share of biomass used as fuel – most of it sourced from managed forests – reached 47% in 2017, according to Statistics Sweden. Successful models such as these can show us the way forward.
Ultimately, a reliable supply of energy is just as important as an adequate supply of productive land. That will be especially true in the coming decades, when the global population is expected to exceed 9.7 billion people. And yet, if global warming is allowed to reach 3°C, the ensuing climatic effects would make almost all land-based mitigation options useless.
That means we must act now to prevent the loss of vital land resources. We need stronger governance mechanisms to keep food, energy, and environmental needs in balance. Failing to unleash the full potential of the land-based mitigation options that are currently at our disposal would be an unforgiveable failure, imposing severe consequences on people who have contributed the least to climate change.
Bioenergy and land-based mitigation are not silver bullets. But they will buy us some time. As such, they must be part of the broader response to climate change. The next decade may be our last chance to get the land working for everyone.

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