Climate shocks in just one country could disrupt global food supply

Climate shocks in just one country could disrupt global food supply

SOURCE: Reuters DATE: March 20, 2020 SNIP: Catastrophic crop failures caused by extreme weather in just one country could disrupt global food supplies and drive price spikes in an interconnected world, exposing how climate change threatens global stability, researchers said on Friday. They examined how the global trade and supplies of wheat, a crop used for food staples like bread and pasta, would be affected by four years of severe drought in the United States, one of the world’s top exporters of the grain. Based on two models of how countries could try to meet their needs, an international research team found the United States would deplete nearly all its wheat reserves after four years in both scenarios, while global stocks could drop by 31%. The 174 countries to which America exports wheat would see their reserves decrease, even though they did not themselves suffer failed harvests, according to a study published in the journal Frontiers in Sustainable Food Systems. “It affects almost every country in the world because the U.S. has so many trade links,” said lead author Alison Heslin, a researcher at Columbia University’s Center for Climate Systems Research and NASA’s Goddard Institute for Space Studies. Those links mean there is a cascading effect, either directly from the United States or via one of its trading partners, which could reduce the amount of wheat available and increase prices, she told the Thomson Reuters Foundation. As reserves are depleted, changes in production would have a bigger impact on the price of food, Heslin added. Reduced global reserves would also mean a smaller buffer against future shocks such as...
The planet’s largest ecosystems could collapse faster than we thought

The planet’s largest ecosystems could collapse faster than we thought

SOURCE: The Daily Climate DATE: March 11, 2020 SNIP: If put under the kind of environmental stress increasingly seen on our planet, large ecosystems —such as the Amazon rainforest or the Caribbean coral reefs—could collapse in just a few decades, according to a study released today in Nature Communications. In the case of Amazon forests, stressors could cause collapse in just 49 years. In Caribbean coral reefs, it could take as little as 15 years. “The messages here are stark,” said lead researcher John Dearing, a professor in physical geography at the University of Southampton, in a statement. Those estimates come from Dearing and colleagues who examined data on how 42 natural environments—small and large, and on both land and water—have transformed. They found that larger ecosystems may take longer than small ones to collapse, but the rate of their decline is much more rapid. Ecosystem stress can come in many forms such as climate change, deforestation, overfishing, pollution and ocean acidification. “Humanity now needs to prepare for changes in ecosystems that are faster than we previously envisaged through our traditional linear view of the world, including across Earth ‘s largest and most iconic ecosystems, and the social–ecological systems that they support,” the authors wrote. Larger ecosystems are made up of smaller “sub-systems” of species and habitats, which provide some resilience against rapid change. However, once these smaller systems start to collapse, the new study finds the large ecosystems as a whole fall apart much faster than previously...
Why Clouds Are the Key to New Troubling Projections on Warming

Why Clouds Are the Key to New Troubling Projections on Warming

SOURCE: Yale e360 DATE: February 5, 2020 SNIP: It is the most worrying development in the science of climate change for a long time. An apparently settled conclusion about how sensitive the climate is to adding more greenhouse gases has been thrown into doubt by a series of new studies from the world’s top climate modeling groups. The studies have changed how the models treat clouds, following new field research. They suggest that the ability of clouds to keep us cool could be drastically reduced as the world warms — pushing global heating into overdrive. Clouds have long been the biggest uncertainty in climate calculations. They can both shade the Earth and trap heat. Which effect dominates depends on how reflective they are, how high they are, and whether it is day or night. Things are made more complicated because cloud dynamics are complex and happen on small scales that are hard to include in the models used to predict future climate. Recent concern about how accurately the models handle clouds has focused on the blankets of low clouds that any international flyer will have seen extending for hundreds of miles below them across the oceans. Marine stratus and stratocumulus clouds predominantly cool the Earth. They shade roughly a fifth of the oceans, reflecting 30 to 60 percent of the solar radiation that hits them back into space. In this way, they are reckoned to cut the amount of energy reaching the Earth’s surface by between 4 and 7 percent. But it seems increasingly likely that they could become thinner or burn off entirely in a warmer world, leaving...
UN Warns of Extreme Weather Ahead After Declaring Hottest Decade in Recorded History

UN Warns of Extreme Weather Ahead After Declaring Hottest Decade in Recorded History

SOURCE: Science Alert DATE: January 16, 2020 SNIP: The past decade has been the hottest on record, the UN said Wednesday, warning that the higher temperatures were expected to fuel numerous extreme weather events in 2020 and beyond.​ The World Meteorological Organization, which based its findings on analysis of leading international datasets, said increases in global temperatures had already had dire consequences, pointing to “retreating ice, record sea levels, increasing ocean heat and acidification, and extreme weather”. WMO said its research also confirmed data released by the European Union’s climate monitor last week showing that 2019 was the second hottest year on record, after 2016. “Unfortunately, we expect to see much extreme weather throughout 2020 and the coming decades, fuelled by record levels of heat-trapping greenhouse gases in the atmosphere,” WMO chief Petteri Taalas said. The UN agency said that average global temperatures during both the past five-year (2015-2019) and 10-year (2010-2019) periods were the highest ever recorded. Since more than 90 percent of excess heat is stored in the world’s oceans, their heat content is a good way to quantify the rate of global warming, WMO said. Conservationists said the UN agency’s findings were to be expected. “It is no surprise that 2019 was the second hottest year on record – nature has been persistently reminding us that we have to pick up the pace,” said Manuel Pulgar-Vidal, leader of WWF’s global climate and energy practice, calling for dramatic measures to halt the warming...
New climate models suggest Paris goals may be out of reach

New climate models suggest Paris goals may be out of reach

SOURCE: Phys.Org DATE: January 14, 2020 SNIP: New climate models show carbon dioxide is a more potent greenhouse gas than previously understood, a finding that could push the Paris treaty goals for capping global warming out of reach, scientists have told AFP. Developed in parallel by separate teams in half-a-dozen countries, the models—which will underpin revised UN temperature projections next year—suggest scientists have for decades consistently underestimated the warming potential of CO2. Vastly more data and computing power has become available since the current Intergovernmental Panel on Climate Change (IPCC) projections were finalised in 2013. “We have better models now,” Olivier Boucher, head of the Institut Pierre Simon Laplace Climate Modelling Centre in Paris, told AFP, adding that they “represent current climate trends more accurately”. The most influential projections from government-backed teams in the US, Britain, France and Canada point to a future in which CO2 concentrations that have long been equated with a 3C world would more likely heat the planet’s surface by four or five degrees. For more than a century, scientists have puzzled over a deceptively simple question: if the amount of CO2 in the atmosphere doubles, how much will Earth’s surface warm over time? The resulting temperature increase is known as Earth’s “climate sensitivity”. That number has been hard to pin down due to a host of elusive variables. Whether oceans and forests, for example, will continue to absorb more than half of the CO2 emitted by humanity is hard to predict. “How clouds evolve in a warmer climate and whether they will exert a tempering or amplifying effect has long been a major source...