Global warming will cause ecosystems to produce more methane than first predicted

Global warming will cause ecosystems to produce more methane than first predicted

SOURCE: University of London, Nature Climate Change DATE: June 29, 2020 SNIP: New research suggests that as the Earth warms natural ecosystems will release more of the greenhouse gas methane than expected from predictions based on temperature increases alone. The study, published today in Nature Climate Change, attributes this difference to changes in the balance of microbial communities within ecosystems that regulate methane emissions. The production and removal of methane from ecosystems is regulated by two types of microorganisms, methanogens – which naturally produce methane – and methanotrophs that remove methane by converting it into carbon dioxide. Previous research has suggested that these two natural processes show different sensitivities to temperature and could therefore be affected differently by global warming. Research led by Queen Mary University of London and the University of Warwick studied the impact of global warming on freshwater microbial communities and methane emissions by observing the effect of experimental warming of artificial ponds over 11 years. They found that warming produced a disproportionate increase in methane production over methane removal, resulting in increased methane emissions that exceeded temperature-based predictions. Professor Mark Trimmer, Professor of Biogeochemistry at Queen Mary, said: “Our observations show that the increase in methane emissions we see is beyond what you could predict based on a simple physiological response to the temperature increase.” Dr Kevin Purdy, Associate Professor of Microbial Ecology at Warwick, added: “Our studies have led to a better understanding of how global warming can affect methane emissions from freshwaters. This means that future predictions of methane emissions need to take into account how ecosystems and their resident microbial communities will...
Climate worst-case scenarios may not go far enough, cloud data shows

Climate worst-case scenarios may not go far enough, cloud data shows

SOURCE: The Guardian DATE: June 13, 2020 SNIP: Worst-case global heating scenarios may need to be revised upwards in light of a better understanding of the role of clouds, scientists have said. Recent modelling data suggests the climate is considerably more sensitive to carbon emissions than previously believed, and experts said the projections had the potential to be “incredibly alarming”, though they stressed further research would be needed to validate the new numbers. Modelling results from more than 20 institutions are being compiled for the sixth assessment by the United Nations Intergovernmental Panel on Climate Change, which is due to be released next year. Compared with the last assessment in 2014, 25% of them show a sharp upward shift from 3C to 5C in climate sensitivity – the amount of warming projected from a doubling of atmospheric carbon dioxide from the preindustrial level of 280 parts per million. This has shocked many veteran observers, because assumptions about climate sensitivity have been relatively unchanged since the 1980s. “That is a very deep concern,” Johan Rockström, the director of the Potsdam Institute for Climate Impact Research, said. “Climate sensitivity is the holy grail of climate science. It is the prime indicator of climate risk. For 40 years, it has been around 3C. Now, we are suddenly starting to see big climate models on the best supercomputers showing things could be worse than we thought.” He said climate sensitivity above 5C would reduce the scope for human action to reduce the worst impacts of global heating. “We would have no more space for a soft landing of 1.5C [above preindustrial levels]. The...
US south-west in grip of historic ‘megadrought’

US south-west in grip of historic ‘megadrought’

SOURCE: The Guardian DATE: May 29, 2020 SNIP: When Ken Pimlott began fighting US wildfires at the age of 17, they seemed to him to be a brutal but manageable natural phenomenon. “We had periodic [fire] sieges in the 80s, but there were breaks in between,” said Pimlott, the former head of the California department of forestry and fire protection. But no longer. “That doesn’t really happen any more. Now you can’t even blink” between fires, he said. “We’re seeing the kinds of fires we have never seen before.” A recent study published in the journal Science helps explains why, revealing that the south-western US is in the grip of a 20-year megadrought – a period of severe aridity that is stoking fires, depleting reservoirs and putting a strain on water supplies to the states of the region. “You see impacts everywhere, in snowpacks, reservoir levels, agriculture, groundwater and tree mortality,” said co-author Benjamin Cook, of Columbia University’s Lamont Doherty Earth Observatory. “Droughts are these amazingly disruptive events. Water sits at the foundation of everything.” Researchers compared soil moisture records from 2000-2019 to other drought events from the past 1,200 years. They found that the current period is worse than all but one of five megadroughts identified in the record. Unlike past megadroughts – brought on by natural fluctuations in the Earth’s climate – this current drought has been heavily influenced by human-induced climate change, “pushing what would have been a moderate drought in south-western North America into megadrought territory”, according to the study. “Global warming has made the drought much worse than it otherwise would have been,” said...
Millions More Americans Will Face Climate Disasters with Warming

Millions More Americans Will Face Climate Disasters with Warming

SOURCE: Scientific American DATE: May 11, 2020 SNIP: Roughly one-third of the U.S. population—or 118 million Americans—could feel one or more extreme weather events annually by 2050 if population and greenhouse gas emissions continue to rise, new research from the Energy Department’s Oak Ridge National Laboratory shows. That more than doubles the 47 million Americans who currently experience extreme heat and cold, prolonged droughts, and intensifying floods. And it reflects the greater frequency of climate disasters nationwide, the researchers said. The findings, published in Earth’s Future, a journal of the American Geophysical Union, are based on supercomputer simulations of county-level data from NOAA’s Climate Extremes Index, or CEI. It also provides one of the most granular analyses to date of projected climate change impacts on the United States, the researchers said. With no population increase, the analysis estimates that 94 million Americans would face one or more extreme climate events annually by midcentury. That’s 20% fewer Americans than under the population growth scenario but still double the 47 million people currently experiencing climate...
50 Years From Now, Many Densely Populated Parts of the World Could be Too Hot for Humans

50 Years From Now, Many Densely Populated Parts of the World Could be Too Hot for Humans

SOURCE: Inside Climate News DATE: May 4, 2020 SNIP: By 2070, the world’s habitable climate zone will shift so much that billions of people will be pushed past human comfort levels. A new study published Monday in the Proceedings of the National Academy of Sciences shows a “surprisingly narrow” human climate niche—between 52 degrees Fahrenheit to 59 degrees Fahrenheit. And it will shift geographically more in the next 50 years than any time during the past 6,000 years. As a result, up to 3 billion people are “likely to live under climate conditions that are warmer than conditions deemed suitable for human life to flourish,”, the international team of researchers wrote. Los Angeles and Paris will bake in fiery desert temperatures, and the world’s most populous cities in Asia and Africa will have deadly heat waves every year. “It looks unlivable for many,” said co-author Tim Lenton, director of the Global Systems Institute at the University of Exeter. “Where we are headed is a place we don’t want to go.” Some cities in North America and Europe that are now in the sweet spot of the human climate zone, with mean annual temperatures from 64 degrees and 68 degrees Fahrenheit, will be as warm as the North African coast by late in the century, Lenton said. “That’s quite a climate shock. We’re going back to temperatures that we haven’t seen for 5 million years, territory that predates the divergence of humans from apes,” he said. Compounding the climate problem for humans is that the greatest population growth is expected exactly in those zones most affected by human-caused warming. If...