Climate Change ☀️
Carbon uptake in regrowing Amazon forest threatened by climate and human disturbance
Large areas of forests regrowing in the Amazon to help reduce carbon dioxide in the atmosphere, are being limited by climate and human activity.

The forests, which naturally regrow on land previously deforested for agriculture and now abandoned, are developing at different speeds. Researchers at the University of Bristol have found a link between slower tree-growth and land previously scorched by fire.
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Australia’s Worst Floods in Decades Quicken Concerns About Climate Change
Two massive storms have converged over eastern Australia, dumping more than three feet of rain in just five days. In a country that suffered the worst wildfires in its recorded history just a year ago, the deluge has become another record-breaker — a once-in-50-years event, or possibly 100, depending on the rain that’s expected to continue through Tuesday night.

Nearly 20,000 Australians have been forced to evacuate, and more than 150 schools have been closed. The storms have swept away the home of a couple on their wedding day, prompted at least 500 rescues and drowned roads from Sydney up into the state of Queensland 500 miles north.

... Scientists note that both forms of catastrophe represent Australia’s new normal. The country is one of many seeing a pattern of intensification — more extreme hot days and heat waves, as well as more extreme rainfalls over short periods.

It’s all tied to a warming earth, caused by greenhouse gases. Because global temperatures have risen 1.1 degrees Celsius, or about 2 degrees Fahrenheit, over preindustrial levels, landscapes dry out more quickly, producing severe droughts, even as more water vapor rises into the atmosphere, increasing the likelihood of extreme downpours.

“There is a very strong link between global warming and that intensification in rainfall,” said Andy Pitman, director of the ARC Center of Excellence for Climate Extremes at the University of New South Wales. “There’s good scientific evidence to say extreme rain is becoming more extreme due to global warming.”

Australia’s conservative government — heavily resistant to aggressive action on climate change that might threaten the country’s fossil fuel industry — has yet to make that link.
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New porous material promising for making renewable energy from water
One prospective source of renewable energy is hydrogen gas produced from water with the aid of sunlight. Researchers have developed a material, nanoporous cubic silicon carbide, that exhibits promising properties to capture solar energy and split water for hydrogen gas production.

Hydrogen has an energy density three times that of petrol. It can be used to generate electricity using a fuel cell, and hydrogen-fuelled cars are already commercially available. When hydrogen gas is used to produce energy, the only product formed is pure water. In contrast, however, carbon dioxide is created when the hydrogen is produced, since the most commonly used technology used today depends on fossil fuels for the process. Thus, 9-12 tonnes of carbon dioxide are emitted when 1 tonne of hydrogen gas is produced.

Producing hydrogen gas by splitting water molecules with the aid of solar energy is a sustainable approach that could give hydrogen gas using renewable sources without leading to carbon dioxide emissions. A major advantage of this method is the possibility to convert solar energy to fuel that can be stored.

"Conventional solar cells produce energy during the daytime, and the energy must either be used immediately, or stored in, for example, batteries. Hydrogen is a promising source of energy that can be stored and transported in the same way as traditional fuels such as petrol and diesel," says Jianwu Sun.
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Arctic methane release due to melting ice is likely to happen again
Beneath the cold, dark depths of the Arctic ocean sit vast reserves of methane. These stores rest in a delicate balance, stable as a solid called methane hydrates, at very specific pressures and temperatures. If that balance gets tipped, the methane can get released into the water above and eventually make its way to the atmosphere. In its gaseous form, methane is one of the most potent greenhouse gases, warming the Earth about 30 times more efficiently than carbon dioxide. Understanding possible sources of atmospheric methane is critical for accurately predicting future climate change.

In the Arctic Ocean today, ice sheets exert pressure on the ground below them. That pressure diffuses all the way to the seafloor, controlling the precarious stability in seafloor sediments. But what happens when the ice sheets melt?
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What early-budding trees tell us about genetics, climate change
Late frosts have caused millions of dollars in losses for orchards over the years. Scientists are investigating the genes that tell trees when to bud out and blossom. A deep understanding of the genetics of bud-break enables scientists to modify or select crop varieties more resilient to late frost, warming winters, diseases and pests.

One of the surest signs of spring is the vibrantly lime-green tinge trees develop as their buds open and tiny new leaves unfurl. Bud-break is the scientific name for this process -- a straightforward term for the grand genetic mechanism that allows trees to leaf out and do their summer work of photosynthesis to store up energy for the coming winter.

Bud-break is precluded by bud-set, which occurs in the autumn. After trees have dropped their leaves and as the days shorten and grow colder, new buds grow on branches. Like many wildflowers, trees require a period of dormancy at colder temperatures -- a process fine-tuned by evolution -- before bud-break can occur.

But as the changing climate becomes increasingly unpredictable, late frosts are more common -- and many trees initiate bud-break too early or too late. For farmers who grow fruit- and nut-bearing trees as well as grape vines, a mistimed bud-break and a frost could mean the difference between a good harvest and none at all.
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Explosive origins of 'secondary' ice and snow
Where does snow come from? This may seem like a simple question to ponder as half the planet emerges from a season of watching whimsical flakes fall from the sky -- and shoveling them from driveways. But a new study on how water becomes ice in slightly supercooled Arctic clouds may make you rethink the simplicity of the fluffy stuff. The study, published by scientists from the U.S. Department of Energy's (DOE) Brookhaven National Laboratory in the Proceedings of the National Academy of Sciences, includes new direct evidence that shattering drizzle droplets drive explosive "ice multiplication" events. The findings have implications for weather forecasts, climate modeling, water supplies -- and even energy and transportation infrastructure.

Precipitating snow from supercooled clouds usually originates from "primary" ice particles, which form when water crystallizes on select tiny specks of dust or aerosols in the atmosphere, known as ice-nucleating particles. However, at slightly supercooled temperatures (i.e., 0 to -10°C), aircraft observations have shown that clouds can contain far more ice crystals than can be explained by the relatively few ice-nucleating particles present. This phenomenon has puzzled the atmospheric research community for decades. Scientists have thought that the explanation is "secondary" ice production, in which the additional ice particles are generated from other ice particles. But catching the process in action in the natural environment has been difficult.

Previous explanations for how secondary ice forms relied mainly on laboratory experiments and limited, short-term aircraft-based sampling flights. A common understanding that came out of several lab experiments was that relatively big, fast-falling ice particles, called rimers, can "collect" and freeze tiny, supercooled cloud droplets -- which then produce more tiny ice particles, called splinters. But it turns out that such "rime splintering" isn't nearly the whole story.

The new results from the Arctic show that larger supercooled water droplets, classified as drizzle, play a much more important role in producing secondary ice particles than commonly thought.
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Climate change, periodic modification of Earth’s climate brought about as a result of changes in the atmosphere as well as interactions between the atmosphere and various other geologic, chemical, biological, and geographic factors within the Earth system.

Source: Climate change - Evidence for climate change | Britannica
Climate Change is the defining issue of our time and we are at a defining moment. From shifting weather patterns that threaten food production, to rising sea levels that increase the risk of catastrophic flooding, the impacts of climate change are global in scope and unprecedented in scale. Without drastic action today, adapting to these impacts in the future will be more difficult and costly.

Source: Climate Change | United Nations