Student climate protests snowballing

Thousands of Belgian students skipped classes for the fourth week in a row on Thursday to protest against global warming, part of a growing youth protest around the world.

Beating drums, chanting and carrying signs, some 30,000 teenagers braved the cold in Brussels and other cities to call on local politicians for stronger action to prevent climate change.

“It’s our planet and the generation before us hasn’t done anything,” said Julian Rume, 17. “In 20, 30 years, we will all be migrants, we’ll all be moved out of our planet.”

The demonstrations are part of a broader grassroots movement started by Swedish student Greta Thunberg, 16, last year.

Students in Germany, Switzerland, France and Australia have followed her lead and also skipped classes to protest.

Thunberg took her protest to this month’s World Economic Forum in Davos to galvanize leaders meeting there to action.

[Reuters]

Why more snow with climate change?

Extreme winter weather often prompts a fresh wave of public skepticism from those who doubt the existence or severity of human-caused climate change. When the Northeast USA received 2 feet of snow earlier this month, President Trump tweeted, “Wouldn’t be bad to have a little of that good old fashioned Global Warming right now!”

As experts point out, short-term variations in the weather—even when they result in extreme snowfall or record-breaking cold—don’t negate the long-term trend of global warming. Decades of data unambiguously demonstrate that average temperatures all over the world are on the rise.

But when it comes to winter weather, and specifically snow, teasing out the effects of climate change is a special challenge. It seems as though snow—arguably the most iconic feature of a cold climate—should be one of the most obvious indicators of global warming. But scientists are finding that it’s not that simple.

Climate change has conflicting influences on snow. In many places, rising temperatures may increase the chances that snow will turn to rain before it hits the earth or that it will melt faster once it’s on the ground. On the other hand, warmer air is capable of holding more moisture and producing more precipitation. That means in some very cold climates, where there’s still plenty of room for temperatures to stay below freezing, warming could actually cause an increase in snow.

Scientists broadly agree that snow will change in most places as the climate continues to warm, said David Robinson, New Jersey’s state climatologist and head of the Rutgers University Global Snow Lab. But exactly how and why, from one location to the next, may be among the most challenging questions about weather and climate change.

A paper published last March found that about a third of all monitoring sites in the western United States are showing significant snowpack declines and that the total amount of water stored in the average April snowpack has declined by 21 percent since 1915. A 2011 paper said the recent declines are likely the most dramatic the region has seen for a thousand years.

A 2016 analysis of satellite records also pointed to a broad pattern of decreasing snow cover across the Northern Hemisphere, particularly in the spring, with the strongest effects seen in western North America and Eurasia.

But the researchers note that the coldest parts of North America—namely, Canada and parts of the northern United States—might be expected to actually see an increase in the amount of snow.

Gerard van der Schrier, a scientist with the Royal Netherlands Meteorological Institute, says that two seemingly conflicting snow trends can be true at the same time. Some of van der Schrier’s research published last year found widespread declines in snow depth across much of Europe. But in the very coldest places, he pointed out, the opposite appears to be true.

[Scientific American, as reprinted from Climatewire]

How climate change leads to colder winters

A record-breaking cold snap is relentlessly descending on parts of the U.S. this month. In a time when climate change is discussed in the context of record highs, droughts, and wildfires, cold weather and blizzards can seem out of place. For those who deny that climate change is happening, it’s an opportunity to undermine scientific consensus.

How do you explain a cold winter in a world that scientists say is getting hotter?

First, it’s important to understand the difference between climate and weather. Climate is defined as the average weather patterns in a region over a long period of time. Each of these climate regions experiences day-to-day fluctuations in temperature, precipitation, air pressure, and so on—daily variations known as weather.

When the term “global warming” was popularized a few decades ago, it referred to the phenomenon of greenhouse gases trapping heat in the atmosphere and warming the average temperature of the planet. Though record high temperatures in many places have been one impact of this decades-long shift, scientists now understand that an atmosphere changed by rising levels of gases like carbon and methane leads to more climate changes than just warming. Scientists believe Earth will experience more extreme, disastrous weather as the effects of climate change play out.

In response to President Trump’s January 20 tweet about cold temperatures, Potsdam University physicist Stefan Rahmstorf noted on Twitter that, while North America was experiencing cold Arctic air, the rest of the world was abnormally hot. And, the polar vortex bringing that cold air to the U.S. may actually become increasingly unstable, Rahmstorf noted. As more Arctic air flows into southern regions, North America can expect to see harsher winters. That was the conclusion of a study published in 2017 in the journal Nature Geoscience.

Record cold temperatures and blizzards aren’t the only extreme weather patterns expected… floods [will] last longer and droughts become more persistent. One study published in Science Advances last October predicted extreme, deadly weather events could increase by as much as 50 percent by 2100. Scientists have already found climate change contributed to California’s historic, deadly wildfires and powerful, destructive hurricanes.

[National Geographic]