When are extreme events part of natural climate variability and when are they due to climate change? It’s important to ask—no matter where you stand on the role of humanity’s impact on the environment.

A group of international scientists decided to address this question, focusing on a dozen or so extreme events from 2012. Their results were published last week in the Bulletin of the American Meteorological Society. (The findings are also available in a downloadable report.)

And the results, were, well, variable.

The researchers did not look at Hurricane Sandy, but they did examine the flooding and the inundation it caused. Because of sea-level rise (a direct result of climate change), the researchers determined that the superstorm did far greater damage than it would have with oceans at normal levels.

The team also determined that heavy rains in the United Kingdom, Japan, and China were not due to global warming, and Australia’s above-average rainfall was due to a La Niña event (or short-term climate variability).

However, a deluge in New Zealand was due to climate change. From Wired:

Total moisture available for this extreme event was 1% to 5% higher as a result of anthropogenic greenhouse gas emissions.

And Arctic sea ice melt? The cap of sea ice covering the North Pole shrunk to its smallest extent last summer. The cause? Climate change.

What about last year’s devastating drought in the Midwest? Scientists judged that climate variability was to blame—not global warming.

However, Stanford researchers did find that the extreme heat that came with last summer’s drought could be attributed to climate change. They also found strong evidence that the high levels of greenhouse gases now in the atmosphere have increased the likelihood of severe heat.

In addition, their findings indicate that extreme weather in the north-central and northeastern United States is more than four times as likely to occur than it was in the pre-industrial era.

The Palo Alto scientists hope the results from these studies can help to quantify the true cost of emissions to society, since the cost of the disaster is measurable.

“Knowing how much our emissions have changed the likelihood of this kind of severe heat event can help us to minimize the impacts of the next heat wave, and to determine the value of avoiding further changes in climate,” says lead author Noah Diffenbaugh, a Stanford associate professor of environmental Earth system science.

Image: Theresa L Wysocki/Flickr

Did you feel a small tremor rumbling underground last fall? Seismometers as far west as Seattle lit up on October 30. But the source of the recorded energy didn’t come from an earthquake. It came from Superstorm Sandy, an extreme hurricane that hit the East Coast thousands of miles away. What the…?

At the recent Seismological Society of America’s annual meeting, researchers presented their findings on seismic waves that are triggered by large storms and sometimes cause the ground at great distances to shake.

In the case of Sandy, the shaking was partly caused by the actual waves hitting the mid-Atlantic coastline. Of greater consequence were the waves colliding with other waves in the ocean, setting up a pattern of “standing waves” that reach the seafloor and transmit their energy. That force becomes seismic waves that travel through the crust and upper mantle under North America.

“They are not earthquakes; they are seismic waves,” says Keith Koper, director of the University of Utah Seismograph Stations. “Seismic waves can be created by a range of causes. We have beautiful seismic records of the meteor that hit Russia. That’s not an earthquake, but it created ground motion.”

Earthquakes, storms, and meteors are only three causes of seismic waves. Seismic activity can also occur from mining, traffic, construction, and even elephants communicating.

At the same meeting, researchers presented findings that Hurricane Irene may have caused aftershocks to a 5.8 magnitude earthquake in Virginia in 2011.

This isn’t the first time large storms have been linked to seismic waves, Koper adds. “Hurricane Katrina in 2005 was recorded by a seismic array in California, and they could track the path of the storm remotely using seismometers.”

Image: Keith Koper, University of Utah Seismograph Stations

Weather on Uranus

Twenty-six years ago, when Voyager 2 took this image of Uranus, scientists were disappointed by the seemingly smooth surface of the distant planet. But earlier this week, astronomers displayed a wholly different picture (see right) of Uranus—sultry and stormy!

It took the Earth-based Keck Observatory to capture what Voyager 2 couldn’t, despite being only 50,000 miles from Uranus in 1986. Keck took sharp, high-resolution infrared images showing bizarre weather on the sideways planet.

The planet’s deep blue-green atmosphere is thick with hydrogen, helium and methane. Winds blow mainly east to west at speeds up to 560 miles per hour, in spite of the small amounts of energy available to drive them.

Scientists believe that the primary driving mechanism for these storms must be solar energy because there is no detectable internal energy source. “But the Sun is 900 times weaker there than on Earth because it is 30 times further from the Sun, so you don’t have the same intensity of solar energy driving the system,” says planetary scientist Larry Sromovsky. That might explain why storms on Uranus are much less violent than those on Earth.

Sromovsky and colleagues announced their findings this week at a meeting of the American Astronomical Society’s Division of Planetary Sciences.

What were you thinking?

That’s what we would like to ask local Russ George. This week, several news outlets report how George dumped 100 tons of iron into the Pacific Ocean off the British Columbia coast illegally.

George has a history of geoengineering attempts like this one. This time a native Canadian group hired him to reduce carbon in the ocean to boost dwindling salmon populations. If you recall from a story we ran last summer about this technique, iron can feed algal blooms, which then sink to the ocean floor, sequestering carbon as they do.

But tampering with the ocean like this is obviously dangerous and highly regulated. According to the New York Times, George dumped ten times as much iron as the experiment mentioned in our story and violated two international agreements on geoengineering.

Tigers, Detroit and otherwise

Even before Detroit finished New York off in the American League Championship Series on Thursday, talks of trading Yankee star Alex Rodriguez were rampant.

His post-season performance was so bad, he was benched for the last two games. And we all know how much the Yanks like to win. But A-Rod’s contract looks to be a losing proposition for the team—even if they are able to unload him, they’ll likely have to pick-up part of his remaining salary. Which is huge, according to ESPN,

Rodriguez, who will turn 38 next July, is signed for the next five years and guaranteed another $114 million.

In addition, his contract includes a marketing agreement with the Yankees that could add as much as $30 million to the deal…

Such a waste. If you’ll remember, a couple of years ago we discussed how his large salary could help save wild tigers. Who could use his help right about now. The Guardian reports that an Indian court lifted a ban on tourism in tiger reserves this week. Officials are hoping tourists and the tiger habitats can co-exist. Hopefully they have more luck co-existing than A-Rod and the Yankees.

Image: Lawrence Sromovsky, Pat Fry, Heidi Hammel, Imke de Pater

We’ve reported on solar storms before, especially NOAA’s and NASA’s urge to prepare and educate agencies and individuals as we head into the solar maximum.

When a solar flare and coronal mass ejection (CME) erupted from the Sun around 9:00 p.m. PDT on January 23, satellites captured the events in stunning detail. The Bad Astronomer offers a great video and description of the events and their power on his Discover blog.

These massive storms affect us here on Earth in many different ways, both beautiful and bad. The beautiful? Aurorae in stunning detail and farther reaches than usual. Universe Today offers two articles on aurora cause and effect; the Geophysical Institute offers a forecast and locations to view the displays.

The bad? Power surges and outages, satellite and radio communication interruptions, even exposure to radiation for astronauts. Luckily, as solar storms go, this recent one is only reaching G1 levels on NOAA’s storm scale—G5 is the highest.

Still, there were reports of a power surge in Norway yesterday and news of airline companies rerouting polar flights to avoid disruptions of aircraft communications.

With satellites such as NASA’s SDO and SOHO constantly gathering data on the Sun from every angle and NOAA interpreting the data for the general public, it appears that the news outlets were ready for anything. Score one for preparedness!

Image: SDO/NASA

With the AGU meeting in town, it was a great week for science news! We covered several topics on Tuesday, Wednesday, and Thursday—and we’ll highlight a few more of them here for you.

Monday’s sessions included several discussions about the 2011 Tohoku tsunami in Japan—its effects on the local population and on far-reaching areas as well as how we can forecast future events.

One of the biggest surprises came during a presentation by Satoko Oki of the Earthquake Research Institute. She collected data from Japanese residents before and after the 2011 tsunami and found them less prepared for tsunamis after the Tohoku hit! When polled post 2011, they misidentified the minimum wave height from which to evacuate. They had correctly identified the minimum height less than a year before. The 80beats blog in Discover identifies the problem succinctly:

The Tohoku tsunami was so large–about 130 feet–that it may have dragged people’s expectations of what’s dangerous higher.

Another presentation revealed why the tsunami was so devastating—it was a “merging tsunami.” NASA researchers found that the tsunami doubled in intensity over rugged ocean ridges, amplifying its destructive power at landfall. This animation on NASA’s website illustrates the direction and power quite well.

The discovery helps explain how tsunamis can cross ocean basins to cause massive destruction at some locations while leaving others unscathed. The data raise hope that scientists may be able to improve tsunami forecasts.

Switching perspective from the oceans to outer space… NASA and NOAA held a joint workshop Tuesday on preparing for the solar max. As solar storms increase over the next 20 months or so, we can be prepared for what might and might not happen. This might remind you of a press briefing held earlier this year at the AAAS meeting that we covered here. It certainly reminded us how active the Sun can be, even during quiet times, as shown in this beautiful NASA video of SDO’s first year in space.

Finally, the Academy’s own Peter Roopnarine presented at the meeting on his research on oysters in the Gulf of Mexico. With colleagues, Peter has been testing for contaminants in the shells of oysters before and after the spill and hopes to model the spread of contaminants to other species through the food web. Check out this Science in Action video to learn more.

Image: Samuel Morse/US Air Force/Wikipedia

But what about the opposite? The US Geological Survey had a conference and issued a press release this month about preparing for severe flooding in our state. Flooding that could cause more damage and be even deadlier than a large earthquake.

What the what? How is this possible?

Atmospheric rivers, my friend, atmospheric rivers.

According to NOAA:

Atmospheric Rivers are narrow corridors of concentrated moisture in the atmosphere and are a key process linking weather and climate. When atmospheric rivers strike land, they produce flooding rains that can disrupt travel, induce mud slides, and cause catastrophic damage to life and property.

The USGS goes on to say that atmospheric rivers are:

a hurricane-like phenomenon that occurs on the west coast.

And the Sacramento Bee defines the phenomenon this way:

a focusing of high-powered winds that drag a fire hose of tropical moisture across the Pacific Ocean, pointed directly at California for days on end.

The big, wet storms we had in northern and southern California in December were due to a series of atmospheric rivers, but apparently only a tame series.

It can get much worse, says USGS,

Beginning on Christmas Eve, 1861, and continuing into early 1862, an extreme series of storms lasting 45 days struck California. The storms caused severe flooding, turning the Sacramento Valley into an inland sea. A storm comparable to that of 1861-1862 could occur again.

“We think this event happens once every 100 or 200 years or so, which puts it in the same category as our big San Andreas earthquakes,” stated Lucy Jones, chief scientist of the USGS Multi-Hazards Demonstration Project, in the recent press release.

To prepare for a storm of this magnitude and greater, USGS has created a model scenario called ARkStorm. The scenario estimates that California’s flood protection system would be overwhelmed and more than $300 billion in damage would result. That could be worse than a large earthquake.

Being prepared is the key.

“The time to begin taking action is now, before a devastating natural hazard event occurs,” said USGS Director, Marcia McNutt. “This scenario demonstrates firsthand how science can be the foundation to help build safer communities. The ARkStorm scenario is a scientifically vetted tool that emergency responders, elected officials and the general public can use to plan for a major catastrophic event to help prevent a hazard from becoming a disaster.”

Image of Sacramento in early 1862 courtesy of the Center for Sacramento History