Nearly half a billion years ago, there was a huge explosion of species development on Earth, causing the biodiversity of animals to increase dramatically -- but the true cause of that event has remained a mystery.
In a new paper published on Wednesday in Science Advances, scientists show that the event's onset coincided with the largest documented asteroid breakup in the asteroid belt over the past two billion years.
That breakup, which was triggered by a collision with another asteroid or comet, would have spread enormous amounts of dust throughout the solar system.
"The blocking effect of this dust could have partly stopped sunlight from reaching the Earth – leading to cooler temperatures," the study's co-author Birger Schmitz, a professor of nuclear physics at Lund University, writes in The Conversation. "We know that this involved the climate changing from being more or less homogeneous to becoming divided into climate zones – from Arctic conditions at the poles to tropical conditions at the equator. The high diversity among invertebrates, including green algae, primitive fish, cephalopods and corals, came as an adaptation to the new climate."
Schmitz and his colleagues also studied the distribution of very fine-grained, extremely tiny dust in the sediment, determining its extraterrestrial origin by discovering helium and other substances inside the sediments.
"Our results clearly show that enormous amounts of fine-grained dust reached Earth shortly after the breakup," writes Schmitz.
I think about things that maybe most people wouldn't worry about. We live in a violent universe. Earth recently had a near-miss with a bus-sized asteroid that could have wiped out a major city with a ten megaton blast. However, chances are it would have just exploded over an ocean someplace. It is unlikely to hit a city. However, there are also more asteroids out there.
The last time the supervolcano in Yellowstone National Park erupted 640,000 years ago, it destroyed life in several nearby states. By comparison, this makes the asteroid look like small potatoes. These explosions are so big they create their own weather over hundreds of miles. We are "overdue" for another eruption, which could wipe out half the country, but the experts say that it will not happen any time soon. I heard that NASA is trying to find a way to relieve some of the pressure below the park.
In 535 AD, multiple volcanic eruptions, and possibly a supervolcano, blackened out the sky everywhere on earth, creating an 18-month winter.
A couple of times in Earth's history the whole planet froze solid with a layer of ice a mile thick.
Over hundreds of millions of years, there have been several mass extinctions on planet Earth. At least one may have been caused by a gamma-ray burst. Gamma-ray bursts are massive amounts of deadly radiation from space given off by black hole formation. Although such events hitting Earth are extremely rare, they have the potential to wipe out all life on Earth.
The Earth was hit by an object the size of the planet Mars 4.5 billion years ago. This is how we got the Moon, which is made of material from the Earth's crust.
These catastrophic events are fortunately very rare.
We have been technically living in an ice age for 2.5 million years. There have been several periods of massive glaciation in human history. These usually had devastating effects on the human population. The human race was almost wiped out 50,000 years ago. All of human civilization, such as farming, writing, working with metals, building cities, occurred during a "brief" 10,000 year warm period after the last period of glaciation. We have been fortunate to live in a "brief" time of very stable climate. No matter what humans do with CO2, and we are going to run out of fossil fuels in 100 years anyway, we expect another period of glaciation 10,00 years from now.
The Earth's orbit around the sun is not entirely stable. The slow precession of the orbit causes dramatic effects on the climate.
Although you could argue that rising CO2 is an issue in the short run, over the long term the decline of CO2 has been very dramatic and looks very bleak. Over the last 40 million years atmospheric CO2 levels have been in a nosedive. This is because natural processes sequester CO2 in the ground. During the last period of glaciation, CO2 levels got down to a record low of 180 parts per million, which is just barely above the level where all terrestrial plants die off from a lack of CO2. If humans are around for another 10,000 years then we will have to deal with this problem.
How exactly did great-power competitiongo from being an "arcane term" a few years ago to "approaching a cliché"?
The pork industry is worth about $128 billion in China and the country's 375 million pigs make up just under half the planet's total.
The number of pigs China will fatten to prepare for slaughter and sale this year is predicted to fall by 20%, from 2018. This is the worst annual slump since the U.S. Department of Agriculture — interested in exports to China — began counting China's pigs in the mid-1970s.
The virus spreads easily among the animals as it can be carried in clothing, infected blood, or fluids from urine, saliva or faeces, and on tires and shoes.
There are concerns that Chinese provincial governments are suppressing data and asking pork companies not to report new outbreaks
The pig flu was first detected outside Africa in 1957, in Portugal, but never before has it spread so rapidly and been so damaging as it did in China now. All of the 33 provinces and regions in China have been affected.
Other countries are battling the outbreak. The disease has been found in Mongolia, Cambodia and North Korea. The UN Food and Agriculture Organization believes that cases reported by local governments are underestimates
This outbreak was first detected in China in August 2018 in Liaoning province in the northeast. The Ministry of Agriculture and Rural Affairs immediately responded with emergency measures.
According to guidelines, all pigs in a three kilometer zone around an infected herd had to be killed. Roadblocks were meant to be set up and inspection and disinfection stations established within a 10-kilometer buffer zone. This was not strictly implemented.
Pork is the meat of choice in China and no meal is complete without it. Braised in sauce, as Mao Zedong demanded, in dumplings or just plainly fried or boiled, pork accounts for nearly three-quarters of Chinese meat consumption.
Pig rearing in China, despite large industrialized farms, remains a predominately small-scale affair. Pigs also provide cheap garbage disposal services.