- Climate change
Image source, Frans Lemmens
Scientists and politicians say we are facing a planetary crisis because of climate change.
But what’s the evidence for global warming and how do we know it’s being caused by humans?
How do we know the world is getting warmer?
Our planet has been warming rapidly since the dawn of the Industrial Revolution.
The average temperature at the Earth’s surface has risen about 1.1C since 1850. Furthermore, each of the last four decades has been warmer than any that preceded it, since the middle of the 19th Century.
These conclusions come from analyses of millions of measurements gathered in different parts of the world. The temperature readings are collected by weather stations on land, on ships and by satellites.
Multiple independent teams of scientists have reached the same result – a spike in temperatures coinciding with the onset of the industrial era.
Image source, ReutersImage caption, Turkey was one of the places hit by devastating wildfires this summer
Scientists can reconstruct temperature fluctuations even further back in time.
Tree rings, ice cores, lake sediments and corals all record a signature of the past climate.
This provides much-needed context to the current phase of warming. In fact, scientists estimate the Earth hasn’t been this hot for about 125,000 years.
How do we know humans are responsible for global warming?
Greenhouse gases – which trap the Sun’s heat – are the crucial link between temperature rise and human activities. The most important is carbon dioxide (CO2), because of its abundance in the atmosphere.
We can also tell it’s CO2 trapping the Sun’s energy. Satellites show less heat from the Earth escaping into space at precisely the wavelengths at which CO2 absorbs radiated energy.
Burning fossil fuels and chopping down trees lead to the release of this greenhouse gas. Both activities exploded after the 19th Century, so it’s unsurprising that atmospheric CO2 increased over the same period.
Image source, Getty Images
There’s a way we can show definitively where this extra CO2 came from. The carbon produced by burning fossil fuels has a distinctive chemical signature.
Tree rings and polar ice both record changes in atmospheric chemistry. When examined they show that carbon – specifically from fossil sources – has risen significantly since 1850.
Analysis shows that for 800,000 years, atmospheric CO2 did not rise above 300 parts per million (ppm). But since the Industrial Revolution, the CO2 concentration has soared to its current level of nearly 420 ppm.
Computer simulations, known as climate models, have been used to show what would have happened to temperatures without the massive amounts of greenhouse gases released by humans.
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They reveal there would have been little global warming – and possibly some cooling – over the 20th and 21st Centuries, if only natural factors had been influencing the climate.
Only when human factors are introduced can the models explain increases in temperature.
Image source, Getty ImagesImage caption, The number of weather-related disasters has increased by a factor of five over 50 yearsWhat impact are humans having on the planet?
The level of heating Earth has experienced already is predicted to cause significant changes to the world around us.
Real-world observations of these changes match patterns scientists expect to see with human-induced warming. They include:
- The Greenland and Antarctic ice sheets melting rapidly
- The number of weather-related disasters has increased by a factor of five over 50 years
- Global sea levels rose 20cm (8ins) in the last century and are still rising
- Since the 1800s, the oceans have become about 40% more acid, affecting marine life
But wasn’t it warmer in the past?
There have been several hot periods during the Earth’s past.
Around 92 million years ago, for example, temperatures were so high that there were no polar ice caps and crocodile-like creatures lived as far north as the Canadian Arctic.
At times in the past, sea level was 25m (80ft) higher than the present. A rise of 5-8m (16-26ft) is considered enough to submerge most of the world’s coastal cities.
There is abundant evidence for mass extinctions of life during these periods. And climate models suggest that, at times, the tropics could have become “dead zones”, too hot for most species to survive.
These fluctuations between hot and cold have been caused by a variety of phenomena, including the way the Earth wobbles as it orbits the Sun over long periods, volcanic eruptions and short-term climate cycles such as El Niño.
For many years, groups of so-called climate “sceptics” have cast doubt on the scientific basis of global warming.
However, virtually all scientists who publish regularly in peer-reviewed journals now agree on the current causes of climate change.
A key UN report released in 2021 said it “is unequivocal that human influence has warmed the atmosphere, oceans and land”.
The COP26 global climate summit in Glasgow in November is seen as crucial if climate change is to be brought under control. Almost 200 countries are being asked for their plans to cut emissions, and it could lead to major changes to our everyday lives.
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Geminid Meteor Shower returns in December – country1053.ca
The best meteor shower of the year are the Geminids and they’ll return this month. They start December 3 and will peak on the evenings of December 13 and 14 at around 2 a.m. ET. What makes this meteor shower interesting is that most come from comets traveling trough the solar system, while this one stems from an asteroid. Hoping for a clear sky both nights and you could see blue and even green colors as the space rocks burn up while passing through Earth‘s atmosphere. More info on the Geminids from NASA. There was already a preview of what you can see on November 3 in Manitoba.
@geminidmeteors strikes over the sky of Victoria, Manitoba, CAN ❣☄#meteror #geminid #december #nightsky #nightphotography #meteorshower #night #canada#geminidmeteorshower #nationalpark pic.twitter.com/NiqTYX5oLo
— Geminid Meteor Shower (@geminidmeteors) November 3, 2021
This 130 million-year-old ichthyosaur was a 'hypercarnivore' with knife-like teeth – Livescience.com
You wouldn’t want to meet an ichthyosaur while taking a dip in the early Cretaceous seas. That goes double for Kyhytysuka sachicarum: This newly identified 130 million-year-old marine reptile, now known from fossils in central Colombia, had larger, more knife-like teeth than other ichthyosaur species, a new study finds — and that is saying something, as ichthyosaurs are famous for their long, toothy snouts.
These big teeth would have enabled K. sachicarum to attack large prey, such as fish and even other marine reptiles.
“Whereas other ichthyosaurs had small, equally sized teeth for feeding on small prey, this new species modified its tooth sizes and spacing to build an arsenal of teeth for dispatching large prey,” paleontologist Hans Larsson of McGill University’s Redpath Museum in Montreal, Canada, said in a statement.
One toothy family
Ichthyosaurs were a large group of marine predators that first evolved during the Triassic period around 250 million years ago from land-dwelling reptiles that returned to the sea. The last species went extinct about 90 million years ago during the late Cretaceous. With long snouts and large eyes, they looked a bit like swordfish. Most species had jaws lined with small, cone-shaped teeth that were good for snagging small prey.
The newly identified species was likely at least twice as long as an adult human, based on the size of the fossils that have been found (most of a skull and a few pieces of spine and ribs). Probable ichthyosaur fossils were first unearthed in Colombia in the 1960s, but researchers couldn’t agree on the species or precisely how ichthyosaurs from the region were related to others from the same time period.
For the new study, Larsson and his colleagues focused on a skull kept in the collections of Colombia’s Museo Geológico Nacional José Royo y Gómez, and also considered another partial skull and bones from the spine and ribcage kept at Colombia’s Centro de Investigaciones Paleontológicas. Larsson and his colleagues announced the discovery and name of the marine reptile Nov. 22 in the Journal of Systematic Paleontology.
“We compared this animal to other Jurassic and Cretaceous ichthyosaurs and were able to define a new type of ichthyosaurs,” Erin Maxwell of the State Natural History Museum of Stuttgart, Germany, said in the statement. “This shakes up the evolutionary tree of ichthyosaurs and lets us test new ideas of how they evolved.”
The researchers named the new ichthyosaur species Kyhytysuka, meaning “the one that cuts with something sharp” in the language of the Indigenous Muisca culture of Colombia.. There are other species of ichthyosaur with big teeth for catching large prey, the researchers wrote in the study, but those species are from the early Jurassic, at least 44 million years earlier than K. sachicarum.
The new species lived at a time when the supercontinent Pangea was breaking up into two landmasses — one southerly and one northerly — and when Earth was warming and sea levels were rising. At the end of the Jurassic, the seas underwent an extinction upheaval, and deep-feeding ichthyosaur species, marine crocodiles and short-necked plesiosaurs died out. These animals were replaced by sea turtles, long-necked plesiosaurs, marine reptiles called mososaurs that looked like a mix between a shark and a crocodile, and this huge new ichthyosaur, said study co author Dirley Cortés of McGill’s Redpath Museum.
“We are discovering many new species in the rocks this new ichthyosaur comes from,” Cortés said in the statement. “We are testing the idea that this region and time in Colombia was an ancient biodiversity hotspot and are using the fossils to better understand the evolution of marine ecosystems during this transitional time.”
Originally published on Live Science
Kyhytysuka: A pure carnivorous `fish lizard` from 130 million years ago discovered – WION
The 130-million-year-old hypercarnivore Kyhytysuka, often known as the “Fish Lizard,” has been unearthed.
A remarkable 130-million-year-old swordfish-shaped marine reptile fossil reveals the emergence of hypercarnivory in these last-surviving ichthyosaurs.
A group of multinational researchers from Canada, Colombia, and Germany have unearthed a new prehistoric marine reptile.
The specimen is a brilliantly preserved meter-long skull from one of the few remaining ichthyosaurs — prehistoric beasts that look alarmingly like live swordfish.
According to researchers, this new species reveals the entire picture of ichthyosaur evolution.
This species, according to experts, originates from a crucial transitional era in the Early Cretaceous.
The Earth had emerged from a comparatively cold phase, sea levels were increasing, and Pangea, the supercontinent, had been split into northern and southern territory.
There were additional worldwide extinction events near the end of the Jurassic, which altered marine and terrestrial ecosystems.
(With inputs from agencies)
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