Lethal Heating: 07/14/21

14/07/2021

(ScienceAlert) Earth's Atmosphere Is Retaining Heat Twice As Fast As It Did Just 15 Years Ago

ScienceAlert - Andy Tomaswick, Universe Today

Sunset over the Indian Ocean as seen from the ISS, showing Earth's atmospheric layers. (NASA)

These days it seems you can't walk through a bookstore without bumping into a book or magazine pointing out the negative consequences of climate change. Everything from the hottest years on record to ruining astronomy can be tied to climate change.

Now some new science lays another potential problem at climate change's feet – Earth is retaining more than twice as much heat annually as it was 15 years ago.

A team from NASA and NOAA found that Earth's "energy imbalance" doubled between 2005 and 2019. The energy imbalance is simple to understand but complex in its causes and impacts. It is the difference between the amount of energy absorbed by Earth and the amount of energy emitted by it.

Any increase in the energy imbalance means the overall Earth system is gaining energy, causing it to heat up.

Simple explanation of the energy imbalance. Credit – NASAeClips YouTube Channel

To quantify this change, the team used data from two separate sources – NASA's Clouds and the Earth's Radiant Energy System (CERES) and a system run by NOAA called Argo. CERES specializes in how much energy is entering and leaving Earth.

Most of the energy entering is in the form of solar radiation, while energy leaving the system could take a variety of forms, including some of that solar radiation bouncing off of white clouds.

Argo, on the other hand, estimates the rate of temperature increase for the oceans. Ninety percent of the energy that is absorbed by the Earth system is absorbed into the oceans, so any significant energy imbalance would be seen as a heating up of the oceans.

Graph of the radiation measured as part of the experiment. (NASA/NOAA)

Data from both sensing platforms pointed to the same conclusions – that Earth was absorbing more energy than it was emitting, that energy is then stored by the ocean, and the annual amount of energy stored has increased dramatically in the recent past. All of these findings have important implications for the future of understanding and coping with climate change.

First, understanding what caused the increase in absorbed heat in order to potentially mitigate it in the near future would be helpful. The researchers cite two main causes of the increasing energy imbalance.

First was a decrease in sea ice and clouds, the white surfaces of which increase the planet's albedo and therefore the amount of energy that is reflected back out into space. Some of that decrease in cloud coverage was caused by what is known as the Pacific Decadal Oscillation.

In the middle of the survey period, a warm phase of this oscillation took hold, which caused a widespread reduction in cloud coverage, and thus lower albedo.

Video description of the Pacific Decadal Oscillation. Credit – Met Office YouTube Channel

The second cause was an increase in both greenhouse gases caused by human emissions and water vapor, which can prevent specific types of radiation from escaping, increasing the overall energy amount of the system. So our own emissions are making it harder for heat to escape Earth.

Consequences of such a change in the energy imbalance are slightly less clear, as is the case with much climate science. There is a chance that this heat-trapping effect could speed the melting of the polar ice caps, thereby speeding up the rise in sea levels that many scientists fear will occur over the next 100 years.

Alternatively, higher ocean temperatures could mean more acidic oceans, which has its own impact on the ecosystems that are reliant on ocean chemistry.

Over the course of a year the orientation of the axis remains fixed in space, producing changes in the distribution of solar radiation. These changes in the pattern of radiation reaching earth's surface cause the succession of the seasons. (NOAA/Thomas G. Andrews)

No matter the consequences, this research is another data point in the argument that climate change is real and that humans are causing it.

It is also something we could potentially reverse in our efforts to fight climate change globally. So it is worth keeping an eye on the overall energy imbalance for the foreseeable future.

Earth as seen from the International Space Station. Credit – NASA

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(Mashable) Scientists Reveal The Wild History Of Earth’s CO2 Since The Dinosaurs Died

Mashable - Mark Kaufman

Earth's climate began changing significantly after the dinosaur extinction. Credit: MARK GARLICK / SCIENCE PHOTO LIBRARY / Getty Images

Big snakes, alligators, giant tortoises, and flying lemurs thrived in a balmy Arctic some 50 million years ago. It was a time when the potent greenhouse gas carbon dioxide had spiked in Earth's atmosphere, making the high polar regions downright tropical.

Scientists who investigate past climates, called paleoclimatologists, have collected bounties of evidence that CO2 has long been a dominant lever on Earth's temperature. The evidence exists in chemicals stored in fossils, which indicate how much CO2 once saturated the atmosphere. Now, paleoclimate researchers have published the most comprehensive history to date of Earth's past CO2, starting after the dinosaurs went extinct some 66 million years ago (likely from an asteroid impact). The research, showing the strongest link yet between past CO2 levels and global temperatures, was recently published in the scientific journal Annual Review of Earth and Planetary Sciences.

The 66 million-year geologic story shows an overall trend of gradual, naturally declining CO2 over tens of millions of years, concluding in the geologically recent ice ages. Crucially, this history also reveals the extreme, unnatural, skyrocketing rise in CO2 levels over the last 150 years.

"CO2 has of course changed before, but it's happened in slow and predicable ways," said James Rae, a paleoclimatologist from the University of St Andrews who led the new research. "What's happening now is so much faster than anything in the geologic record. There's nothing in comparison to what’s happening now."

What's happening now is humans have grown extremely proficient at digging up prodigious amounts of some of the most carbon-rich materials on Earth ("fossil fuels") and are burning them. Much of this carbon ends up in the atmosphere. "You couldn't design a better way to put more CO2 into the atmosphere," Rae said.

"You couldn't design a better way to put more CO2 into the atmosphere."

Crucially, the latest research also demonstrates a strong correspondence between CO2 levels and past reconstructions of global temperatures. In short, when CO2 levels were high, so was temperature; when CO2 levels dropped, so did temperatures.

"This paper is a tour de force, an overview of what we know about the history of CO2 over last 60 [million years] that is broad in scope and comprehensive in its level of detail," said Maureen Raymo, a paleoclimatologist and marine geologist at Columbia University. It also paints a picture of modern CO2 trends. "Humans are now a geological scale force of nature" as we exert control over the planet's climate, Raymo, who wasn't involved in the research, added.

The chart below shows the strong link between past CO2 levels and global temperatures.

The clear CO2-temperature link. Credit: Annual Review of Earth and Planetary Sciences via James Rae

The evidence

To determine ancient climes from tens of millions of years ago, paleoclimatologists use fossilized evidence, like dead creatures preserved in ocean mud. These are called "proxies," a term that refers to preserved materials that provide clues or evidence of past environments. For a view of CO2 over the past 66 million years, researchers employed chemical evidence stored in tiny, common, and widespread fossilized shells (called foraminifera) and organic compounds (called alkenones) produced by algae.

These critters are sensitive to changes in the ocean's CO2 chemistry (including acidity), which is controlled by how much CO2 is in the atmosphere. (Oceans soak up CO2 from the air, naturally forming carbonic acid, which makes the oceans more acidic — a process that's happening as you read this.) It's a reliable way to sleuth out Earth's past climate.

"We're doing environmental forensics," explained Rae. "We're looking at the fingerprints environmental change leaves on the geologic record." "We're doing environmental forensics."
The foraminifera are a good example. They're made mostly of calcium carbonate, similar to oysters and corals. As the shells grow in the ocean, they mix in a handful of other atoms. One of these is the element boron, which changes slightly in different ocean acidities. Evidence of a more acidic ocean, stored in the fossils, equates to higher atmospheric CO2 levels. This allows paleoclimatologists, like Rae, to construct past CO2 trends over millions of years.

Scientists can also estimate what global temperatures were once like, and compare this to CO2 levels. Past temperatures are sleuthed out by analyzing past sea levels (preserved by ancient beaches), where certain fossils are found (it was clearly quite warm when alligators flourished in the Arctic), the chemical makeup of fossilized shells, and beyond.

In this latest comprehensive research, there's a clear, compelling connection between past CO2 levels (measured by marine proxies) and global temperature.

"Rae and coauthors apply state-of-the-art understanding of how the marine CO2 proxies really work, leading to a much refined CO2 record," noted Tom Marchitto, a paleoclimatologist at the University of Colorado Boulder who had no role in the research. "Its correspondence with global temperature over the past 66 million years is very striking, and supports CO2 as the principal driver of global climate change."

Importantly, paleoclimatologists don't rely on any single proxy to reveal environmental conditions in the deep past. They use multiple proxies, like the shells and algae used in the new research.

"These two methods produce very similar results, lending confidence that they are reliable proxies for atmospheric CO2," explained Kathleen Johnson, a paleoclimatologist at the University of California, Irvine, who had no role in the study.

A foraminifera shell as seen through a microscope. Credit: University of St Andrews

But why stop this particular CO2 investigation at 66 million years ago (for now, anyway)? Well, as you know, Earth experienced a dramatic extinction event at the time, significantly altering ecosystems and the life therein. Famously, the dinosaurs disappeared. Researchers simply have a much better understanding of life (like foraminifera shells) since that dramatic, asteroid-triggered environmental change on Earth, explained Rae. But 65 or 66 million years is more than enough time to establish what's largely controlled the planet's climate. As Mashable previously reported:

"CO2 levels were extremely elevated during the age of the dinosaurs (which ended 65 million years ago), perhaps at some 2,000 to 4,000 ppm. Tremendous CO2 emissions, from incessant and extreme volcanism, heated Earth and allowed dinosaurs to roam a sultry Antarctic. But over millions of years, Earth’s natural processes (specifically the slow, grinding, but potent process of rocks absorbing CO2 from the atmosphere, dubbed 'the rock thermostat') gradually reduced CO2 levels."

Eventually, by the start of the Industrial Revolution, CO2 levels hovered around a stable 280 parts per million, or ppm. Since then, they've shot up to around 416 ppm. That quick jump is unprecedented in the geologic record. "We have become a geologic force."
"Geologic records like this one present us with some loud warnings," said Marchitto, noting that today's CO2 levels are the highest they've been in some 3 million years. (Sea levels then were some 30 feet higher than today, but possibly much more). "The history of the human race has never seen anything like this, and it continues to climb," Marchitto said.

What's more, the rate of atmospheric CO2 is rising much faster than at any point since the dinosaurs died. How much faster? "We can confidently say that the rate of anthropogenic CO2 rise is around 10 times faster than the fastest natural CO2 change seen over the last 66 million years," said Johnson.

Humanity's having a potent influence.

"We have become a geologic force," said Marchitto.

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(SMH) Southern Australian Sharks And Rays Being ‘Cornered’ By Climate Change

Sydney Morning Herald - Peter Hannam

Southern Australia’s sharks and rays face mounting threats as warmer waters push more tropical species southwards and habitats change, exacerbating threats to critically endangered species.

A study aimed at identifying the risks to some 132 different species found in waters ranging from south-west Western Australia to NSW has been published in the Fish and Fisheries journal. It seeks to give authorities a method to prepare for the threats of overfishing and climate change.

A grey nurse shark, one of the shark species in Australian waters that is already endangered before the impacts of climate change take effect. Credit: Erik Schlögl

“This is the first time we’re actually bringing them together as a risk assessment,” said Terence Walker, a research fellow at both Melbourne and Monash universities and lead author of the paper. “The challenges for fisheries managers are growing all the time.”

While tighter controls on commercial fishing since the early 2000s had arrested the decline of many shark, ray and chimaera species such as elephant fish, those gains could be eroded as more tropical species such as tiger and bull sharks extend their ranges southwards, the researchers said.

Region covered by fisheries study

Source: Fish and Fisheries

The East Australian Current, which shifts tropical water southwards, is strengthening and making the Tasman Sea one of the world’s warming hot spots as sea-surface temperatures rise at about four times the global rate. The Leeuwin Current, which flows south along the WA coast, is also

Extreme weather

From drying rainforests to heavier downpours,
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“Global warming is literally going to push southern sharks and rays into a corner, because they can only go so far south and west,” said Leonardo Guida, a shark scientist with the Australian Marine Conservation Society and a co-author of the paper.

“Everything points to an urgent need to rapidly adjust how fisheries work.”

The paper also found that at present fishing levels, as many as six species already assessed as endangered including the school shark and maugean skate will have their recovery hampered by southward-migrating rivals.

Richard Reina, a marine ecologist at Monash University and another of the paper’s authors said southern Australian waters were changing faster than other parts of the country and it was also the most heavily fished by commercial firms.

The endangered Maugean Skate which has an extremely narrow distribution. It is closely related to a Gondwana ancestor which lived off southern Australia some 80 million years ago. Credit: CSIRO

While fisheries had made major efforts to monitor fish stocks and modify approved take accordingly, they were already struggling to adjust to “the southward movement of so many species ... everybody’s moving south”, Professor Reina said.

An elephant fish in Victoria’s Westernport Bay. The animal is among those at risk as waters warm and northern species move in. Credit: Kelvin Aitken

Those sharks and rays that breed or feed in shallow waters “will struggle to establish themselves if they get pushed off the [continental] shelf into deeper waters”, he said.

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Dr Guida said it was vital Australia and other nations cut greenhouse gas emissions that was driving the hotter climate. In the meantime, fisheries managers should start to use the new methods to assess risk.

In some cases, that will involve increasing the areas where fishing is restricted or banned to give the at-risk species a chance of survival.

Many sharks in particular sit at the top of the food chains, keeping ocean ecosystems stable.

“If you look after sharks and rays, you’re looking after our broader food chains,” Dr Guida said. “It affects what fish ends up on your table – if it gets there at all.”

A great white shark approaching a huge school of salmon close to shore at Tamarama Beach. Credit: Dronesharkapp.com

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