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Explaining climate change science & rebutting global warming misinformation

Scientific skepticism is healthy. Scientists should always challenge themselves to improve their understanding. Yet this isn't what happens with climate change denial. Skeptics vigorously criticise any evidence that supports man-made global warming and yet embrace any argument, op-ed, blog or study that purports to refute global warming. This website gets skeptical about global warming skepticism. Do their arguments have any scientific basis? What does the peer reviewed scientific literature say?


2020 SkS Weekly Climate Change & Global Warming News Roundup #47

Posted on 28 November 2020 by John Hartz

2020A chronological listing of news articles linked to on the Skeptical Science Facebook Page during the past week: Sun, Nov 22, 2020 through Sat, Nov 28, 2020

Editor's Choice

Republicans Remain Opposed to Any Policies That Would Reduce Fossil-Fuel Use


Photo: Barry Lewis/In Pictures via Getty Images

Last week, U.K. prime minister Boris Johnson laid out his plan for a “Green Industrial Revolution,” which is sort of British for “Green New Deal.” His plan calls for a ban on selling gas-powered vehicles starting in 2030, net-zero emissions by 2050, and billions in new green tech investments.

Environmentalists can, and do, question the specific choices in his blueprint. But a world in which the problem with the right-wing party’s climate stance is that it doesn’t move quickly enough in the right direction is so remote from the American imagination it may as well be taking place not on a different continent but on a different planet.

Back in the U.S., the relief of Donald Trump’s long good-bye will begin yielding to the stark reality that his party remains fundamentally pathological. No issue highlights this depressing reality more clearly than climate change.

For more than a decade, the GOP has stood alone among major right-of-center parties in industrialized democracies worldwide in its refusal to endorse climate science. But during the Trump era, the party’s rhetorical emphasis shifted. The major Republican point of agreement is now to insist on fossil-fuel use as an inherent good.

Click here to access the entire article as originally published on the New York Magazine website. 

Republicans Remain Opposed to Any Policies That Would Reduce Fossil-Fuel Use’ by Jonathan Chait, Intelligencer, New York Magazine, Nov 28, 2020



Media reaction: Boris Johnson’s ‘10-point’ net-zero plan for climate change

Posted on 27 November 2020 by Guest Author

This is a re-post from Carbon Brief

The UK prime minister Boris Johnson has announced a long-awaited “10-point plan” laying out measures to scale up the nation’s climate ambition.

These policy proposals and funding packages have been framed as a means to create jobs, promote a “green recovery” from Covid-19 and help the UK achieve its net-zero emissions target by 2050.

A ban by 2030 on the sale of new petrol and diesel cars is the most eye-catching policy, but there is also around £4bn in new funding for a variety of emissions-cutting proposals.

There has been blanket coverage across UK newspapers of the plan, with the story appearing on the frontpages of the Daily Mail, the Daily Telegraph, the Financial Times, the Times and the Independent

After nearly two days of media coverage, the government published a policy document laying out more details of its strategy and stating it was “only the start” of its net-zero plans.

In this article, Carbon Brief has documented what the prime minister has proposed, how the media has responded and how the measures stack up against the UK’s legally binding net-zero emissions goal.

It also examines each of the sectors targeted in the plan and how they have been addressed.

‘Green industrial revolution’

Johnson laid out how he wanted the plan to be viewed in an opinion piece for the Financial Times, published on the evening of its release.

The article talks of a “green industrial revolution” that will invest £12bn of government funds, create 250,000 green jobs and help drive a green recovery from Covid-19 by “build[ing] back better”:



Skeptical Science New Research for Week #47, 2020

Posted on 25 November 2020 by doug_bostrom

"Don't make us stop the car." 

Climate change of a different kind: Examining the climate effects of a regional nuclear weapons exchange using a multiscale atmospheric modeling approach, investigated by Wegman, Lundquist et al. 

There's good news: the main proximate cause of the resulting global mess might last only about 4 years instead of 15. 

Because it's about warfare and warfare is inherently useless and undesirable, this work nicely simplifies for discussion some moral and ethical puzzles, including: for what purposes are external costs acceptable to impose on others, and does any country have a "sovereign right" to impose costs for arguably useless objectives on bystanders in the form of excess mortality, economic devastation, etc.? 

In the immediate case of this research: if such a spat is imminent, what fundamental rights do bystander nations have to interdict? By extension, how do we establish thresholds for acceptable freeloading in other forms by nations imposing costs on others?

What we're talking about is neatly analogous to a couple of astronauts on the ISS becoming angry with one another, assembling Molotov cocktails from "materials found 'round the home," going at it. Are bystander  astronauts expected to take this as the normal course of affairs, pretend nothing is happening, do nothing?

Short of open domestic violence in space, would opening a cigar shop on the ISS be OK, if some astronauts objected to the workload imposed by smoke contamination? (kids: claiming that lit cigars do not make smoke won't wash, no matter how much whining we hear)

When do adults get to say "no?"



Gas-powered cars: Beginning of the end in California?

Posted on 24 November 2020 by Guest Author

This is a re-post from Yale Climate Connections by Bruce Lieberman

Can California really do it? Can it completely ban the sale of new gas-powered cars in 15 years – 15 years – and lead the country toward a fossil fuel-free future?

Democratic Governor Gavin Newsom says so. In a late September executive order, Newsom announced a ban on in-state sales of new gas-powered cars and trucks by 2035, and medium- and heavy-duty trucks by 2045. Newsom isn’t the first politician to make such moves – several countries in Europe including Norway, the Netherlands, France, the UK, and Denmark have set similar goals. But he is the first governor in the U.S. to take that step. And California, the fifth largest economy in the world, sets trends – economic, environmental, cultural – that often reverberate across the nation and the world.

Still, the executive order only sets goals for 2035 and 2045. And it will still allow people to drive gas-powered automobiles after 2035, and also sell used ones. In other words, internal combustion engines aren’t disappearing anytime soon after 2035.

It’s still unclear exactly how California will pursue Newsom’s ambitions – or to what extent his executive order will outlive the first-term governor’s time in office. But he has ordered the state’s powerful Air Resources Board to immediately begin developing new “passenger vehicle and truck regulations requiring increasing volumes of new zero-emission vehicles sold in the state towards the target of 100 percent of in-state sales by 2035.”

It will be interesting to see what those regulations actually look like.

Newsom’s order includes other aggressive measures too. Along with passenger cars and trucks in 2035, it sets the goal of a full transition to zero-emission drayage trucks – the big diesel-powered haulers that transport shipping containers and bulk to and from the state’s ports, rail yards, and other locations. Also by 2035, Newsom wants to transition all off-road vehicles and equipment to zero emissions “where feasible.”

Newsom’s order separately calls for the state to achieve “carbon neutrality by no later than 2045” and for the state government to “expedite regulatory processes to repurpose and transition upstream and downstream oil production facilities.” In his announcement, Newsom said he is asking the state Legislature to stop issuing new permits for hydraulic fracturing (fracking) by 2024.



Can shearing of Thwaites glacier slow or stop if humans control greenhouse gas emissions?

Posted on 23 November 2020 by greenman3610

This is a re-post from Yale Climate Connections

Here’s the take-home message from this month’s original video by independent videographer Peter Sinclair for Yale Climate Connections:

Let’s hope Thwaites in Antarctica waits. Waits patiently, quietly, and long-term, perhaps even indefinitely.

And here’s a moral of this Thwaites video, adapted freely from Las Vegas tourism interests: What happens in Antarctica, and in particular in this instance at Thwaites, doesn’t stay in Antarctica. Not by a long shot.

The video addresses fairly widespread concerns and misunderstandings not about ongoing loss of Antarctic ice at Thwaites and Pine Island, but rather about whether that loss has become unstoppable, is rapidly accelerating, and is reaching the proverbial doomsday point of no return.

Let’s face it: Thwaites has the makings of being the lead role in an upcoming cli-fi thriller, one strong on emotion and drama but lacking something when it comes to hard science. The Sinclair video strives to set things straight.

Runaway feedback ‘not very likely’

It does so through quick and concise interviews with scientists most familiar with the issue. None of them takes a “What? Me worry?” Mad magazine/Alfred E. Neuman approach, nor that of Bobby McFerrin’s popular “Don’t Worry. Be Happy.” Rather, each points to the empirical evidence that human actions still could help determine the eventual prospects for Thwaites.

Scripps Institution of Oceanography scientist Jeffrey Severinghaus opens the video pointing to someone’s gradually rolling a large round boulder down a hill: Stop pushing a few moments, and the boulder may pause, may sit in place. But in time, the pushing gets to the point that the boulder sets apace on its own. Severinghaus calls that a “runaway positive feedback,” something to be avoided. Is that runaway prospect inevitable? he asks rhetorically. “We are possibly in a collapse right now,” he says. “but I would say it’s not very likely.” There’s a “but” coming, as Severinghaus adds “but we can’t completely rule it out either.”

Susheel Adusumilli of Scripps says the problem with Thwaites comes in large part from the increased ocean heat delivered to the ice shelves, primarily as a result of greenhouse gas emissions.

It all comes down to what humans know … and do

Severinghaus shares with climate scientist Eric Rignot, of the University of California, Irvine, a concern that so little is known about the underlying topography of the Antarctic ice sheets. “We know more about the topography of Mars than we know about the topography beneath Antarctic Ice,” he says. Rignot agrees, pointing to “not enough observations.”

“The accident of where it is, is that Thwaites can cause tremendously more sea-level rise by itself than these others can,” says Penn State climate scientist Richard Alley. He notes that some models show the unending shearing and collapse of Thwaites ice “keeps going,” but says other models hold that the shearing can be constrained – and the resulting sea-level rise kept “small, slow, and expected” – if greenhouse emissions can be substantially reduced, and soon.

That’s a point Twila Moon, scientist with the National Snow and Ice Data Center, fully buys into. “All of these different elements of the cryosphere” in the future will look “dramatically different if we are taking very strong action to reduce GHG emissions, versus if we are following a path like today.”



2020 SkS Weekly Climate Change & Global Warming Digest #47

Posted on 22 November 2020 by John Hartz

Story of the Week... Toon of the Week... Coming Soon on SkS... Climate Feedback Claim Review... SkS Week in Review... Poster of the Week...

Story of the Week...

Warm Arctic, Cold Continents? It Sounds Counterintuitive, but Research Suggests it’s a Thing

Scientists suspect that rapid warming in the Arctic is causing more climate extremes farther south, including bouts of severe cold and snow in the Northeast.


A satellite view of Northwestern Greenland in the Arctic Circle on Aug. 12, 2019. Credit: Orbital Horizon/Copernicus Sentinel Data 2019/Gallo Images via Getty Images)

By any measure, the Arctic has changed profoundly in the last 40 years, warming three times as fast as the global average, and losing half its summer sea ice, as well as billions of tons of land-based glacier ice.

And even though the Arctic only encompasses about 6 percent of the Earth's surface area, the warming there has kicked off climate chain reactions that are disrupting weather and climate patterns across the mid-latitudes of the Northern Hemisphere, including most major North American and European cities and agricultural areas. The abrupt and accelerating Arctic warming directly harms the communities, livelihoods and traditions of the 4 million people who live in the polar region.

Some scientists say a more frequently recurring cycle they refer to as "warm Arctic, cold continents," is a sign of that disruption. The pattern seemed to emerge as a global warming signal about 10 years ago, as researchers documented an increase of summer and winter extremes in parts of North America and Eurasia, including heat waves, killer blizzards, floods and cold snaps, occurring even as Arctic warming and ice loss accelerated.

Click here to access the entire article as originally posted on the InsideClimate News website.

Warm Arctic, Cold Continents? It Sounds Counterintuitive, but Research Suggests it’s a Thing by Bob Berwyn, InsideClimate News, Nov 22, 2020



2020 SkS Weekly Climate Change & Global Warming News Roundup #47

Posted on 21 November 2020 by John Hartz

2020A chronological listing of news articles linked to on the Skeptical Science Facebook Page during the past week: Sun, Nov 15, 2020 through Sat, Nov 21, 2020

Editor's Choice

The 'market' won't save us from climate disaster. We must rethink our system

Expecting the free market to fix global warming is like trying to pound nails with a saw


Nicholas Stern, the former chief economist of the World Bank, calls climate change the ‘greatest and widest-ranging market failure ever seen’. Photograph: David McNew/Getty Images

The massive wildfires that have been rampaging across the American west this year are not purely natural disasters. They are partly products of the unnatural disaster of climate change – “unnatural”, in that the ultimate responsibility for global warming belongs not to physics but to our economic system. Nicholas Stern, the former chief economist of the World Bank, calls climate change the “greatest and widest-ranging market failure ever seen”. Sadly, climate change is only one – albeit a whopper – of the countless market failures that degrade our lives.

Though it sounds like a generic phrase, “market failure” is actually a technical term. It doesn’t refer to scams like insider trading or corporate fraud. A failure occurs when the marketplace allocates resources in a way that does not optimally deliver wellbeing. We understandably focus a lot of attention on the depredations of greedy tycoons and corporations, but many of the most consequential market failures stem from innate characteristics of our current market system.

Many of us probably already have a gut feeling that our current market system often fails. In order to build a more sustainable, just and prosperous economy, however, it’s vital that we better comprehend the shortcomings deep in the market’s DNA. Greater awareness would reduce blind faith in the market and enable people to see the market for what it is: a tool. It can be an excellent tool when used for the right job, but relying on the market to deal with something like climate change is like trying to pound nails with a saw.

Click here to access the entire Opinion Piece as originally published on The Guardian website.

Solar Panels + Agriculture: You Ain’t Seen Nothing Yet by Tina Casey, CleanTechnica, Nov 19, 2020



Observations of past climate change help rule out natural causes of current climate change

Posted on 20 November 2020 by ScottKnapp

This post is an updated intermediate rebuttal to the myth "climate is changing now because climate has always changed". It was written by Scott Knapp as part of the George Mason University class Understanding and Responding to Climate Misinformation, combining climate science and communication best practices to debunk common climate myths.

The total rate of global warming observed since the industrial revolution can only be explained by the observed excess of CO2 in the atmosphere. The excess of CO2 can only be explained via human sources. Let us first examine the post-industrial revolution warming and some of the telltale signs that humans are responsible.

The human fingerprint

How can we be sure that humanity’s release of greenhouse gases are to blame for the observed rise in global temperature? First, let’s look at evidence showing that greenhouse gases are causing the current warming. Then we will explore how we know that the recent increase in greenhouse gases is due to human activity.

Greenhouse gases like CO2 are understood quite well, so we can make predictions about what we should observe. When CO2 is added to the atmosphere, it causes the lower atmosphere (aka the troposphere where we live and experience its weather) to warm. This warming occurs because the added CO2 traps infrared heat emitted from the Earth's warm surface - heat that would otherwise escape to space. However, in the stratosphere, above the troposphere, adding CO2 to the atmosphere causes it to cool. This is because the extra CO2 in the stratosphere radiates more heat to space. The stratosphere has been cooling in recent decades, as atmospheric CO2 increases. This also rules out the sun, as an increase in solar energy would heat the whole atmosphere.

Another example, predicted by Arrhenius in 1896, states that winters should warm more than summers. Hemispheres receive less sunlight in winter and cool down by radiating energy away into space. If greenhouse gases were increased, they would act to prevent some of that energy from radiating away, thus warming the winter hemisphere. The warming effect on winter was predicted to be greater than that of summer. Again, this is observed.

It is also possible to use statistical techniques, like detection and attribution studies, to compare the relative contributions of various factors (such as greenhouse gases, aerosols, etc.) towards the recent global warming trend. These too show that the recent global warming trend cannot be explained without the additional greenhouse gases humans have released into the atmosphere.

Given that the warming is caused by greenhouse gases, how do we know that human CO2 emissions are specifically to blame for their sudden increase? This too can be quantified.

Figure 1. Examples of human fingerprints on global warming. Source



What is causing the increase in atmospheric CO2?

Posted on 19 November 2020 by eharrin5

This post is an updated intermediate rebuttal to the myth "CO2 increase is natural, not human-caused". It was written by Erika Harrington as part of the George Mason University class Understanding and Responding to Climate Misinformation, combining climate science and communication best practices to debunk common climate myths.

Atmospheric CO2 has increased by more than 100 parts per million since the Industrial Revolution in the mid-1700s, when humans began burning fossil fuels like coal and oil. Human activity has increased CO2 to levels not seen in the past 800,000 years.

CO2 over 800,000 years

Figure 1: Atmospheric CO2 concentrations in parts per million (PPM). Levels have peaked throughout time but we’ve seen a steep increase of 100 PPM since the industrial revolution, Climate.Gov 

To understand atmospheric CO2 levels, we must look to the carbon cycle. The carbon cycle allows us to track the CO2 being emitted into the atmosphere and absorbed by the planet.

Bathtub Simulation

Figure 2: Bathtub Simulation, Climate Interactive



Skeptical Science New Research for Week #46, 2020

Posted on 18 November 2020 by doug_bostrom

If you learn something, say something

The American Meteorological Society publication The Journal of the Atmospheric Sciences is encouraging authors to think about a wider readership's needs when submitting papers:

The American Meteorological Society (AMS) mission statement specifically calls for advancing “the atmospheric and related sciences . . . for the benefit of society.” To further the goal of communicating the importance of the science in our journals more widely, AMS is encouraging the inclusion in submitted papers of a “significance statement,” written in plain language and aimed at an educated layperson without formal training or education in the atmospheric and related sciences.

Integrating the public mind into research publications in this way lends institutional backing to help combat a myth— that a researcher pointing out hazards identified as a result of their normal work is being "activist," committing an act of political  or ideological advocacy.  In reality public information on hazards and risks is a perfectly normal moral obligation, hardly a transgression of the "correct" role for a researcher. But scientists are sometimes criticized for pointing out factually broad  impacts revealed by research output. This is a puzzling outcome, akin perhaps to an engineer arranging a safety belt for vehicle occupants but not being allowed to say what safety belts do or how to use them.

At this juncture a significant proportion of climate research is effectively safety research. Commensurately, expecting the general public and policy makers to guess at significance of findings with negative impacts on the wider well being is clearly not smart. For the general public's benefit a key skill for any given researcher is ability to "join up" immediate findings with the bigger picture. This AMS journal correctly puts contextual communication  to the public squarely in the normal, expected path of the publication process.  More, please.  The full statement.



The harmful impacts of climate change outweigh any benefits

Posted on 18 November 2020 by sophia_whitaker

This post is an updated intermediate rebuttal to the myth "global warming is good". It was written by Sophia Whitaker as part of the George Mason University class Understanding and Responding to Climate Misinformation, combining climate science and communication best practices to debunk common climate myths.

The Pros and the Cons

Our current climate crisis poses an existential threat unlike any that our species has experienced before. Emerging evidence suggests that the rapid increase in global average temperature will wreak havoc on not only our climate system, but also our day-to-day lives. In 2019, global average temperature was 0.99 °C (1.78 °F) above the 1951-1980 average temperature. While we are already seeing the effects of a changing climate, scientists warn of significantly worsening impacts if warming is not kept below 1.5 °C. These severe impacts can include substantial land and sea ice loss, ocean acidification, changes in ocean circulation, and shifts in weather patterns which ultimately lead to food and water shortages along with economic and social unrest.

There are also ways in which society may benefit from a warming climate. Reduced sea ice will open more passageways for ships and will allow the poles to be more accessible. A warmer climate may grant certain areas, especially northern latitudes, longer and earlier growing seasons. Warmer winters mean less cold-induced deaths. Increased carbon dioxide levels may help vegetation to flourish for a greener world. Unfortunately, though, many of these benefits are short-term and are greatly overshadowed by the negative impacts that climate change brings.



How we know human CO2 emissions have disrupted the carbon cycle

Posted on 17 November 2020 by jensensun

This post is an updated intermediate rebuttal to the myth "Human CO2 emissions is tiny compared to natural CO2 emissions". It was written by Ziheng Sun as part of the George Mason University class Understanding and Responding to Climate Misinformation, combining climate science and communication best practices to debunk common climate myths.

Nature emits and absorbs CO2 to and from the atmosphere, with emissions and absorptions largely in balance before the Industrial Revolution. As depicted in Figure 1, CO2 emissions come from a variety of sources, including human activities, land use changes, vegetation respiration, volcanoes, and ocean release. CO2 sinking sources include weathering, photosynthesis, increased uptake by plants, and ocean absorption.

Figure 1. CO2 sources and sinks with pre-industrial fluxes in green and the recent changes shown in red (New Scientist)

In Figure 1, the green arrows show natural emission and absorption with the ocean and land respectively. This demonstrates that natural emissions and absorptions were largely in balance before the industrial revolution. Atmospheric CO2 levels and human CO2 emission significantly increased after industrial revolution. As Figure 2  shows, the recent increase in atmospheric CO2 is unseen in the past 800,000 years and as will be explained below, must be caused by human activity.

Figure 2. Average concentration of carbon dioxide (CO?) in the atmosphere, measured in parts per million (ppm) from 803,719 BCE to 2018 (data source: NOAA



Human Fingerprints on Climate Change Rule Out Natural Cycles

Posted on 16 November 2020 by Kai Huang

This post is an updated intermediate rebuttal to the myth "global warming is caused by natural cycles". It was written by Kay Huang as part of the George Mason University class Understanding and Responding to Climate Misinformation, combining climate science and communication best practices to debunk common climate myths.

Global warming refers to the long-term warming of global temperature since the 1850s. The cause of global warming has been investigated by many scientists, who have summarized their finding in multiple assessment reports by the Intergovernmental Panel on Climate Change (IPCC). The only plausible mechanism of global warming is a planetary energy imbalance, with our climate system building up heat. This and the observed fingerprints left on global warming confirm the dominant role of human activities.

Fossil fuel burning is causing recent global warming

Scientists have identified two factors that drive global climate change: internal variability and external forcings. Internal variability refers to the internal processes moving heat around within the climate system. External forcings cause an energy imbalance - with the planet either building up or losing heat - and can be both natural and human caused. The only plausible mechanism accounting for the long-term temperature increase of global warming is through a buildup of heat in the climate system (Li et al., 2007).

Among the various external forcings that can cause the climate system’s energy imbalance, scientists have concluded the main cause of recent global warming is the increase of atmospheric CO2 due to fossil fuel burning.

In order to understand how scientists came to the above conclusion, it is important to understand the various drivers of climate changes.

Internal variability moves heat around the climate system

Climate change is like the motion of water in a kitchen sink with an inflow from the faucet and an outflow through the drain. The motion consists of both the water sloshing around and the rising and falling of water level. The random sloshing around is what scientists call "internal variability," while the rising and falling of water level is what scientists call "forced variability". Internal variability (e.g., ocean cycles such as El Niño South Oscillation, Pacific Decadal Oscillation, and Atlantic Multidecadal Oscillation) moves heat around to give rise to regional climate change on timescales ranging from annual to millennial timescales. Like the water sloshing around, internal variability doesn't build up or dissipate the total amount of heat in the climate system. In contrast, external forcings (e.g., 11-year solar cycle and changes in the Earth’s orbit) change the climate by causing a buildup or loss of heat, similar to the change in water level being determined by the difference between the inflow and outflow.

The single cause fallacy committed by the natural cycle myth

One climate myth argues that recent global warming is caused by natural cycles rather than human activity. The so-called “natural cycles” in the myth may include climate variation due to internal variability or external forcings. Natural external forcings, such as the 11-year solar cycle and changes in the Earth’s orbit, are part of nature and not influenced by human activities. Other external forcings like greenhouse gases and aerosol concentrations in the atmosphere are significantly influenced by human activities, and thus are excluded from natural cycles.

The argument that global warming is due to natural cycle commits single cause fallacy, by assuming there is only one driver of climate change (e.g., natural factors) when there may be others (e.g., human activity). In this case, the myth argues that the same factors, namely internal variability and natural external forcings, that drove past natural cycles must also be the same factors causing current global warming. But the fact is that humans have emitted large amounts of CO2 into atmosphere by burning fossil fuel since the industrial revolution, and it is the main cause of recent global warming. 

One version of this myth is that the natural cycles may cause cyclic climate change with timescales ranging up to millennial timescales, and therefore recent global warming is just the rising phase of such a cycle. However, this argument is ruled out by the observed fingerprints on global warming (seen in Figure 1) since no natural cycles fit all these fingerprints. For example, natural cycles cannot explain why the satellites measures less heat escaping to space at the precise wavelengths which CO2 absorbs (Philipona 2004, Wang 2009).

The observed fingerprints on global warming and the fact that only external forcings can cause a buildup in heat in the climate system work together to not only rule out natural cycles, but also confirm that the anthropogenic CO2 increase in the atmosphere is the main cause of modern global warming.



Can animals and plants adapt to global warming?

Posted on 15 November 2020 by fhaychap

This post is an updated intermediate rebuttal to the myth "animals can adapt to global warming". It was written by Finley Hay-Chapman as part of the George Mason University class Understanding and Responding to Climate Misinformation, combining climate science and communication best practices to debunk common climate myths.

There have been five “big” mass extinction events in Earth’s history, each one driven by rapid climatic change. When climate changes too fast for species to be able to adapt, extinctions are bound to occur. Figure 1 shows prior extinction events and atmospheric CO2 concentration over geological time. Each open circle denotes an extinction event (big or small), with the “Big Five” mass extinctions highlighted. Note that nearly every extinction event occurred after a sharp increase in CO2 levels, including four out of the Big Five. 

The only one of the Big Five mass extinctions where this did not occur is the most recent Paleocene Thermal Extinction, that wiped out the dinosaurs 65 million years ago. This was kicked off by a large meteor strike (a different, more jarring change in climate). Most extinctions have been linked to immense volcanic events, called Large Igneous Province (LIP) eruptions. These events spew billions of metric tonnes of carbon dioxide (CO2) and sulfur dioxide (SO2) into the atmosphere, in many cases triggering marine anoxia (oxygen loss) and ocean acidification due to rapid greenhouse warming. 



2020 SkS Weekly Climate Change & Global Warming Digest #46

Posted on 15 November 2020 by John Hartz

Story of the Week... Toon of the Week... Coming Soon on SkS... Poster of the Week... SkS Week in Review...

Story of the Week...

Seeing Clouds Clearly: Are They Cooling Us Down or Heating Us Up?

Though scientists know that clouds are critical to the climate system, their exact role is still uncertain. New studies are starting to fill in the knowledge gap.


Two new studies are adding to the knowledge about how clouds impact the climate. Credit: Bob Berwyn 

On any given day, clouds spread across about two-thirds of the globe. They control global surface temperature more than any other single influencing factor, including greenhouse gases. And even though they are one of the most critical parts of the global climate system, clouds are still the greatest source of uncertainty when it comes to projecting how much Earth will heat up in the future.

But that's starting to change as scientists peer deep inside clouds to study changes at the microscopic level and use new satellites that capture the big picture. Depending how high and thick they are, and how much water and ice they contain, they either cool or heat the planet by reflecting incoming solar radiation back to space or trapping it at the surface, like a blanket.

For now, the overall effect of clouds is to cool the planet. But two new studies published recently in the journal Nature Geoscience suggest that clouds are likely to change in ways that will intensify global warming.

One of the research projects led by scientists at the Swiss Federal Institute of Technology in Zürich, found that, when tiny soot particles combine with ozone or sulfuric acid, the result can be changes in clouds—both low-lying and high altitude—that cause more heating. The second study, by Norwegian climate scientists, suggests that changes to clouds, particularly over the Southern Ocean, could end up causing the planet to warm by more than the 9 degrees Fahrenheit expected if atmospheric carbon dioxide doubles from the pre-industrial level.

Click here to access the entire article as originally published on the InsideClimate News website.

Seeing Clouds Clearly: Are They Cooling Us Down or Heating Us Up? by Bob Berwyn, InsideClimate News, Nov 10, 2020



2020 SkS Weekly Climate Change & Global Warming News Roundup #46

Posted on 14 November 2020 by John Hartz

A chronological listing of news articles linked to on the Skeptical Science Facebook Page during the past week: Sun, Nov 8, 2020 through Sat, Nov 14, 2020

Editor's Choice

Two U.S. Oil Companies Join Their European Counterparts in Making Net-Zero Pledges

Occidental Petroleum and ConocoPhillips define their net-zero goals differently, and neither is signaling a shift to clean energy, as some European companies are.

OXY (Occidental Petroleum) Building

Occidental Petroleum announced on Tuesday that it will reach net-zero emissions for all the oil and gas it produces by mid-century. Credit: Jay L. Clendenin/Los Angeles Times via Getty Images</>

The past few years have brought a widening gap between American oil companies and their European counterparts when it comes to pledging to address global warming. But two recent announcements may signal a change.

Occidental Petroleum announced on Tuesday that it will reach net-zero emissions for all the oil and gas it produces by mid-century, becoming the first major American oil company to make such a pledge. The target aligns the company with the position of an incoming Biden administration that has made addressing climate change a central part of its agenda.

News of the company's pledge came just weeks after ConocoPhillips announced a goal of zeroing out its direct greenhouse gas emissions, which are much less than the emissions that come from burning the oil and gas the company sells. Taken together, the two corporate pledges could increase pressure on ExxonMobil and Chevron, the nation's largest oil companies, which have yet to announce such far-reaching goals.

Click here to access the entire article as originally published on the InsideClimate News website.

Two U.S. Oil Companies Join Their European Counterparts in Making Net-Zero Pledges by Nicholas Kusnetz, InsideClimate News, Nov 12, 2020



How much does animal agriculture and eating meat contribute to global warming?

Posted on 13 November 2020 by ZackChester

This post is an updated intermediate rebuttal to the myth "Animal agriculture account for 51% of CO2 emissions". It was written by Zack Chester as part of the George Mason University class Understanding and Responding to Climate Misinformation, combining climate science and communication best practices to debunk common climate myths.

The three largest contributors to global greenhouse gas emissions are as follows:

  1. Burning fossil fuels for electricity and heat (31% of annual global human greenhouse gas emissions);
  2. Transportation (15%); and
  3. Manufacturing (12.4%).

The fourth largest contributor is animal agriculture accounting for 11% of greenhouse gas (GHG) emissions according to estimates from the World Resources Institute, as shown in Figure 1.

One myth argues that animal agriculture is the greatest contributor to global greenhouse gas emissions, claiming it accounts for 51% of annual global GHG emissions.

WRI GHG Emissions


Figure 1: Global manmade GHG emissions by sector reported by the World Resources Institute. Electricity and heat make the largest contribution at 31% with animal agriculture making up 11%.



What did 1970’s climate science actually say?

Posted on 12 November 2020 by morr6

This post is an updated intermediate rebuttal to the myth "scientists wrongly predicted an ice age in the 1970s so can't be trusted now". It was written by Margaret Orr as part of the George Mason University class Understanding and Responding to Climate Misinformation, combining climate science and communication best practices to debunk common climate myths.

In the 1970s, climate scientists were investigating the effects of rising industrial emissions on Earth’s climate. These emissions have two main components that affect the climate system. One of these components is carbon dioxide (CO2), a greenhouse or heat-trapping gas, that causes overall increases in global temperatures. The other component is aerosols, small atmospheric particles that block incoming sunlight. This can have a cooling effect on the Earth’s overall temperature, but aerosols only stay in the atmosphere for about two weeks before being rained out. These two contrasting effects led climate scientists to two different conclusions regarding what might happen to Earth’s climate in the future.

The Case for Cooling

Studies that projected aerosol-related cooling, such as Rasool and Schneider’s 1971 paper, said that “An increase by only a factor of 4 in global aerosol concentration may be sufficient to reduce surface temperature by as much as 3.5 K.” This speculation of quadrupling was based on the rapidly increasing concentration of aerosols like sulfur dioxide leading up to the 1970’s. However, with the adoption of policies like the Clean Air Act, aerosol emissions began to decrease in the late 1970’s. Figure 1 below from a 2004 paper shows this decrease in aerosol emissions. Note the peak in the late 1970s and the downslope since approximately 1980:

Figure1: Aerosol emissions from 1850-2000. Different colors of the graph indicate different sources of aerosols.



2020 on course to be warmest year on record

Posted on 12 November 2020 by Zeke Hausfather

This is a re-post from Carbon Brief

While this year will be memorable for many reasons, it is now more likely than not that 2020 will also be the warmest year for the Earth’s surface since reliable records began in the mid-1800s. 

This is all the more remarkable because it will lack any major El Niño event – a factor that has contributed to most prior record warm years. 

However, with three months remaining, there is still some uncertainty. There is a chance that a growing La Niña in the tropical Pacific may drive cooler temperatures leading to a second-place finish – at least in some of the global temperature records produced by different groups of researchers around the world.

The first nine months of the year saw record concentrations of major greenhouse gases – CO2, methane, and nitrous oxide – in the atmosphere. Arctic sea ice extent was at record low levels for much of the summer and the summer minimum clocked in as the second lowest on record after 2012.  

While climate records are a useful benchmark to highlight the warming of the planet, the change in temperatures, sea ice and other climate factors over time are much more important than if any single year sets a new record. 

There has been a clear warming trend over the past 50 years, along with hints in some datasets of potential acceleration in recent years. Similarly, both sea ice extent and volume are clearly declining over time. 



Skeptical Science New Research for Week #45, 2020

Posted on 11 November 2020 by doug_bostrom

Rocks as data loggers

Improving our confidence with quantifying paleoclimate is important to our understanding of how Earth's systems have responded to past climate change, and for refinement of climate models.

Reconstructing paleoclimate is accomplished via proxy indicators of various climatic features. Pollen, tree rings, varves and other methods have been successfully employed for this purpose. Each approach is somewhat limited in scope of coverage. 

Building on other recent work, a team led by Rabiul Biswas have revived and claim to have significantly extended a largely dormant but fundamentally promising technique. Thermoluminescence of the common mineral feldspar tantalizes with paleoclimatic rewards— if a method can be developed to make it a continuous measure of past temperature. Biswas et al show how that may be done. If successfully applied on a broad scale, this new data source will fill in some substantial gaps in our record of paleoclimate.  With each current particular recording mechanism working only for particular and individually relatively narrow contexts, a temperature proxy with a significantly broadened range would be very helpful indeed. Feldspar is a widely distributed mineral on Earth's surface and easily sampled, so this is a potentially high impact advancement. 

From the abstract:

Thermoluminescence (TL) of feldspar is investigated for its potential to extract temperature histories experienced by rocks exposed at Earth's surface. TL signals from feldspar observed in the laboratory arise from the release of trapped electrons from a continuous distribution of trapping energies that have a range of thermal stabilities. The distribution of trapping energies, or thermal stabilities, is such that the lifetime of trapped electrons at room temperature ranges from less than a year to several billion years. Shorter lifetimes are associated with low-temperature TL signals, or peaks, and longer lifetimes are associated with high temperature TL signals. Here we show that trapping energies associated with shorter lifetimes, or lower-temperature TL signals (i.e. between 200 and 250 C), are sensitive to temperature fluctuations occurring at Earth's surface over geological timescales. Furthermore, we show that it is possible to reconstruct past surface temperature histories in terrestrial settings by exploiting the continuous distribution of trapping energies. 

Open access and free to read, with a citation lineage including footprints on the moon: Surface paleothermometry using low-temperature thermoluminescence of feldspar



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