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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Climate Hustle

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?


Evidence Squared: Episode 9

Posted on 28 April 2017 by John Cook

In Episode 9 of their podcast, John Cook and Peter Jacobs talk about the March for Science, including interviews with people from the DC march.



New study: global warming keeps on keeping on

Posted on 27 April 2017 by John Abraham

As humans continue to dump heat-trapping gases like carbon dioxide into the atmosphere, the Earth continues to warm. In fact, it has been warming for decades and we now routinely hit temperatures that are 1°C (about 2°F) above the temperatures from 100 years ago.

But despite what we may expect, temperatures across the globe don’t rise little by little each year in a straight line. Rather, temperature changes are a bit bumpy. They go up and they go down somewhat randomly as they increase. Think of a wiggly line superimposed on a straight rising line.

A great depiction of the behavior is seen from the NASA data, shown below. Each black mark is the Earth’s temperature for a given year. The red line is calculated from 5-year averages of the black data marks and is much smoother than the black line. As you move from left to right, you pass from the year 1880 to the most recent year (2016), which is shown in the very upper right corner.

Careful observation of the graph shows that the last three years (2014, 2015, and 2016) were all record-breakers. It makes you wonder, what the chances are that global warming has sped up?




5 Year Study: What Happens in the Arctic Does not Stay in the Arctic

Posted on 26 April 2017 by greenman3610

This is a re-post from Climate Crocks

After two years of interviews from Seattle, to Oslo, to Greenland, boiling down hundreds of hours of detailed questioning with some of the most renowned arctic experts from the entire host of Arctic nations, the Arctic Monitoring and Assessment Program today releases a 5 year study on the state of our knowledge of arctic change.



March against madness - denial has pushed scientists out to the streets

Posted on 25 April 2017 by dana1981

This past weekend, hundreds of thousands of people in the US and around the world marched in support of science. Next weekend, the People’s Climate Marchwill follow.

Redglass Pictures and StarTalk Radio created a short film in which the brilliant scientist and communicator Neil deGrasse Tyson – though not specifically talking about the science marches – perfectly articulated the motivations behind them.


For example, last weekend’s March for Science was largely a pushback against the creeping science denial among today’s political leaders, about which Dr. Tyson said:



SkS Analogy 2 - Ferrari Without Gas

Posted on 24 April 2017 by Evan

Tag Line

A Ferrari without gasoline goes nowhere.
Greenhouse gases without infrared radiation cause no warming.

Elevator Statement

  • The concentration of greenhouse gases is like the size of a car engine: higher greenhouse gas concentration is like a bigger engine.
  • Infrared radiation is like the gasoline in the tank of a car.
  • Just as gasoline is the fuel that drives an engine, infrared radiation is the fuel that drives the greenhouse effect.

Climate Science

Global warming occurs because infrared radiation emitted from the surface of the Earth is captured by greenhouse gases in the atmosphere, increasing the temperature of the atmosphere. Increased greenhouse-gas concentrations in an atmosphere with constant background infrared radiation will absorb an increasing fraction of the emitted infrared radiation, causing warming. Increased greenhouse-gas concentrations in the atmosphere combined with increased infrared radiation (e.g., due to reflective snow and ice melting exposing dark oceans that absorb solar radiation and reemit it as infrared radiation) causes even faster heating, such as is happening in the arctic.

Some skeptics point to Snowball Earth to “prove” that CO2 does not cause warming, by noting that 650 million years ago CO2 concentrations exceeded 1000 ppm yet the world was frozen solid, even down to the equator. Part of what allowed Snowball Earth to occur was because solar radiation was 4% lower than today, but a major reason that Snowball Earth persisted for so long is that snow and ice reflect 90% of incoming solar radiation, reducing infrared radiation to the point that the greenhouse effect was severely reduced.

Snowball and Dirtball Earth Radiation Balances



2017 SkS Weekly Climate Change & Global Warming Digest #16

Posted on 23 April 2017 by John Hartz

Story of the Week... Event of the Week... El Niño Update... Toon of the Week... Quotes of the Week... Graphic of the Week... SkS in the News... Photo of the Week... SkS Spotlights... Video of the Week... Reports of Note... Coming Soon on SkS... Poster of the Week... Climate Feedback Reviews... SkS Week in Review... 97 Hours of Consensus...

Story of the Week...

We Just Breached the 410 Parts Per Million Threshold

The world just passed another round-numbered climate milestone. Scientists predicted it would happen this year and lo and behold, it has.

On Tuesday, the Mauna Loa Observatory recorded its first-ever carbon dioxide reading in excess of 410 parts per million (it was 410.28 ppm in case you want the full deal). Carbon dioxide hasn’t reached that height in millions of years. It’s a new atmosphere that humanity will have to contend with, one that’s trapping more heat and causing the climate to change at a quickening rate.

CO2 Concentrations

In what’s become a spring tradition like Passover and Easter, carbon dioxide has set a record high each year since measurements began. It stood at 315 ppm when record keeping began at Mauna Loa in 1958. In 2013, it passed 400 ppm. Just four years later, the 400 ppm mark is no longer a novelty. It’s the norm.

“Its pretty depressing that it’s only a couple of years since the 400 ppm milestone was toppled,” Gavin Foster, a paleoclimate researcher at the University of Southampton told Climate Central last month. “These milestones are just numbers, but they give us an opportunity to pause and take stock and act as useful yard sticks for comparisons to the geological record.” 

We Just Breached the 410 Parts Per Million Threshold by Brian Kahn, Climate Central, Apr 20, 2017 



2017 SkS Weekly Climate Change & Global Warming News Roundup #16

Posted on 22 April 2017 by John Hartz

A chronological listing of news articles posted on the Skeptical Science Facebook page during the past week. Articles of signifigance as determined by the editor are highlighted in the Editor's Picks' section.

Editor's Picks

For the first time on record, human-caused climate change has rerouted an entire river 

Kaskawulsh Glacierin Kluane National Park in the Yukon

A stream flows through the toe of Kaskawulsh Glacier in Kluane National Park in the Yukon. In 2016, this channel allowed the glacier’s meltwater to drain in a different direction than normal, resulting in the Slims River water being rerouted to a different river system. (Dan Shugar)

A team of scientists on Monday documented what they’re describing as the first case of large-scale river reorganization as a result of human-caused climate change.

They found that in mid-2016, the retreat of a very large glacier in Canada’s Yukon territory led to the rerouting of its vast stream of meltwater from one river system to another — cutting down flow to the Yukon’s largest lake, and channeling freshwater to the Pacific Ocean south of Alaska, rather than to the Bering Sea.

The researchers dubbed the reorganization an act of “rapid river piracy,” saying that such events had often occurred in the Earth’s geologic past, but never before, to their knowledge, as a sudden present-day event. They also called it “geologically instantaneous.”

For the first time on record, human-caused climate change has rerouted an entire river by Chris Mooney, Energy & Environment, Washington Post, Apr 17, 2017



Neil deGrasse Tyson on science vs. denial

Posted on 21 April 2017 by Guest Author



Heartland Institute's misinformation campaign into schools

Posted on 21 April 2017 by John Cook

Last month, the Heartland Institute sent a climate denial booklet to 25,000 teachers around the US. In Episode 8 of the Evidence Squared podcast, we look at the why and how of this book. What is the chief motivation for the book’s misinformation and what are the techniques they employ to cast doubt on climate science?

Follow Evidence Squared on iTunesFacebookTwitterYouTube and Soundcloud.



SkS Analogy 1 - Speed Kills

Posted on 19 April 2017 by Evan

Tag line

Speed Kills

Elevator Statement

Deceleration from 60 mph to 0 in …

  • 30 seconds (base rate): Normal exit from a freeway; no drinks spilled, life goes on.
  • 3 sec (10 times base rate): Slam on the brakes. All drinks and loose items end up on dash board. People not wearing seat belts do ungraceful face plants. Survivable injuries.
  • 0.3 sec (100 times base rate): Like running into a parked car. Crumple zones in both cars absorb much of the energy, but people are seriously injured, some mortally.
  • 0.03 sec (1000 times base rate): Like running into a brick wall. Most don’t live to tell about it.

Climate Science

It is not only the CO2 concentration that is important, but the annual rate of increase of CO2 concentration, because the rate of increase determines the rate at which natural systems must adapt … or go extinct.

For 1 million years life on earth has adapted itself to going into and out of glacial cycles over approximately 100,000-year cycles. We come out of glacial cycles in about 10,000 years, with CO2 rising 100 ppm in that time. That is a rate of increase of about 0.01 ppm/year. If we use this as a typical rate to which nature has adapted, and has done so already for at least 10 cycles, then we can determine how much faster than this we are now moving. The idea is that if we limit CO2 rise to this rate, we expect nature will adapt; the further away we move from this base rate the more difficulty nature will have adapting.



Yes, we can do 'sound' climate science even though it's projecting the future

Posted on 18 April 2017 by Guest Author

Kevin Trenberth, Distinguished Senior Scientist, National Center for Atmospheric Research and Reto Knutti, Professor, Eidgenössische Technische Hochschule (ETH) Zürich

This article was originally published on The Conversation. Read the original article.

Increasingly in the current U.S. administration and Congress, questions have been raised about the use of proper scientific methods and accusations have been made about using flawed approaches.

This is especially the case with regard to climate science, as evidenced by the hearing of the House Committee on Science, Space and Technology, chaired by Lamar Smith, on March 29, 2017.



Humans on the verge of causing Earth’s fastest climate change in 50m years

Posted on 17 April 2017 by dana1981

A new study published in Nature Communications looks at changes in solar activity and carbon dioxide levels over the past 420 million years. The authors found that on our current path, by mid-century humans will be causing the fastest climate change in approximately 50 million years, and if we burn all available fossil fuels, we’ll cause the fastest change in the entire 420 million year record.


Changes in atmospheric carbon dioxide and in the combined solar and carbon dioxide forcing over the past 420 million years. Illustration: Foster et al. (2017); Nature Communications.

The study relates to a scientific conundrum known as the “faint young sun paradox” – that early in Earth’s history, solar output was 30% less intense than it is today, and yet the planet was warm enough to have a liquid ocean. A stronger greenhouse effect due to higher carbon dioxide levels in the atmosphere may be one explanation.

Over time, solar output has grown stronger, and atmospheric carbon dioxide levels have fallen due to an effect known as “weathering” of rocks and an increase in plant life. The authors of this study found that over the past 420 million years, the slow heating of the sun and slow decline of the greenhouse effect have roughly offset each other, leading to a fairly stable long-term global climate.



2017 SkS Weekly Climate Change & Global Warming Digest #15

Posted on 16 April 2017 by John Hartz

Story of the Week... Editorial of the Week... Toon of the Week... Quote of the Week... Graphic of the Week... SkS in the News... Photo of the Week... SkS Spotlights... Video of the Week... Reports of Note... Coming Soon on SkS... Poster of the Week... Climate Feedback Reviews... SkS Week in Review... 97 Hours of Consensus...

Story of the Week...

Ruins, Not Reefs: How Climate Change Is Fast-Forwarding Coral Science

Great Barrier Reef Bleached Staghorn Coral 

A bleached coral near the Great Barrier Reef on March 16, 2017

At about the same moment that millions of Americans sat staring at their television or laptop or phone—watching the results from the presidential election stream in, seeing state after state called for Donald Trump—Kim Cobb was SCUBA diving near the center of the Pacific Ocean. She did not watch the same trickle of news as other Americans. She surfaced, heard the results, and dove in the water again. She was, after all, attending to devastation.

Cobb is a climate scientist at the Georgia Institute of Technology. On November 8, she was on her most recent of many research trips to Kiritimati Island reef, the largest coral atoll in the world. (Kirimati is pronounced like Christmas.) She first began studying the reef in 1997, during the last big El Niño warming event; she has returned nearly every year since. Last year, she went three times.

“We had been waiting for the big one. And boy… did it happen,” she told me earlier this year. “It really rolled out at an unprecedented magnitude. This particular El Niño event had its maximum temperature loading almost in a bulls-eye almost around Kirimati Island.” 

Ruins, Not Reefs: How Climate Change Is Fast-Forwarding Coral Science by Robinson Meyer, The Atlantic Magazine, Apr 11, 2017 



2017 SkS Weekly Climate Change & Global Warming News Roundup #15

Posted on 15 April 2017 by John Hartz

A chronological listing of news articles posted on the Skeptical Science Facebook page during the past week. Articles of signifigance as determined by the editor are highlighted in the Editor's Picks' section.

Editor's Picks

An Indian court says glaciers and rivers are 'living entities.' Could the same approach work in the US?

Ganges River Kolkata India Chaiti Chhath Festival 

A Hindu devotee performs a ritual as she offers prayers to the Sun god in the waters of the Ganges River during the Chaiti Chhath Festival in Kolkata, India. The Gangotri glacier feeds the Ganges. (Rupak De Chowdhuri/Reuters

Just weeks after a high court in the Indian state of Uttarakhand granted legal personhood to the Ganges and Yamuna rivers, the same court recently extended that same standing to the Gangotri and Yamunotri glaciers that feed them. 

The finding follows New Zealand’s mid-March passage of a law recognizing the Whanganui River – a feature that the Maori people consider an ancestor – as a living entity. And the Indian court’s effort to protect the vanishing glaciers also carries religious overtones, since both the rivers and glaciers are considered sacred sites to many Hindus.

“The past generations have handed over the ‘Mother Earth’ to us in its pristine glory and we are morally bound to hand over the same Mother Earth to the next generation,” the two ruling justices wrote, according to India’s Hindustan Times. 

An Indian court says glaciers and rivers are 'living entities.' Could the same approach work in the US? by David Iaconangelo, Christian Science Monitor, Apr 7, 2017



New study shows worrisome signs for Greenland ice

Posted on 14 April 2017 by John Abraham

As humans put more heat-trapping gases into the atmosphere, like carbon dioxide, ice around the planet melts. This melting can be a problem, particularly if the melting ice starts its life on land. That’s because the melt water flows into the oceans, contributing to rising sea levels. Right now there are three main reasons that sea levels are rising. First, as ocean waters heat, they expand. Second, melting of ice in Antarctica flows into the ocean. Third, melting of ice on Greenland flows into the ocean. There is other melting, like mountain glaciers, but they are minor factors.

Okay, so how much is melting of Greenland contributing to sea level rise? Estimates are that about 270 gigatons of water per year are melting. The melting of an ice sheet like that atop Greenland can occur from the surface as air temperatures and sunlight warm the upper layer of ice. It can also occur from the edges as ice shelves collapse and fall into the oceans in large chunks.

Increase in surface melting from Greenland.

 Increase in surface melting from Greenland. Illustration: National Snow and Ice Data Center



Scientists can be advocates and maintain scientific credibility

Posted on 13 April 2017 by dana1981

Scientists are often hesitant to engage in what might be considered “advocacy,” for fear of losing credibility with the public. But a recent study led by John Kotcher at George Mason’s Center for Climate Change Communication found that “climate scientists who wish to engage in certain forms of advocacy have considerable latitude to do so without risking harm to their credibility, or the credibility of the scientific community.”

The study found that the perceived credibility of a hypothetical scientist did not decline when that scientist advocated for generalities such as a “strong effort” to curb the impacts of climate change—nor did credibility decline if the scientist called for more specific and concrete actions such as “strict limits on carbon emissions from coal power plants.” But perceived credibility did decline when the hypothetical scientist advocated building more nuclear power plants, which are relatively unpopular amongst the American public.

These results suggest that as long as scientists don’t advocate for specific unpopular policies, a range of advocacy positions are available that won’t harm their credibility. For example, polling has shown that most Americans—including Trump voters—support policies to combat climate change. They also think it’s a bad idea to cut scientific research funding, they support clean energy, and they want the government to do more to mitigate climate change risks.



Video: Climate scientists discuss record lows in Arctic and Antarctic sea ice

Posted on 12 April 2017 by Guest Author

This is a re-post from Carbon Brief by Roz Pidcock

Scientists confirmed last month that sea ice in both the Arctic and Antarctic fell to record low levels in March, capping off an exceptional few months at the Earth’s poles. Carbon Brief has asked some polar scientists to put the much-reported findings in context.



From the eMail Bag: A Deep Dive Into Polar Ice Cores

Posted on 11 April 2017 by David Kirtley

We occasionally receive excellent questions and/or comments by email or via our contact form and have then usually corresponded with the emailer directly. But, some of the questions and answers deserve a broader audience, so we decided to highlight some of them in a new series of blog posts.

The Keeling Curve (Figure 1) is one of the most iconic graphs illustrating modern climate change. Since 1958, the Keeling Curve has shown the increase in atmospheric CO2 from about 315 ppm to the present value of 405 ppm. CO2 measurements at Mauna Loa are taken hourly so this record has a very high time-resolution and is remarkably complete, even though there are occasional short gaps in the record.

Figure 1. The Keeling Curve. Source:

Another iconic graph shows CO2 concentrations going back 800,000 years through eight of the Earth's ice age cycles (Figure 2). Our sudden anthropogenic CO2 spike is almost literally "off the charts" compared to the rest of the ice ages record. At no time during the last 800,000 years has there been any comparable increase in CO2 concentrations.



Heartland: What's your story?

Posted on 10 April 2017 by Sarah

 If you teach physical science your mailbox may have recently been assaulted by a tract from the Heartland Institute titled "Why scientists disagree about global warming." The lie in the title is an excellent preview of the book's contents. Its numerous specific errors mask the fundamental mistake of all these piecemeal attacks on the scientific consensus: lack of a coherent narrative to describe the data. 

The two essential ingredients of science are data collection and a coherent narrative about what the data tells us. Heartland's repeated attacks on climate science utterly fail on the second point. In decades of promoting their pro-fossil fuel agenda Heartland has never presented a single coherent story to explain recent or past climate changes, and none of their accomplices have either (Benestad et al. 2015). Like many science deniers, they confuse science with data collection. They imagine that a story can be discredited by discovery of a misplaced comma. 

 heartland word cloud

A kettle of words is not a story.

(These words are from the Heartland tract.)




2017 SkS Weekly Climate Change & Global Warming Digest #14

Posted on 9 April 2017 by John Hartz

Story of the Week... Editorial of the Week... El Niño/La Niña Update... Toon of the Week... Quote of the Week... Graphic of the Week... SkS in the News... Photo of the Week... SkS Spotlights... Video of the Week... Reports of Note... Coming Soon on SkS... Poster of the Week... Climate Feedback Reviews... SkS Week in Review... 97 Hours of Consensus...

Story of the Week...

How do you manage climate risk? Ask those on the frontline

 Dry river bed near Uland iSouth Africa Jan 202016

A woman gets water from a well dug in the Black Imfolozi River bed, which is dry due to drought, near Ulundi, northeast of Durban, South Africa, Jan. 20, 2016. REUTERS/Rogan Ward 

More than 20 million people are at risk of dying from starvation within six months, the U.N. World Food Programme warned several weeks ago. Persistent armed conflict and prolonged droughts have crippled the economies of Somalia, South Sudan, Yemen and northern Nigeria, where communities are suffering the worst hunger.

That means we need to change the way we look at climate risk, Maarten van Aalst, director of the Red Cross Red Crescent Climate Centre, told a meeting in Nairobi this week.

Experts at the gathering called for the U.N.’s climate science panel to change the way it works, and examine how climate risk plays out locally and interlinks with other factors like the economy and health.

“Rising levels of food insecurity are not just due to a lack of rainfall, but also because people are vulnerable to conflict,” van Aalst told the Thomson Reuters Foundation by phone from Kenya. “Climate is only one piece of a much bigger puzzle.”

He urged scientists and policy makers to focus on what matters to people in highly vulnerable places. “They aren’t interested in rainfall projections for the next 100 years – they want to understand what is happening to them now,” he told the event convened by the Climate Centre and the Intergovernmental Panel on Climate Change (IPCC).

How do you manage climate risk? Ask those on the frontline by Zoe Tabary, Thomson Reuters Foundation, Apr 7. 2017 



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