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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?


2015 Arctic melting season won't break records, but could wipe the 'recovery'

Posted on 29 July 2015 by Neven

After the record smashing 2012 melting season had ended, Arctic sea ice watchers awaited the following melting season with a mix of anticipation and apprehension. Anticipation, because the annual ebb and flow of Arctic sea ice is one of the most spectacular natural events on the planet, accentuated by the dramatic loss of the past 30 years. Apprehension, because further losses would bring the Arctic yet one step closer to virtually ice-free conditions, an iconic image entailing many unpredictable consequences.

sea ice concentration

Arctic sea ice concentration on July 26, 2015. Source: University of Bremen.

But just as the previous record low reached in 2007 was followed by a short-lived rebound, the 2013 melting season proved to be sufficiently cold and cloudy to make up for the large amount of thin first year ice in the Arctic. When the following 2014 melting season was relatively cold again, with little wind to compact the ice and transport it to lower latitudes, extent and area numbers yet again ended up well above 2012 levels. Consequently, this year’s melting seasonstarted out with more volume and more multi-year ice.



2015 SkS Weekly News Roundup #31A

Posted on 28 July 2015 by John Hartz

40 percent of adults on Earth have never heard of climate change

A major concern for climate activists is figuring out what drives the public’s beliefs about climate change. This information can help scientists better engage with the public and help activists understand what factors are likely to make people take climate change seriously as a threat.

Until now, most research into public attitudes on climate change have focused on Western nations, like the United States, Europe and Australia, leaving scientists with little knowledge of how much awareness there is about climate change in other parts of the world and how people feel about it. But a new study, published Monday in the journal Nature Climate Change, provides a more inclusive look at the issue, giving scientists greater insight into what factors are most likely to make people care about climate change — if they know it’s happening at all.

The study focused on two major questions: what factors most influence whether a person is aware of climate change and, for those that know it’s happening, what factors influence how big of a risk that person thinks it poses. The researchers found that, worldwide, education is the biggest predictor of climate change awareness. Major factors that affected a person’s risk perception included understanding that climate change is caused by humans — this was especially true in the Americas and Europe — and noticing local changes in temperature, a particularly high indicator in many countries in Africa and Asia.

40 percent of adults on Earth have never heard of climate change by Chelsea Harvey, Energy & Environment, Washington Post, July 27, 2015



The Daily Mail and Telegraph get it wrong on Arctic sea ice, again

Posted on 28 July 2015 by dana1981

Cherry-picking is one of the five telltale techniques of climate change denial. By focusing on short-term blips in noisy data, those who want to maintain the status quo can distract from the long-term threats posed by climate change. Climate contrarians most frequently deploy this strategy using global temperature and Arctic sea ice data.

A recent study in Nature Geoscience concluded that, not surprisingly, there is a strong relationship between the summer temperatures in the Arctic (specifically the number of “melting degree days”), and the amount of sea ice that melts in a given year. 2013 happened to be a relatively cool year in the Arctic – the coolest since 2004. As a result, there was relatively little ice melt in 2013. The annual minimum Arctic sea ice extent and volume were their largest since at least 2009, or perhaps as far back as 2005, according to the data used in this new study.

The following figure from the paper is as clear as ice – while there was a short-term increase from 2012 to 2013, the Arctic has lost more than half its sea ice over the past three decades.

sea ice volume

PIOMAS model Arctic sea ice volume for autumn 1980–2014 (solid line) and spring 1981–2014 (dashed line). CryoSat-2 volume estimates (red stars) are plotted for 2010–2014.

The following video by programmer Andy Lee Robinson also illustrates the dramatic rate of sea ice decline over the past 35 years.



2015 SkS Weekly News Roundup #30D

Posted on 27 July 2015 by John Hartz

5 bold and beautiful solar projects from around the world

China is building its largest solar plant covering 6,301 acres in the Gobi desert and with capacity to provide electricity to 1 million households.

This is just another record breaker for China. But there’s good reason.

In a recent Greenpeace East Asia investigation, we found that air pollution levels have improved in the first six months of 2015, though still remain below global and domestic standards. Once completed the new solar plant will cut standard coal use by 4.26 million tons every year, reducing emissions of carbon dioxide and sulfur dioxide by 896,000 tons and 8,080 tons, respectively, according to state-run Xinhua news agency.

It’s part of a global trend. Check out these other bold and beautiful solar projects from around the world. Which one is your favorite?

5 Bold and Beautiful Solar Projects From Around the World by Shuk-Wah Chung, Greenpeace East Asia, EcoWatch, July 24, 2015



Conspiracy theories about Skeptical Science

Posted on 27 July 2015 by John Cook

There is a growing body of research linking climate science denial and conspiratorial thinking. While Stephan Lewandowsky's Moon Landing paper has attracted most of the attention, another important paper from Yale University has flown somewhat under the radar. This research found that when those who deny climate change are asked to name the first thing that came to mind regarding climate change, the most common type of response involved conspiracy theories.




2015 SkS Weekly Digest #30

Posted on 26 July 2015 by John Hartz

SkS Highlights

The importance of good climate communication: a recent Arctic example by John Mason attracted the highest number of comments of the articles posted on SkS during the past week. Global warming deniers are an endangered species by Dana drew the second highest number of comments. 

Quote of the Week

Climate deniers who claim that thousands of scientists are engaging in a global fraud are "one step way from a conspiracy theory" that is too fantastical to be even feasible, he added.

"Think about it. We have an administration that could not roll out a proper health care website. You think they can manage a global scientific conspiracy? They could not do it if they wanted to," said Titley*, who also holds a doctorate in meteorology. And he scoffed at the idea that scientists are deliberately lying about climate change just to obtain short-term research grants.

*David Titley, Ret. Rear Adm., U.S Navy 

Navy climate change expert sees opponents ignoring science by Brian Nearing, Times Union (Albany, NY), July 22, 2015 

Toon of the Week

2015 Toon 30 

Hat tip to I Heart Climate Scientists 



2015 SkS Weekly News Roundup #30C

Posted on 25 July 2015 by John Hartz

A new climate-change danger zone?

w much does the climate have to change for it to be “dangerous”? This question has vexed scientists ever since the first climate models were developed, back in the nineteen-seventies. It was provisionally answered in 2009, though by politicians rather than scientists. According to an agreement known as the Copenhagen Accord, which was brokered by President Barack Obama, to avoid danger, the world needs “to hold the increase in global temperature below 2 degrees Celsius” (3.6 degrees Fahrenheit).

Now a group of climate modellers is arguing that the danger point is, in fact, a lot lower than that. In a paper set to appear online this week in Atmospheric Chemistry and Physics, the modellers, led by James Hansen, the former director of NASA’s Goddard Institute for Space Studies, warn that an increase of two degrees Celsius could still be enough to melt large portions of Antarctica, which, in turn, could result in several metres’ worth of sea-level rise in a matter of decades. What’s important about the paper from a layperson’s perspective—besides the fate of the world’s major coastal cities, many of which would be swamped if the oceans rose that high—is that it shows just how far from resolved, scientifically speaking, the question of danger levels remains. And this has important political implications, though it seems doubtful that politicians will heed them.

A new climate-change danger zone? by Elizabeth Kolbert, The New Yorker, July 23, 2015



Scientific consensus and arguments from authority

Posted on 24 July 2015 by Guest Author

This is a re-post of Potholer's latest YouTube video



2015 SkS Weekly News Roundup #30B

Posted on 23 July 2015 by John Hartz

Climate treaty's finances on shaky ground

Faith in the Green Climate Fund, the finance arm long believed to hold a key to achieving a global climate change accord in Paris in December, is beginning to wane.

The Green Climate Fund is supposed to be the primary distributor of tens of billions of dollars in climate aid to help the world's poorest countries deal with climate change caused primarily by the actions of others. It was designed to help heal the deep divisions between rich and poor nations that have long dimmed hopes for a meaningful global warming solution. 

But with just one more board meeting to go before the Paris climate talks begin, the money it has to work with is not close to what's needed, the $3 billion contribution from the United States is looking iffy, and the fund has partnered with several financial institutions that developing nations distrust. 

Climate Treaty's Finances on Shaky Ground by Elizabeth Douglass, InsideClimate News, July 20, 2015



The importance of good climate communication: a recent Arctic example

Posted on 23 July 2015 by John Mason

Here's the abstract of a new paper in Nature Geoscience on Arctic sea-ice volume:

Changes in Arctic sea ice volume affect regional heat and freshwater budgets and patterns of atmospheric circulation at lower latitudes. Despite a well-documented decline in summer Arctic sea ice extent by about 40% since the late 1970s, it has been difficult to quantify trends in sea ice volume because detailed thickness observations have been lacking. Here we present an assessment of the changes in Northern Hemisphere sea ice thickness and volume using five years of CryoSat-2 measurements. Between autumn 2010 and 2012, there was a 14% reduction in Arctic sea ice volume, in keeping with the long-term decline in extent. However, we observe 33% and 25% more ice in autumn 2013 and 2014, respectively, relative to the 2010–2012 seasonal mean, which offset earlier losses. This increase was caused by the retention of thick sea ice northwest of Greenland during 2013 which, in turn, was associated with a 5% drop in the number of days on which melting occurred—conditions more typical of the late 1990s. In contrast, springtime Arctic sea ice volume has remained stable. The sharp increase in sea ice volume after just one cool summer suggests that Arctic sea ice may be more resilient than has been previously considered.

OK, let's pick this apart. Arctic sea-ice volume is the trickiest of the sea-ice variables to measure. Extent and area are by contrast straightforward. Volume depends on the survival of multi-year ice in any melt season. A pronounced melt season, like 2012, sees some of the multi-year ice lost. But if any of the ice that didn't melt in 2012 makes it through the 2013 season, you are going to get a volume increase. The authors state that they observed 33% more ice volume in autumn 2013 relative to the 2010-2012 mean. They go on to state that in 2014 there was 25% more ice volume relative to 2010-2012 – in other words it dropped again. That shows up on the following ice thickness distribution plot: the thickest ice is in red. Big red blob for 2013, much smaller one for 2014.

ice thickness map

Such observations are reasonably consistent with PIOMAS:

arctic sea ice volume - PIOMAS



Global warming deniers are an endangered species

Posted on 22 July 2015 by dana1981

At the end of this year there will be a critically important international climate change conference in Paris. At this conference, nations will attempt to reach an agreement to reduce greenhouse gas emissions and slow global warming.

Over the past few months there’s been a flood of big climate-related news, most of which will help build support and pressure for a strong agreement to curb global warming at the Paris conference. The political and social climate is shifting, and those in denial about human-caused climate change are struggling to adapt.

Scientific research underscores climate risks

John Abraham recently reported on two separate studies published in Nature andNature Climate Change, both of which found that global warming is intensifying several types of extreme weather. California is in the midst of a drought unprecedented in over a millennium, a heat wave is killing thousands of people in India and Pakistan, another has been baking Europe, and it seems as though half of North America is on fire.



2015 SkS Weekly News Roundup #30A

Posted on 21 July 2015 by John Hartz

4C degree rise in global temperature may make outdoor work impossible in North India

If the world warms up by 4 degrees Celsius, there is 30 per cent probability that temperatures will be so high that even moderate outdoor work cannot be carried out in the hottest month in northern India, a study on the risks of climate change has said.

There would also be a 40 per cent chance that individuals in northern India will not be able to participate in competitive outdoor activities in summertime if global average temperature rises on an average by one degree.

An international group of climate scientists, energy analysts and experts from finance and military recently released an independent assessment of the risks of climate change commissioned by the United Kingdom's Foreign and Commonwealth Office.

4 Degree Rise in Global Temperature May Make Outdoor Work Impossible in North India: Study, All India/KDTV. July 19, 2015



NOAA State of the Climate report: Which seven records were broken in 2014?

Posted on 21 July 2015 by Guest Author

This is a re-post from Carbon Brief by Robert McSweeney

From greenhouse gas levels to ocean heat content, 2014 was a record-breaking year for the Earth system in many different ways. That's the finding of the latest State of the Climate report from the US National Oceanic and Atmospheric Administration's (NOAA) published today.

Now in its 25th year, the report provides a checkup of global climate using data collected from land, sea, ice and space. We take a look at seven of the records that tumbled last year.

Greenhouse gases

All the major greenhouse gases in the atmosphere, including carbon dioxide, methane and nitrous oxide, hit record high average concentrations last year.

After briefly passing 400ppm in May 2013, carbon dioxide levels at Mauna Loa in Hawaii stayed above this mark for the whole of April, May and June in 2014, the report says. Globally, 1.9ppm of carbon dioxide was added to the atmosphere in 2014, taking the average for the year to 397.2ppm.

State Of Climate 2014_Fig1

Global average carbon dioxide concentrations since 1980, with photo of Mauna Loa Observatory in background. Adapted from Figure 2.36 in State of the Climate in 2014



The oceans are warming faster than climate models predicted

Posted on 20 July 2015 by John Abraham

As I have said many times on this blog, if you want to know how much “global warming” is happening, you really have to be able to measure “ocean warming”. That is because more than 90% of the excess energy coming to the Earth from greenhouse gases goes into the ocean waters. My colleagues and I have a new publication, which better characterizes this heating and also compares climate model predictions with actual measurements. It turns out models have under-predicted ocean warming over the past few decades. 

But how would you measure the ocean? How would you make consistent, long-term measurements that would allow people to compare ocean heat from decades ago to today? How would you make enough measurements throughout the ocean so that we have a true global picture?

This is one of the most challenging problems in climate science, and one that my colleagues and I are working hard on. We look throughout measurement history; first measurements were made with canvas buckets, then insulated buckets, and other more progressively complex devices. Many measurements were made along ocean passageways as ships transported goods across the planet. 

As more ship travel occurred, and more measurements were made, the coverage of temperature measurements across the globe increased. So, over time, we say the temporal and spatial resolution increased. As these changes occurred, you have to be careful that any trend you see isn’t just an artifact of the resolution or the instrument accuracy. 

We also pay attention on one particularly important measurement device called the eXpendable BathyThermograph (XBT). This device, originally designed to make crude measurements for navies, has been used for years by climate scientists. There is systematic bias in XBT data, which creates spurious “ocean warm decades” from 1970s to early 1980s as reported in the IPCC Fourth Assessment Report.

What my colleagues determined was that we could reduce past errors in the ocean heat content (OHC) record by correcting systematic measurement biases, filling in gaps where no information is available, and by choosing a proper comparison climate. This new paper doesn’t solve all of the OHC issues, but it makes a great stride in clearing up past questions.

Lead author, Dr. Lijing Cheng (who works for the International Center for Climate and Environment Sciences in China) applied four separate improvements to data. He focused his attention on the heating in the upper 700 meters of ocean waters because that depth has the best measurements and it also is the region where much of the global warming heat goes.

Going back to 1970, we find that the upper 700-meter water layer temperature has increased approximately 0.3°C (approximately 0.55°F). While that may not sound like a lot, we have to remember this is a huge amount of water and consequently it requires an enormous amount of energy.

We separated the world’s oceans into the Atlantic, Pacific, and Indian. All three of these oceans are warming with the Atlantic warming the most. We also calculated the ocean heating by using 40 state-of-the-art climate models. Over the period from 1970, the climate models have under-predicted the warming by 15%. 

models vs obs



2015 SkS Weekly News Roundup #29

Posted on 19 July 2015 by John Hartz

4 takeaways from the annual climate review

As has been seen year after year, the warming of the Earth is causing major changes in many aspects of the planet’s climate, and 2014 was yet another year that showed this trend in stark relief, a report released Thursday says.

Numerous records were broken last year, according to the State of the Climate report, an annual checkup of the global climate published in a special issue of the journal Bulletin of the American Meteorological Society.

Now in its 25th year, the report pulls together hundreds of scientists from dozens of countries to piece together the changes from the previous year in all aspects of the Earth’s climate — from carbon dioxide levels to the planet’s rising temperature, from glacier melt to change in soil moisture — and puts them in the context of decades-long trends.

4 Takeaways from the Annual Climate Review by Andrea Thompson, Climate Central, July 16, 2015



2015 SkS Weekly Digest #29

Posted on 19 July 2015 by John Hartz

SkS Highlights

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018 by Stephen Leahy (reprinted from The Leap) generated quite the buzz on its comment thread. It garnered, by a wide margin, the most comments of the articles posted on SkS during the past week. If you have not yet read this important article, you will want to do so.  

El Niño Watch

Long-range model forecasts from NOAA, the U.K. Met Office, Australia's Bureau of Meteorology, and the European Centre for Medium Range Weather Forecasting, among others, all suggest the current El Niño is not only a virtual lock to be strong, but may eventually rival the strongest in modern records dating to 1950, with anomalies approaching or exceeding the 2.3 degrees Celsius observed in late 1997.

This may place the El Niño of 2015-2016 in the discussion with the "Super El Niños" of 1997-1998 and 1982-1983. 

In fact, the latest available three-month mean sea-surface temperature anomalies in the Niño 3.4 region – April through June – were pacing 0.3 degrees Celsius warmer 

Record Strong El Niño Ahead? by John Erdman, The Weather Channel. July 17, 2015 

Toon of the Week

2015 Toon 29 

Hat tip to I Heart Climate Scientists



Climate pledge puts China on course to peak emissions as early as 2027

Posted on 18 July 2015 by Guest Author

This is a re-post from Carbon Brief by Simon Evans

China is aiming to peak its carbon dioxide (CO2) emissions "around 2030" and will make "best efforts" to peak early, its climate pledge to the UN confirms.

China's  intended nationally determined contribution (INDC) includes a new target to reduce its carbon intensity by 60-65% of 2005 levels by 2030. Carbon Brief analysis suggests the top end of this range would see CO2 peaking in 2027. China also says it will source 20% of its energy in 2030 from low-carbon sources.

The announcement, which adds to existing  Chinese commitments, came on a busy day on Tuesday for climate pledges. South Korea, Serbia and Iceland all filed INDCs with the UN, bringing the share of global emissions covered by pledges to nearly 56%. Tuesday also saw Brazil and the US announce new commitments to renewable energy at a joint summit in Washington.

Largest emitter

As the world's largest emitter responsible for nearly a quarter of global greenhouse gas emissions, China's announcement is the most significant. Amber Rudd, UK energy and climate change secretary, said it was a sign that momentum was  building for a deal in Paris this December. We'll look at what China says it wants from that deal in a moment.

China become the world's largest emitter in 2005-6 (red line, below), after overtaking the EU in 2003 and the US in 2005. It rapidly eclipsed the world's other major economies through  coal-fuelled expansion and double-digit economic growth.

Screen Shot 2015-06-30 At 12.11.18

Energy-related CO2 emissions in major economies and the rest of the world, 1970-2014. Source: BP Statistical Review of World Energy 2015. Chart by Carbon Brief.



Dutch government ordered to cut carbon emissions in landmark ruling

Posted on 17 July 2015 by Guest Author

A court in The Hague has ordered the Dutch government to cut its emissions by at least 25% within five years, in a landmark ruling expected to cause ripples around the world.

To cheers and hoots from climate campaigners in court, three judges ruled that government plans to cut emissions by just 14-17% compared to 1990 levels by 2020 were unlawful, given the scale of the threat posed by climate change.

Jubilant campaigners said that governments preparing for the Paris climate summit later this year would now need to look over their shoulders for civil rights era-style legal challenges where emissions-cutting pledges are inadequate.

“Before this judgement, the only legal obligations on states were those they agreed among themselves in international treaties,” said Dennis van Berkel, legal counsel for Urgenda, the group that brought the suit.

“This is the first a time a court has determined that states have an independent legal obligation towards their citizens. That must inform the reduction commitments in Paris because if it doesn’t, they can expect pressure from courts in their own jurisdictions.”

In what was the first climate liability suit brought under human rights and tort law, Judge Hans Hofhuis told the court that the threat posed by global warming was severe and acknowledged by the Dutch government in international pacts.

“The state should not hide behind the argument that the solution to the global climate problem does not depend solely on Dutch efforts,” the judges’ ruling said. “Any reduction of emissions contributes to the prevention of dangerous climate change and as a developed country the Netherlands should take the lead in this.”

After a legal campaign that took two and a half years to get to its first hearing in April, normally dispassionate lawyers were visibly moved by the judge’s words. “As the verdict was being read out, I actually had tears in my eyes,” Roger Cox, Urgenda’s lead advocate, told the Guardian. “It was an emotional moment.”



No, the sun isn't going to save us from global warming

Posted on 16 July 2015 by dana1981

Some zombie myths just won’t die. In fact, I debunked this one two years ago at The Guardian

To sum up, a number of scientific studies have asked the question, ‘if the sun were to enter another extended quiet phase (a grand solar minimum), how would that impact global surface temperatures?’. Every study agrees, it would cause no more than 0.3°C cooling, which would only be enough to temporarily offset about a decade’s worth of human-caused global warming.


The global mean temperature difference is shown for the time period 1900 to 2100 for the IPCC A2 emissions scenario. The red line shows predicted temperature change for the current level of solar activity, the blue line shows predicted temperature change for solar activity at the much lower level of the Maunder Minimum, and the black line shows observed temperatures through 2010. Adapted from Feulner & Rahmstorf (2010).

Denial101x lecture debunking the ‘impending mini ice age’ myth by Dana Nuccitelli 

Solar activity is actually quite stable. That’s a good thing for us on Earth, because without big swings in the amount of energy reaching the planet from the sun, our climate is likewise generally quite stable. That’s allowed us to build big immobile cities and farms, with the confidence that the climate and weather will be pretty consistent in those areas. It’s allowed human civilization to develop over the past 10,000 years. Though with human-caused global warming in the process of destabilizing the climate, we’re putting that civilization under serious stress.



Are we overestimating our global carbon budget?

Posted on 15 July 2015 by Andy Skuce

The latest research suggests that natural sinks of carbon on land may be slowing or even turning into sources, creating climate consequences potentially worse than first thought.

Nature has provided humans with a buffer against the worst effects of our carbon pollution. Since 1750, we have emitted about 580 billion tonnes of carbon into the atmosphere by burning fossil fuels, cutting down forests and making cement. If those emissions had simply accumulated in the air, the concentration of carbon dioxide would have increased from 280 parts per million (ppm), as it was before the Industrial Revolution, to about 550 ppm today. Instead, we currently measure around 400 ppm, which is still a whopping 40 per cent above the planet’s pre-industrial atmosphere, but much less than a doubling.

Some 60 per cent of our emissions have been taken up in natural sinks by, in roughly equal parts, dissolving into the ocean and by being taken up by plants growing faster on land. Were it not for these natural carbon sinks, we would by now be much deeper into dangerous climate change.

As we continue to burn fossil fuels, our climate troubles will become worse should those sinks start to falter. And the outlook will be worse still if those sinks turn into sources of carbon. 

New research

According to the latest research, the carbon sink on land is unfortunately starting to show signs of trouble. Instead of providing a brake on human emissions, the land carbon sink could instead soon be giving our emissions a boost. (The ocean sink appears to be relatively safe for now, although there is a price to pay: the consequence of the process of carbon dioxide dissolving into seawater, ocean acidification, has been called climate change’s evil twin with its own, non-climate related consequences for marine life.)

Plants don't thrive solely on carbon dioxide

Plants don’t thrive solely on carbon dioxide.



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