Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.


Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup


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.

Home Arguments Software Resources Comments The Consensus Project Translations About Donate

Twitter Facebook YouTube Pinterest

RSS Posts RSS Comments Email Subscribe

Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...

Keep me logged in
New? Register here
Forgot your password?

Latest Posts


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?


Sizzling Midwest Previews a Hotter Future Climate

Posted on 29 July 2016 by Guest Author

This is a re-post from Inside Climate News by Bob Berwyn

June 2016 featured record heat across the U.S.

This June was the hottest ever, and July has brought even more heat, particularly in the Midwest. Credit: NOAA

Extreme heat waves like the current string of scorching days in the Midwest have become more frequent worldwide in the last 60 years, and climate scientists expect that human-caused global warming will exacerbate the dangerous trend in coming decades. It comes with potentially life-threatening consequences for millions of people.

Research has shown that overall mortality increases by 4 percent during heat waves compared to normal days in the U.S. A study in the journal Environmental Health Perspectives in 2011 suggested that rising summer temperatures could kill up to 2,200 more people per year in Chicago alone during the last two decades of the 21st century.

"The climate is changing faster than we've ever seen during the history of human civilization on this planet, and climate change is putting heat waves on steroids," Katharine Hayhoe, director of the Climate Science Center at Texas Tech University, said during a news conference on Thursday. "Heat waves are getting more frequent and stronger."

Temperatures this week soared into the 90s from Minnesota to Iowa, combining with high humidity to send heat indices well above the 100-degree Fahrenheit mark, considered a threshold for conditions dangerous to human health.

Current temperatures in large parts of the Midwest have been rising steadily for more than 100 years, with accelerated warming in the past few decades. According to the 2014 National Climate Assessment, the average temperature in the region increased by more than 1.5 degrees Fahrenheit between 1900 and 2010. Between 1950 and 2010, the rate of increase doubled, and since 1980, the pace of warming is three times faster than between 1900 and 2010.

But while the Midwest joins the overall warming trend, it has not been hit frequently by summer heat waves, according to Ken Kunkel of NOAA's National Centers for Environmental Information



Analysis: How UK leaving the EU would increase climate targets for others

Posted on 28 July 2016 by Guest Author

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

The European Commission has laid out proposals on dividing up 2030 emissions reduction goals for buildings, transport and agriculture.

The proposed 2030 Effort Sharing Regulation would allocate binding annual targets to each member state for sectors not covered by the EU Emissions Trading System (EU ETS). Countries would have to cut non-ETS emissions in 2030 by between zero and 40%, against 2005 levels.

Though uncertainty shrouds the UK’s future within the bloc following the Brexit vote, the proposal still includes the UK. It will also hand binding targets to Norway and Iceland, both non-EU member states.

Carbon Brief runs through the key points of the proposal and analyses what would happen if the UK were no longer part of the 2030 effort-sharing targets.

2030 targets

The EU has pledged to cut its greenhouse gas emissions in 2030 by at least 40% below 1990 levels. The ETS sector, including power stations and industry, will cut emissions in 2030 by 43% below 2005 levels (note the confusingly inconsistent base year). Non-ETS sectors, such as buildings and transport, will cut emissions in 2030 by 30% below 2005 levels.

The EU maintains that its 2030 target is in line with the goals of the Paris Agreement, which aims to keep temperature increases “well below 2C”. However, it has not changed its goal since Paris and Climate Action Tracker, a group of scientists and policy experts, says the EU’s pledge is “not yet sufficient” to be considered a fair share of global ambition.
Today’s proposal sets out how the 2030 non-ETS target of 30% below 2005 levels should be divided between the EU’s 28 (current) member states. The division of labour ranges from a 0% cut on 2005 levels for Bulgaria to a 40% reduction for Luxembourg and Sweden (see chart, below).

Proposed 2030 non-ETS emissions reduction targets for each EU member state, and the EU average. The reductions are relative to 2005 emissions. Source: European Commission. Chart by Carbon Brief.

Effort is shared out using two factors: first, countries with higher per-capita GDP are expected to do more; and, second, for those with above-average per-capita GDP, contributions are adjusted to reflect their cost-effective emissions-reduction potentials.

Broadly speaking, this division of labour means that the EU’s richest nations, including Sweden, Germany and the UK, are at the top end of ambition within the EU, while eastern European member states including Poland and Bulgaria, are at the bottom end.

When the non-ETS targets for 2020 were handed out, only GDP per-capita was taken into account. The 2020 targets are shown below.

Non-ETS emissions reduction targets for 2020 for each member state, and the EU average. The reductions are relative to 2005 emissions. Source: European Commission. Chart by Carbon Brief.

The new adjustment for cost-effective reduction potentials reduces the effort required by Ireland, Spain and Finland while increasing it for Germany. Changes in relative GDP since 2009 mean some countries, particularly Greece, will have less stringent targets for 2030 than they do for 2020.

Differences between proposed 2030 emissions reduction targets and what would have been expected if the 2020 division of labour had been repeated. Source: Carbon Brief analysis.



Climate models are accurately predicting ocean and global warming

Posted on 27 July 2016 by John Abraham

For those of us who are concerned about global warming, two of the most critical questions we ask are, “how fast is the Earth warming?” and “how much will it warm in the future?”.

The first question can be answered in a number of ways. For instance, we can actually measure the rate of energy increase in the Earth’s system (primarily through measuring changing ocean temperatures). Alternatively, we can measure changes in the net inflow of heat at the top of the atmosphere using satellites. We can also measure the rate of sea-level rise to get an estimate of the warming rate. 

Since much of sea-level rise is caused by thermal expansion of water, knowledge of the water-level rise allows us to deduce the warming rate. We can also use climate models (which are sophisticated computer calculations of the Earth’s climate) or our knowledge from Earth’s past (paleoclimatology). 

Many studies use combinations of these study methods to attain estimates and typically the estimates are that the planet is warming at a rate of perhaps 0.5 to 1 Watt per square meter of Earth’s surface area. However, there is some discrepancy among the actual numbers.

So assuming we know how much heat is being accumulated by the Earth, how can we predict what the future climate will be? The main tool for this is climate models (although there are other independent ways we can study the future). With climate models, we can play “what-if scenarios” and input either current conditions or hypothetical conditions and watch the Earth’s climate evolve within the simulation.

Two incorrect but nevertheless consistent denial arguments are that the Earth isn’t warming and that climate models are inaccurate. A new study, published by Kevin Trenberth, Lijing Cheng, and others (I was also an author) answers these questions.

The study was just published in the journal Ocean Sciences; a draft of it is available here. In this study, we did a few new things. First, we presented a new estimate of ocean heating throughout its full depth (most studies only consider the top portion of the ocean). Second, we used a new technique to learn about ocean temperature changes in areas where there are very few measurements. Finally, we used a large group of computer models to predict warming rates, and we found excellent agreement between the predictions and the measurements.

According to the measurements, the Earth has gained 0.46 Watts per square meter between 1970 and 2005. Since, 1992 the rate is higher (0.75 Watts per square meter) and therefore shows an acceleration of the warming. To put this in perspective, this is the equivalent of 5,400,000,000,000 (or 5,400 billion) 60-watt light bulbs running continuously day and night. In my view, these numbers are the most accurate measurements of the rate at which the Earth is warming.



More CO2 won’t help northern forests or stave off climate change

Posted on 26 July 2016 by Guest Author

Noah Charney, Postdoctoral Research Associate of Ecology and Evolutionary Biology, University of Arizona

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

We’ve heard the predictions of how greenhouse gas emissions will drive changes in the temperatures and precipitation people experience. But how these changes affect the world’s forests has broad implications for the future as well.

Could warmer winters, and thus longer growing seasons, cause trees to grow faster? If so, perhaps faster tree growth could slow the pace of climate change, since trees suck carbon out of the air as they grow.

Or perhaps hotter summers will mean more drought-like conditions, thereby hampering trees' ability to grow and thus cause deterioration of our woodlands.

In a recent paper, my colleagues and I set out to make a map of how climate change might influence tree growth across the entire continent of North America. To do this, we dug into historical records of tree growth over the period 1900-1950 collected by many dedicated field ecologists over the decades and deposited in the International Tree Ring Data Bank.

What we found was that the daily life of trees across much of North America will become more challenging, despite the potential benefit that rising carbon dioxide concentrations may have for trees. This is contrary to some scientists' hopes that climate change will strongly benefit northern latitude forests.

How trees respond to climate

The first hurdle in predicting future tree growth is to understand how trees in different ecosystems respond to climate fluctuations.

You might guess that in cold northern forests, a little heat might help trees grow, whereas more heat in the desert Southwest is likely the last thing trees there want. This observation motivated previous scientists to formulate a “boreal greening” hypothesis – that global warming will cause northern boreal forests to grow faster and help mitigate climate change.

We used the historic tree ring data to map the relationship between regional climate and tree growth. Matching each growth ring to the weather patterns in the corresponding year, we can get a sense for how trees respond to climate fluctuations. For instance, we saw that above-average June temperatures caused faster tree growth in places with climates similar to Fairbanks, Alaska, but slower growth in Phoenix-like climates.

Boreal forests such as this one in Alaska are projected to enter into a different climatic zone from rising temperatures due to climate change and fare worse in the future. akgypsy37/flickr, CC BY-NC-ND



These are the best arguments from the 3% of climate scientist 'skeptics.' Really.

Posted on 25 July 2016 by dana1981

When I give a presentation and mention the 97% expert consensus on human-caused global warming, I’m often asked, “what’s the deal with the other 3%?”. These are the publishing climate scientists who argue that something other than humans is responsible for the majority of global warming, although their explanations are often contradictory and don’t withstand scientific scrutiny.

A few months ago, the world’s largest private sector coal company went to court, made its best scientific case against the 97% expert consensus, and lost. One of coal’s expert witnesses was University of Alabama at Huntsville climate scientist Roy Spencer - a controversial figure who once compared those with whom he disagreed to Nazis, and has expressed his love for Fox News.

Last week, Spencer wrote a white paper for the Texas Public Policy Institute (TPPI) outlining the contrarian case against climate concerns. TPPI is part of the web of denial, having received substantial funding from both the tobacco and fossil fuel industries, including $65,000 from ExxonMobil and at least $911,499 from Koch-related foundations since 1998, and over $3 million from “dark money” anonymizers Donors Trust and Donors Capital Fund.

Spencer’s arguments should of course be evaluated on their own merits, regardless of who commissioned them. However, it turns out that they have little merit on which to stand. The white paper is a classic example of a Gish Gallop – producing such a large volume of nonsense arguments that refuting all of them is too time-consuming. NASA Goddard director Gavin Schmidt rightly described Spencer’s paper as:

A great example of how making nonsense arguments undermines his whole point. Sad! 

A mishmash of myths

Most of Spencer’s white paper consists of repeating a variety of long-debunked myths. It’s laid out in the form of 13 basic climate questions that Spencer tries to answer. Fortunately, has a database of over 200 climate myths, and summaries of what the peer-reviewed scientific research says about each. This makes it possible to handle Spencer’s 13-point Gish Gallop by simply referring to the relevant myth rebuttals. So here we go:



2016 SkS Weekly Digest #30

Posted on 24 July 2016 by John Hartz

SkS Highlights... Toon of the Week... Quote of the Week... Graphic of the Week... SkS Spotlights... Coming Soon on SkS... Poster of the Week... SkS Week in Review... 97 Hours of Consensus...

SkS Highlights

The best strategies to keep bodies cool in a heatwave, according to researchers by John Abraham (Climate Consensus-the 97%, Guardian) attracted the highest number of comments of the articles posted on SkS during the past week. Study links heatwave deaths in London and Paris to climate change by Robert McSweeney (Carbon Brief) garnered the second highest number of comments.

Toon of the Week

2016 Toon 30 

Hat tip to I Heart Climate Scientists



2016 SkS Weekly News Roundup #30

Posted on 23 July 2016 by John Hartz

A chronological listing of the news articles posted on the Skeptical Science Facebook page during the past week.

Sun July 17, 2016



Study links heatwave deaths in London and Paris to climate change

Posted on 22 July 2016 by Guest Author

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

In 2003, more than 70,000 people across Europe died in a sweltering heatwave that spanned much of the summer.

France was among the worst-affected countries, with 15,000 deaths in August alone. In the UK, the summer saw more than 2,000 heat-related fatalities.

A new first-of-a-kind study works out how many of the deaths in Paris and London are down to the heatwave being intensified by human-caused climate change.

The findings suggest that 506 of the 735 summer fatalities in Paris in 2003, and 64 of the 315 in London, were a result of human influence on the climate.

Human influence

The European summer heatwave of 2003 has been something of a focal point for scientists looking at if and how human-caused climate change influences extreme weather events.

In 2004, the heatwave was the subject of the first ever attribution study, which found that climate warming from human activity had at least doubled the likelihood of such an event. In 2014, another study found that a similar “extremely hot” summer in Europe has become 10 times more likely over the last 10-15 years because of climate change.

Taking this a step further, the new study, published in Environmental Research Letters, attributes the number of deaths during the 2003 heatwave to our warming climate.

The study makes use of the weather@home project, where members of the public offer spare capacity on their home computers for scientists to run model simulations.

The researchers ran thousands of simulations of European weather in 2003. One set of model runs simulated the weather according to the climate as it was – i.e. in a world warmed by past greenhouse gas emissions. The second set simulated the weather in a hypothetical world with no human influences on climate.

The researchers then compared the heat and humidity between the hypothetical world and the one better matched to reality to see how they affect the number of premature deaths in the summer of the same year. Lead author Dr Daniel Mitchell, a researcher in the Department of Physics at the University of Oxford, explains to Carbon Brief:



The best strategies to keep bodies cool in a heatwave, according to researchers

Posted on 21 July 2016 by John Abraham

As we hit high-heat season in the Northern Hemisphere, it is useful to clarify tactics that can be used to help maintain healthy body temperatures. These tips are not commonly known and can be adopted by anyone, anywhere. While I am a climate scientist, my funded work is in the area of heat transfer, particularly in the human body. I work with medical companies to maintain healthy body temperatures during surgeries or other situations. I also deal with scald burns and I often serve in burn injury litigation.

Here are some key tips. First, avoid hyperthermia in the first place – drink plenty of fluids, avoiding direct sunlight, trying to get a respite from heat each day, avoiding physical exertion during the hottest parts of the day are all great suggestions. But, if you need to lower a body temperature, Dr. Robert Huggins, VP of Research and Athlete Performance at the Korey Stringer Institute suggests:

The general rule is to cool as much of the body’s surface as possible …. the larger the area you cool and the colder the device you use to cool it the faster the cooling rate. An appropriate goal is to use a method that cools at a rate of 0.15°C per minute. This can typically be achieved by immersion techniques using a tub or other basin filled with ice cold water or via rotating cold ice towels over the body.

During exercise if there is limited access to the entire body (e.g. football or fire-fighters), cooling the hands, face and feet will help, and if possible, use a fan to increase evaporation from these surfaces. However, when heat stroke is suspected, these strategies are not nearly as effective as whole body methods; opt for immersion cooling.

So how do you know if someone is suffering from hyperthermia or heat stroke? A great resource is the Korey Stringer Institute, which lists many symptoms for heat stress such as fatigue, weakness, pale appearance, headache, nausea, vomiting, fainting, dizziness, and others. The heat stroke treatment they recommend, while geared toward athletes, is still useful for the rest of us. 



Cold and calculating: what the two different types of ice do to sea levels

Posted on 20 July 2016 by Guest Author

Matt King, Professor, Surveying & Spatial Sciences, School of Land and Food, University of Tasmania; Ben Galton-Fenzi, Senior Scientist, and Will Hobbs, Physical Oceanographer, Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania

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

It was back in 250ʙⅽ when Archimedes reportedly stepped into his bathtub and had the world’s first Eureka moment – realising that putting himself in the water made its level rise.

More than two millennia later, the comments sections of news stories still routinely reveal confusion about how this same thing happens when polar ice melts and sea levels change.

This is in marked contrast to the confidence that scientists have in their collective understanding of what is happening to the ice sheets. Indeed, the 2014 Assessment Report of the Intergovernmental Panel on Climate Change reported “very high confidence” that the Greenland Ice Sheet was melting and raising sea levels, with “high confidence” of the same for the Antarctic Ice Sheet.

Despite this, commenters below the line on news stories frequently wonder how it can be true that Antarctica is melting and contributing to sea-level rise, when satellite observations show Antarctic ice expanding.

Unravelling the confusion depends on appreciating the difference between the two different types of ice, which we can broadly term “land ice” and “sea ice” – although as we shall see, there’s a little bit more to it than that. The two different types of ice have very different roles in Earth’s climate, and behave in crucially different ways.

Sea levels rise when ice resting on land, grounded ice, melts (often after forming icebergs). Floating sea ice that melts has a very important role in other areas of our climate system.



Reshuffle: DECC folded into new department headed by Greg Clark

Posted on 19 July 2016 by Guest Author

This is a re-post from Carbon Brief by Sophie Yeo

Theresa May, the new prime minister, has axed the Department of Energy and Climate Change, by folding it into the Department for Business, Innovation & Skills and thereby creating a new ministry called the Department for Business, Energy and Industrial Strategy.

Greg Clark, who was the secretary of state for the Department for Communities and Local Government under David Cameron, was appointed head of the new department during a dramatic cabinet reshuffle on Thursday.

Reacting to his appointment, Clark said:

I am thrilled to have been appointed to lead this new department charged with delivering a comprehensive industrial strategy, leading government’s relationship with business, furthering our world-class science base, delivering affordable, clean energy and tackling climate change.

It is not Clark’s first brush with the climate change brief. Between 2008 and 2010, while the Conservatives were in opposition, he was shadow secretary for energy and climate change.

In this time, he made his views clear on climate change. Here are some quotes that might give us some idea of what to expect from him in the future.

2009: On climate science

Advances in climate science mean that we have an increasingly good idea of what the most likely outcome is for a particular level of carbon in the atmosphere – and, on current trends, this would be bad enough. Yet, we can’t overlook the fact that these represent midrange estimates. That might not matter if we could be certain that the actual outcomes won’t deviate very far from the central predictions; but, to use the statistical jargon, these are left-tailed, fat-tailed distributions – meaning that the worst that could happen is really very bad indeed.

2009: On extreme risks

Thanks to factors such as the release of methane from melting permafrost, there is a danger that higher temperatures could trigger a vicious circle of runaway global warming, with truly disastrous consequences. There are some risks, which are so extreme, so unpredictable, so global in their consequences, that they can’t be tolerated.
We’ve come to know these as ‘black swans’, a term made infamous by the credit crunch, where conventional risk management techniques came spectacularly unstuck. When faced with a black swan risk the only way to protect yourself is to reduce your exposure in the first place. In the case of climate change, that means ending our grand experiment with the planet’s atmosphere. The net costs of decarbonising the economy should therefore be regarded as an insurance policy – much as any sensible householder would pay to insure themselves against the remote, but real, risk of fire and flood. And not just the climate risks.The insurance principle doesn’t just apply to climate change.

2009: On climate sceptics

Some have asked can we continue to afford to fight climate change at a time like this? Shouldn’t we perhaps put it off until the economy gets moving again? It’s a good question… though one that is sometimes asked in bad faith by those who’d oppose action on climate change at anytime. That might be because they just don’t believe the mainstream scientific position on climate change or, in some cases, because it doesn’t suit their vested interests. Either way, the recession argument is, for them, just the latest in a series of delaying tactics.



Déjà vu: as with tobacco, the climate wars are going to court

Posted on 18 July 2016 by dana1981, JohnMashey

Investigative journalism has uncovered a “web of denial” in which polluting industries pay “independent” groups to disseminate misinformation to the public and policymakers. The same groups and tactics were employed first by the tobacco industry, then fossil fuel companies. Big Tobacco has been to court and lost; now it’s Big Oil’s turn. Political leaders are choosing sides in this war.

Research by Inside Climate News revealed that Exxon did top notch climate science research in the late 1970s and early 1980s, which revealed the dangers its products posed via climate change. Soon thereafter, Exxon launched misinformation campaigns by funding “think tanks” and front groups to manufacture doubt about climate science and the expert consensus on human-caused global warming.

exxon knew vs did

What #ExxonKnew vs what #ExxonDid. Illustration: John Cook,

Exxon wasn’t alone. Koch Industries, Peabody Energy, and other fossil companies have similarly funneled vast sums of money to these groups. Last week, Senate Democrats, including presidential candidate Bernie Sanders and vice presidential contenders Elizabeth Warren and Al Franken signed a Resolution expressing congressional disapproval of the fossil fuel industry’s misinformation campaign.19 Senate Democrats also took to the floor of the Senate to speak out against the web of denial, with repeated references to the tobacco/fossil connections.


Senator Elizabeth Warren speaking about the web of denial on the Senate floor.



2016 SkS Weekly Digest #29

Posted on 17 July 2016 by John Hartz

SkS Highlights... Toon of the Week... Quote of the Week... He Said What?... SkS Spotlights... Coming Soon on SkS... Poster of the Week... SkS Week in Review... 97 Hours of Consensus...

SkS Highlights

Using the metric of number of comments garnered, the two most popular articles posted on SkS during the past week were:

Toon of the Week

 2016 Toon 29



2016 SkS Weekly News Roundup #29

Posted on 16 July 2016 by John Hartz

A chronological listing of the news articles posted on the Skeptical Science Facebook page during the past week.

Sun July 10, 2016

  • Christiana Figueres launches UN secretary general bid by Ed King, Climate Home, July 7, 2016
  • Figueres win would mainstream climate change at UN by Nick Mabey, Climate Home, July 8, 2016
  • 'Shocking images' reveal death of 10,000 hectares of mangroves across Northern Australia by Kate Wild, ABC News, July 10, 2016
  • Nearly half a million leave home as storm left by super typhoon Nepartak hits China by Nathaniel Taplin, Reuters, July 9, 2016
  • The Carbon Brief Interview: Averil Macdonald by Simon Evans, Carbon Brief, July 5, 2016
  • How the World’s Most Fertile Soil Can Help Reverse Climate Change by David Suzuki, Ecowatch, July 6, 2016
  • Neocons linked to Tea Party paid for Andrea Leadsom’s flights to US by Jamie Doward, Observer/Guardian, July 9, 2016
  • Facing historically low levels, Lake Mead officials are fending off a water war. Here's how by William Yardley, Los Angeles Times, July 6, 2016
  •


    Humans are greening the planet, but the implications are complicated

    Posted on 15 July 2016 by John Abraham

    The Earth’s climate is changing – in fact, it always changes. But in the current context of human influence, scientists try to decipher how much of the change is natural compared to human-induced.

    One clear way humans influence the Earth is through the biosystem. For instance, farming changes the biosystem. By removing natural growth and planting annual crops that are harvested, we change the system in a way that could in turn affect other parts of the Earth system. In addition, the use of nitrogen based fertilizers can increase growth rate and lead to a greening of areas that are subject to fertilization. 

    Another more indirect potential for humans to alter plant growth is through fertilization involving carbon dioxide. We know that humans have increased the amount of carbon dioxide in the atmosphere by approximately 40%. We also know that airborne carbon dioxide is a fertilizer for plants. So the obvious question is, “do our carbon emissions affect plant growth?”.

    A new study, just out in Nature Climate Change, helps answer that question. This study focused on land areas in the northern hemisphere that were outside the tropical region. They obtained information from satellites to measure the greening of these lands areas to determine whether there was any significant change. The find that yes, in fact there is. Over approximately 30-year durations, this area has indeed gotten greener.

    So, the next question is, what is causing the greening? To answer this question, the authors used computer simulations and ran them with and without human influences. When we say “human influences” we can mean many things, such as increase or decrease of farming, use of fertilizers, and airborne increase of carbon dioxide, just to name a few. The authors found that the only way the simulations matched the observations is when these human influences were included. That is, solely natural variations cannot be the cause. Not only that, but the match worked best when airborne carbon dioxide had a major role.


    The spatial distribution of the linear trends in the growing season (April–October) leaf area index during the period 1982–2011 in the mean of satellite observations (upper figure), Earth system model (ESM) simulations with natural forcings alone (lower left figure), and ESM simulations with anthropogenic and natural forcings (lower right figure). Illustration: Oak Ridge National Laboratory



    Will the health dangers of climate change get people to care? The science says: maybe

    Posted on 14 July 2016 by Guest Author

    Matthew Nisbet, Associate Professor of Communication, Northeastern University

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

    Climate change is a major public health threat, already making existing problems like asthma, exposure to extreme heat, food poisoning, and infectious disease more severe, and posing new risks from climate change-related disasters, including death or injury.

    Those were the alarming conclusions of a new scientific assessment report released by the Obama administration this week, drawing on input from eight federal agencies and more than 100 relevant experts.

    “As far as history is concerned this is a new kind of threat that we are facing,“ said U.S. Surgeon General Vivek Murthy at a White House event. Pregnant women, children, low-income people and communities of color are among the most at risk.

    Despite ever more urgent warnings of scientists, Americans still tend to view climate change as a scientific or environmental issue, but not as a problem that currently affects them personally, or one that connects to issues that they already perceive as important.

    Yet research suggests that as federal agencies, experts, and societal leaders increasingly focus on the public health risks of climate change, this reframing may be able to overcome longstanding public indifference on the issue. The new communication strategy, however, faces several hurdles and uncertainties.

    Putting a public health focus to the test

    In a series of studies that I conducted with several colleagues in 2010 and 2011, we examined how Americans respond to information about climate change when the issue is reframed as a public health problem.

    In line with the findings of the recent Obama administration report, the messages we tested with Americans stressed scientific findings that link climate change to an increase in the incidence of infectious diseases, asthma, allergies, heat stroke and other health problems – risks that particularly impact children, the elderly and the poor.



    Global warming implicated in dinosaur extinction

    Posted on 13 July 2016 by howardlee

    In a paper published on Tuesday in the journal Nature Communications, scientists from the University of Michigan and the University of Florida show that there were big jumps in climate warming when the dinosaurs went extinct at the end of the Cretaceous. This brings the end-Cretaceous mass extinction in line with the other mass extinction events, which occurred at times of abrupt and sometimes extreme climate change (including the end-Permian, the end-Triassic, the Toarcian, and others).

    By employing a relatively new ancient-temperature-measuring technique called “carbonate clumped isotope paleothermometry,” scientists have uncovered an 8ºC jump in seawater temperatures that unfolded rapidly, at the same time as massive CO2 emissions from the Indian Deccan Traps eruptions (“rapidly” here means anything less than about 30,000 years, possibly centuries; such are the limits of time resolution). They also found a second, smaller spike in warming about 150,000 years later, at around the same time as the asteroid impact at Chicxulub in Mexico.


    A mollusk that lived in Antarctica in the final years of the Cretaceous, showing the holes made by scientists extracting material to measure ancient sea temperatures. Photograph: Sierra V. Petersen



    Why Paris climate pledges need to overdeliver to keep warming to 2C

    Posted on 12 July 2016 by Guest Author

    This is a re-post from Carbon Brief by Dr Joeri Rogelj, a research scholar at the International Institute for Applied Systems Analysis (IIASA) in Austria. Rogelj was recently awarded the inaugural Piers Sellers Prize for world leading contribution to solution-focused climate research.

    Last year’s Paris Agreement is considered a major global step in addressing the threat of climate change.

    It was a diplomatic victory to bring 195 governments together to agree a goal to limit global average temperature increase to “well below 2C” relative to pre-industrial levels, and to “pursue efforts” to limit it to 1.5C.

    It was a similar tour de force that 186 parties submitted “intended nationally determined contribution” (INDCs) in the run up to Paris. INDCs set out each country’s contribution to cutting greenhouse gas emissions in order to meet the collective global temperature goal. The INDC process succeeded in overcoming decades of hesitation across the international community.

    Moreover, every five years, these contributions are to be updated or renewed, steadily increasing in ambition.

    But accompanying this success came a set of puzzling questions: what do the INDCs add up to in terms of global emissions reductions? Are they sufficient to keep warming to well below 2C? If not, what temperature increase are we heading for? What about 1.5C? And, are the INDCs at least a step in the right direction?

    An added complication is that INDCs don’t all follow the same approach. Some countries’ emissions pledges are conditional on receiving funding, for example, while others depend on the growth of their economy. This is why various studies (pdf) addressing these questions have often come up with different answers.

    Our new paper, just published in Nature, provides some clarity on this issue by carrying out a “meta-analysis” to see what conclusions we can draw from ten of these studies.

    And to cut a long story short, the INDCs alone do not keep warming to well below 2C.



    We just broke the record for hottest year, nine straight times

    Posted on 11 July 2016 by dana1981

    2014 and 2015 each set the record for hottest calendar year since we began measuring surface temperatures over 150 years ago, and 2016 is almost certain to break the record once again. It will be without precedent: the first time that we’ve seen three consecutive record-breaking hot years.

    But it’s just happenstance that the calendar year begins in January, and so it’s also informative to compare all yearlong periods. In doing so, it becomes clear that we’re living in astonishingly hot times.

    June 2015 through May 2016 was the hottest 12-month period on record. That was also true of May 2015 through April 2016, and the 12 months ending in March 2016. In fact, it’s true for every 12 months going all the way back to the period ending in September 2015, according to global surface temperature data compiled by Kevin Cowtan and Robert Way. We just set the record for hottest year in each of the past 9 months.

    CW13 running

    Running 12-month average global surface temperature using data compiled by Kevin Cowtan and Robert Way. Illustration: Dana Nuccitelli



    2016 SkS Weekly Digest #28

    Posted on 10 July 2016 by John Hartz

    SkS Highlights... Toon of the Week... Quote of the Week... They Said What?... Graphic of the Week... Coming Soon on SkS... Poster of the Week... SkS Week in Review... 97 Hours of Consensus...

    SkS Highlights

    The SkS Facebook page has reached a new milestone of 175,000 Likes. Try it, you'll like it. 

    Toon of the Week

    2016 Toon 28 

    Hat tip to I Heart Climate Scientists



The Consensus Project Website



(free to republish)



The Scientific Guide to
Global Warming Skepticism

Smartphone Apps


© Copyright 2016 John Cook
Home | Links | Translations | About Us | Contact Us