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).
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.
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?
There has been some confusion about the human contribution to California’s drought, now entering its fourth consecutive year, because some reports have said that humans have not influenced the amount of precipitation falling in the state thus far. This is a subject of debate – some studies have found evidence of a human ‘fingerprint’ in the high pressure ridge that’s diverted storms away from California over the past three years. But overall, while precipitation has been low, there have been a few years in the historical record where it was lower.
Part of the challenge is that the term “drought” can be defined in different ways: for example, meteorological, hydrological, agricultural, and socioeconomic drought. Drought, most simply defined, is the mismatch between the amounts of water nature provides and the amounts of water that humans and the environment demand.
California’s worst droughts have historically happened in years that are both dry and hot. While humans may or may not be influencing the amount of rain falling in the state, we are indisputably making it hotter. If we could flip coins representing precipitation and temperature each year, the first could come up wet or dry, but humans are weighting the second such that it will increasingly come up hot. This will make conditions like those that caused California’s current record-breaking drought return more often as the planet keeps warming.
California temperature (°F) and precipitation (inches) anomalies from January 1895 to November 2014, plotted as 3-year anomalies relative to 1901–2000 mean. Data from the National Climatic Data Center nClimDiv dataset. Source: PNAS; Mann & Gleick (2015).
I won't go over every mistake Richard (Tol) has made, while flailing about looking for his "something wrong". Many of them have been well documented already. In addition to Friday's HW article, there are more demolitions at HotWhopper (here and here and here and here), at SkepticalScience (here), in a booklet by John Cook and colleagues (here) and in a rebuttal paper to Richard Tol (here) as well as an article in The Guardian by Dana Nuccitelli (here).
Richard Tol has another article about how claims of a scientific consensus don’t stand up (you can read it here if you really want to). It’s the standard message that he’s been promoting for quite some time now and I really can’t bring myself to point out the flaws again; it’s just getting tedious. I’m also tired of always being a critic. I thought I might, instead, try to write something a bit more positive.
Richard (Tol) is obsessed with the study by John Cook et al, which determined that almost all scientific papers on climate science, which attributed a cause to global warming, attributed it to human activity. Now anyone who's kept up with climate science knows that's a no-brainer. There is no doubt that the current global warming is caused by us. Richard himself doesn't doubt it.
Earth Hour: 4 things to know about the annual evironmental event
Hundreds of millions of homes and businesses around the world will go dark Saturday night as part of Earth Hour, an annual event meant to raise awareness about climate change and the environment.
Now in its ninth year, Earth Hour encourages individuals and organizations around the world to turn off all of their non-essential lights for one hour. This year, it’s scheduled to start at 8:30 p.m. local time on Saturday, March 28.
Organizers say Earth Hour has become the world’s largest grassroots movement in support of the environment, and it has continued to grow with each passing year. More than 7,000 cities and towns in 162 countries and territories took part in Earth Hour in 2014. This year, the group behind the campaign says 172 countries are expected to take part.
Whether you’ve participated in Earth Hour before or are thinking about taking part for the first time, here are a few things to know about it.
Bob Ward, policy and communications director of the Grantham Research Institute on Climate Change and the Environment at London School of Economics and Political Science, filed a complaint with the Independent Press Standards Organisation (Ipso) about Rose’s piece. Ipso is intended to police the UK print media. It replaced the Press Complaints Commission (PCC) in this assignment after the latter was roundly criticised for failing to take action in the News of the World phone hacking affair. Ipso describes itself as,
“Winter 2014 set to be 'coldest for century' Britain faces ARCTIC FREEZE in just weeks”.
That was the Daily Express headline on October 10th 2014. Quoting self-styled "independent" long-range weather forecaster James Madden, it warned of an icy apocalypse on the way:
“A number of potentially very cold periods of weather and major snow events are likely to develop throughout this winter across large parts of the country, in particular, throughout the latter part of December and into January. The worst case and more plausible scenario could bring something on a similar par to the winter of 2009/10, the coldest in 31 years, or an event close to 2010/11 which experienced the coldest December in 100 years.”
Snow-enthusiasts will recall both January and December 2010 with fondness. The whole of the UK was affected: in Mid-Wales where I live snow covered local beaches above the high water mark and there were copious large ice-floes bobbing about on the Dyfi Estuary. For a while in the days following December 18th 2010, even low-lying towns like Machynlleth were blanketed in thick snow up to a foot deep. 2009-10 was the 59th coldest winter (meteorological period December/January/February) on the Central England Temperature (CET) record which goes back to 1659. 2010-11 was 112th, losing out due to milder conditions arriving in the New Year, although December 2010 at a shocking -0.7C was the second coldest December in the monthly CET record.
That sets the scene. As readers might have guessed, this post is about the UK tabloid press and its ridiculously sensationalistic weather-stories. Firstly, here is the timeline, and brief descriptions of the very severe past winters referred to in the forecasts.
SNOWMAGGEDDON ON ITS WAY!
Not to be outdone, the Daily Mirror had the following message for its readers on October 29th:
Amazon forest becoming less of a climate change safety net
The ability of the Amazon forest to soak up excess carbon dioxide is weakening over time,researchers reported last week. That finding suggests that limiting climate change could be more difficult than expected.
For decades, Earth’s forests and seas have been soaking up roughly half of the carbon pollution that people are pumping into the atmosphere. That has limited the planetary warming that would otherwise result from those emissions.
The forests and oceans have largely kept up even as emissions have skyrocketed. That surprised many scientists, but also prompted warnings that such a robust “carbon sink” could not be counted on to last forever.
A very important study was just published in the Journal of Climate a few days ago. This paper, in my mind, makes a major step toward reconciling differences in satellite temperature records of the mid-troposphere region. As before, it is found that the scientists (and politicians) who have cast doubt on global warming in the past are shown to be outliers because of bias in their results.
The publication, authored by Stephen Po-Chedley and colleagues from the University of Washington, discusses some major sources of error in satellite records. For instance, after satellites are launched, they scan the Earth’s atmosphere and calibrate the atmospheric measurements using a warm target onboard the satellite and cold space. The accuracy with which the atmospheric measurements are calibrated can influence the inferred temperature of the atmosphere (called the warm-target bias). Additionally, over the years, multiple satellites have been launched and the selection of which satellite data are used can play a role. Finally, biases can occur because the satellite orbits drift during their lifetime and the influence of diurnal temperature variation can affect the global temperature trends.
Of these three errors, the last one (probably the most important one), was the focus of the just-published paper.
It is known that there is a problem because there are multiple groups that create satellite temperature records. For instance, NOAA, Remote Sensing Systems (RSS), and the University of Alabama Huntsville (UAH). The problem is, their results don’t agree with each other. In particular, the UAH team, led by Dr. John Christy and Dr. Roy Spencer (who have discounted the importance and occurrence of climate change for years) present results that differ quite a bit from the others. In fact, in the current paper, it is stated that “Despite using the same basic radiometer measurements, tropical TMT trend differences between these groups differ by a factor of three.”
Shell evaluates all of its projects using a shadow carbon tax of $40 per tonne of carbon dioxide. That's great. But why is the company still exploring in the Arctic and busy exploiting the Alberta oil sands?
You cannot talk credibly about lowering emissions globally if, for example, you are slow to acknowledge climate change; if you undermine calls for an effective carbon price; and if you always descend into the ‘jobs versus environment’ argument in the public debate.
Shell also has a position they call Vice President CO2, currently occupied by Angus Gillespie. Here's Gillespie talking recently at Stanford on the company's internal shadow carbon pricing strategy (hat-tip to John Mashey). It's worth watching if only for Gillespie's vivid example of the limitations of looking at averages. The slides can be downloaded here.
New measurements from Alaska and Oklahoma have confirmed that recent increases in carbon dioxide (CO2) in the air, caused mostly by burning coal, oil and gas, are indeed heating up Earth's surface by making the greenhouse effect stronger (Feldman et al., 2015).
This was already beyond all reasonable doubt: satellites (Harries et al., 2001), computer simulations tested with measurements from planes (Tjemkes et al., 2004) and other ground experiments (Evans & Puckrin, 2006, Philipona et al., 2004) confirmed that more CO2 is making us hotter. This new study is still important though. Unlike satellites, these measurements were taken from Earth's surface. And unlike the previous surface measurements, this experiment combines a decade-long experiment with the right instruments to be able to untangle the causes of heating.
Rather like a tuning fork humming to the right note, greenhouse gases like CO2 respond to specific frequencies of light. The Earth glows constantly in the infrared (a bunch of colours we can't see) and greenhouse gases respond. They absorb very specific fractions of some frequencies and then recycle the energy they absorbed, sending some of it back down to Earth to warm us up.
John Mason's The cause of the greatest mass-extinctions of all? Pollution (Part 1 and Part 2) generated a lively discussion among readers and attracted the most comments of the articles posted on SkS during the past week.
El Niño Watch
NOAA's Climate Prediction Center is saying that there is an approximately 50-60% chance that El Niño conditions will continue through Northern Hemisphere summer 2015. This outlook was issued before the recent record-strength MJO and counter-rotating Pacific tropical cyclones emerged, so it will interesting to see how their outlook changes in the next update on April 9.
That means two consecutive years of the concentration of warm water in the Pacific Ocean that brings West Coast storms, quiet hurricane seasons in the Atlantic and busy ones in the Pacific. The danger is that this could mean more than a few months of odd weather, but instead usher in a new phase of climate change. Last year was the warmest year on record; 2015 looks set to be even warmer.
Amazon rainforest soaking up less carbon as trees die young
The Amazon rainforest's ability to soak up greenhouse gases from the air has fallen sharply, possibly because climate change and droughts mean more trees are dying, an international team of scientists said on Wednesday.
The world's biggest rainforest has soaked up vast amounts of carbon dioxide. Plants use the heat-trapping gas to grow and release it when they rot or burn, but the report said that role in offsetting global warming may be under threat.
The study, of 321 plots in parts of the Amazon untouched by human activities, estimated the net amount of carbon dioxide absorbed by the forest had fallen by 30 percent, to 1.4 billion tonnes a year in the 2000s from 2.0 billion in the 1990s.
"Forest growth has flatlined over the last decade," lead author Roel Brienen of the University of Leeds told Reuters of the findings in the journal Nature. At the same time "the whole forest is living faster - trees grow faster, die faster."
Part Two: the Siberian Traps and the end Permian mass extinction
With more than 90% of all marine species and 75% of land species wiped out, the end Permian mass extinction was the worst biosphere crisis in the last 600 million years. The extinction was global in reach: almost all animals and plants in almost all environmental settings were affected. An idea of the severity can be visualised by considering that the time afterwards was marked by the beginning of a coal gap lasting for ten million years: coal-forming ecosystems - i.e. forests - simply did not exist for that time.
The onset of the mass extinction coincided with the main part of the eruption of the late Permian Siberian Traps Large Igneous Province (LIP), 251.9 million years ago (Ma). It contains what may be the largest known volume of terrestrial flood basalt in the world. Estimates vary but they start at volumes of at least 3 million cubic kilometres of igneous rocks that were erupted onto and intruded beneath the surface during the event. There are some much larger volume estimates that take into account "missing" erupted rocks since eroded away and the likely ratio of intruded to erupted rocks. Either way, as eruptive cycles go this was one of the biggest ever.
At the same time, there was a dramatic perturbation to the global carbon cycle, involving the injection of enough carbon dioxide to the atmosphere to triple the pre-existing levels and raise temperatures substantially. There were severe problems with other pollutants: acid rain, soil erosion, algal blooms and ocean acidification and anoxia all took a dramatic toll on life on land and in the seas.
That the Siberian Traps eruptions, the greatest of the Big Five mass-extinctions and carbon cycle havoc all happened in broadly the same geological timezone suggests they may not be unrelated. However, coincidence is not necessarily cause. For example, what if the extinction occurred a million years before the Traps were erupted?
Part One: Large Igneous Provinces and their global effects
A mass extinction is an event in the fossil record, a fossilised disaster if you like, in which a massive, globally widespread and geologically rapid loss of species occurred from numerous environments. The “Big five” extinctions of the Phanerozoic (that time since the beginning of the Cambrian period, 541 million years ago) are those in which, in each instance, over half of known species disappeared from the fossil record.
How did they happen? The causes of such events, with a truly global reach, have been a well-known bone of contention within the Earth Sciences community over many decades. The popular media likes to portray such things as Hollywood-style disasters, in which everything gets wiped out in an instant. But in the realms of science, things have changed. The critically important development has been the refinement of radiometric dating, allowing us to age-constrain events down to much narrower windows of time. We can now, in some cases, talk about the start and end of an event in terms of tens of thousands (rather than millions) of years.
Such dating, coupled with the other time-tools of palaeomagnetism and the fossil record, have made it possible to develop a much clearer picture of how mass-extinctions occur. That picture is one of periods of global-scale pollution and environmental stress associated with large perturbations to the carbon cycle, lasting for thousands of years. Such upheavals are related to unusual episodes of volcanic activity with an intensity that is almost impossible to imagine. The geological calling-cards of such events are known as Large Igneous Provinces (LIPs). Bringing environmental and climatic changes at rates similar to the ones we have been creating, they have been repeat-offenders down the geological timeline. This introductory piece examines LIPs in the framework of more familiar volcanic activity: it is the only way to get a handle on their vastness.
For those readers already familiar with LIPs, you may want to skip this and go straight to Part Two, which covers the biggest extinction of them all, at the end of the Permian period, 252 million years ago (Ma). With more than 90% of all species wiped out, it was the most severe biotic crisis in Phanerozoic history. The extinction was global: almost all animals and plants in almost all environmental settings were affected. An idea of the severity can be visualised by considering that the time afterwards was marked by the beginning of a coal gap lasting for ten million years: coal-forming ecosystems simply did not exist for that time. Likewise, Howard Lee has recently considered the relationship between the end-Cretaceous extinction - the one that got the dinosaurs - and LIP volcanism here. But for those who are new to LIPs, it is recommended that you read this post first.
Amazon rainforest is taking up a third less carbon than a decade ago
The amount of carbon that the Amazon rainforest is absorbing from the atmosphere and storing each year has fallen by around a third in the last decade, says a new 30-year study by almost 100 researchers.
This decline in the Amazon carbon sink amounts to one billion tonnes of carbon dioxide - equivalent to over twice the UK's annual emissions, the researchers say.
If this pattern exists in other forests around the world, deeper cuts in human-caused carbon dioxide emissions are needed to meet climate targets, the researchers say.
A new paper published in Climatic Change estimates that when we account for the pollution costs associated with our energy sources, gasoline costs an extra $3.80 per gallon, diesel an additional $4.80 per gallon, coal a further 24 cents per kilowatt-hour, and natural gas another 11 cents per kilowatt-hour that we don’t see in our fuel or energy bills.
Levelized generation costs for new US electricity generation and environmental damages by fuel type. Source: Climatic Change, Shindell (2015).
The study was done by Drew Shindell, formerly of Nasa, now professor of climate sciences at Duke University, and Chair of the Scientific Advisory Panel to theClimate and Clean Air Coalition. Shindell recently published research noting that aerosols and ozone have a bigger effect on the climate in the northern hemisphere, where humans produce more of those pollutants.
If the Greenland ice sheet took a selfie, it might look like this:
In these images, everything that is soot-colored, brown/grey, is ice. Yes, ice. The dark surface absorbs sunlight, making the ice melt faster than scientists predicted. Since Greenland can't take pictures of itself, a group of scientists is sending a few drones aloft so they can see the situation for themselves.
Greenland was never green, or grey or brown, until now. To find out why the ice is dark, Glaciologist Jason Box and his team started the Dark Snow project. Box is featured in this week's This Planet video, What Is Dark Snow?
There has been a lot of attention on the influence of rapid warming of the Arctic on weather in the Northern Hemisphere mid-latitudes. Much of the work has focused on changes to the Jetstream amplitudes and association of these changes to ice loss in the Arctic.
We know that the Arctic is heating faster than the planet as a whole. Consequently, there is more energy in the Arctic which can be transmitted to the atmosphere. Much of the excess heat is transferred to the atmosphere in the late fall or early winter. This extra energy is connected to what’s called Arctic geopotential height, which has increased during the same times of the year. As a consequence, the Jetstream might weaken in the cold seasons.
But what about summer? Have these changes been detected then too? Well just recently, a paper was published in that answered this question. The authors, from the Potsdam Institute for Climate Impact Research and from the University of Potsdam reported on three measures of atmospheric dynamics (1) zonal winds, (2) eddy kinetic energy, and (3) amplitude of the fast-moving Rossby waves. Rossby waves are very large waves in the upper atmospheric winds. They are important because of their large influence on weather.
Dr. Dim Coumou. Photograph: Potsdam Institute for Climate Impact Research
Artic sea ice and Antractic sea ice and land ice were a lively topic of discussion on the comment thread to the 2015 SkS Weekly News Roundup #11A. Consequently, itgenerated the highest number of comments of the items posted on SkS during the past week. So what did-in the dinosaurs? A murder mystery… by howardleee drew the second highest number of comments proving once again that everyone loves a good mystery story.
There had never been as hot a 12-month period in NASA’s database as February 2014–January 2015. But that turned out to be a very short-lived record.
NASA reported this weekend that last month was the second-hottest February on record, which now makes March 2014–February 2015 the hottest 12 months on record. This is using a 12-month moving average, so we can “see the march of temperature change over time,” rather than just once every calendar year.
With less than a year to go before the United Nation’s annual climate change meeting scheduled to take place in Paris in November 2015, citizens and civil society groups are pushing their elected leaders to take stock of national commitments to lower carbon emissions in a bid to cap runaway global warming.
Industrialised countries’ trade, investment and environment policies are under the microscope, with per capita emissions from the U.S., Canada and Australia each topping 20 tonnes of carbon annually, double the per capital carbon emissions from China.
But despite fears that a rise in global temperatures of over two degrees Celsius could lead to catastrophic climate change, governments around the world continue to follow a ‘business as usual’ approach, pouring millions into dirty industries and unsustainable ventures that are heating the planet.
In Australia, coal mining and combustion for electricity, for instance, has become a highly divisive issue, with politicians hailing the industry as the answer to poverty and unemployment, while scientists and concerned citizens fight fiercely for less environmentally damaging energy alternatives.
The Arctic is warming up, and the impacts are being felt right across the world. A new study suggests rising temperatures there could even be contributing to longer-lasting heatwaves in the northern hemisphere, like the one Russia experienced in 2010.
Published today in the journal Science, the paperis the latest in a line of research suggesting how rising temperatures in the high north could be affecting our weather patterns much further south.
But there's a lot still to understand before the links can be well and truly pinned down, scientists say.
Part of the reason for it is that, as sea ice is diminishing, heat from the sun that would have beenreflectedback to space by snow and ice is being absorbed by the oceans instead, warming them up.
As the Arctic warms faster than the rest of the world, the temperature difference between the pole and the equator is getting smaller. Since this temperature contrast drives much of the atmospheric circulation in the northern hemisphere, the smaller it gets, the weaker the circulation becomes.
These atmospheric circulation patterns are responsible for delivering the weather systems that create warm, cold or wet conditions in the northern hemisphere. So, it follows that disrupting the circulation will, in turn, have consequences for the weather we see.
Arctic sea ice extent for February 2015 was 14.41 million square kilometers. The magenta line shows the 1981 to 2010 median extent for that month. Source: NSIDC