An ice sheet forms when snow falls on land, compacts into ice, and forms a system of interconnected glaciers which gradually flow downhill like play-dough. In Antarctica, it is so cold that the ice flows right into the ocean before it melts, sometimes hundreds of kilometres from the coast. These giant slabs of ice, floating on the ocean while still attached to the continent, are called ice shelves.
For an ice sheet to have constant size, the mass of ice added from snowfall must equal the mass lost due to melting and calving (when icebergs break off). Since this ice loss mainly occurs at the edges, the rate of ice loss will depend on how fast glaciers can flow towards the edges.
Ice shelves slow down this flow. They hold back the glaciers behind them in what is known as the “buttressing effect”. If the ice shelves were smaller, the glaciers would flow much faster towards the ocean, melting and calving more ice than snowfall inland could replace. This situation is called a “negative mass balance”, which leads directly to global sea level rise.
Ice shelves are perhaps the most important part of the Antarctic ice sheet for its overall stability. Unfortunately, they are also the part of the ice sheet most at risk. This is because they are the only bits touching the ocean. And the Antarctic ice sheet is not directly threatened by a warming atmosphere – it is threatened by a warming ocean.
The atmosphere would have to warm outrageously in order to melt the Antarctic ice sheet from the top down. Snowfall tends to be heaviest when temperatures are just below 0°C, but temperatures at the South Pole rarely go above -20°C, even in the summer. So atmospheric warming will likely lead to a slight increase in snowfall over Antarctica, adding to the mass of the ice sheet. Unfortunately, the ocean is warming at the same time. And a slightly warmer ocean will be very good at melting Antarctica from the bottom up.
Posted on 22 January 2015 by John Hartz
- Al Gore: oil companies 'use our atmosphere as an open sewer'
- Climate change researcher to sit with first lady at SOTU
- Food diversity under siege from global warming, U.N. says
- Former Saudi oil boss says it can handle low price
- How ‘Warmest Ever’ headlines and debates can obscure what matters about climate change
- Is a climate disaster inevitable?
- ‘It is profitable to let the world go to hell’
- Matt Ridley wants to gamble the Earth’s future because he won’t learn from the past
- Obama calls out Republicans for their “I’m not a scientist” line
- Obama strikes first in war of words with Congress over global warming
- Satellite treats Earth as terrarium
- US conservatives erupt over pope's plan for encyclical on moral duty to address climate change
- Was 2014 hot enough for you?
- Why it's good to laugh at climate change
- Yup, a climate change denier will oversee NASA. What could possibly go wrong?
Al Gore: oil companies 'use our atmosphere as an open sewer'
It’s not possible to listen to petroleum industry executives defending their reckless extraction of oil without feeling that we are living in an age of madness.
In a recent private conversation under the Chatham House rule, one of the world’s most senior industry leaders, who is considered to be at the more moderate end of the spectrum, insisted that we are going to burn all the world’s hydrocarbons despite the consequences.
His reasoning is that a growing population in the developing world needs energy to raise living standards, that renewables will not become a dominant energy source till the end of the century and that politicians don’t have the courage or power to limit production.
He acknowledged that the burning of all reserves would almost certainly lead to temperature rises of up to 4C, but argued the best way forward is to focus on limiting the damage through such technologies as carbon capture and storage.
Al Gore: oil companies 'use our atmosphere as an open sewer' by Jo Confino, The Guardian, Jan 21, 2015
Posted on 22 January 2015 by John Abraham
Wow, was this a bad year for those who deny the reality and the significance of human-induced climate change. Of course, there were the recent flurry of reports that 2014 surface temperatures had hit their hottest values ever recorded. The 2014 record was first called on this blog in December and the final results were reported as well, here. All of this happened in a year that the denialists told us would not be very hot.
But those denialists are having a tough time now as they look around the planet for ANY evidence that climate change is not happening. The problem is, they’ve been striking out.
Posted on 21 January 2015 by dana1981
Have you ever watched a zombie movie and wondered if the protagonists will grow physically tired from having to repeatedly kill zombies that inevitably rise once again from the dead? That’s how people often feel when confronted with climate change myths that were debunked years ago. These myths never seem to stay dead, inevitably being revived by climate contrarians no matter how conclusively and repeatedly they’ve been debunked.
And so we have writer Matt Ridley once again published in the London Times complaining, “Rather than attack my arguments, my critics like to attack my motives.” That’s undoubtedly because when an individual keeps repeating the same myths over and over again, people eventually grow tired of debunking those myths and naturally question the motives of the individual who keeps making them.
Let’s look at a few examples from Ridley’s latest article. He claims not to be worried about global warming for a few reasons, including,
The failure of the atmosphere to warm anywhere near as rapidly as predicted was a big reason: there has been less than half a degree of global warming in four decades - and it has slowed down, not speeded up.
This is incorrect – average global surface temperatures have warmed between 0.6 and 0.7°C over the past 40 years (lower atmospheric temperatures have also likely warmed more than 0.5°C, though the record hasn’t yet existed for 40 years). During that time, that temperature rise has temporarily both slowed down (during the 2000s, when there was a preponderance of La Niña events) and sped up (during the 1990s, when there was a preponderance of El Niño events). Climate models accurately predicted the long-term global warming trend. Ridley continues,
Posted on 20 January 2015 by John Hartz
Dana's Global warming made 2014 a record hot year – in animated graphics received the highest number of comments of the articles posted on SkS during the past week.
Comments Policy Update
The SkS Comments Policy was amended with the addition of the following sentence.
Moderation complaints are always off topic and will be deleted.
El Niño Watch
There has been a lot of buzz over the last few months of an El Nino taking shape across the globe. These often bring wet conditions to the southern and western U.S. and warmer conditions to the state of Minnesota. But recent observations are showing that our El Nino may not even happen.
There are many different ways to measure if an El Nino is occurring, but the main way is to measure sea surface temperatures in the equatorial Pacific… it's this area that is often most affected by an El Nino event. Well, the latest trends aren't promising…
Our El Nino year may not happen by Cody Matz KMSP (Detroit), Jan 18, 2015
As colder than seasonal temperatures have taken hold across Canada this winter, you may be asking, “Where is El Niño?” The answer is that El Niño conditions are already in place in the Pacific, but not all El Niños are created equal. Analysis of current conditions shows how this year’s unique flavour of El Niño will help keep some parts of Canada warm, while others will remain in the deep freeze.
El Niño update explains impact on Canada in months to come by Michael Carter, The Weather Newtwork, Jan 16, 2015
Toon of the Week
Posted on 19 January 2015 by John Cook
On 7 September 2014, we launched 97 Hours of Consensus. Every hour for 97 consecutive hours, we published a cartoon of a climate scientist with a quote about climate change. We also published a very cool interactive webpage. Our purpose: to raise awareness of the scientific consensus on human-caused global warming.
On 7 September 2015, we're repeating 97 Hours of Consensus with another 97 climate scientists. But with a different approach. This time, we're asking climate scientists to submit their quotes to us. So this is my call to action to the climate science community. If you're a climate scientist who:
- has something to say about the issue of human-caused global warming,
- and is interested in your words reaching millions of people,
- and would like to be drawn in cartoon form
Posted on 17 January 2015 by John Hartz
- 2014 breaks heat record, challenging global warming skeptics
- 2014 highlights: Clean energy up 16%, Green bonds, U.S.-China climate change deal
- 2014 officially the hottest year on record
- Activists say Obama action on methane emissions 'misses 90% of pollution'
- As waters acidify, Maine looks to Pacific Northwest peers for help
- Global sea levels rising faster than previously thought, study shows
- Global warming made 2014 a record hot year – in animated graphics
- Hillary is hiring John Podesta, and that’s good for climate hawks
- Losing the climate fight: Has 400 ppm become planet's new normal?
- Obama Administration to unveil plans to cut methane emissions
- Ocean life faces mass extinction, broad study says
- Q&A: Reading the New York Times with Naomi Klein
- Rate of environmental degradation puts life on Earth at risk, say scientists
- Smoke and mirrors will not save us from Anthropogenic climate disruption
- The Antarctic ice sheet is a sleeping giant, beginning to stir
2014 breaks heat record, challenging global warming skeptics
Last year was the hottest on earth since record-keeping began in 1880, scientists reported on Friday, underscoring warnings about the risks of runaway greenhouse-gas emissions and undermining claims by climate-change contrarians that global warming had somehow stopped.
Extreme heat blanketed Alaska and much of the Western United States last year. Records were set across large areas of every inhabited continent. And the ocean surface was unusually warm virtually everywhere except near Antarctica, the scientists said, providing the energy that fueled damaging Pacific storms.
In the annals of climatology, 2014 surpassed 2010 as the warmest year. The 10 warmest years have all occurred since 1997, a reflection of the relentless planetary warming that scientists say is a consequence of human activity and poses profound long-term risks to civilization and nature.
2014 breaks heat record, challenging global warming skeptics by Justin Gillis, New York Times, Jan 16, 2015
Posted on 17 January 2015 by dana1981
But what’s really remarkable is that 2014 set this record without the aid of an El Niño event. El Niño events create conditions in which sea surface and hence global surface temperatures are anomalously hot. We call this part of the Earth’s “internal variability” because these events just temporarily shift heat around between the ocean surface and its depths.
As this graphic shows (click here for an animated version), the last five record hot years of 2010, 2005, 1998, 1997, and 1995 were all assisted by El Niño events.
Posted on 15 January 2015 by Kevin C
The surface thermometer record forms a key part of our knowledge of the climate system. However it is easy to overlook the complexities involved in creating an accurate global temperature record from historical thermometer readings. If the limitations of the thermometer record are not understood, we can easily draw the wrong conclusions. I reevaluated a well known climate sensitivity calculation and found some new sources of uncertainty, one of which surprised me.
This highlights two important issues. Firstly the thermometer record (while much simpler than the satellite record) requires significant expertise in its use - although further work from the record providers may help to some extent. Secondly, the policy discussion, which has been centered on the so called 'warming hiatus', has been largely dictated by the misinformation context, rather than by the science.
At the AGU fall meeting I gave a talk on some of our work on biases in the instrumental temperature record, with a case study on the implications from a policy context. The first part of the talk was a review of our previous work on biases in the HadCRUT4 and GISTEMP temperature records, which I won't repeat here. I briefly discussed the issues of model-data comparison in the context of the CMIP-5 simulations, and then looked at a simple case study on the application of our results.
The aim of doing a case study using our data was to ascertain whether our work had any implications beyond the problem of obtaining unbiased global temperature estimates. In fact repeating an existing climate sensitivity study revealed a number of surprising issues:
- Climate sensitivity is affected by features of the temperature data which were not available to the original authors.
- It is also affected by features of the temperature record which we hadn't considered either, such as the impact of 19th century ship design.
- The policy implications of our work have little or nothing to do with the hiatus.
The results highlight the fact that significant expertise is currently required to draw valid conclusions from the thermometer record. This represents a challenge to both providers and users of temperature data.
Let's start by looking at the current version of our temperature reconstruction, created by separate infilling of the Hadley/CRU land and ocean data. The notable differences are that our reconstruction is warmer in the 2000's (due to rapid arctic coverage), and around 1940, and cooler in the 19th century due to poor coverage in HadCRUT4 (figure 1).
Posted on 14 January 2015 by John Abraham
In a paper I just published with colleague Dr. Ted Scambos from the National Snow and Ice Data Center, we highlight the impact of southern ice sheet loss, particularly the West Antarctic Ice Sheet on sea-level rise around the world.
We know that human emissions of greenhouse gases are causing the Earth’s temperature to rise and are creating other changes across the Earth’s climate system. One change that gets a great deal of attention is the current and future rates of sea-level rise. A rising sea level affects coastal communities around the world; approximately 150 million people live within 1 meter of current sea level.
The waters are rising because of a number of factors. First, water expands as it warms. In the past, this “thermal expansion” was the largest source of sea-level rise. But as the Earth’s temperatures continued to increase, another factor (melting ice, particularly from large ice sheets in Greenland and Antarctica) has played an ever increasing role.
In the Southern Hemisphere, the largest player is the Western Antarctic Ice Sheet (WAIS). It is less stable than Eastern Antarctica and is particularly vulnerable to melting from below by warmed ocean waters. Scientists are closely watching the ice near the edges of the WAIS because they buttress large volumes of ice that are more inland. When these buttressing ice shelves melt, the ice upstream will slide more rapidly toward the ocean waters.
As reported in our paper, according to some studies, “no further acceleration of climate change and only modest extrapolations of the current increasing mass loss rate are necessary for the system to eventually collapse ... resulting in 1-3 m of sea-level rise.” And this is from just one component of the great southern sheets.
Posted on 13 January 2015 by John Hartz
- 2015 begins with CO2 above 400 PPM mark
- China vulnerable to climate change
- Climate change takes a village
- Climate leadership under China's economic domination?
- For the love of carbon
- How the U.S. and India can work together on global warming
- Ice researchers capture catastrophic Greenland melt
- Is the climate movement at a tipping point?
- Losing streak continues for U.S. coal export terminals
- Moderate Republicans believe in climate change. There just aren’t many moderate Republicans.
- NASA’s year of climate change research kicks off, with a little help from Washington companies
- Pope Francis says no to fracking
- Social cost of climate change too low
- The U.S. and India keep pushing toward a climate deal
- Will Gadd: 'We were climbing ice that isn’t going to be there next week'
2015 begins with CO2 above 400 PPM mark
The new year has only just begun, but we’ve already recorded our first days with average carbon dioxide levels above 400 parts per million, potentially leading to many months in a row above this threshold, experts say.
The Scripps Institution of Oceanography records of atmospheric carbon dioxide levels show that Jan. 1 was the first day of the new year above that concentration, followed by Jan. 3 and Jan. 7. Daily averages have continued at this level or higher through Jan. 9, though they could continue to dance up and down around that mark due to day-to-day variations caused by weather systems. But even with those fluctuations, 2015 will likely see many months above 400 ppm, possibly starting with the very first month of the year.
“My guess at this point is that January 2015 will be very slightly above 400 ppm, but it's too early to tell for sure,” Ralph Keeling, the scientist in charge of the CO2 monitoring project atop Hawaii’s Mauna Loa, said in an email. Keeling’s father, Charles, began the project in 1958. The graph that shows the decades-long rise in CO2 is eponymously called the Keeling Curve.
2015 Begins With CO2 Above 400 PPM Mark by Andrea Thompson, Climate Central, Jan 12, 2015
Posted on 13 January 2015 by howardlee
Homo incendius – “fire man” – is an informal nickname for our ancestors who first learned how to make fire. As one of the quintessential human attributes, you might expect fire-making to have arisen along with our own species, Homo sapiens when we emerged in Africa some 208,000 years ago.
You have to go much further back in time, before Neanderthals and even before the earlier Homo heidelbergensis. The first solid evidence for our ancestors’ regular use of fire dates to 1 million years ago, and possibly as far back as 1.5 million years ago. That’s during the reign of Homo erectus – our first fire-making, food-cooking, big-game-hunting, art-making, intercontinental-travelling ancestor.
Homo erectus took fire-making skills to the Levant and all the way to China by about 770,000 years ago, but strangely our contemporary ancestors who traveled to the fringes of the ice sheets in Europe don’t seem to have been habitual fire-users until much later - about 400,000 years ago.
Posted on 12 January 2015 by Rob Painting
Posted on 11 January 2015 by John Hartz
Not pHraud but pHoolishness, a guest post by Richard Telford attracted the most comments of the articles posted on SkS during the past week. Another guest post, Climate Deniers Employ Predatory Tactics in Fight Against Facts: Scientist by Deirdre Fulton attracted the second highest number of comments.
Be sure to check out our new feature, Media Matters Posts about Environment & Science
El Niño Watch
Japan's weather bureau said on Friday the El Nino weather pattern, often linked to both heavy rainfall and drought, is continuing but added that the phenomena could end over spring.
The Japan Meteorological Agency forecast said the El Nino, which emerged during last summer for the first time in five years, was already starting to ease.
El Nino likely to head to an end over spring: Japan weather bureau, Reuters, Jan 9, 2015
Toon of the Week
Posted on 10 January 2015 by John Hartz
- Brazil’s former Sports Minister is moved to science post despite rejection of global warming science
- Clean energy investment jumps 16%, shaking off oil’s drop
- Climate change: Why some of us won't believe it's getting hotter
- EPA Chief: Weather, climate scientists’ work is ‘essential’
- Four reasons to worry about global warming: Beyond scientific consensus
- Fracking breaks the CO2 budget
- Giant deep-sea wave in Tasman Sea could help improve climate predictions
- Integrated farming: The only way to survive a rising sea
- Oil sands must remain largely unexploited to meet climate target
- Pakistan's coastal villagers retreat as seas gobble land
- Pope's Asia trip to address poverty, dialogue, climate change
- Showdown between Obama and Congress over Keystone XL accelerates after court ruling
- Stanford professors urge withdrawal from fossil fuel investments
- Top global warming skeptic explains global warming
- Unusual number of UK flowers bloom
Brazil’s former Sports Minister is moved to science post despite rejection of global warming science
For the president in any democracy, compromises are often necessary in assembling a cabinet that satisfies a range of constituencies. But even with that in mind, it’s really hard to understand how President Dilma Rousseff of Brazil, who has repeatedly pressed for strong global action to curb climate change, could possibly justify her choice of Aldo Rebelo as her new minister of science, technology and innovation.
It’s unfortunate that Rebelo has no scientific background and probably didn’t absorb many relevant insights in the position he held since 2011 — minister of sports. But that’s a minor issue compared to his attacks on even the most basic, established aspects of science pointing to human-driven global warming.
To get a feel for his views, which put the longtime Communist Party legislator in line with Tea Party talking points, start with the blistering critique of the appointment by Steve Schwartzman of the Environmental Defense Fund, who’s been immersed in Brazilian environmental and forest science and politics for decades.
Brazil’s Former Sports Minister is Moved to Science Post Despite Rejection of Global Warming Science by Andrew Revkin, Dot Earth, New York Times, Jan 7, 2015
Posted on 9 January 2015 by Guest Author
Climate Deniers Employ Predatory Tactics in Fight Against Facts: Scientist by Deirdre Fulton was originally posted on Common Dreams on Jan 6, 2015.
Michael Mann writes that the strategy 'is similar to what happens when a group of lions on the Serengeti seek out a vulnerable individual zebra at the edge of a herd.'
"The 'Serengeti strategy' is often employed wherever there is a strong and widespread consensus among the world’s scientists about the underlying cold, hard facts of a field, whether the subject be evolution, ozone depletion, the environmental impacts of DDT, the health effects of smoking, or human-caused climate change," Mann writes. (Photo: Bulletin of Atomic Scientists/Brocken Inaglory)
Like lions targeting lone zebras in the Serengeti grasslands, industry-backed climate change deniers prefer to target individual scientists rather than take on an entire scientific field at once, climatologist Michael Mann writes in a paper published this month in the Bulletin of the Atomic Scientists.
In "The Serengeti Strategy: How Special Interests Try to Intimidate Scientists, and How Best to Fight Back," Mann describes a concerted effort on the part of fossil fuel interests who find themselves facing overwhelming scientific consensus about the threat of human-caused climate change—and, by implication, the necessity to reduce global carbon emissions.
"By singling out a sole scientist, it is possible for the forces of 'anti-science' to bring many more resources to bear on one individual, exerting enormous pressure from multiple directions at once, making defense difficult," writes Mann, director of the Earth System Science Center at Pennsylvania State University. "It is similar to what happens when a group of lions on the Serengeti seek out a vulnerable individual zebra at the edge of a herd."
Unfortunately, the strategy is effective, he says, which is why similar tactics have been employed by the chemical and pharmaceutical industries, big agriculture, and "just about any corporate interest that has found itself on a collision course with scientific research—particularly research that reveals specific potential damages or threats caused by their product."
Posted on 8 January 2015 by dana1981
Lately there seems to have been a shift away from climate science denial, toward arguments downplaying the costs of human-caused climate change. Specifically, some economists publishing reports for Bjorn Lomborg’s Copenhagen Consensus Center have argued that we should focus our efforts more on adapting to climate impacts and on other issues, rather than on cutting carbon pollution and slowing global warming.
According to the Climate Action Tracker, current international climate policies will result in a global surface warming of about 4°C. If we act on all conditional pledges, including those recently made by China and the USA, we’ll see about 3°C warming. This (3–4°C) is the range of global warming that the Copenhagen Consensus Center claims would be the most optimal for the global economy.
One might ask, what sorts of climate impacts would we expect to see as a result of this much global warming? Research indicates that the consequences would be quite severe. For example, widespread coral mortality would occur, and 40–70% of global species would be at risk of extinction. Glacier retreats would threaten water supplies in Central Asia and South America. Sea level rise of 1 meter or more would be expected by 2100, with the possibility of destabilization of the Greenland and West Antarctic ice sheets, which would cause much more sea level rise and flooding of coastal communities.
Posted on 7 January 2015 by John Hartz
- 7 trends that will affect the Planet in 2015
- 2014 may set a new temperature record. So can we please stop claiming global warming has “stopped”?
- Australia is burning, and climate change is making it worse
- California drought: Early months of 2015 will be critical
- California Gov Jerry Brown unveils ambitious energy goals
- Climate change isn't just a Leftist cause
- Climate deniers employ predatory tactics in fight against facts: Scientist
- How climate change is making its mark on the world – pictures
- Keystone, climate change and the US economy: the truth behind the myths
- Limiting global warming means forgoing vast fuel reserves - study
- Oil’s swoon creates the opening for a carbon tax
- Playing dumb on climate change
- Pope Francis declares war on climate change, other religions follow
- Pope Francis plants a flag in the ground on climate change
- Solar is changing the game
7 trends that will affect the Planet in 2015
Here are some trends and expected events in 2015 and beyond that may have a significant impact upon the planet and life on Earth.
7 trends that will affect the Planet in 2015 by Parick J. Kiger, Discovery News, Jan 5, 2015