Hotter, weirder: How climate change has changed Earth

December 2, 2014, 8:37 AM

Smoke rises from trees burnt overnight by the King Fire in Fresh Pond northeast of Sacramento, California September 18, 2014. REUTERS/Stephen Lam

WASHINGTON (AP) — In the more than two decades since world leaders first got together to try to solve global warming, life on Earth has changed, not just the climate. It’s gotten hotter, more polluted with heat-trapping gases, more crowded and just downright wilder.

The numbers are stark. Carbon dioxide emissions: up 60 percent. Global temperature: up six-tenths of a degree. Population: up 1.7 billion people. Sea level: up 3 inches. U.S. extreme weather: up 30 percent. Ice sheets in Greenland and Antarctica: down 4.9 trillion tons of ice.

“Simply put, we are rapidly remaking the planet and beginning to suffer the consequences,” says Michael Oppenheimer, professor of geosciences and international affairs at Princeton University.

Diplomats from more than 190 nations opened talks Monday at a United Nations global warming conference in Lima, Peru, to pave the way for an international treaty they hope to forge next year.

To see how much the globe has changed since the first such international conference – the Earth Summit in Rio de Janeiro in 1992 – The Associated Press scoured databases from around the world. The analysis, which looked at data since 1983, concentrated on 10-year intervals ending in 1992 and 2013. This is because scientists say single years can be misleading and longer trends are more telling.

Our changing world by the numbers:

WILD WEATHER

Since 1992, there have been more than 6,600 major climate, weather and water disasters worldwide, causing more than $1.6 trillion in damage and killing more than 600,000 people, according to the Centre for Research on the Epidemiology of Disasters in Belgium, which tracks the world’s catastrophes.

While climate-related, not all can be blamed on man-made warming or climate change. Still, extreme weather has noticeably increased over the years, says Debby Sapir, who runs the center and its database. From 1983 to 1992 the world averaged 147 climate, water and weather disasters each year. Over the past 10 years, that number has jumped to an average 306 a year.

In the United States, an index of climate extremes – hot and cold, wet and dry – kept by the National Oceanic and Atmospheric Administration has jumped 30 percent from 1992 to 2013, not counting hurricanes, based on 10-year averages.

NOAA also keeps track of U.S. weather disasters that cost more than $1 billion, when adjusted for inflation. Since 1992, there have been 136 such billion-dollar events.

Worldwide, the 10-year average for weather-related losses adjusted for inflation was $30 billion a year from 1983-92, according to insurance giant Swiss Re. From 2004 to 2013, the cost was more than three times that on average, or $131 billion a year.

Sapir and others say it would be wrong to pin all, or even most, of these increases on climate change alone. Population and poverty are major factors, too. But they note a trend of growing extremes and more disasters, and that fits with what scientists have long said about global warming.

It’s this increase that’s “far scarier” than the simple rise in temperatures, University of Illinois climate scientist Donald Wuebbles says.

TEMPERATURE

It’s almost a sure thing that 2014 will go down as the hottest year in 135 years of record keeping, meteorologists at NOAA’s National Climatic Data Center say. If so, this will be the sixth time since 1992 that the world set or tied a new annual record for the warmest year.

The globe has broken six monthly heat records in 2014 and 47 since 1992. The last monthly cold record set was in 1916.

So the average annual temperature for 2014 is on track to be about 58.2 degrees (14.6 degrees Celsius), compared with 57.4 degrees (14.1 degrees Celsius) in 1992. The past 10 years have averaged a shade below 58.1 degrees (nearly 14.5 degrees Celsius) – six-tenths of a degree warmer than the average between 1983 and 1992.

THE OCEANS

The world’s oceans have risen by about 3 inches since 1992 and gotten a tad more acidic – by about half a percent – thanks to chemical reactions caused by the absorption of carbon dioxide, scientists at NOAA and the University of Colorado say.

Every year sea ice cover shrinks to a yearly minimum size in the Arctic in September – a measurement that is considered a key climate change indicator. From 1983 to 1992, the lowest it got on average was 2.62 million square miles. Now the 10-year average is down to 1.83 million square miles, according to the National Snow and Ice Data Center.

That loss – an average 790,000 square miles since 1992 – overshadows the slight gain in sea ice in Antarctica, which has seen an average gain of 110,000 square miles of sea ice over the past 22 years.

ON LAND

The world’s population in 1992 was 5.46 billion. Today, it’s nearly a third higher, at 7.18 billion. That means more carbon pollution and more people who could be vulnerable to global warming.

14 Photos

Wildfires in California

The effects of climate change can be seen in harsher fire seasons. Wildfires in the western United States burned an average of 2.7 million acres each year between 1983 and 1992; now that’s up to 7.3 million acres from 1994 to 2013, according to the National Interagency Fire Center.

And some of the biggest climate change effects on land are near the poles, where people don’t often see them. From 1992 to 2011, Greenland’s ice sheet lost 3.35 trillion tons of ice, according to calculations made by scientists using measurements from NASA’s GRACE satellite. Antarctica lost 1.56 trillion tons of ice over the same period.

THE AIR

Scientists simply point to greenhouse gas emissions, mostly carbon dioxide, that form a heat-trapping blanket in our air.

There’s no need to average the yearly amount of carbon dioxide pollution: It has increased steadily, by 60 percent, from 1992 to 2013. In 1992, the world spewed 24.9 billion tons of carbon dioxide; now it is 39.8 billion, according to the Global Carbon Project, an international consortium.

China has tripled its emissions from 3 billion tons to 11 billion tons a year. The emissions from the U.S. have gone up more slowly, about 6 percent, from 5.4 billion tons to 5.8 billion tons. India also has tripled its emissions, from 860 million tons to 2.6 billion tons. Only European countries have seen their emissions go down, from 4.5 billion tons to 3.8 billion tons.

WHAT SCIENTISTS SAY

“Overall, what really strikes me is the missed opportunity,” Andrew Dessler, a climate scientist at Texas A&M University, said in an email.

“We knew by the early 1990s that global warming was coming, yet we have done essentially nothing to head off the risk. I think that future generations may be justifiably angry about this.”

“The numbers don’t lie,” said Michael Mann, a climate scientist at Penn State. “Greenhouse gases are rising steadily and the cause is fossil fuel burning and other human activities. The globe is warming, ice is melting and our climate is changing as a result.”

© 2014 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.

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Rush to Uncover Ancient Human History Before Glaciers Melt June 27, 2014

Prehistoric items already recovered from Alpine ice. This bow and arrow set was found on the Schnidejoch ice sheet in the Bernese Oberland.

A Swiss researcher is rushing to retrieve items covered for hundreds or even thousands of years by ice that is now melting due to global warming.

Leandra Naef told the Swiss Broadcasting Corp. that the project in the country’s eastern mountains “has to happen now, or else it will be too late, if it’s not already too late.”

Her plan is to search for well-preserved artifacts trapped beneath ice patches in the highest elevations of the Alps.

Since a 5,000-year-old corpse was discovered by hikers in melting ice nearly a quarter of a century ago, items like leather leggings from about 3000 B.C., as well as an ancient arrow quiver, have also emerged from the receding glaciers.

Naef has targeted 40 points that she believes are most likely to yield artifacts.

She urges hikers and wardens to turn in anything they find over upcoming summers as the Alpine glaciers vanish.

Naef hopes to uncover some artifacts herself this summer.

Photo: Archäologischer Dienst Kt. Bern

 

© MMXIV Earth Environment Service

This May Was Hottest In Recorded History

The month of May was the hottest in recorded history, a dire finding for scientists warning of global warming.

The National Oceanic and Atmospheric Administration announced Monday that May 2014 was the hottest May since records started being kept in the mid 20th century. The research found that land and sea surfaces were 1.33 degrees Fahrenheit above the 20th Century average of 58.6 degrees.

The steamy month of May was not a one-off, the NOAA warned.

“Four of the five warmest Mays on record have occurred in the past five years,” the NOAA also wrote in its report.

El Niño last made an appearance in 1997, climate scientists believe there is an 80 percent chance it will return by the fall.

“I don’t think we’ve seen anything like this before,” said Kevin Trenberth, a climate scientist at the National Center for Atmospheric Research.

The effects of global warming are being seen elsewhere. Researchers have found that glaciers in Antarctica are melting at a fast rate, and elsewhere sea levels are rising.

The higher waters have even uncovered graves of dead WWII soldiers on the Marshall Islands.

“These last spring tides in February to April this year have caused not just inundation and flooding of communities but have also undermined regular land, so that even the dead are affected,” said Republic of the Marshall Islands Foreign Minister Tony De Brum, at the United Nations climate negotiations in Bonn, Germany.

He added, “There are coffins and dead people being washed away from graves, it’s that serious.”

Scientists say the effects of global warming are clear when looking at the previous hottest month of May ever, which was just four years ago.

We Cannot Know Too Much About ALBEDO

Ponds can predict extent of Arctic ice melt.

DDN Correspondent Posted on 18 Jun, 2014 at 12:02:PM IST

According to a recent research, the quantity of water in ponds that accumulates on top of icebergs at the time of spring warming can assist to forecast how much the Arctic ice will melt during the summer.

 The new research is conducted by the University of Reading.

The scientists have anticipated that the extent of minimum Arctic ice this September will be around 5.4 million sq km, which is similar to what it was last year. The scientists concluded it on the basis of observing the melt-pond region in spring, as they discovered a strong association between the spring pond fraction and sea ice extent in September.

According to the researchers, this has connection with the albedo, which is the reflective power of ice. The scientists found in the month of April that the maximum extent of sea ice in the Arctic was reducing, with the melting season continuing five more days.

The study says existence of more ponds decrease the albedo and a lesser albedo results in more melting and more melting increases pond fraction. The findings help elucidate the acceleration of Arctic sea-ice reduction that took place during the past decade.

Another research published in February indicated that the loss of ice shows that a smaller amount of sun heat was being reflected back into the atmosphere, which was increasing global warming.

A Hint at a possible solution to Global Warming

Microbial Garden Taking The Shine Off Glaciers

June 14, 2014

Image Caption: Stefanie Lutz (center) and Professor Liane G. Benning (left) collecting a biofilm sample on the Mittivakkat Glacier in Greenland. Credit: Stefanie Lutz, Professor Liane G. Benning and Dr Alexandre Anesio

University of Leeds

The first ecological study of an entire glacier has found that microbes drastically reduce surface reflectivity and have a non-negligible impact on the amount of sunlight that is reflected into space.

The research, led by the University of Leeds and published June 12 in the journal FEMS Microbiology Ecology, will help improve climate change models that have previously neglected the role of microbes in darkening the Earth’s surface.

Observing how life thrives at extreme cold temperatures also has important implications for the search for life on distant worlds, such as Jupiter’s icy moon Europa.

Stefanie Lutz, a PhD student at the School of Earth and Environment at the University of Leeds, and lead author of the study, said: “Our three-week field trip revealed a ‘microbial garden’ of life forms flourishing in this cold environment, including snow algae, bacteria, fungi and even invertebrates.

“Skiers may have seen snow algae before, but not been able to identify it. They are visible to the naked eye as colored snow – most often red – and are frequently referred to as ‘watermelon snow’.”

The study was carried out on the Mittivakkat Glacier in south east Greenland during the summer of 2012, which was the hottest summer and thus the fastest melting season recorded for 150 years.

“Our timing was serendipitous, as it meant we were able to see changes in microbial processes over an extremely fast melting season and observe a process from start to end across all habitats on a glacier surface. This is the most comprehensive study of microbial communities living on a glacier to date,” said Lutz.

The research showed that, compared to pure snow and ice, the reflectivity of the glacier (known as the “albedo“) can be reduced by up to 80% in places where colored microbial populations are extremely dense, leading to the darkening of the glacier surface.

Professor Liane G. Benning from the School of Earth and Environment at the University of Leeds and co-author of the study, said: “Previously, it was assumed that low albedo, which is most often measured from satellites, was primarily due to soot or dust. However, our research provides a first, ground-based measure for the microbial contribution to albedo. We have shown that albedo is strongly affected by and dependent upon the development and dominance of microbial communities.

“In future climate scenarios, where even more melting is predicted, it is crucial that we are able to better discriminate between all factors affecting albedo.”

The research leading to these results received funding from the European Union Seventh Framework Programme [FP7/2007-2013] under grant agreement n° 262693 [INTERACT] and a University of Leeds, School of Earth and Environment grant to Stefanie Lutz and Liane G. Benning.

Remember the word, ALBEDO

Dust Darkens Greenland Ice Sheet Speeding Melt due to a change in Albedo

08.06.2014

A new paper in Nature Geoscience says dust on the surface of the Greenland ice sheet is absorbing solar warmth and accelerating melting. It suggests that the dust comes from other Arctic areas losing snow cover earlier due to climate change.

Click to enlarge. Observed broadband diuse albedo above 2,000 m a.s.l. Diffuse broadband albedo derived from MODIS MCD43A3 products for the May–July period from 2003 to 2013. The values are averaged over the GrIS above 2,000 m elevation. Only data with local solar elevation larger than 25o and labelled as high quality are used. The 2003–2008 mean and the standard deviation are indicated in grey shades. Individual 2003 to 2008 albedo series are shown as grey dashed lines. Courtesy: authors and Nature Geoscience.

Click to enlarge. Melting snow containing light absorbing impurities.

Melting snow containing light absorbing impurities. Courtesy: Florent Domin

é.

Snow surface at Summit, Greenland. Courtesy: Florent Dominé.

Here is the Nature press release relating to this story.

The springtime darkening of the Greenland ice sheet since 2009 may be attributable to an increase in the amount of impurities—such as dust—in snow, according to a study published online in Nature Geoscience. Impurities, which increase the solar energy absorbed by snow, can lead to enhanced melting and thus contribute to the loss of Greenland’s ice.

Marie Dumont and colleagues analysed satellite observations to show that the observed darkening of Greenland’s ice in springtime months is consistent with a widespread increase in the amount of light-absorbing impurities. They propose that dust originating from other Arctic areas, which are losing their snow cover earlier in the spring as the climate warms, may be the source of the impurities.

Numerical snow models suggest that the darkening of springtime snow due to light-absorbing impurities has led to significant mass loss of the Greenland ice sheet in recent years.

Abstract

The surface energy balance and mass balance of the Greenland Ice Sheet depends on the albedo of snow, which governs the amount of solar energy that is absorbed. The observed decline of Greenland’s albedo over the past decade has been attributed to an enhanced growth of snow grains as a result of atmospheric warming. Satellite observations show that, since 2009, albedo values even in springtime at high elevations have been lower than the 2003–2008 average. Here we show, using a numerical snow model, that the decrease in albedo cannot be attributed solely to grain growth enhancement. Instead, our analysis of remote sensing data indicates that the springtime darkening since 2009 stems from a widespread increase in the amount of light-absorbing impurities in snow, as well as in the atmosphere. We suggest that the transport of dust from snow-free areas in the Arctic that are experiencing earlier melting of seasonal snow cover as the climate warms may be a contributing source of impurities. In our snow model simulations, a decrease in the albedo of fresh snow by 0.01 leads to a surface mass loss of 27 Gt yr, which could induce an acceleration of Greenland’s mass loss twice as large as over the past two decades. Future trends in light-absorbing impurities should therefore be considered in projections of Greenland mass loss.

 

“No Mo Joe”

How climate change and a deadly fungus are threatening our coffee supply

By Gwynn Guilford @sinoceros June 2, 2014

Time to switch to tea? Reuters/Mario Anzuoni

 

In the next 24 hours, the world will guzzle 1.6 billion cups of coffee, the most popular beverage on the planet besides water and tea. It’s big business, too: Global coffee exports totaled $28.6 billion in 2013—after oil, it is the world’s most traded commodity.But there’s something else that likes coffee even more than humans: Hemileia vastatrix, better known as coffee rust or roya disease. It’s a fungal parasite that survives on coffee tree leaves, and in the 2012-13 crop year alone, it caused nearly $499 million in losses (pdf, p.3) among Central American coffee growers. Worse, big swings in weather resulting from climate change are hastening the spread of this fungus, reports National Geographic, and causing epic droughts on plantations elsewhere in the region. The devastating double-whammy of climate and disease could wipe out as much as two-fifths of Central America’s coffee crop.

Most likely originating in East Africa, coffee rust infects the leaves of the coffee plant, speckling them with pale yellow spots that scramble photosynthesis, leaving the plant unable to breathe. The fungus first arrived in the Western Hemisphere in the 1970s, when it suffocated more than half of Central America’s crops, spreading both by wind and on the clothes of migrant workers.

Coffee rust.Flickr user Neil Palmer (CIAT)

Scientists eventually came up with rust-resistant coffee species. But those commercial crops are stuck with a limited range of genes, while rust keeps evolving, expanding its range. In evolutionary terms, the coffee plants can’t keep up. And in 2010, rust bounced back in a more aggressive form, this time in Guatemala and Colombia . By 2013, the fungus infected three-quarters of El Salvador’s crops, and more than two-thirds of Guatemala’s and Costa Rica’s. Not only Guatemala, but Honduras and Costa Rica have since declared national emergencies to free up funds for pesticides.

+One reason for the fungus’ return is that rust spores need a lot of moisture to grow—around a day or two of continuous rain or heavy dew. While those conditions normally exist only during the rainy season, climate variation—the term for dramatic changes in weather that have intensified in recent years—means downpours are happening more frequently. Tellingly, 2010 was an unusually wet year in Central America (pdf, p.8). Climate variation is also responsible for the drought that’s devastated the coffee crop of Brazil, one of the world’s biggest suppliers.

Weird weather isn’t the only problem tethered to climate change; so is global warming. Hotter temperatures are a particular menace to Arabica, a type of coffee that makes up seven-tenths of global coffee production and requires cool climes to grow. A recent study predicted that by 2080,  global warming would make two-thirds of current farms too hot to grow Arabica—and that is the best-case scenario.

Warmer weather is also allowing rust to attack at higher altitudes, and is accelerating the spread of a slew of other coffee parasites. For instance, research in Ethiopia, the cradle of coffee civilization, found that an insect called the coffee berry borer struggled to reproduce in low temperatures. Once things warmed up, the borers could be grandparents within a year.

This is bad not only for global caffeination but also for small Central American farmers, millions of whom depend on coffee for their livelihoods. In Guatemala alone, the blight robbed coffee farmers of up to three-fifths of their income in 2013.

John Boehner: I’m ‘not qualified’ to debate climate change

 

House Speaker John Boehner of Ohio, center, leaves a news conference on Capitol Hill in Washington, on May 29, 2014.

J. Scott Applewhite/AP

 

By Aliyah Frumin

John Boehner is qualified to lead Congress. But in his mind, he’s apparently not qualified to weigh in on climate change.

“Listen, I’m not qualified to debate the science over climate change,” the House Speaker said at a press conference Thursday. But that doesn’t mean Boehner is withholding his opinions on the Obama administration’s plans to deal with the continuing rise of the Earth’s temperature.

“I am astute to understand that every proposal that has come out of this administration to deal with climate change involves hurting our economy and killing American jobs. That can’t be the prescription for dealing with changes to our environment,” he said.

Boehner made the remarks in response to a reporter asking the Ohio Republican about his previously stated concerns over federal, environmental regulations. “Are there steps you would support to take action against climate change and do you think that’s a problem?” the reporter questioned.

Earlier this month, Sen. Marco Rubio of Florida pushed back on the overwhelming scientific evidence to announce that he doesn’t believe human activity causes climate change.

Rubio, a potential 2016 Republican presidential candidate, told ABC: “I don’t agree with the notion that some are putting out there, including scientists that somehow there are actions we can take today that would actually have an impact on what’s happening in our climate.” He added: “Our climate is always changing.”

His comments came just days after the White House issued a report insisting climate change is a potentially catastrophic reality being hastened by human behavior. Boehner’s own “I’m not a scientist” moment comes ahead of new, stricter standards for coal-fired power plants that are expected to be announced by the Obama administration on Monday.

Denying human activity is to blame for the warming of the planet could put lawmakers in good standing with the far right – but not the majority of Americans. According to a poll by Pew Research, two thirds of Americans – 67% – said there is solid evidence that the Earth has been getting warming over the last few decades. However, among Tea Party Republicans, only 25% agreed with that statement.

Climate Change Doomed the Ancients

By ERIC H. CLINEMAY 27, 2014

 

Photo

THIS month, a report issued by a prominent military advisory board concluded that climate change posed a serious threat to America’s national security.

The authors, 16 retired high-ranking officers, warned that droughts, rising seas and extreme weather events, among other environmental threats, were already causing global “instability and conflict.”

But Senator James M. Inhofe of Oklahoma, the ranking Republican on the Senate Armed Services Committee and a stalwart believer that global warming is a “hoax,” dismissed the report as a publicity stunt.

Perhaps the senator needs a history lesson, because climate change has been leading to global conflict — and even the collapse of civilizations — for more than 3,000 years. Drought and famine led to internal rebellions in some societies and the sacking of others, as people fleeing hardship at home became conquerors abroad.

One of the most vivid examples comes from around 1200 B.C. A centuries-long drought in the Aegean and Eastern Mediterranean regions, contributed to — if not caused — widespread famine, unrest and ultimately the destruction of many once prosperous cities, according to four recent studies.

The scientists determined the length and severity of the drought by examining ancient pollen as well as oxygen and carbon isotope data drawn from alluvial and mineral deposits. All of their conclusions are corroborated by correspondence, inscribed and fired on clay tablets, dating from that time.

Ancient letters from the Hittite kingdom, in what is now modern-day Turkey, beseech neighboring powers for shipments of grain to stave off famine caused by the drought. (The drought is thought to have affected much of what is now Greece, Israel, Lebanon and Syria for up to 300 years.) One letter, sent from a Hittite king, pleads for help: “It is a matter of life or death!”

Another letter, sent from the city of Emar, in what is now inland Syria, states simply, “If you do not quickly arrive here, we ourselves will die of hunger.” The kingdom of Egypt, as well as the city of Ugarit, on the coast of what is now Syria, responded with food and supplies, but it is not clear if they were able to provide enough relief.

It certainly created problems of national security for the great powers of the time. Correspondence between the Egyptians, Hittites, Canaanites, Cypriots, Minoans, Mycenaeans, Assyrians and Babylonians — effectively, the Group of 8 of the Late Bronze Age — includes warnings of attacks from enemy ships in the Mediterranean. The marauders are thought to have been the Sea Peoples, possibly from the western Mediterranean, who were probably fleeing their island homes because of the drought and famine and were moving across the Mediterranean as both refugees and conquerors.

One letter sent to Ugarit advised the king to “be on the lookout for the enemy and make yourself very strong!” The warning probably came too late, for another letter dating from the same time states: “When your messenger arrived, the army was humiliated and the city was sacked. Our food in the threshing floors was burned and the vineyards were also destroyed. Our city is sacked. May you know it! May you know it!”

While sea levels may not have been rising then, as they are now, changes in the water temperature may have been to blame for making life virtually unlivable in parts of the region

A 2012 study published in the Journal of Archaeological Science found that the surface temperatures of the Mediterranean Sea cooled rapidly during this time, severely reducing precipitation over the coasts. The study concluded that agriculture would have suffered and that the conditions might have influenced the “population declines, urban abandonments and long-distance migrations associated with the period.”

HOLY SHIT !!!

Global warming: it’s a point of no return in West Antarctica. What happens next?

Last week saw a ‘holy shit’ moment in climate change science. A landmark report revealed that the collapse of a large part of Antarctica is now unstoppable

Ross Island, Antarctica – taken by a Nasa ice-monitoring team. Photograph: Michael Studinger/EPA

Last Monday, we hosted a Nasa conference on the state of the West Antarctic ice sheet, which, it could be said, provoked something of a reaction. “This Is What a Holy Shit Moment for Global Warming Looks Like,” ran a headline in Mother Jones magazine.

We announced that we had collected enough observations to conclude that the retreat of ice in the Amundsen sea sector of West Antarctica was unstoppable, with major consequences – it will mean that sea levels will rise one metre worldwide. What’s more, its disappearance will likely trigger the collapse of the rest of the West Antarctic ice sheet, which comes with a sea level rise of between three and five metres. Such an event will displace millions of people worldwide.

Two centuries – if that is what it takes – may seem like a long time, but there is no red button to stop this process. Reversing the climate system to what it was in the 1970s seems unlikely; we can barely get a grip on emissions that have tripled since the Kyoto protocol, which was designed to hit reduction targets. Slowing down climate warming remains a good idea, however – the Antarctic system will at least take longer to get to this point.

The Amundsen sea sector is almost as big as France. Six glaciers drain it. The two largest ones are Pine Island glacier (30km wide) and Thwaites glacier (100km wide). They stretch over 500km.

Many impressive scientists have gone before us in this territory. The concept of West Antarctic instability goes back to the 1970s following surveys by Charles Bentley in the 1960s that revealed an ice sheet resting on a bed grounded well below sea level and deepening inland. Hans Weertman had shown in 1974 that a marine-based ice sheet resting on a retrograde bed was unstable. Robert Thomas extended his work to pursue the instability hypothesis. Terry Hughes suggested that the Pine Island sector of West Antarctica was its weak underbelly and that its retreat would collapse the West Antarctic ice sheet. Considerable uncertainty remained about the timescale, however, due to a lack of observation of this very remote area.

Things changed with the launch of the ERS-1 satellite which allowed glaciers in this part of antartica to be observed from space. In 1997, I found that the grounding line (where the glacier detaches from its bed and becomes afloat) of Pine Island glacier had retreated five kilometres in the space of four years, between 1992 and 1996. Stan Jacobs and Adrian Jenkins had found a year earlier that the glacier was bathing in unusually warm waters, which suggested the ocean had a major influence on the glacier. Duncan Wingham and others showed that the glacier was thinning. In 2001, I found that Thwaites glacier was retreating too .

At that point, the scientific community took a different look at the region. Work by the British Antarctic Survey, Nasa and Chile led to more detailed observations, a monitoring programme was initiated, instruments were placed on the ice, in the ocean and scientific results started to pile up from a variety of research programmes. From that point, we all sought to find out whether this was really happening. Now, two decades after this process started, we have witnessed glacier grounding lines retreat by kilometres every year, glaciers thinning by metres every year hundreds of kilometres inland, losing billions of tons of water annually, and speeding up several percent every year to the flanks of topographic divides.

Thwaites glacier started to accelerate after 2006 and in 2011 we detected a huge retreat of the glacier grounding lines since 2000. Detailed reconstructions of the glacier bed further confirmed that no mountain or hill in the back of these glaciers could act as a barrier and hold them up; and 40 years of glacier flow evolution showed that the speed-up was a long story.

All these results indicate a progressive collapse of this area. At the current rate, a large fraction of the basin will be gone in 200 years, but recent modelling studies indicate that the retreat rate will increase in the future. How did this happen? A clue is that all the glaciers reacted at the same time, which suggested a common force that can only be the ocean. Ocean heat is pushed by the westerly winds and the westerlies have changed around Antarctica in response to climate warming and the depletion of the ozone. The stronger winds are caused by a world warming faster than a cooling Antarctica. Stronger westerlies push more subsurface warm waters poleward to melt the glaciers, and push surface waters northward.

Nerilie Abram and others have just confirmed that the westerlies are stronger now than at any other time in the past 1,000 years and their strengthening has been particularly prominent since the 1970s as a result of human-induced climate warming. Model predictions also show that the trend will continue in a warming climate.

What this means is that we may be ultimately responsible for triggering the fast retreat of West Antarctica. This part of the continent was likely to retreat anyway, but we probably pushed it there faster. It remains difficult to put a timescale on it, because the computer models are not good enough yet, but it could be within a couple of centuries, as I noted. There is also a bigger picture than West Antarctica. The Amundsen sea sector is not the only vulnerable part of the continent. East Antarctica includes marine-based sectors that hold more ice. One of them, Totten glacier, holds the equivalent of seven metres of global sea level.

Controlling climate warming may ultimately make a difference not only about how fast West Antarctic ice will melt to sea, but also whether other parts of Antarctica will take their turn. Several “candidates” are lined up, and we seem to have figured a way to push them out of equilibrium even before warming of air temperature is strong enough to melt snow and ice at the surface.

Unabated climate warming of several degrees over the next century is likely to speed up the collapse of West Antarctica, but it could also trigger irreversible retreat of marine-based sectors of East Antarctica. Whether we should do something about it is simply a matter of common sense. And the time to act is now; Antarctica is not waiting for us.