Climate Central News

A feed from Climate Central, an independent organization of leading scientists and journalists researching and reporting the facts about our changing climate and its impact on the public.


 

19 July 2017. The Larsen C Iceberg Is Already Cracking Up

The trillion-ton iceberg that broke off Antarctica last week will not go quietly into the night.

New satellite imagery reveals that the iceberg, dubbed A68, is already shifting shape along with the remaining Larsen C ice shelf itself.

The iceberg has traveled about 1.5 miles from the ice shelf it was formerly attached to. A piece of ice the size of Delaware moving across the choppy waters of the Weddell Sea was bound to experience an almost unbearable amount of stress. And on Tuesday, the European Space Agency showed the iceberg has begun to crack up.


The Sentinel-1 satellite captured iceberg A68 breaking up as it moves away from the Larsen C ice shelf.
Credit: ESA/Copernicus

Satellite images from ESA and the European Union’s Copernicus Program show that the massive iceberg is splintering and a constellation of smaller icebergs are surrounding it. The vagaries of ocean currents and buoyancy of ice will dictate how long the pack of ‘bergs travels together. It’s possible the smaller chunks could be the first drift north toward warmer waters in the South Atlantic where they would meet their likely demise.

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What remains of Larsen C is also reacting to the powerful forces of ice and water. The floating ice shelf is the smallest it has been in recorded history, and it’s searching for a new equilibrium.

Scientists with Project MIDAS who doggedly documented the rift published new information on the remaining ice shelf on Wednesday. In it, they note that there are a number of potential follow-up icebergs clinging to the remaining ice shelf. Those icebergs will be nowhere near the size of A68, but losing them could still have grave consequences for the ice shelf.

“A new rift appears to be extending northwards and may result in further ice shelf area loss,” the scientists wrote on their blog. “Although this new rift will probably soon turn towards the shelf edge, there may be a risk that it will continue on to Bawden ice rise, a crucial point of stabilization for Larsen C Ice Shelf.”

Scientists are monitoring new rifts that formed on the Larsen C ice shelf in the wake a major calving event last week.
Credit: Project MIDAS

The rise is where the ice shelf climbs over an island. The Bawden ice rise along with the Gipps ice rise, a rise on the southern end of where A68 used to be attached, are both crucial points that help anchor the ice shelf.

Researchers will be monitoring changes to those rises as well as across the ice shelf to unravel what the future holds. While most scientists have said the rift that led to iceberg A68 is due to natural causes, the fate of the remaining Larsen C ice shelf — and other ice shelves that ring Antarctica — is intertwined with climate change. Rising temperatures could melt them and send land ice tumbling into the sea faster, raising sea levels around the world.

“They are lying at sea level, in the warmest part of the continent, they are sitting on salty water that melts them from below,” Eric Rignot, an ice researcher at the University of California, Irvine, said in an email earlier this month. “Warm water is the main driver (of melt) now. If warmer air is sufficient to melt the surface, then the ice shelf will break up and sea level rise from Antarctica will enormous.”

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19 July 2017. Rising Seas Spark Tobacco-Style Lawsuits in California

Several flood-prone municipalities in California filed first-of-their-kind lawsuits against fossil fuel companies this week as they attempt to recoup the cost of coping with rising seas.

The suits point to indisputable climate science and decades of industry efforts to mar that science. Experts likened the legal complaints to those brought against the tobacco industry in decades past, which succeeded by alleging the use of anti-science tactics to mask the dangers of their products.

High tide flooding in the city of Sausalito in California's Marin County, which is suing energy companies over rising seas.
Credit: secretivemarshbird/Flickr

The new lawsuits come as 21 young Americans pursue a federal case in Oregon that alleges the U.S. government is violating their rights by failing to take far-reaching measures against global warming. A similar case previously failed in a different federal court.

“This is the next stage in climate change liability litigation,” said Tracy Hester, an environmental law lecturer at the University of Houston. “The first set of cases were all posted in federal court, and as a result they were pretty constrained.”

The sea level rise lawsuits were filed in state superior courts by the oceanfront city of Imperial Beach in southern California and by Marin and San Mateo counties in northern California. Those counties face severe impacts from rising seas on dual fronts: increased erosion and flooding risks at the Pacific Ocean and flooding along the shores of San Francisco Bay.

“It’s time to hold the fossil fuel producers accountable,” said David Pine, a local elected official in San Mateo. “San Mateo County has already incurred considerable expenses in planning for and adapting to the impacts of sea level rise, so we seek damages from the companies to help us pay.”

Although the municipalities face “significant hurdles” in the cases, they have a better chance of success now than would have been the case before decades of industry obfuscation of climate science had been laid bare in the pages of InsideClimate News and elsewhere, said Michael Burger, executive director of Columbia University’s Sabin Center for Climate Change Law.

“The entire framing of the lawsuit is much closer to the tobacco litigation than anything we’ve seen before,” Burger said. “It makes use of all of the information that’s been coming to light over the last several years about the extent of industry research into climate change, and the vast network of think tanks and lobbyists that were deployed to create smokescreens.”

The lawsuit names Chevron, Phillips 66, Arch Coal and dozens of other energy companies as defendants, stating they’re collectively responsible for a fifth of global greenhouse gas pollution released since the mid-1960s. ExxonMobil and Royal Dutch Shell are also being targeted in federal court by the nonprofit Conservation Law Foundation, which alleges rising sea levels have worsened water pollution from some of the energy companies’ facilities in New England.

The companies “have known for decades” that climate change from their products “could be catastrophic and that only a narrow window existed to take action before the consequences would not be reversible,” the California lawsuits state. “They have nevertheless engaged in a coordinated, multi-front effort to conceal and deny their own knowledge of those threats.”

Pollution from fossil fuels produced by the companies has “substantially contributed” to “dire effects” including rising temperatures, more extreme weather and rising sea levels, the lawsuits state — with county residents and taxpayers forced to “suffer the consequences.”

Seas rose worldwide more than five inches last century. The effects of rising temperatures caused by fossil fuel pollution and deforestation are causing seas to rise 50 percent faster now than 20 years ago, leading to frequent flooding around the U.S. and the world.

Natural cycles have temporarily limited sea level rise along the West Coast in recent decades but cities, residents and infrastructure are already being affected. Local officials warn 5,000 acres of land in Marin County, including 1,300 parcels of property and 700 buildings, could be vulnerable to floodwaters in the coming decades.

“I’m all about public education — how do we get our residents engaged on this issue, and then how do we adapt to climate change?” said Kathrin Sears, a local elected official in Marin who works on regional efforts to cope with rising seas through marsh restorations and other efforts.

“How do we move forward? How do we hold accountable companies who are really significantly responsible for these sea-level rise impacts?” Sears said. “This lawsuit against the fossil fuel industry was really just a logical next step.”

The energy companies haven’t commented publicly on the new lawsuits, though they have previously denied being deceptive about climate science. Western States Petroleum Association attorney Oyango Snell said in a brief statement that the group is “aware of the lawsuit and monitoring the situation” but, “as a matter of policy, we don’t comment on active litigation.”

18 July 2017. At Midway Point, 2017 Is 2nd-Hottest Year on Record

At the halfway point of the year, 2017 remains the second-hottest year to date — a surprise given the demise of the El Niño that helped boost temperatures to record levels last year.

The continued near-record warmth is a marker of just how much global temperatures have risen thanks to the greenhouse gases accumulating in the atmosphere from fossil fuel use.

How monthly temperatures differ from the 1951-1980 average. So far, 2017 ranks behind only 2016 for the temperature for the first six months of the year.
Click image to enlarge. Credit: NASA

“Personally, I wasn't expecting it to be as warm as it has been,” Ahira Sanchez-Lugo, a National Oceanic and Atmospheric Administration climate scientist, said in an email. “After the decline of the strong El Niño I was expecting the values to drop a bit and rank among the top five warmest years. This year has been extremely remarkable.”

The odds are good that 2017 will stay in second place through the end of the year, and it is even more likely that it will remain in at least the top three hottest years.

NOAA released its global temperature data for June on Tuesday, and ranked June as the third warmest in its records. The four-warmest Junes in its records have all happened in the past four years. (NASA, which released its June numbers on Friday, ranked June as the fourth hottest. The two agencies handle the data slightly differently, which can lead to small differences in their rankings, though they strongly agree on recent warming.)

The hotspots around the world for June included central Asia and western and central Europe. A searing heat wave in western Europe that helped fuel deadly wildfires in Portugal was made up to 10 times more likely because of Earth’s rising temperature, according to a recent study done in partnership with Climate Central.

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The U.S. Southwest was another stand-out, with a heat wave that pushed temperatures so high they prevented some airplanes from taking off at Phoenix’s airport.

Every month of the year so far, including June, has ranked in the top three hottest for that month. Overall, the first six months of the year were 1.64°F (0.91°C) above the 20th century average of 56.3°F (13.5°C), according to NOAA. They were 0.29°F (0.16°C) behind the same period in 2016, which turned out to be hottest year on record, but ahead of 2015 by 0.09°F (0.05°C).

According to NASA, the first six months were 1.64°F above the 1951-1980 average.

The Paris Climate agreement, which President Trump has pledged to pull the U.S. out of, set a goal of limiting warming to under 2°C (3.6°F) above pre-industrial levels by the end of this century (and to aim for an even more ambitious 1.5°C (2.7°F)). To make the global temperatures more relevant to that measure, Climate Central re-analyzed the numbers by averaging together NASA and NOAA’s data and comparing them to the average for 1881-1910. June 2017 was 1.81°F (1.01°C) above that average, showing how little wiggle room is left to keep temperatures under that level.

While there were several spots that have seen record-warm years so far — including Mexico, parts of eastern Russia and China and western Europe — the heat is fairly broadly spread around the globe.

How temperatures around the world differed from the 20th century average over the first six months of 2017.
Click image to enlarge. Credit: NOAA

Five of the six continents had a top 10 warmest January-June, with South America hitting the No. 2 spot for that period (tying with 2010 and behind only 2015, according to NOAA.

Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, said that there was a 57 percent chance that 2017 would remain the second-hottest year on record through December, and even higher odds that it will end up in the top three. Sanchez-Lugo said that if the rest of the months of the year rank in the top two, 2017 will clinch the No. 2 spot; if they rank in the top three, it will fall to No. 3.

Wherever its final rank ends up, 2017 will almost certainly be hot enough to knock 1998 — the only remaining 20th century year among the top 10 warmest — down another spot, to No. 9 in NOAA’s rankings.

At the time, 1998’s heat was exceptional, and was fueled in part by a major El Niño, which tends to raise global temperatures. But as Earth’s temperature has steadily risen because of heat-trapping greenhouse gases, an El Niño isn’t necessary to reach those heights anymore.

In fact, years with La Niñas (which tend to cool global temperatures) are today warmer than El Niño years several decades ago. 2017 actually started out with a La Niña, albeit a weak one, but it is 0.38°F (0.21°C) ahead of 1998, Sanchez-Lugo, said.

If the streak of very warm years continues, “I wouldn't be surprised if the next two to three years we would see '98 drop out of the top 10 warmest years on record,” she said.

15 July 2017. Countries With Coral Reefs Must Do More on Climate

By Michael Slezak, The Guardian

Countries with responsibility over world heritage-listed coral reefs should adopt ambitious climate change targets, aiming to cut greenhouse gas emissions to levels that would keep global temperature increases to just 1.5°C, the UN agency responsible for overseeing world heritage sites has said.

At a meeting of Unesco’s world heritage committee in Kraków, Poland, a decision was adopted that clarified and strengthened the responsibility of countries that have custodianship over world-heritage listed coral reefs.

The Belize Barrier Reef, a UNESCO World Heritage Site.
Credit: f.ermert/flickr

Until now, most countries have interpreted their responsibility over such reefs as implying they need to protect them from local threats such as water pollution and overfishing.

But between 2014 and 2017, reefs in every major reef region bleached, with much of the coral dying, in the worst global bleaching event in recorded history. Over those three years, 21 of the 29 listed sites suffered severe or repeated heat stress.

Last month Unesco published the first global assessment of climate change’s impacts on world heritage-listed reefs and it concluded that local efforts were “no longer sufficient” – concluding the only hope was to keep global temperature increases below 1.5°C.

The new decision builds on that assessment, clarifying the responsibility of countries with custodianship over world-heritage listed coral reefs.

The decision adopted by the world heritage committee said it “reiterates the importance of state parties undertaking the most ambitious implementation of the Paris agreement”, which it noted meant pursuing efforts to limit global average temperature increase to 1.5°C above pre-industrial levels.

It went on that it “strongly invites all state parties … to undertake actions to address climate change under the Paris agreement that are fully consistent with their obligations within the world heritage convention to protect the [outstanding universal values] of all world heritage properties”.

The decision appeared to implement the earlier finding that local efforts were insufficient to protect reefs, and indicated the committee considered that countries were obliged under the world heritage convention to undertake strong action on climate change.

The decision put most countries’ emissions targets in stark contrast with what was needed to protect their reefs. Combined, all countries’ commitments made so far are projected to allow warming of as much as 2.7°C by 2100.

But some countries with coral reefs are not contributing their fair share to even that level of ambition.

Australia, which has responsibility over the world’s largest coral reef system — the Great Barrier Reef — has climate change targets consistent with between 3°C and 4°C of warming by 2100, according to Climate Action Tracker.

The Great Barrier Reef, a UNESCO World Heritage Site.
Credit: FarbenfroheWunderwelt/flickr

Moreover, Australia doesn’t have any policies in place that will help it achieve those targets, with official government projections showing emissions are not expected to be cut at all, and instead will rise for at least decades to come.

The first indication that Unesco would consider action on climate change an obligation of custodians of world-heritage listed coral reefs came in June when it assessed Australia’s progress in protecting the Great Barrier Reef, following back-to-back mass bleaching in 2016 and 2017 that killed as much as half its coral.

Despite acknowledging Australia’s progress in addressing water quality on the reef, and deciding not to put the reef on its “in-danger” list, Unesco noted that climate change was the most serious threat to it, and said there was the need to consider how bleaching was affecting the effectiveness of the country’s plan to protect it.

“Last week the Australian government bragged that the Great Barrier Reef was not put on the in-danger list at this meeting,” said Imogen Zethoven from the Australian Marine Conservation Society, who was at the world heritage committee meeting in Poland.

“However, this week the Australian government should be worried. It knows very well that it is still on probation with the world heritage committee. This decision means Australia needs to rapidly reduce carbon pollution and reject new coalmines – otherwise our reef is at great risk of being placed on the world heritage in-danger list in 2020.

“The Australian government must now, more than ever, rule out any new coalmines and urgently develop a climate policy that will protect our global icon. It must do its fair share of the global effort to reduce pollution.

“If it doesn’t, the world heritage committee should hold Australia to account for failing to tackle the single greatest threat to our Great Barrier Reef – and for putting all other world heritage coral reefs at risk.”

An Earthjustice attorney, Noni Austin, who also attended the world heritage committee meeting, said: “The world heritage committee’s decision has confirmed what scientists have been saying for years: urgent and rapid action to reduce global warming and implement the Paris agreement is essential for the survival of coral reefs into the future.”

Reprinted from The Guardian with permission.

14 July 2017. Today’s Extreme Heat May Become Norm Within a Decade

When 2015 blew the record for hottest year out of the water, it made headlines around the world. But a heat record that was so remarkable only two years ago will be just another year by 2040 at the latest, and possibly as early as 2020, regardless of whether the greenhouse gas emissions warming the planet are curtailed.

That is the conclusion of a new study that uses climate models to project when today’s climate extremes will become commonplace — or the “new normal” as they are often called in both media reports and scientific analyses.

Weather stations in the U.S. that are having a warmer than normal, colder than normal and record hot year.

Just how soon that record heat will become the norm surprised even its researchers, but the information could be useful to officials around the world trying to plan for the changes global warming will bring to their cities and countries. It will help show when notable heat waves, downpours, or other extremes may become run-of-the-mill, and would allow planners to develop the infrastructure and policies to withstand those extremes.

“At the moment, it doesn’t seem like such a big deal when we have record-hot summers or years,” study leader Sophie Lewis, a climate researcher at Australian National University, said in an email. “But this study really shows the nasty side of our current records becoming more frequent in the near future.”

While the phrase new normal has been used in different ways, it was rarely explicitly defined, so Lewis and her colleagues wanted to come up with a definition that could be used on all kinds of climate extremes.

The team used the climate models developed for the most recent report of the Intergovernmental Panel on Climate Change to see when a global temperature like that of 2015, or higher, becomes normal. When such temperatures happened at least half the time in a 20-year period, they defined that normal as having been reached in the first year of the period.

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(The average global temperature of 2015 was 0.23°F (0.13°C) warmer than the previous warmest year, 2014, according NASA. It was the second largest year-over-year jump. 2015 was subsequently beaten as the hottest year by 2016.)

The researchers found that the global climate firmly met that threshold by 2040, regardless of whether greenhouse gas emissions continued on their current path or were significantly curtailed. On average, the new normal emerged between 2020 and 2030 — much earlier than any of the scientists expected.

“I was shocked when I made the first calculations for this study, and went back and checked everything twice and then three times,” Lewis said. “When I first shared a full draft with my co-authors, I remember getting an edit back that included a swear word in the comments about these times.”

Deke Arndt, a National Oceanic and Atmospheric Administration climate scientist who wasn’t involved in the study, said this kind of disappearance of extremes into the bounds of normal was already happening. He cited the then-record high temperature of 1998, “which was astonishing at the time,” but has since been “fading into the pack” of annual temperatures. (It now sits in eighth place, according to NOAA, and is the only year in the top 10 warmest not from the 21st century.)

“We are moving into new neighborhoods in many of our climate variables. This paper is perhaps a way to help quantify some discussions around that topic,” Arndt said.

“I think it’s useful that they’re defining [the new normal],” Noah Diffenbaugh, a Stanford climate scientist who has done similar work, said.

Click image to enlarge.

The work, published in the June issue of the Bulletin of the American Meteorological Society, takes the opposite tack of the field of climate science known as attribution, which uses observations and climate models to conduct climatological autopsies of events.

Attribution is useful in gleaning the effect that global warming is already having on today’s extreme weather, but it doesn’t say anything about when those extremes stop being extremes and start becoming the new climate.

“It is useful for preparing for the risks of climate change to know that the 2013 record-hot Australia summer was five times more likely because of climate change, but it is more useful to know that within just a few decades this extreme could be mild,” Lewis said.

Lewis and her co-authors also looked at record annual temperatures at spots across the land surface, “because these are a little more relevant for actual impacts on ecosystems, health, infrastructure than global average temperatures,” Lewis said.

In that case, the particular emissions scenarios did make a difference, because different parts of the world are warming at different rates and have different patterns of natural variability, which can make the signal of warming more difficult to pick out. Today’s record heat became the new normal earlier and for a larger portion of the globe with higher greenhouse gas emissions than for lower ones. Those differences show that if emissions are significantly reduced, such records can be prevented from becoming the norm in some areas.

The method can be further drilled down to study specific extreme events, like heat waves, droughts or floods, which Lewis said the team is hoping to do.

Arndt said this is where such a method would have the most usefulness. “Where I think this approach may have real utility is to help people process and understand things at the local level,” he said. “Global temperature is an important climate marker, but it's not the design metric for your town's wastewater treatment or storm sewers.”

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13 July 2017. Greenhouse Gases Are Rapidly Changing the Atmosphere

Humanity’s grand experiment in the atmosphere continues, and a new report documents just how far it’s gone.

On Tuesday, the National Oceanic and Atmospheric Administration released its annual index of 20 key greenhouse gases. It shows that their direct influence on the climate has risen 140 percent since 1750, with 40 percent of that rise coming in just the past 26 years. That increase is almost entirely due to human activities and has caused the planet to warm 1.8°F (1°C) above pre-industrial temperatures.

Radiative forcing, relative to 1750, of all the long-lived greenhouse gases. The NOAA annual greenhouse gas index, which is indexed to 1 for the year 1990, is shown on the right axis.
Credit: NOAA

The index takes greenhouse gas measurements from about 80 ships and observatories around the world — gathered in all their parts per million and parts per billion glory — and boils them down into a simple numerical index, which defines the rise from 1700-1990 as 100 percent or simply 1. This year’s number: 1.4.

It’s a simple number that contains multitudes. For example, carbon dioxide's influence on the climate has increased 54 percent overall since 1990. The four other major greenhouse gases in the index, which include nitrous oxide, methane and two types of chlorofluorocarbons, are responsible for 42 percent of the increase with 15 minor greenhouse gases accounting for the missing 4 percent.

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Carbon dioxide has risen rapidly in the atmosphere, with 2016 marking the second-largest annual increase ever observed at the Mauna Loa Observatory, the world’s main measuring station.

This May, monthly carbon dioxide peaked at 409.65 parts per million. That’s a record high and a mark unseen in human history. If emissions continue on their current trend, the atmosphere will hit a state unseen in 50 million years.

A bright spot in the report is the decline of chlorofluorocarbons’ warming influence on the planet. The chemicals were commonly used as refrigerants until the Montreal Protocol banned them in 1989. The treaty came about because they deplete the protective ozone layer, but phasing them out has also helped reduce their warming impact on the climate.

Even with their decrease, there are still a lot of greenhouse gases swirling in the atmosphere and trapping more energy on the planet’s surface. Michael Mann, a Penn State climate researcher, said the change in the amount of energy being trapped by all the extra greenhouse gases is roughly the equivalent of adding a Christmas tree light to every square yard around the world since 1982.

“(It) might seem small but it's not. That alone is enough to raise Earth’s temperature by roughly 1.5°F,” he said in an email.

Changes in carbon dioxide equivalent and the NOAA annual greenhouse gas index since 1750.
Credit: NOAA

Aerosols — light reflecting particles — and the slow nature of the earth’s climate to reach equilibrium are the main reason the planet hasn’t warmed that much since 1982, the first year in Mann’s calculation.

Carbon emissions have held steady the past three years after rising nearly every year since the Industrial Revolution. That plateau still means humans are putting tons upon tons of carbon dioxide and other greenhouse gases in the atmosphere, further altering it.

The world only has a finite amount of greenhouse gases it can safely put in the atmosphere. Researchers recently warned that emissions need to begin declining in the next three years in order to have a chance of limiting global warming to within 3.6°F (2°C) of pre-industrial temperatures.

The 1.8°F (1°C) of warming fueled by greenhouse gas pollution has already caused seas to rise nearly a foot, Arctic sea ice to vanish at a quickening pace and made some extreme weather more likely and extreme.

Low-lying small island states and coral ecosystems could vanish if warming hits 2.3°F (1.5°C). Passing the 3.6°F (2°C) threshold would put humanity outside the “safe” range of warming outlined by policymakers and scientists.

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13 July 2017. Rising Temps Could Bring Flight Delays Worldwide

Imagine boarding a summertime flight at LaGuardia Airport in New York City, only to be told that the airline needs a dozen or so passengers to take a later flight because it’s too hot outside for the plane to take off fully loaded.

That could become a common scenario at 19 major airports worldwide as extreme heat caused by global warming disrupts an increasing number of flights departing during the hottest times of day, according to a new Columbia University study.

If human greenhouse gas emissions are not reduced, global average temperatures are expected to rise by more than 4°C (7.2°F) by 2100. But high temperatures at the world’s busiest airports could rise even more — by up to 8°C (14.4°F), leading to more days each year that are hotter than average, especially at airports in the tropics, according to the study, published Thursday in the journal Climatic Change.

A Boeing 787, an aircraft that may be vulnerable to rising temperatures.
Credit: RS Deakin/flickr

By 2065, LaGuardia Airport could see about 25 days each year that will be hotter than today’s average yearly high temperature, up from fewer than 10 days in 2025.

Extreme heat disrupted flights in Phoenix in June when American Airlines cancelled 50 flights aboard small commuter jets as temperatures soared above 120°F. Such summertime temperatures are likely to become more frequent as the climate changes. Air is less dense in extreme heat, preventing an airplane's wings from generating enough lift to take off unless the plane sheds weight.

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“Higher temperatures are going to mean more people having to be removed from flights, more delays on the ground,” said study co-author Radley Horton, a climate scientist at Columbia University.

The amount of weight and number of passengers a flight would have to shed depend on the type of aircraft and the airport’s altitude and runway length. LaGuardia could be affected by the heat more than New York’s Kennedy International Airport because its runways are nearly half the length of Kennedy’s longest runway.

Between 10 and 30 percent of annual flights departing at the hottest hours of the day from 19 major airports will have to fly with weight restrictions, the study says. On average, flights will have to cut their weight by up to 4 percent in order to take off on the hottest days after 2050.

An Airbus A320, one of the most common airliners flown worldwide.
Credit: Caribb/flickr

Some larger planes, especially those that fly long-haul international flights to mid-sized or small airports, could be affected more than smaller planes because they weigh more. However, the largest plane flying today, the double-decker Airbus A380, may not be affected as much by the heat because it can only fly to airports with the longest runways.

The study suggests that one way airlines could avoid heat-related flight disruptions is to schedule flights at night or in the morning when the air is cooler. But airplanes and airports may need to be designed differently in the future in order to deal with the heat as the globe warms.

“As it gets warmer, air expands,” said Lou McNally, an assistant professor of applied aviation sciences at Embry-Riddle Aeronautical University in Daytona Beach, Fla., who is unaffiliated with the study. “That means you need more of everything in order to get enough air molecules onto the wing and fly. It means more thrust — bigger or more engines — and more runway length for takeoff, or larger wings, or all of the above. And also more runway length and better braking because of higher landing speeds at the other end.”

McNally said that airlines could also adapt by moving major hubs to regions with a cooler climate. Many regional jets based at regional hubs cannot fly at temperatures above 120°F.

Patrick Smith, an airline pilot and aviation writer, said even some of the newest airplanes flying today are not designed to account for extreme heat. New airplanes take nearly a decade to develop, and it will take more than simple design tweaks to existing airplanes for the aviation industry to overcome the challenges extreme heat poses, he said.

“This is something that nobody’s really taken seriously,” Smith said. “Planes really aren’t yet being designed with this in mind. And for that to happen, because it takes so long to develop and build a new commercial airplane, this is something that’s pretty far out.”

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13 July 2017. Arctic Heat Is Becoming More Common and Persistent

The Arctic is a bastion of cold, blustery weather. But in the latest sign of how quickly changes are happening, new research published this week shows that the Arctic has seen more frequent bouts of warm air and longer stretches of mild weather.

The new findings show that while warm snaps have occurred even as far as back as the 1890s, a massive shift is afoot in the region, which is warming twice as fast as the rest of the world.

The average and maximum winter temperatures (left and center) as well as the probability of minus-10°C (14°F).
Credit: Graham et al., 2017

The North Pole region has been ground zero for these changes. Since 1979, the number of warm events has doubled and the number of days with mild air has tripled. There are now 21 days of mild weather at the North Pole in an average winter compared to just seven mild winter days at the start of record keeping.

An international team of scientists used data from buoys, land and a ship mired in winter ice in 2015 — as well as historical records from a 19th century expedition — as the basis for the new study, published Tuesday in Geophysical Research Letters.

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They defined a “warm” event as any time when the temperature rose above 14°F (minus-10°C). That’s chilly by winter standards for most regions of the globe, but is significantly warmer than the minus-22°F (minus-30°C) temperatures that are the norm for the Arctic in winter. They also looked at other extremes up to 32°F (0°C).

“In recent years, the frequency of these events and their duration have increased, together with the peak temperature recorded during these events,” said Robert Graham, a researcher at the Norwegian Polar Institute who led the study.

Graham and his colleagues also looked at the Pacific side of the region and found an uptick in warm winter days and events, albeit at a lower magnitude than the North Pole.

Julienne Stroeve, a sea ice expert at the National Snow and Ice Data Center, said the change is an important one to note and could help further research on changes in winter ice pack.

An ice floe slides down the starboard side of the Coast Guard Cutter Healy.
Credit: Patrick Kelley, U.S. Coast Guard

The North Pole sits on the Atlantic side of the Arctic, an area that has seen more storms come swirling up from the Atlantic, dragging warmer air along with them. Graham said that was one reason for the larger increase in the length and duration of mild winter days there. Warm water is also pushing deeper into the Arctic Ocean from the Atlantic, further changing the region.

Background temperatures have also been rising faster there. The North Pole region has warmed 2.3°F (1.3°C) per decade since 1979, a trend largely driven by climate change. Though the new study doesn’t tease out whether the increase in warm days is due directly to climate change, it’s part of a huge pile of evidence of how rising carbon pollution is altering the Arctic faster than the rest of the world.

“While surface temperature data from the Arctic are less reliable than elsewhere, the authors tap into a variety of different measurements that all tell the same story,” Jennifer Francis, an atmospheric scientist at Rutgers University, said. “The trends go hand-in-hand with dwindling sea ice and thawing permafrost.”

Winter sea ice has hit a record low three years in a row and the summer minimum has been declining by more than 13 percent per decade since the late 1970s. That’s a sign of how warm the Arctic is becoming, creating a feedback loop that ensures ever more warming because dark, open water absorbs more heat than white sea ice.

Francis said it’s still an open question of whether climate change is making the Arctic stormier, but she noted that “as the globe warms, the atmosphere gains more water vapor, so when one of these storms does enter the Arctic, it has more moisture to draw from.”

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12 July 2017. These Images Show Just How Big the Larsen C Iceberg Is

The Larsen C ice shelf has calved an iceberg after months of waiting and watching.

With an area the size of Delaware and a volume of 277 cubic miles, its measurements boggle the mind. Even written comparisons don’t fully convey the hulking hunk of ice currently adrift in the Weddell Sea. After all, can you really imagine 463 million Olympic-sized pools, let alone all those pools filled with ice?

To help create a more helpful visual frame of reference, Climate Central has created a series of images showing the ice next to familiar places. There are a few things to consider as you view these.

First, this is an idealized ice ball. The real iceberg is obviously not uniform and its shape will change as it drifts and melts.

Second, while some of the images show it near coastal locations like New York, that doesn’t mean it will inundate these areas as it melts. It broke off from a floating ice shelf, making its contribution to sea level rise minimal. Gavin Schmidt, a climate scientist at NASA, calculated that it would lead to 0.1 millimeters of sea level rise as it melts.

With those considerations in mind, see what the Larsen C iceberg, technically dubbed iceberg A68, looks like in settings you may be more familiar with than the Weddell Sea.

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12 July 2017. The Larsen C Iceberg Finally Broke Away. Now There’s a Trillion-Ton Iceberg Adrift

The inevitable moment of reckoning for the Larsen C ice shelf arrived. The growing rift that carved across one of the Antarctica Peninsula’s largest ice shelves reached its end, sending a 2,240-square mile iceberg spiraling into the sea. Welcome to the world, iceberg A68.

The massive slab of ice, equivalent to the size of Delaware and large enough to cover the U.S. in 4.6 inches of ice, will slowly melt over the coming years as it drifts away from Antarctica.

Satellites show when the Larsen C crack finally broke through.
Credit: Stef Lhermitte

The health of the remaining ice shelf will serve as a bellwether for how climate change could interact with natural processes to reshape Antarctica’s vast stores of ice. The growing instability of the continent’s ice has major implications for coastal communities around the world as it melts and pushes sea levels higher.

“The Peninsula as a whole is losing mass, it has been doing that for many, many decades, but more so now than 30-40 years ago,” Eric Rignot, an Antarctic researcher at the NASA Jet Propulsion Laboratory, said.

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The Larsen C crack had been growing since 2010 largely due to natural causes, according to most researchers. When it finally broke through sometime between Monday and Wednesday, it reduced the Larsen C ice shelf to its smallest size on record. The ice shelf was the fourth-largest ice shelf in the world, but following the calving event that cleaved off more than 12 percent of its area, it has been knocked down to fifth in the rankings.

Adrian Luckman, a scientist who has been watching the iceberg for years with Project MIDAS, said it would take months or years to document the health of the remaining ice shelf.

Though it has lost 2,240-square miles, Larsen C still spans roughly 15,000 square miles. That could make it more resilient than the neighboring Larsen B ice shelf that collapsed due a warm spell following a major calving event in 2002, but it’s not a guarantee.  

Bethan Davies, a glacier researcher at Royal Holloway, University of London, said one of the first things that researchers will look at is the “stress regime” that losing so much ice puts on the rest of the ice shelf. It’s akin to standing up against a teetering pile of books. If you shift your weight or put less effort to propping up the pile, it might start to wobble differently, a few books might fall off or the whole thing could topple over.

Scientist got am aerial view of the Larsen C rift in February.
Credit: Project MIDAS

Scientists will also be looking to see if other rifts open on the ice shelf. If that happens, it could mean more big calving events, putting further stress on the remaining ice. They’ll also be looking at the surface of the ice sheet for melt ponds, a process that’s already weakening ice shelves in other other parts of Antarctica.

“The critical time will be during the next warm austral summer,” Davies said. “If the ice shelf is destabilized by the removal of this large frontal portion, meltwater ponding on the ice surface may contribute to increased calving.”

Though most researchers agree that the rift itself was mostly due to natural causes, climate change will have a major role to play in defining a new era for the ice shelf and Antarctica as a whole. The disappearance of floating ice shelves will mean that land ice can spill into the sea faster.

“Climate change is a long-term trend. The peninsula has been warming for decades,” Rignot said. “Warm water is the main driver now (in Antarctica as a whole). If warmer air is sufficient to melt the surface, then the ice shelves will break up and sea level rise from Antarctica will be enormous.”

Rignot has previously led research showing that West Antarctica is on the brink of an unstoppable melt that could push seas up to 13 feet higher over a period of centuries. Other recent research has shown that even stable parts of East Antarctica, which tends to be colder, have experienced surface melt events and bizarre lakes forming inside ice shelves.

Coupled with a slew of other findings ranging from spectacularly ominous waterfalls to widespread melt ponds, it’s clear the Antarctic landscape is rapidly shifting due the ravages of climate change above and below the ice.

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11 July 2017. This Map Shows Warming’s Fingerprints on Weather

The field of climate science that looks for the fingerprints of climate change on extreme weather events has been growing rapidly in recent years, making it hard to keep track of the dozens of studies that have been done.

A new interactive map put together by Carbon Brief, a UK-based data journalism site, makes that task easier. It rounds up the results of those attribution studies, as they are called, and color-codes them according to whether or not they found a discernable influence from human-induced warming. Nearly two-thirds of the 137 studies did find such an influence, in particular those looking at heat waves.

One of the authors of the analysis, Roz Pidcock, has written about many of the individual studies but said she was unaware of any place where they were gathered together. She thought such a map would be useful for keeping track of a fast-developing field that is aiming to broaden its scope.

“The temptation is to look at the result of one study and think that is the definitive last word, but in reality, the evidence needs to be considered in its entirety to make sense of how climate change is influencing extreme weather,” she said. “This technique avoids being selective and gives that necessary overview.”

Pidcock consulted with climate scientists who work in attribution, including Friederike Otto, a climate scientist at the University of Oxford in England who works with a Climate Central-affiliated attribution program. “I think this is a very useful resource, in particular for the scientific community,” Otto said.

Attribution analyses look at whether or not the greenhouse gas-driven warming of the planet has changed either the likelihood or severity (or both) of an event like a heat wave or a drought by using weather observations and climate models. Observations can be used to see how the odds of such an event have changed over time, while climate models can compare how they change in a climate with and without warming.

Carbon Brief found 137 peer-reviewed studies that examined 143 individual weather events, ranging from the record setting rains that fell in Louisiana last summer to the deadly 2003 European heat wave.

Warming increased the frequency or severity of an event in 63 percent of the studies, according to Carbon Brief’s analysis. Nearly half of those were heat waves, which have a clear, direct link to overall warming temperatures.

A tourist uses an umbrella to cover from the sun and a fan to cool herself off as she walks in Alameda del Tajo park during a heat wave in Ronda, Spain on June 21, 2017.
Click image to enlarge. Credit: REUTERS/Jon Nazca

A recent analysis done as part of Climate Central’s rapid assessment program found that global warming made the recent heat wave in Europe that helped fuel deadly wildfires both more likely and more severe. That study, which Otto collaborated on, wasn’t included in the map as it hasn’t yet been published in a peer-reviewed journal, though the methods used have been.

Some studies found no clear influence from human-caused warming or were inconclusive, which could simply mean any climate change signal has yet to emerge from the noise of the natural year-to-year variations in the Earth’s climate.

Acknowledging when this is the case is important, Otto said, because “many people think all extreme events are getting more extreme and often blame events on climate change.” That can draw attention away from addressing other factors that exacerbate the impacts of extreme weather, like the way cities and towns are built.

Both Otto and Adam Sobel, a climate scientist at Columbia University who led a National Academies report on attribution, emphasized that the studies in the map don’t tell the whole story of how climate change is impacting extreme weather because they are not a random selection of events. They are often picked because they happen in researchers’ backyards or were particularly impactful.

“I think we cannot say often and loud enough that these studies are by no means representative of the impacts of human-induced climate change on extreme weather events in recent years, as they are only a very small and highly selective subset of all the events happening,” Otto said.

Attribution researchers are working to remedy this by expanding the types of events they are examining, as well as delving into relatively little studied areas, like South America and Africa. As new studies roll in, Carbon Brief plans to update its map.

10 July 2017. The West Is on Fire As Heat Records Fall

From Phoenix to Boise, high temperature records fell like dominoes over the weekend as an impressive heat wave engulfed the western U.S., helping to fuel several wildfires.

While heat waves are a regular part of summer weather, the steady warming of the planet means those heat waves are getting ever hotter, making record heat more and more likely.

The heat came courtesy of a ridge of high pressure that moved in over the West, with the peak temperatures, including several records, occurring on Friday and Saturday:

  • Las Vegas hit 116°F on Friday, besting the record set in 1989 of 114°F. The city had a record-long streak of 23 days with highs above 105°F.
  • On Saturday, Reno, Nev., bested its old record of 99°F with a temperature of 104°F.
  • Los Angeles broke a record that had stood for 131 years, with the temperature downtown hitting 98°F (the old record was 95°F).
  • Temperatures in Phoenix soared to 118°F on Friday, besting the old record of 115°F set in 1905, and marking the third day of 2017 where temperatures were at or above that level, the second most on record.
  • In Salt Lake City, the temperature reached a record 104°F on Saturday. The city had three record highs in just four days last week.
  • The Boise airport also saw 104°F on Saturday, besting the record of 103°F set in 1968.

Daytime highs weren’t the only concern, as overnight lows stayed downright hot in some places, particularly in the Phoenix area. The temperature from Friday night to Saturday morning only reached as low as 95°F in Scottsdale, a record. (It was still 106°F at 1 a.m. that night.)

Overnight lows on Saturday morning in the Phoenix area stayed in the 90s.
Click image to enlarge. Credit: NOAA

The heat and accompanying dry conditions can also set the stage for wildfires, as was the case during this heat wave, which saw several wildfires ignited and grow across the region.

The Whittier fire, which started on Saturday in the Santa Ynez Mountains in Southern California, has burned more than 10,000 acres, while the nearby Alamo fire has burned nearly 29,000 acres and forced several thousand people to evacuate.

The ridge of high pressure is moving eastward this week, bringing sweltering temperatures — and the threat of wildfires — to the northern and central Plains before shifting back to bake the West again at the end of the week.

At that point it could strengthen, meteorologist Guy Walton wrote on his blog, keeping the West good and toasty for the next week or two.

Extreme heat is one of the hallmarks of global warming; as the average temperature of the planet rises, record heat becomes much more likely than record cold. And cities in the Southwest — where most of the region’s population lives — are some of the fastest-warming in the country.

While no formal attribution study has been conducted to see how much more likely a heat wave like this has become with warming, a recent study found that heat records were made both more likely and more severe for about 80 percent of the area of the globe that had good enough observational data.

With temperatures continuing to rise — and no substantial effort yet to curtail the greenhouse gas emissions driving that rise — the world at large stands to see more such extreme heat in the future. Another recent study found that half of the world’s population could be exposed to heat that reaches deadly levels by the end of the century even with the most stringent reductions in greenhouse gases.

These kind of heat waves pose threats to public health, local economies and infrastructure. The increased use of air conditioning can tax the electric grid, while the heat can damage crops and curtail outdoor activities, such as construction. During a June heat wave, planes in Phoenix couldn’t take off because higher temperatures lead to thinner air, making it more difficult for planes to get off the ground.

And searing heat can be deadly to already vulnerable populations, such as the elderly, small children and those suffering from illnesses. High overnight temperatures are a particular concern when it comes to the health effects of heat waves, because they prevent the body from cooling down and recovering from the heat of the day.

Nighttime lows have risen across the Southwest since 1970, ranging from an increase of 1.7°F on average in California to 3°F in New Mexico.

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8 July 2017. Warming May Turn Africa’s Arid Sahel Green: Researchers

By Alex Whiting, Thomson Reuters Foundation

LONDON — One of Africa's driest regions — the Sahel — could turn greener if the planet warms more than 2 degrees Celsius and triggers more frequent heavy rainfall, scientists said on Wednesday.

The Sahel stretches coast to coast from Mauritania and Mali in the west to Sudan and Eritrea in the east, and skirts the southern edge of the Sahara desert. It is home to more than 100 million people.

The road to Djenne, on the Bani River in Mali. The Sahel region could turn greener if the planet warms more than 2 degrees Celsius.
Credit: Carsten ten Brink/flickr

The region has seen worsening extreme weather — including more frequent droughts — in recent years.

But if greenhouse gas emissions continue unabated, the resulting global warming — of more than 2 degrees Celsius above pre-industrial levels — could change major weather patterns in the Sahel, and in many different parts of the world, scientists say.

Some weather models predict a small increase in rainfall for the Sahel, but there is a risk that the entire weather pattern will change by the end of the century, researchers at the Potsdam Institute for Climate Impact Research (PIK) said.

"The sheer size of the possible change is mindboggling — this is one of the very few elements in the Earth system that we might witness tipping soon," said co-author Anders Levermann from PIK and the Lamont-Doherty Earth Observatory of New York's Columbia University.

If the Sahel becomes much rainier, it will mean more water for agriculture, industry and domestic use. But in the first few years of the transition, people are likely to experience very erratic weather — extreme droughts followed by destructive floods, the researchers said.

This level of unpredictability makes it very hard for people to plan for coming changes, they said.

"The enormous change that we might see would clearly pose a huge adaptation challenge to the Sahel," said Levermann.

"More than 100 million people are potentially affected that already now are confronted with a (multitude) of instabilities, including war," he said.

The region faces a range of conflicts, including some driven by groups such as Boko Haram and al Qaeda in the Islamic Maghreb.

The researchers studied rainfall patterns in the months of July, August and September when the region receives most of its annual rain.

"There's a range of possible outcomes for societies in the Sahel which depend on the climate that eventually (develops)... and whether they are prepared for fluctuations," lead author Jacob Schewe, from PIK, told the Thomson Reuters Foundation.

Climate change from burning fossil fuels "really has the power to shake things up", he said.

"It is driving risks for crop yields in many regions and generally increases dangerous weather extremes around the globe," he added.

The study was published on Wednesday in Earth System Dynamics, a journal of the European Geosciences Union.

(Reporting by Alex Whiting @Alexwhi, Editing by Laurie Goering)

7 July 2017. The Larsen C Iceberg Is Expected to Have Company

It’s stressful being an iceberg hanging on by a thread. If you want proof, look no further than the Larsen C ice shelf.

Just three miles stand between the crack that’s been cutting across the ice shelf since 2010 and open water. When it breaks through, it will cleave a trillion-ton iceberg. The stress of having a huge iceberg-to-be nearing its inevitable conclusion has caused that crack to crack up.

Animation of Sentinel-1 interferograms show the significant stages of the Larsen C rift, culminating in multiple branches observed in early July 2017.
Credit: Project MIDAS

New satellite imagery shows a host of new cracks branching off the end of the main rift. According to scientists working on Project MIDAS, an effort that’s closely monitoring the ice shelf, that means there will likely be a swarm of smaller icebergs that break off with or shortly after the main iceberg does.

“It is remarkable how the moment of calving is still keeping us waiting,” Project MIDAS researchers wrote on their blog.

Those icebergs will likely be formidable in their own right, but they’ll look lilliputian next to the iceberg that’s been in the process of breaking off since 2010. That iceberg represents 10 percent of the area of the Larsen C ice shelf and will stretch across an area the size of Delaware. If you squeezed all the ice into a column the area of a football field, it would reach more than halfway to the moon.

After losing icebergs large and small, Larsen C will be the smallest it has been in recorded history. The causes of the massive calving event are likely largely natural. But climate change could have a role in writing the next chapter for the ice shelf. Warm waters are likely to continue their push into the region, eating away at Larsen C and other ice shelves around Antarctica from below.

Editor's Note: This story has been updated to reflect that the ice would reach more than halfway to the moon (56 percent to be exact) if squished into the area of a football field, not two-thirds of the way.

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6 July 2017. The Arctic Has Been Crazy Warm All Year. This Is What It Means for Sea Ice

Melt season has begun in earnest in the Arctic. Scientists will spend the next few months watching sea ice turn into open water until the ice pack hits its nadir in early fall.

The vagaries of the weather and ocean currents will play a major role in determining where this year’s Arctic sea ice minimum ranks. But the steady drumbeat of climate change ensures that it will likely be among the lowest on record.

Total Arctic sea ice thickness and its departure from normal for June.
Credit: Zack Labe

New data from the National Snow and Ice Data Center show that sea ice extent was at its sixth-lowest mark for June. Sea ice was missing from 348,000 square miles of the Arctic Ocean, an area about three times the size of Arizona.

After the string of record- or near-record low months late last year and early this year, the sixth-lowest extent might sound like an improvement. It’s not. As of July 2, sea ice extent was on par with 2012, a year that went on to set the mark for lowest Arctic sea ice minimum on record. That year, a major storm in August helped churn the ocean and smash ice to smithereens.

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There are signs this year’s ice would struggle to sustain itself if a similar scenario plays out. This winter saw a string of warm weather like no other in the Arctic. The number of freezing-degree days, a measure of how cold it’s been, are well below 2012. Fewer freezing-degree days translates to higher temperatures that cut into ice pack.

And while ice extent isn’t record low right now, ice volume is at a record-low level, according to data gathered by the University of Washington’s PIOMAS program. Thinner ice is largely driven by rising temperatures.

Departures from average in cumulative freezing degree days, from July 1 for a given year through July 1 of the next year.
Credit: NSIDC

“The lack of winter cold is consistent with the low spring ice thickness seen in PIOMAS,” Mark Serreze, the director of NSIDC, said in an email. “But the winter warmth is also a result of low ice extent in winter. In areas of open water in winter, there are large heat fluxes from the ocean to the atmosphere, warming the atmosphere. Hence, it’s a two-way street.”

The brittle ice covering the Arctic now is part of a long-term trend. Warming air and water have eaten away at older, more solid ice. That has in turn been replaced by younger, thinner ice more prone to melting each year.

As newer ice spreads across the Arctic Ocean, it makes widespread melt more likely in a vicious feedback cycle that’s compounded by dark ocean water trapping more heat and melting ice even further.

Rising carbon emissions have caused this scenario to play out and the sea ice minimum has shrunk 13.7 percent per decade since record keeping began in the late 1970s. Scientists project that even if the world manages to cut carbon pollution enough to keep global warming below 3.6°F (2°C), the Arctic could still face ice-free summers in the coming decades.

While climate change has helped weaken this year’s sea ice, weather will ultimately be the big driver in determining how low it will go. Serreze said the weather patterns that usually drive widespread sea ice loss haven’t set up this year, but there are still two more months of summer. If 2012 is a reminder, things can change in a hurry.

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