Tag Archives: climate change science

Mapping the Impossible: Extreme Weather Events

The heatwave that struck parts of North America’s Pacific coast in 2021 propelled temperatures in Lytton, a village in British Columbia, to 49.6°C—4.6° higher than the previous record. On the fourth day of this torment the place erupted in flames and was almost completely destroyed. These events were so out of the ordinary that, in a press conference held some weeks later by climate modelers, they struggled to explain how circumstances had conjured them.

Climatologists reckon the North American heatwave of 2021 was one of the most extreme deviations from meteorological norms ever recorded, anywhere. But others have come close. As the world gets hotter, phenomena once considered rare are becoming common and others, believed impossible, are happening.

This shift in weather patterns has inspired modelers to pay more attention to the tails of the frequency distributions of meteorological possibility which their models generate (see chart), in search of such unprecedented extremes. One recent exercise, led by Erich Fischer at eth Zurich, a technology university in Switzerland, shows how the heatwave that destroyed Lytton could have been foreseen with data available at the time….The approach Dr Fischer used is one of several developed recently. Another, from Britain’s Met Office, is UNSEEN  (Unprecedented Simulation of Extremes with Ensembles)…Researchers in the UK are looking at another sort of extreme event—the risk of “wind droughts” which would wipe out a lot of the country’s wind-turbine-base electricity supply. It would be ironic indeed if Britain’s huge effort to combat climate change in this way were, itself, to fall victim to a changing climate.

The Paris Olympics, to be held in 2024, will take place during that city’s hottest weeks. A group of meteorologists from various French research institutes therefore wondered just how bad a heatwave manifesting itself then might be. Using yet another approach, they found a chance of temperatures being more than 4°C higher than they were during a catastrophic heatwave in 2003, in which tens of thousands died. Since that happened, France has built a “heat plan” which includes an early-warning system and provisions for opening cool spaces if needed.

Excerpts from How to predict record-shattering weather events, Economist, Feb. 11, 2023

How Forests Create Clouds and Cool the Earth

Tropical forests have a crucial role in cooling Earth’s surface by extracting carbon dioxide from the air. But only two-thirds of their cooling power comes from their ability to suck in CO2 and store it. The other one-third comes from their ability to create clouds, humidify the air and release cooling chemicals. This is a larger contribution than expected for these ‘biophysical effects’ says Bronson Griscom, a forest climate scientist.

The analysis, published in Frontiers in Forests and Global Change in March 2022, could enable scientists to improve their climate models, while helping governments to devise better conservation and climate strategies. The findings underscore growing concerns about rampant deforestation across the tropics. Scientists warn that one-third of the world’s tropical forests have been mown down in the past few centuries, and another one-third has been degraded by logging and development. This, when combined with climate change, could transform vast swathes of forest into grasslands

Trees in the tropics provide shade, but they also act as giant humidifiers by pulling water from the ground and emitting it from their leaves, which helps to cool the surrounding area in a way similar to sweating, Griscom says. “If you go into a forest, it immediately is a considerably cooler environment,” he says.

This transpiration, in turn, creates the right conditions for clouds, which like snow and ice in the Arctic, can reflect sunlight higher into the atmosphere and further cool the surroundings. Trees also release organic compounds — for example, pine-scented terpenes — that react with other chemicals in the atmosphere to sometimes create a net cooling effect… When they considered only the biophysical effects, the researchers found that the world’s forests collectively cool the surface of the planet by around 0.5 °C.

Threats to tropical rainforests are dangerous not only for the global climate, but also for communities that neighbour the forests, Lawrence says. She and her colleagues found that the cooling caused by biophysical effects was especially significant locally. Having a rainforest nearby can help to protect an area’s agriculture and cities from heatwaves, Lawrence says. “Every tenth of a degree matters in limiting extreme weather. And where you have forests, the extremes are minimized.”

Excerpts from Freda Kreier, Tropical forests have big climate benefits beyond carbon storage, Nature, 

A Breach Too Far: 413 PPM

The abundance of heat-trapping greenhouse gases in the atmosphere once again reached a new record in 2021, with the annual rate of increase above the 2011-2020 average. That trend has continued in 2021, according to the World Meteorological Organization (WMO) Greenhouse Gas Bulletin.

Concentration of carbon dioxide (CO2), the most important greenhouse gas, reached 413.2 parts per million in 2020 and is 149% of the pre-industrial level. Methane (CH4) is 262% and nitrous oxide (N2O)  is 123% of the levels in 1750 when human activities started disrupting Earth’s natural equilibrium.

Roughly half of the CO2 emitted by human activities today remains in the atmosphere. The other half is taken up by oceans and land ecosystems. The Bulletin flagged concern that the ability of land ecosystems and oceans to act as “sinks” may become less effective in future, thus reducing their ability to absorb carbon dioxide and act as a buffer against larger temperature increase…Such changes are already happening, for example, transition of the part of Amazonia from a carbon sink to a carbon source

The Bulletin shows that from 1990 to 2020, radiative forcing – the warming effect on our climate – by long-lived greenhouse gases increased by 47%, with CO2 accounting for about 80% of this increase…The amount of CO2 in the atmosphere breached the milestone of 400 parts per million in 2015. And just five years later, it exceeded 413 ppm. 

“Carbon dioxide remains in the atmosphere for centuries and in the ocean for even longer. The last time the Earth experienced a comparable concentration of CO2 was 3-5 million years ago, when the temperature was 2-3°C warmer and sea level was 10-20 meters higher than now. But there weren’t 7.8 billion people then,” said Prof. Taalas.

Excerpt from Greenhouse Gas Bulletin: Another Year Another Record, WMO, Oct. 25, 2021

The Northern Frontier: Who’s Taking Advantage of Climate Change?

Owing to climate change…the share of boreal land that can support farming could increase from 8% to 41% in Sweden. It could increase from 51% to 83% in Finland. Efforts to farm these areas will alarm people who value boreal forests for their own sake. And cutting down such forests and ploughing up the soils that lie beneath them will release carbon. But the climatic effects are not as simple as they might seem. Northern forests absorb more heat from the sun than open farmland does, because snow-covered farmland reflects light back into space…

The fact that felling boreal forests may not worsen climate change, though, says nothing about the degree to which it could affect biodiversity, ecosystem services or the lives of forest dwellers, particularly indigenous ones.

Some governments are already keen to capitalize on climate change. Russia’s has long talked of higher temperatures as a boon. President Vladimir Putin once boasted that they would enable Russians to spend less money on fur coats and grow more grain. In 2020 a “national action plan” on climate change outlined ways in which the country could “use the advantages” of it, including expanding farming. Since 2015 Russia has become the world’s largest producer of wheat, chiefly because of higher temperatures.

Russia’s government has started leasing thousands of square kilometers of land in the country’s far east to Chinese, South Korean and Japanese investors. Much of the land, which was once unproductive, is now used to grow soybeans. Most are imported by China, helping the country reduce its reliance on imports from America. Sergey Levin, Russia’s deputy minister of agriculture, has predicted that soya exports from its far-eastern farmlands may reach $600m by 2024. That would be nearly five times what they were in 2017. The government of Newfoundland and Labrador, a province on the north-eastern tip of Canada, is also trying to promote the expansion of agriculture into lands covered by forests…

All told, the northern expansion of farmland will only go some way towards mitigating the damage climate change may do to agriculture. The societies that will benefit from it are mostly already wealthy. Poor places, which rely much more heavily on income from exporting agricultural produce, will suffer.

Excerpts from Farming’s New Frontiers: Agriculture, Economist, August 28, 2021

Planting Trees Can be Bad for the Planet

Some scientists argue that deforestation is not always harmful for the planet. Christopher A. Williams, a professor at Clark University’s Graduate School of Geography (Worcester, Massachusetts), says that instead of warming up the Earth, deforestation can actually cool it down. (See Climate impacts of U.S. forest loss span net warming to net cooling, Feb. 2021) But some experts are concerned that Williams’ work is likely to be misconstrued as permission to continue deforesting, which is not his intention.

It’s widely accepted that our existing forests are vital carbon sinks, and the best course of action is to stop deforestation, while rewilding and reforesting areas already lost. Deforestation contributes to climate change, can cause wildfires, desertification, soil erosion and most of all – releases huge amounts of carbon dioxide which causes global warming.

While the above may be true, Williams’ new research argues that there are two factors we are not acknowledging: the significance of location and something known as ‘the albedo effect’. Put simply, ‘the albedo effect’ is the process in which forests retain heat. Forests tend to be darker than other surfaces, which means they absorb more sunlight and hold onto heat, explains Williams. As a result, some scientists believe that deforestation gets rid of unwanted heat which is contributing to global warming.

“We found that in some parts of the country like the Intermountain West, more forest actually leads to a hotter planet when we consider the full climate impacts from both carbon and albedo effects,” says Professor Williams. He adds that it is important to consider the albedo effect of forests alongside their well-known carbon storage when aiming to cool the planet.

The team discovered that for approximately one quarter of the US, forest loss causes a persistent net cooling because the albedo effect outweighs the carbon effect.  “It is all about putting the right trees in the right place,” explains Williams, “and studies like ours can help identify where the potential for cooling is greatest.”

For instance, loss of forests east of the Mississippi River caused planetary warming, while forest loss in the Intermountain and Rocky Mountain West led to a net cooling. “If we fail to consider both the carbon and the albedo effects, large-scale tree-planting initiatives, such as Canada’s 2Billion Trees Initiative and The Nature Conservancy’s Plant a Billion Trees campaign, could end up placing trees in locations that are counterproductive for cooling the climate system,” he says.

Maeve Campbell, DEFORESTATION COULD BE COOLING THE PLANET DOWN, Euronews, SAY SCIENTISTS, Feb. 17,2021

Greening Natural Gas: How to Record Gas Leaks with Hand-Held Cameras

Energy companies are producing record volumes of natural gas, thanks in part to the U.S. fracking boom. They have ambitious plans to make the cleaner-burning fuel a big part of the global energy mix for decades to come by sending tankers of liquefied gas around the world.But growing public concern over leaks and intentional releases of gas and its primary component, methane, threaten to derail the dominance of gas in the new energy world order.  Methane is far more potent than carbon dioxide in contributing to climate change. That makes it particularly harmful to the environment when it is discharged into the atmosphere.

In the U.S. alone, the methane that leaks or is released from oil and gas operations annually is equivalent to the greenhouse gas emissions from more than 69 million cars, according to a Wall Street Journal analysis using conversion formulas from the Environmental Protection Agency and emissions estimates for 2015 published last year in the journal Science….The Intergovernmental Panel on Climate Change, a United Nations body, says methane is even more potent than the estimates the EPA uses. By its calculation the annual releases would be equal to those of about 94 million cars, or roughly a third of the nation’s registered vehicles.

About 2.3% of the natural gas produced in the U.S. escapes directly into the atmosphere due in part to leaky equipment or intentional discharges, according to the Science study, which analyzed 2015 emissions. (Some discharges are legally permitted.) At that rate, it would have amounted to about $7.6 million worth of gas lost each day last year.  Another roughly $4.5 million in U.S. gas went up in smoke each day in 2018, World Bank data show, as energy companies burned fuel  (a practice known as flaring) they couldn’t move to market or chose not to ship because the cost of doing so would have exceeded the price the gas would fetch in some regions. Many companies drill primarily for oil and treat the gas released in the process as a byproduct.

Leaking and flaring are a global problem. As gas displaces coal for electricity production in the U.S. and other countries its side effects are drawing more attention, not just from environmental activists but investors fretting about how gas will compete over the long term against renewable energy sources such as wind and solar, which are dropping in price.

President Trump’s administration has moved to relax existing federal requirements for monitoring and fixing leaks. Still, from oil giants to the independent drillers powering the shale boom, companies are scrambling to rein in emissions over concerns from their executives, shareholders and environmentalists that gas waste could undermine the argument for gas as the “bridge fuel” to a cleaner future of renewables.

Methane is invisible to the naked eye, so companies detect leaks with infrared cameras and lasers. That can be a tall task—the gas can seep out of countless places, from wells to pipelines to storage facilities.  As a result, energy companies are increasingly supplementing manual inspections with aerial monitoring to survey large swaths of land checkerboarded with oil and gas infrastructure.  In West Texas, BP has begun monthly flights over its wells by a drone equipped with methane-detection equipment.   The company also is looking to cut back on flaring, which many companies do in the Permian Basin of Texas and New Mexico because they lack access to pipelines to move the product to market….BP is investing in a new gas-gathering and compression system that will allow it to send more gas to customers instead of burning it away…

Kairos,  a company, specializes in identifying larger methane releases by flying small planes about 3,000 feet above the ground. …Kairos has received funding from the Oil and Gas Climate Initiative, an industry organization whose members include Exxon Mobil Corp. and Chevron Corp. The companies in the organization have pledged to collectively cut average methane emissions to less than 0.25% of gas sold by 2025.

One reason companies are stepping up monitoring is that environmental activists are watching, using technology to record leaks as they seek to boost public awareness of methane emissions.  Sharon Wilson, an organizer for the advocacy organization Earthworks, visits the Permian almost every month to monitor leaks from oil and gas sites, using a hand-held infrared camera. She submits the footage as evidence in state regulatory complaints against energy companies and often posts it on YouTube…Earthworks has filed more than 100 complaints in Texas and New Mexico since the beginning of 2018. State regulators issued violations or compelled operators to make repairs or install new equipment in fewer than 10% of the instances as of July, according to estimates by the group.

Excerpts from Rebecca Elliott, The Leaks that Threaten the Clean Image of Natural Gas, WSJ,  Aug. 10, 2019

Islands are not Disappearing. They Just Suffer

Every so often comes news of islands just up and disappearing. Eight in Micronesia. Five in the Solomon Islands. One off the coast of Hokkaido, Japan. Yet there’s also been a crop of studies and researchers, led by coastal geomorphologist Paul Kench from Simon Fraser University, saying that island nations such as Tuvalu (long a poster child for the existential threat of sea level rise) not only aren’t disappearing—they’re actually growing. So how do we make sense of this? Are the low-lying islands we know today doomed? Or are we seeing some other process at work? The answer is that a million complicated things are happening all at once, and it provides a window into how hard it is to talk about what’s currently happening to the planet….

Tuvalu not sinking. Growing.

One big culprit that comes up when we talk about disappearing islands is sea level rise, of course. The Sea level was, for a few thousand years up to around the late 19th century, pretty constant, on average. Since the late 1800s, it’s been steadily rising. On average.We keep saying “on average” because sea level changes are not the same in all places. In fact, in a lot of places, the sea level is dropping.… The single largest cause of global sea level rise, right now, isn’t melting glaciers, but the phenomenon called thermal expansion.  Thermal expansion is the tendency of matter, including sea water, to change its volume in response to a change in temperature… Global temperatures have risen by about 1.4 degrees Fahrenheit since 1880, with most of that in the last half-century. And that means the water already in the ocean is getting bigger…

Yes, all of this is going to have a major impact on any low-lying land the world over. But the researchers I talked to for this story don’t necessarily think that islands are disappearing right now at a higher rate than they were in past centuries. Of the independent island nations most at risk of disappearing, Tuvalu is near the top of the list. But a 2018 Paul Kench study of all 101 islands—all small and low-lying—that make up Tuvalu reported that there’s no consistency in what is happening there at all. About three quarters of the islands actually grew in size, to one quarter that shrank, over the past 40 years. Overall, during this time period, Tuvalu grew almost three percent. This is not to say that Tuvalu isn’t in a period of intense crisis right now, because the country certainly is. But disappearing—which is a very specific thing—might not be the cause of that crisis, at least not today…. [It is imporant] to  realize that the impacts of the direction that global climate is headed in are simply not going to be the same everywhere.

Paul Kench’s work—which ran counter to the narrative that the days of the low-lying, habitable islands that we know are gone—angered some, who see it as unhelpful to the very real plight of Tuvalu and other South Pacific island nations. But Kench notes that the mere disappearance of some islands shouldn’t be the whole story. Those harsher and more frequent storms send waves of salt water inland—sometimes over entire islands, sometimes into fields, or into fragile island freshwater sources. Homes and infrastructure are at risk, as are the unusual plant, insect, and bird species found on small islands and nowhere else. Scientists are already exploring simply moving endemic species to more stable islands.

Excerpts from DAN NOSOWITZ, How Alarming Is It That Islands Are Just Disappearing? Atlas Obscura, Mar. 2019

Who to Blame for Climate Change? the Carbon Majors

 Whether the damage caused by extreme weather events can be linked to human emissions of greenhouse gases is one of the hottest topics in climate science. And that debate leads directly to another: if this link can be established, who bears the responsibility?  Both of these questions are at the center of an inquiry by the Philippine Commission on Human Rights, whose latest hearings took place in London in November 2018. It is the first time a human-rights commission has heard evidence on whether large emitters violate basic human rights by causing climate change

 Where the hearings become more unusual is in investigating the link between the damage caused by climate change and the behaviour of large industrial companies. This is predicated on recent efforts to trace greenhouse-gas emissions back to large corporate and state-owned producers of fossil fuels and cement, dubbed the “carbon majors”. The latest analysis by cdp (formerly the  Carbon Disclosure Project), a non-governmental organisation that works with companies, cities and states to measure their environmental impact, published in 2017, found that 100 of them had produced just over half of emissions since the Industrial Revolution.

The Philippine hearings will come to a close in December in Manila. The commission does not have the power to compensate victims of typhoons or to sanction emitters of carbon dioxide. According to Roberto Cadiz, one of the commissioners, that isn’t even the point. His wish is to open a dialogue about possible solutions to climate change that includes the industrial emitters. So far, however, only one side of the story is being heard. The emitters have declined to participate.

Excerpts from Climate Change: The Blame Game, Economist, Nov. 17, 2018

Climate Change 2015

 

Global carbon emissions were 58% higher in 2012 than they were in 1990. The atmospheric concentration of carbon dioxide has risen from just under 340 parts per million in 1980 to 400 in 2015.  To stand a fair chance of keeping warming to just 2°C by the end of the century—the goal of global climate policy—cumulative carbon emissions caused by humans must be kept under 1 trillion tonnes. Estimates vary but, according to the Intergovernmental Panel on Climate Change, the total had hit 515 billion tonnes by 2011. Climate Interactive, a research outfit, reckons that if emissions continue on their present course around 140 billion tonnes of greenhouse gases will be released each year and temperatures could rise by 4.5°C by 2100. And even if countries fully honour their recent pledges, temperatures may still increase by 3.5°C by then.

The world is already 0.75°C warmer than before the Industrial Revolution….

Melting glacier ice, and the fact that warmer water has a larger volume, mean higher sea levels: they have already risen by roughly 20cm since 1880 and could rise another metre by 2100. That is perilous for low-lying islands and flat countries: the government of Kiribati, a cluster of tropical islands, has bought land in Fiji to move residents to in case of flooding. Giza Gaspar Martins, a diplomat from Angola who leads the world’s poorest countries in the climate talks, points out that they are particularly vulnerable to the effects of a warming planet. Money alone, he argues, will not fix their problems. Without steps to reduce emissions, he predicts, “there will be nothing left to adapt for.”…

For every 0.6°C rise in temperature, the atmosphere’s capacity to hold water grows by 4%, meaning storms will pour forth with greater abandon. The rains of the Indian monsoon could therefore intensify, cutting yields of cereals and pulses.

Climate change seems also to be making dry places drier, killing crops and turning forests into kindling. Forest fires in Indonesia, more likely thanks to the current El Niño weather phenomenon, could release 2 billion tonnes of carbon dioxide, about 5% of annual emissions due to human activity, says Simon Lewis of University College London. In recent months fires have swallowed more than 2.4m hectares of American forests. Alaska suffered 80% of the damage—a particular problem because the soot released in these blazes darkens the ice, making it less able to reflect solar radiation away from the Earth.

Developments in the Arctic are worrying for other reasons, too. The region is warming twice as fast as the rest of the world, a trend that could start a vicious cycle. Around 1,700 gigatonnes of carbon are held in permafrost soils as frozen organic matter. If they thaw, vast amounts of methane, which is 25 times more powerful as a global-warming gas than carbon dioxide when measured over a century, will be released. One hypothesis suggests that self-reinforcing feedback between permafrost emissions and Arctic warming caused disaster before: 55m years ago temperatures jumped by 5°C in a few thousand years…

And on September 29th Mark Carney, the governor of the Bank of England, warned that though measures to avoid catastrophic climate change are essential, not least for long-term financial stability, in the shorter term they could cause investors huge losses by making reserves of oil, coal and gas “literally unburnable”.

Excerpts from Climate Change: It’s Getting Hotter, Economst, Oct. 3, 2015, at 63

 

Weather Modification and the CIA

image from wikipedia

According to US website ‘Mother Jones’ the CIA is helping fund a study by the National Academy of Sciences (NAS) that will investigate whether humans could use geoengineering – which is defined as deliberate and large-scale intervention in the Earth’s climatic system – to stop climate change.The NAS website describes the study as an investigation into “a limited number of proposed geoengineering techniques, including examples of both solar radiation management (SRM) and carbon dioxide removal (CDR) techniques.”  The purpose of this is to comment “generally on the potential impacts of deploying these technologies, including possible environmental, economic, and national security concerns”, the website claims.  Solar radiation management (SRM) is a theoretical branch of geoengineering which moots the idea of reflecting sunlight in an attempt to block infrared radiation and halt rising temperatures.

The cost of the project is reported to be $630,000, which NAS is splitting with the CIA, the National Oceanic and Atmospheric Administration, and NASA reports say.  A reference on the NAS website to “the US intelligence community” funding the project refers to the CIA, an NAS spokesman claimed.

Much speculation has surrounded claims that the US government has long been involved in types of weather manipulation, including a much-discussed attempt to cloud-seed – the process of dispersing substances into the air to create cloud condensation or ice nuclei and subsequently rain or snow – during the Vietnam war.

It was also widely reported that the Chinese government seeded clouds ahead of the 2008 Olympics opening ceremony to create a downpour elsewhere and keep the stadium dry by firing iodide crystals into rain clouds over Beijing.

Weather manipulation was most recently in the news after claims by some American commentators that devastating tornadoes in Oklahoma, along with other extreme weather events like Hurricane Sandy, were created by the US government using the Haarp antenna farm in Alaska.

CIA backs $630,000 study into how to control global weather through geoengineering,The Independent, July 21, 2013

Himalayas and Climate Change: the Third Pole

Though the amount of ice on the plateau of Tibet and its surrounding mountains, such as the Himalayas, Karakoram and Pamirs, is a lot smaller than that at the poles, it is still huge. The area’s 46,000 glaciers cover 100,000 square kilometres (40,000 square miles)—about 6% of the area of the Greenland ice cap. Another 1.7m square kilometres is permafrost, which can be up to 130 metres deep. That is equivalent to 7% of the Arctic’s permafrost. Unlike the ice at the poles, the fate of this ice affects a lot of people directly. The area is known by some as Asia’s water tower, because it is the source of ten of the continent’s biggest rivers. About 1.5 billion people, in 12 countries, live in the basins of those rivers. Welcome, then, to the Earth’s “Third Pole”.

Until recently studies of the Third Pole were piecemeal—not surprising, given its remoteness, the altitude, the harsh weather and the fact that little love is lost between the countries among which it is divided. In 2009, however, Yao Tandong of the Institute of Tibetan Plateau Research, in Beijing, Lonnie Thompson of the Ohio State University and Volker Mosbrugger of the Senckenberg World of Biodiversity, in Frankfurt, started an international programme involving these countries, called the Third Pole Environment (TPE). Last month, its fourth workshop met in Dehradun, India.

One question on everyone’s mind is whether the glaciers are retreating, as is happening in parts of the real polar regions. The Intergovernmental Panel on Climate Change’s report in 2007 foolishly suggested that the Himalayas’ glaciers could disappear as early as 2035. Given the amount of ice they contain, it would take weather gods armed with blow torches to melt them that quickly, and this suggestion was rapidly discredited…..

One outcome of the workshop, then, has been to establish that the overall ice cover of the Third Pole, like that of the two real poles, is shrinking. Another is to show how precarious and piecemeal data about the area are. Its role as the source of so many rivers means that absence of data matters. The Chinese Academy of Sciences, of which both Dr Yao’s and Dr Wu’s institutes are part, has therefore set up a fund of 400m yuan ($65m) for research on the Third Pole and, crucially, a quarter of this is earmarked for work outside China.

The TPE’s researchers will now monitor a set of bellwether glaciers every six months. They will set up observatories to measure solar radiation, snowfall, meltwater and changes in the soil, as well as air temperature, pressure, humidity and wind. And they plan to take cores from the ice on the Tibetan plateau. These will let them reconstruct the area’s climate over the past few hundred thousand years. Together, these data will give them a better grip on how much—and why—the Third Pole is changing.

The climate of Tibet: Pole-land, Economist,, May 11, 2013,  at 84

The Evaporation of Andes Glaciers: a study

The glacier retreat in the tropical Andes over the last three decades is unprecedented since the maximum extension of the Little Ice Age (LIA, mid-17th–early 18th century). In terms of changes in mass balance, although there have been some sporadic gains on several glaciers, we show that the trend has been quite negative over the past 50 yr, with a mean mass balance deficit for glaciers in the tropical Andes that is slightly more negative than the one computed on a global scale. A break point in the trend appeared in the late 1970s with mean annual mass balance per year decreasing from −0.2 m w.e. in the period 1964–1975 to −0.76 m w.e. in the period 1976–2010.

In addition, even if glaciers are currently retreating everywhere in the tropical Andes, it should be noted that this is much more pronounced on small glaciers at low altitudes that do not have a permanent accumulation zone, and which could disappear in the coming years/decades. Monthly mass balance measurements performed in Bolivia, Ecuador and Colombia show that variability of the surface temperature of the Pacific Ocean is the main factor governing variability of the mass balance at the decadal timescale. Precipitation did not display a significant trend in the tropical Andes in the 20th century, and consequently cannot explain the glacier recession. On the other hand, temperature increased at a significant rate of 0.10 °C decade−1 in the last 70 yr. The higher frequency of El Niño events and changes in its spatial and temporal occurrence since the late 1970s together with a warming troposphere over the tropical Andes may thus explain much of the recent dramatic shrinkage of glaciers in this part of the world.

A. Rabatel, et al.,Current state of glaciers in the tropical Andes: a multi-century perspective on glacier evolution and climate change. The Cryosphere: An Interactive Open Access Journal of the European Geosciences Union

Coerced Transparency: Leaked Climate Change Report

The fifth assessment report (AR5) by the Intergovernmental Panel on Climate Change, which is not due to be published in full until September 2013, was uploaded onto a website called Stop Green Suicide on Thursday and has since been mirrored elsewhere on the internet.  The IPCC, which confirmed the draft is genuine, said in a statement: “The IPCC regrets this unauthorized posting which interferes with the process of assessment and review. We will continue not to comment on the contents of draft reports, as they are works in progress.”

A little-known US-based climate sceptic called Alex Rawls, who had been accepted by the IPCC to be one of the report’s 800 expert reviewers, admitted to leaking the document. In a statement posted online, he sought to justify the leak: “The addition of one single sentence [discussing the influence of cosmic rays on the earth’s climate] demands the release of the whole. That sentence is an astounding bit of honesty, a killing admission that completely undercuts the main premise and the main conclusion of the full report, revealing the fundamental dishonesty of the whole.”  Climate sceptics have heralded the sentence – which they interpret as meaning that cosmic rays could have a greater warming influence on the planet than mankind’s emissions – as “game-changing”.

The isolation by climate sceptics of one sentence in the 14-chapter draft report was described as “completely ridiculous” by one of the report’s lead authors. Prof Steve Sherwood, a director of the Climate Change Research Centre at the University of New South Wales, told ABC Radio in Australia: “You could go and read those paragraphs yourself and the summary of it and see that we conclude exactly the opposite, that this cosmic ray effect that the paragraph is discussing appears to be negligible … It’s a pretty severe case of [cherry-picking], because even the sentence doesn’t say what [climate sceptics] say and certainly if you look at the context, we’re really saying the opposite.”  The leaked draft “summary for policymakers” contains a statement that appears to contradict the climate sceptics’ interpretation.  It says: “There is consistent evidence from observations of a net energy uptake of the earth system due to an imbalance in the energy budget. It is virtually certain that this is caused by human activities, primarily by the increase in CO2 concentrations. There is very high confidence that natural forcing contributes only a small fraction to this imbalance.”  By “virtually certain”, the scientists say they mean they are now 99% sure that man’s emissions are responsible. By comparison, in the IPCC’s last report, published in 2007, the scientists said they had a “very high confidence” – 90% sure – humans were principally responsible for causing the planet to warm.

Richard Betts, a climate scientist at the Met Office Hadley Centre and an AR5 lead author, tweeted that the report is still a draft and could well change: “Worth pointing out that the wording in the leaked IPCC WG1 [working group 1, which examines the “physical science basis” of climate change] draft chapters may still change in the final versions, following review comments.”  Bob Ward, policy and communications director at the Grantham Research Institute on Climate Change and the Environment at London School of Economics and Political Science, said that Rawls appeared to have broken the confidentiality agreement signed by reviewers: “As a registered reviewer of the IPCC report, I condemn the decision by a climate change sceptic to violate the confidentiality of the review process. The review of the IPCC report is being carried out in line with the principles of peer review which operate throughout academic science, including an expectation of high standards of ethical behaviour by reviewers. It is disappointing, if not surprising, that climate change sceptics have been unable to meet these high standards of ethical behaviour.”

The IPCC, which publishes a detailed synthesis of the latest climate science every seven years to help guide policy makers, has experienced leaks before. In 2000, the third assessment report was leaked to the New York Times, while the fourth assessment report was published in 2006 by the US government a year ahead of its official publication.

Prof Bill McGuire, Professor of Geophysical & Climate Hazards at University College London and contributing author on the recent IPCC report on climate change and extreme events, said that sceptics’ reading of the draft was incorrect: “Alex Rawls’ interpretation of what IPCC5 says is quite simply wrong. In fact, while temperatures have been ramping up in recent decades, solar activity has been pretty subdued, so any interaction with cosmic rays is clearly having minimal – if any – effects. IPCC AR5 reiterates what we can be absolutely certain of: that contemporary climate change is not a natural process, but the consequence of human activities.”

Prof Piers Forster, Professor of Climate Change at the University of Leeds, said: “Although this may seem like a ‘leak’, the draft IPCC reports are not kept secret and the review process is open. The rationale in not disseminating the findings until the final version is complete, is to try and iron out all the errors and inconsistencies which might be inadvertently included. Personally, I would be happy if the whole IPCC process were even more open and public, and I think we as scientists need to explore how we can best match the development of measured critical arguments with those of the Twitter generation.”

Landmark climate change report leaked online, Guardian, Dec. 14,2012