With climate change, uncertainty is no-one’s friend

Uncertainty cuts both ways highlights University of Bristol's Stephan Lewandowsky - if your preferred estimate is at the low end of a range, you're neglecting similarly likely high end estimates. Image credit: University of Bristol

Uncertainty cuts both ways highlights University of Bristol’s Stephan Lewandowsky – if your preferred estimate is at the low end of a range, you’re neglecting similarly likely high end estimates. Image credit: University of Bristol

Waiting longer to act on climate change will cost us more than taking immediate action. It’s a message that’s getting louder and louder, repeated from many sides. In March it was stressed by US Secretary of State John Kerry. In April it was highlighted by the UN Intergovernmental Panel on Climate Change (IPCC)’s latest report. Last month it was underlined by Hank Paulson, treasury secretary under George Bush, hedge fund manager Tom Steyer, and former New York Mayor Michael Bloomberg. This week the Council of Economic Advisors, the agency advising President Obama on economic policy, joined in.

These messages could hardly be any clearer, but still some of us remain uncertain on the need to act. The best argument for waiting until we’re more certain to act is that if climate change turns out to be harmless, our efforts to fight it will be wasted. Even simple things like current weather are enough to sway our opinions, and when uncertain it’s always tempting to feel like we don’t need to do anything. But that’s the wrong reaction to uncertainty on climate change, according to psychologist Stephan Lewandowsky from the University of Bristol, UK.

The researchers have found that greater uncertainty over how much Earth warms in response to our CO2 emissions would actually raise forecasts of average damage costs from climate change. Greater uncertainty also means projections see it as more likely that steps to cut emissions won’t keep the world below warming levels governments have agreed we must avoid. So, if we are unsure whether we can slow the climate juggernaut down before we smash into the wall, we’re better off hitting the brakes earlier. As Stephan explained, ‘uncertainty is no one’s friend’.

Evidence is piling up against the economic argument for waiting to see if climate sensitivity is less than 1C per doubling of CO2. Image copyright Springer, see reference below.

Evidence is piling up against the economic argument for waiting to see if climate sensitivity is less than 1°C per doubling of CO2. Image copyright Springer, see reference below.

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Temperatures make our global warming opinions change like the weather

The 2010 blizzards in the northeastern US they called the 'Snowpocalypse' buried this Maryland street, drove senators to deride the idea of global warming, and Columbia University researchers to look at how temperature influences our outlook on climate change. Image credit: BKL, used via Flickr Creative Commons license.

The 2010 blizzards in the northeastern US they called the ‘Snowpocalypse’ buried this Maryland street, drove senators to deride the idea of global warming, and Columbia University researchers to look at how temperature influences our outlook on climate change. Image credit: BKL, used via Flickr Creative Commons license.

On June 23, 1988, record 38°C temperatures in Washington DC provided a persuasive backdrop for NASA’s Jim Hansen to force the greenhouse effect into our consciousness. At least one of the senators hearing his landmark congressional testimony was well aware that the heat would help sear the message into people’s minds. Tim Wirth has since admitted turning off the air conditioning and opening the windows the night before, so Jim’s sweat would be obvious for the TV cameras.

That baking hearing likely played on how we think in a way psychologists had just started to untangle in the previous decade. That is, how we judge things is often dominated by a simple sense of our personal experience, rather than a deeper analysis of evidence available to us. “Numerical judgments are hard, so we grasp at whatever more tangible we can find,” Elke Weber, from Columbia University in New York, explained.

Identifying this tendency to answer an easier question, known as substitution, helped psychologist Daniel Kahneman win a Nobel Prize for Economics. And when it comes to our opinion on climate change, recent temperatures are especially important, Elke and her colleagues have shown over the last three years.

In 2010, a rather different extreme in the US capital drew Elke’s husband Eric Johnson to study this effect. Then, two massive snowstorms struck in one week in February, an event that was dubbed the ‘Snowpocalypse’, leading senators to deride the possibility of climate change. His team therefore looked at whether local weather information gets falsely substituted for global climate in three studies in the US and Australia.

Across three studies they asked people their opinions on global warming and whether the temperature on the day of the study was warmer or cooler than normal. Those who thought that day was warmer than usual believed more in and had greater concern about global warming than people who thought that day was colder than usual. They would also donate more money to a global-warming charity if they thought that day seemed warmer than usual. Read the rest of this entry »

CO2 emissions drive heatwaves on despite warming ‘hiatus’

A measurement taken on a shaded back deck in Oswego, Oregon on July 29, 2009 at 6pm. 41.3°C or 106.34°F - just one example of increasingly common hot summers in the Northern Hemisphere. Image copyright  Sean Dreilinger used via Flickr Creative Commons licence.

A measurement taken on a shaded back deck in Oswego, Oregon on July 29, 2009 at 6pm. 41.3°C or 106.34°F – just one example of increasingly common hot summers in the Northern Hemisphere. Image copyright Sean Dreilinger used via Flickr Creative Commons licence.

Human influence on climate is set to make otherwise unusually hot summers in the Northern Hemisphere more frequent, even if the current warming slowdown continues. That finding, from a new study by Youichi Kamae from the National Institute for Environmental Studies in Tsukuba, Japan, and his colleagues, could now heat up climate talks. “The recent hot summers over land regions and the climate hiatus have opposite effects on ongoing global negotiations for climate policies,” Youichi underlined. “The findings of this study can have significant implications for policy makers.”

Over the past 15 years, growing ‘anthropogenic’ or human-emitted CO2 hasn’t turned into significant average temperature rises on the Earth’s surface. The top levels of the oceans haven’t warmed significantly either, even though heat is still building up deeper down. However in that time sometimes deadly hot summers have become more common in Earth’s northern half. It’s not clear how that’s happening without average temperatures increasing faster. One possible part of the explanation could be a fast response to greenhouse gas emissions that Youichi and other scientists had previously found. “The fast response over can largely be interpreted as direct land surface warming due to CO2,” Youichi told me.

The Japanese team’s search for a better explanation had a big question at the centre: How much of this climate change is natural, and how much is man-made? Not able to easily experiment on the planet to investigate, they did what climate scientists usually do for such ‘attribution studies’, and turned to computer models. Simulating the world with and without human greenhouse gas emissions and comparing the results, scientists are increasingly trying to pinpoint whether climate change directly caused particular extreme weather events. They’re trying to build up lots of evidence about a single event to be sure that their result isn’t random, and that takes lots of computer time and power. Read the rest of this entry »

Could climate’s crop impact catch us with our plants down?

The odds that yields of maize will fall by a tenth over the next 20 years have shortened from 1-in-200 to 1-in-10. Image copyright Raman Sharma used via Flickr Creative Commons license.

The odds that yields of maize will fall by a tenth over the next 20 years have shortened from 1-in-200 to 1-in-10. Image copyright Raman Sharma, used via Flickr Creative Commons license.

With the next two decades set to see a stronger increase in demand for food than the rest of the 21st century, declining harvests would cause some serious problems. Right now crop yields are growing, but could climate trends cause them to fall by a tenth, say, over the next 10-20 years?

That’s the question David Lobell from Stanford University in California and Claudia Tebaldi from the US National Center for Atmospheric Research in Boulder, Colorado have tried to answer. They find that if the world wasn’t warming, the chance of yields decreasing by a tenth over the next 20 years would be less than 1-in-200. However, climate change has made shrinking yields more likely, shortening the odds to a 1-in-10 chance for maize and a 1-in-20 chance for wheat.

“It was surprising to see how likely it is nowadays for climate trends to significantly cut into yield progress,” David told me. “It is still more likely than not that climate will be a slight drag on progress instead of a major factor. But we can’t rule out a major slowdown, and that means we should probably think through that type of scenario to figure out how to prepare for it.”

Such near-future climate forecasts are unusual, David underlined. “Longer periods allow the signal of climate change to become clearer compared to natural variability,” he explained. “But it may simply be that most of the initial questions about climate change were about the long timescales, to decide about questions related to energy choices and emissions. Now, a lot of questions are related about how to properly adapt to the changes happening now.”

What will happen to crops is central to David’s interests as associate director of Stanford’s Center on Food Security and the Environment. “I often get asked by governments or the private sector if climate change will threaten food supply in the next couple of decades, as if it’s a simple yes or no answer,” the scientist revealed. “This was especially true of a committee I recently served on focused on social stresses from climate change in the near-term. The truth is that over a 10 or 20 year period, it depends largely on how fast things warm, and we can’t predict that very precisely. So the best we can do is put odds on things.” Read the rest of this entry »

Who can afford to hold back rising seas?

UK Prime Minister David Cameron visiting Dawlish a week after the storms that demolished the sea wall that supported the train line. Image copyright Number 10, used via Flickr Creative Commons license.

UK Prime Minister David Cameron visiting Dawlish a week after the storms that demolished the sea wall that supported the train line. Image copyright Number 10, used via Flickr Creative Commons license.

Taking the train along the Devon, UK, coast earlier this week I was hypnotised by the lapping waves I saw through the window, and their concealed power. On such a sunny day, the rail journey through Dawlish is perhaps the most beautiful I’ve been on. But in February its ocean-hugging route became its downfall, when storms demolished the sea wall it rests on. Now, thanks to 300 fluorescent-jacket clad workers who performed £35 million worth of repairs, the dangling tracks I saw on TV news are a fading memory. It’s an impressive achievement, but could we afford it if – due to climate change, for example – such ‘orange armies’ had to do battle more often?

The significance of that question was emphasised by Chris Field from Stanford University in California, when I saw him talk recently. Highlighting that all parts of the world are vulnerable to climate change, Chris showed the below image of New York City in 2011, during Hurricane Sandy. “The existing climate created a situation that caused over $50 billion in economic damage for a region of the world that had a vast amount of economic resources and had a response plan in place,” he underlined. “It just wasn’t a plan that was up to the challenges that they faced.” If climate change causes more $50 billion-damage events, can we afford that?

If New York can be taken unaware by Hurricane Sandy, what happens elsewhere, when sea level's higher? Image credit: Chris Field/IPCC

If New York can be taken unaware by Hurricane Sandy, what happens elsewhere, when sea level’s higher? Image credit: Chris Field/IPCC

Just before the ocean crippled the south-west UK’s rail services, Jochen Hinkel from the Global Climate Forum in Berlin, Germany, and his team were answering a similar question. In a paper published in the Proceedings of the National Academy of Sciences of the USA in February, Jochen looked at coastal flood damages from projected sea level rise. When I therefore asked him about his work, he was quick to put climate change-driven sea level rise’s role in Hurricane Sandy and this year’s UK storms into context. Read the rest of this entry »

Shrinking dairy’s carbon hoofprint

After 10,500 years of farming them, does climate change mean we humans must limit our reliance on cows, or just change how we treat them? Image copyright fishhawk, used via Flickr Creative Commons licence.

After 10,500 years of farming them, does climate change mean we humans must limit our reliance on cows, or just change how we treat them? Image copyright fishhawk, used via Flickr Creative Commons licence.

Whenever I come across cows here in the southwest of the UK, usually placidly munching on a mouthful of grass, they always seem too lovable to be villains. But as we face growing twin challenges of feeding the world and fighting climate change, they’re increasingly getting a bad reputation.

Some scientists highlight reducing how much beef we eat, in particular, as an important step towards future sustainability. They say only about three or four parts in 100 of the energy in livestock feed becomes our food, while the rest is lost as manure, heat, digestive gases and slaughter by-products. Switching to more intensively farmed chicken or pork and plant-based food would be more efficient, the argument goes. It also gives a greater chance to trap carbon from waste material, which might otherwise become planet-warming greenhouse gases, as biochar that can help improve soil fertility.

A couple of years back I put this to Peter and Henri Greig who run my favourite local butchers, Pipers Farm. As they showed us round their farm Peter explained how their Red Ruby cattle can graze Devon moorland that can’t be used for crops, before moving on to pasture. While I still don’t eat a lot of beef for both environmental and health reasons, that seems a good reason for not demonising cows entirely. In fact, a paper in the June 2014 issue of the Journal of Dairy Science highlights previous research that found more grazing land exists, unusable for human food, than cropping land.

We can’t ignore what that promises for feeding the world in the future, but we can’t ignore cows’ greenhouse gas emissions either. However, rather than beef cattle, the new paper’s authors focussed on reducing levels of the potent greenhouse gas methane coming out of the digestive systems of dairy cattle. Joanne Knapp, a consultant who has researched nutrition in ruminant animals like cattle, told me her team’s interest comes in part thanks to its backers: Innovation Center for US Dairy.

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Unique and unnatural: modern warming from an historical viewpoint

A Roman altar with the Sun in its chariot on the left, and Vulcan, the god of fire and volcanoes on the right. The climate gods long favoured the Roman Empire, with wobbles in Earth's orbit credited for increasing the amount of solar energy falling on Earth at the time. Image copyright: Nick Thompson, used via Flickr Creative Commons License.

A Roman altar with the Sun in its chariot on the left, and Vulcan, the god of fire and volcanoes on the right. The climate gods long favoured the Roman Empire, with Earth’s orbital dance credited for increasing the amount of solar energy falling on Earth at the time. Image copyright: Nick Thompson, used via Flickr Creative Commons License.

Our climate has changed before. It’s something most of us realise and can agree on and, according to Skeptical Science, it’s currently the most used argument against human-caused warming. If such changes have happened naturally before, the argument goes, then surely today’s warming must also be natural. It’s an appealing idea, with an instinctively ‘right’ feel. Nature is so huge compared to us puny humans, how can we alter its course? The warming we’re measuring today must just be a natural fluctuation.

It’s such an appealing argument that at the beginning of the 20th century that’s just what many scientists thought – that humans couldn’t alter Earth’s climate. In the time since, our knowledge has come a long way. We’ve explored space, become able to build the electronics that are letting you read this, and climate science has likewise advanced and benefited from these advances.

So what do we know today that might convince the sceptical scientists of 115 years ago that we’re warming the planet? Recently, Richard Mallett, one of my Twitter friends who describes himself as sceptical about mainstream climate science, made a point that serves as an excellent test of our current knowledge:

Of the historical warmings he’s referring to, perhaps the least familiar is the Holocene, which is ironic, as the Holocene is now. It’s the current period of geological time that started at the end of the last ice age, 11,700 years ago. By 1900 scientists would have known the term, but they couldn’t explain why it wasn’t as icey as before.

Three variables of the Earth’s orbit—eccentricity, obliquity, and precession—affect global climate. Changes in eccentricity (the amount the orbit diverges from a perfect circle) vary the distance of Earth from the Sun. Changes in obliquity (tilt of Earth’s axis) vary the strength of the seasons. Precession (wobble in Earth’s axis) varies the timing of the seasons. For more complete descriptions, read Milutin Milankovitch: Orbital Variations Image credit: NASA/Robert Simmon.

Three variables of the Earth’s orbit—eccentricity, obliquity, and precession—affect global climate. Changes in eccentricity (the amount the orbit diverges from a perfect circle) vary the distance of Earth from the Sun. Changes in obliquity (tilt of Earth’s axis) vary the strength of the seasons. Precession (wobble in Earth’s axis) varies the timing of the seasons. For more complete descriptions, read Milutin Milankovitch: Orbital Variations. Image credit: NASA/Robert Simmon.

The explanation we have today comes thanks to the calculations Milutin Milanković worked out by hand between 1909 and 1941. Milutin showed that thanks to the gravitational pull of the Moon, Jupiter and Saturn, Earth’s orbit around the Sun varies in three ways. Over a cycle of roughly 96,000 years our path varies between more circular and more oval shapes. The other two ways come because Earth’s poles are slightly tilted relative to the Sun’s axis, which is why we have seasons. The angle of that tilt shifts over a roughly 41,000 year cycle. Earth also revolves around that tilted axis, like a spinning top does when it slows down, every 23,000 years.

Together these three cycles change how much of the Sun’s energy falls on and warms the Earth, in regular repeating patterns. Though that idea would be the subject of much controversy, by the 1960s data measured from cylinders of ancient ice and mud would resolve any doubt. The slow descent into ice ages and more abrupt warmings out of them – like the one that ushered in the Holocene – come from Earth’s shimmies in space. Read the rest of this entry »

Heavier people mean weightier vehicle emissions

Between 1970 and 2010 the average weight across all overweight and obese American men and women increased approximately 5 kg and 6 kg, respectively, and that has added to the fuel needed to transport them, and greenhouse gas emissions in turn. Image copyright Neil Hester, used unaltered via <a href="https://creativecommons.org/licenses/by-nc/2.0/">Flickr Creative Commons license</a>.

Between 1970 and 2010 the average weight across all overweight and obese American men and women increased approximately 5 kg and 6 kg, respectively, and that has added to the fuel needed to transport them, and greenhouse gas emissions in turn. Image copyright Neil Hester, used unaltered via Flickr Creative Commons license.

In case we needed any reasons other than health to watch our weight, a team at Carnegie Mellon University in Pittsburgh, Pennsylvania, has found some. Michelle Tom and her co-workers have looked at how our extra weight adds to the cost and carbon footprint of transport in the US. From 1970 to 2010, the extra fuel needed to carry overweight passengers’ ‘excess weight’ cost $103 billion in total. That in turn created extra greenhouse gas emissions over the 40-year period equivalent to half a billion tonnes of CO2. “Obesity is not just a public health issue, but also has implications for natural resource use and environmental degradation,” Michelle told me.

Weight is important in vehicle fuel use, with developing lighter cars playing a key role in recent efforts to make them more efficient. Working with PhD supervisor Chris Hendrickson, Michelle is studying the strain our heavier societies put on our resources, and therefore tackled the fuel burden from extra weight. “There have been headlines about the health issues associated with people being overweight and obese, but there has been very little analysis of what this means in terms of things like fuel use and calorie intake,” Chris noted.

Michelle pulled together data for personal vehicles, public transport and aircraft, including how many there are, how full they are, and how much fuel they’ve used. And thanks to efforts made to lighten vehicles, she also had access to good information on how weight affects fuel consumption. She could bring this together with records of the US population, how many of them drive, and how much they exceed the highest ‘normal’ body mass index. Combining all this with data on vehicle greenhouse gas emissions and fuel costs meant Michelle could calculate how heavy the impact of heavier people has been. Read the rest of this entry »

IPCC: Millions of words on climate change are not enough

The latest IPCC report has highlighted that it's dead certain that the world has warmed, and that it's extremely likely that humans are the main cause. Credit: IPCC

The latest IPCC report has highlighted that it’s dead certain that the world has warmed, and that it’s extremely likely that humans are the main cause. Credit: IPCC

The most recent UN Intergovernmental Panel on Climate Change (IPCC) report saw perhaps the most severe conflict between scientists and politicians in the organisation’s existence. As its name suggests, governments take an active part in the IPCC process, whose latest main findings appeared between September 2013 and May 2014. Debate over what information makes the high-profile ‘Summaries for Policymakers’ is usually intense, but this time three graphs were dropped on politicians’ insistence. I show these graphs later in this blog entry.

At the Transformational Climate Science conference in my home town, Exeter, UK, earlier this month, senior IPCC author Ottmar Edenhofer discussed the ‘battle’ with governments on his part of the report. Another scientist who worked on the report highlighted confidentially to me how unusual the omission was.

To me, it’s more surprising that this hasn’t happened more often, especially when you look more closely at the latest report’s findings. There’s concrete certainty that warming is happening, and it’s extremely likely that humans are the dominant cause, it says. Governments have even – in some cases, begrudgingly – already signed up to temperature and CO2 emission targets reflecting this fact.

The inadequacy of those words is becoming ever more starkly obvious. Ottmar stressed that the emissions levels agreed at the United Nations’ Climate Change Conference in Cancún, Mexico, in November 2010, would likely need later emissions cuts the likes of which we’ve never seen before to avoid dangerous climate change. The latest IPCC report shines a floodlight on that inertia, which understandably cranks up the tension between researchers and politicians.

Ottmar was one of two co-chairs who led the ‘working group three’ (WGIII) section of the IPCC report that looks at how to cut greenhouse gas emissions. He stressed that the need to make these cuts comes from a fundamental difference between the risks that come from climate change and the risks of mitigation. We can heal economic damage arising from cutting emissions – reversing sea level rise isn’t so easy.

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The urgent voice who refused to be silenced on climate danger

  • This is part three of this profile. Read part one here and part two here.
In response to the revelations of his ongoing research, NASA scientist Jim Hansen has become increasingly active in campaigning to halt climate change over the past decade. Image credit: Greenpeace

In response to the revelations of his ongoing research, NASA scientist Jim Hansen has become increasingly active in campaigning to halt climate change over the past decade. Image credit: Greenpeace

By December 6, 2005, NASA Goddard Institute of Space Studies’ (GISS) temperature record was already sending a clear message: worldwide, 2005 would likely be the warmest year so far. For GISS director Jim Hansen, speaking to the annual American Geophysical Union conference, arguably the world’s largest environmental research meeting, it seemed fair to reveal. For several listening journalists it was newsworthy enough for them to cover Jim’s talk. But it would anger some of Jim’s colleagues at NASA headquarters enough to try to stop him talking to the media. In the process they’d drag him outside the world of pure research he was most comfortable in. “The undue influence of special interests and government greenwash pose formidable barriers to a well-informed public,” Jim would later write about the situation. “Without a well-informed public, humanity itself and all species on the planet are threatened.”

The comments came during a lecture in honour of Dave Keeling, the CO2 tracking pioneer, who’d died of a heart attack in June that year. Soothing Jim’s hesitation, Dave’s son Ralph stressed he was continuing the work of his father, who had even been discussing one of Jim’s papers minutes before his death. And so Jim had brought together evidence showing that Earth’s climate was nearing a ‘tipping point’ beyond which it will be impossible to avoid dangerous changes. However, warming from 2000 onwards might still be kept below the 1°C level that Jim at that time considered hazardous if CO2 levels in the air were held at about 450 parts per million (ppm). Emissions of other greenhouse gases would also need to be significantly reduced. The message was clear: how we get our energy would must change, mainly by shifting away from coal and the vast volumes of CO2 burning it produces.

NASA headquarters was already reviewing all publicity on climate change research, but the latest coverage would force it into even more severe action. The following week it laid out new restrictions on Jim’s ability to comment publicly, and the global GISS temperature record was temporarily taken off the internet. Prominent amongst those setting the new conditions was NASA’s new head of public affairs, appointed by George Bush’s administration, David Mould. His previous jobs included a senior media relations role at the Southern Company of Atlanta, the second largest holding company of coal-burning power stations in the US. Only one company had donated more to the Republican Party than the Southern Company during George Bush’s 2000 election campaign: Enron. Read the rest of this entry »

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