Why measuring fugitive methane emissions from shale gas production matters

  • 24 Jul 2014, 14:40
  • Mat Hope

CC 2.0 Tim Evanson

As an ever-increasing number of countries consider exploiting their shale gas resources, and researchers scramble to understand what a production boom could mean for the climate, two new pieces of research appear to come to opposite conclusions.

What is the climate impact of shale gas?

Since gas has about half the emissions of coal when it's burned for electricity, it has been touted as  a 'bridging fuel' for countries seeking to decarbonise their economies to use as a stop gap on the way to a low carbon electricity system.

But as we've  explored before, scientists are struggling to establish the full impact of increased shale gas production on the climate, due to methane that escapes during the extraction process - known as fugitive methane emissions.

Two papers released this month examine what the actual climate impact of natural gas is. At first glance they seem to show opposite things. The graph on the left, taken from a paper by Robert Howarth appears to show natural gas electricity generation emissions - the towering left bar - can be much higher than coal's. The second graph, from  Heath et al, appears to show the opposite - that coal's generation emissions (on the left) are much higher than those from both conventional and shale gas.

Howarth Vs Heath Coal And Gas Emissions

Both papers examine the 'lifecycle emissions' of the fuels: the amount of gas emitted from extraction to combustion. So why is there such a large discrepancy between two papers?

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Have satellites overestimated Antarctic sea ice growth?

  • 22 Jul 2014, 15:30
  • Roz Pidcock

It's puzzling why Antarctic sea ice seems to be growing while earth's other icy expanses are shrinking as temperatures rise.

Now new research questions whether there has been much of a rise in Antarctic sea ice after all. The paper suggests the small but significant growth scientists thought had occurred since 1979 could be little more than a "spurious artifact" of how satellite data is interpreted.

But other polar scientists tell us the implications of the new findings" are very limited indeed" and they're confident Antarctic sea ice is still growing.

Bucking the trend

Scientists know ice is being lost from both the Greenland and Antarctic ice sheets. They also know the amount of sea ice in the Arctic is rapidly decreasing.

But satellite data suggest the amount of sea ice around Antarctica has been growing since 1979. A report from the Intergovernmental Panel on Climate Change (IPCC) last year put the size of the increase at  1.5 per cent on average per decade.

For comparison, that's about a third of the rate of sea ice retreat in the Arctic. A  new paper just published in journal The Cryosphere explains the puzzle this poses for scientists:

"[T]here has been substantial interest in the trend in Antarctic sea ice extent … primarily because of the observed asymmetry between increasing ice extent in the Antarctic and rapidly diminishing ice extent in the Arctic, and the inability of current climate models to capture this."

The new paper raises an interesting point. It notes that the growth in Antarctic sea ice in the latest IPCC report is much bigger than suggested in the previous one in 2007. The authors say:

"[The 2007 report] reported the trend in Antarctic sea ice extent to be small and statistically indistinguishable from zero".

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Slow surface warming since 1998 is “not exceptional”, say scientists

  • 21 Jul 2014, 19:30
  • Roz Pidcock

Scientists know greenhouse gases are causing the world to warm. But an interesting question is why warming at earth's surface speeds up and slows down.

new paper shows surface temperature "slowdowns" like we're experiencing now aren't unusual - and capturing the timing of natural ups and down in the climate is key to predicting them.

But as a  second paper explains, the planet as a whole has warmed up in the last decade even as surface temperature rise has been sluggish.

Model mismatch

Temperatures are rising due to long term greenhouse gas warming. But natural variability causes temperatures to go up and down from one year to the next.

Natural variability can at least partly explain slower surface warming in the last 15 years, the Intergovernmental Panel on Climate Change (IPCC)  concluded in its latest report. Recent evidence  points to changes in the  Pacific causing the deep oceans to absorb more heat.

But most climate models didn't predict the slowdown. And as a  new paper in Nature Climate Change explains, some parts of the media have argued that since models don't replicate recent temperatures, we shouldn't trust their predictions for future warming.

But the paper, lead by Australian climate scientist Dr James Risbey, finds that 15 years of temperatures rising slower than models predict "does not constitute evidence against the fidelity" of models in general. Let's take a closer look at why not.

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New mega-map details all the ways climate change will affect our everyday lives

  • 18 Jul 2014, 00:00
  • Roz Pidcock

From flood barriers to fish stocks, a new super-graphic from the Met Office and the UK Foreign and Commonwealth Office shows how climate change is likely to alter human activity.

Looking at where our food comes from and how countries interact through travel and trade, it makes for a stark visualisation of what different regions can expect as climate change kicks in.


The  Human Dynamics of Climate Change project is a huge venture, designed to illustrate the range and complexity of the potential impacts of unmitigated climate change.

It contains a massive amount of information but a good place to start is the map below, which shows how humans interact in today's world.

The colours, arrows, symbols and shading show shipping routes, population density, crop importers and exporters, areas under water stress, busy ports and airports, fishing regions, tropical cyclone regions and melting glaciers.

HDCC_map _present

Present day human dynamics (1981-2010). Source: Human Dynamics of Climate Change  ( HDCC), a joint project from the Met Office and UK Foreign and Commonwealth Office.

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Arctic summer sea ice is disappearing fast, but can we rescue it?

  • 14 Jul 2014, 15:30
  • Roz Pidcock

Diminishing Arctic sea ice is perhaps the most iconic consequence of climate change. And there's a good chance we'll lose it in summer before too long if emissions stay high, according to a new paper. But its demise is not a foregone conclusion - with a swift peak and decline in greenhouse gases we could still reverse that trend, the scientists say.

Losing ice

Arctic sea ice cover is declining by about  four per cent per decade. But the seasonal low in summer is shrinking particularly quickly, at more like 11.5 per cent per decade.

At the other end of the planet, Antarctic sea ice is growing - but much slower than it's being lost in the Arctic. We've written more about global sea ice loss  here.

AR5_summer _Arctic _sea _ice _extent

Arctic sea ice summer extent has decreased by between 9.4 to 13.6% per decade. Source: IPCC 5th Assessment Report,  Summary for Policymakers


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What’s your city doing to protect you from climate change? In six charts

  • 10 Jul 2014, 16:45
  • Roz Pidcock

From London to São Paulo, half the world's population resides in huge urban metropolises. But living in some cities will be worse for your health than others. New research pinpoints more than 200 cities leading the way in tackling climate, protecting citizens and businesses along the way.

Is yours one of them?

Cities under pressure

Cities are hubs of economic and human activity. They house at least 50 per cent of the world's population and produce more than  80 per cent of its gross domestic product (GDP).

But the concentration of people and assets make cities vulnerable when disaster strikes. In its  latest report, the Intergovernmental Panel on Climate Change (IPCC)  warned of an increasing risk to cities from climate change, through rising temperatures, increasing frequency and severity of heatwaves, and greater risk of flooding. Coastal cities also have to deal with rising sea level rise.

But cities are taking the initiative in tackling climate change, according to a  new report from the Cities Climate Leadership Group (  C40). It looked at what 207 cities across the world are doing to alleviate climate change's impacts.

Waking up to climate change threats

Cities Report Infographic

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Six things to know about Antarctic ice

  • 07 Jul 2014, 15:00
  • Roz Pidcock

This article was originally published in November 2012.

When scientists talk about ice and climate change, it's often about how quickly it's disappearing. So recent  news stories  about Antarctic sea ice growing may come as a surprise. 

The amount of ice in the ocean around Antarctica is indeed increasing, but this is only part of what's going on in the Antarctic as a whole. We've put together six things you should know about climate change and Antarctic ice.

1. Antarctic waters are warming faster than the global average

Along with the rest of the world, the Antarctic is warming up. The Southern Ocean, which surrounds the continent of Antarctica, has been warming faster than the rest of the world's oceans since the 1950s, at a rate of  0.17 degrees Celsius compared to a global average of 0.1 degrees. The increased rate of warming is mainly due to the way large weather systemstransport heat to the poles.

2. Despite rapid warming, there's more Antarctic sea ice

Despite rapidly warming water, the amount of ice that floats on the Southern Ocean around Antarctica - known as sea ice - is slightly increasing. On 26 September 2012, the USNational Snow and Ice Data Centre (NSIDC) confirmed that Antarctic sea ice reached a record extent - a measure of sea ice cover - of 19.44 million square kilometres.

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Updated: The science of fracking and earthquakes

  • 04 Jul 2014, 11:55
  • Mat Hope

CC: G Thomasen

Should you worry that fracking will cause earthquakes? The short answer is: probably not.

But as more studies are conducted, researchers are developing their understanding of how the fracking process interacts with seismic activity.

Last year, a widely-cited study concluded that compared to other kinds of mining, fracking usually only causes minor tremors. But two papers in the past twelve months suggest the processes associated with fracking could increase the likelihood of small tremors.

We take a look at the evidence.

Fracking and earthquakes

Hydraulic fracturing - known as fracking - involves pumping a fluid made of water mixed with chemicals at high pressure into a drilled well. The fluid creates fractures in the rock, making it possible to extract oil or gas trapped there. So fracking essentially causes minor earthquakes by design, as cracking the rock causes tremors.

But research shows fracking very rarely causes earthquakes people can actually feel. The US Geological Survey found the number of small earthquakes in the USA increased significantly as the fracking industry was developed there. But the vast majority of those earthquakes were "micro" earthquakes registering less than 1 on the  moment magnitude scale - a modern version of the better known Richter scale.

Shale gas exploration is simply not in the "premier league" of serious earthquake causes, says Professor Richard Davies, director of Durham University's Energy Research Institute. Its study of 198 locations showed fracking caused much smaller tremors than other mining processes. Davies has said most fracking induced earthquakes release less energy than someone  jumping off a ladder onto the floor.

Wastewater earthquakes

The Durham study caught the media's attention, with a  swathe of headlines declaring fracking was not a significant cause of earthquakes. But it is worth pointing out that fracking has been linked to some earthquakes that have been felt, if only in three places: one each in Lancashire, the USA, and Canada.

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Explained: Fugitive methane emissions from natural gas production

  • 03 Jul 2014, 16:20
  • Mat Hope

CC: T Evanson

For half a decade, researchers have tried to answer the question of how much methane escapes from natural gas wells into the atmosphere. The recent emergence of fracking and shale gas has brought the issue to the fore. But studies continue to present varying results. 

Natural gas is mainly methane, some of which escapes during the drilling, extraction, and transportation process. Such outbreaks are known as fugitive emissions.

They're a problem because methane is a potent greenhouse gas - approximately  25 times more powerful than carbon dioxide over a 100 year timescale. The issue has been thrown into sharp relief because gas production has undergone a boom in recent years.

The discovery of large amounts of gas locked in shale rock means the US's production has  increased by about 25 per cent in recent years. That's helped  push energy prices down and  reduce the US's emissions. Many other countries are now also keen to explore shale gas's potential, citing the US as an example.

Gas emits about half the carbon dioxide of coal when it's burned, leading some to tout it as a  relatively "clean" fuel. But if fugitive emissions are too high, it makes gas a less attractive fuel for policymakers and industries interested in reducing greenhouse gas emissions. And so the question of just how big fugitive emissions are is a pressing one.

Contested evidence

The data is contested. Some people - often advocates of decarbonisation - suggest the fuel is  nowhere near as "clean" as some companies declare. Others - often industry voices - accuse campaigners of  cherry-picking evidence.

There's certainly a wide range of estimates on the extent of the problem.

Estimates of gas production leakage rates are expressed as a percentage of total production. When we looked at this question in 2012, they ranged from 0.6 to four per cent.  

Over the past two years, the upper end of this range has increased. Some studies now suggest the amount of gas leaking from wells could be as high as nine per cent.

We've put some of the key estimates in the chart below:

Fugitive Emissions Bar Chart

Source: Various, see  this Google Doc for details. Graph by Carbon Brief. Note: ^ means value is for unconventional - i.e. shale - gas wells only, * means the value in the graph is the mid-estimate or mean of a range where a 'best estimate' is not given.

So why is there such a range of results?

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Overconfident predictions risk damaging trust in climate science, prominent scientists warn

  • 02 Jul 2014, 18:15
  • Roz Pidcock

There's a heated academic tussle going on over climate predictions. A high profile group of scientists has criticised the results of a paper published in Nature last year, which made some very precise forecasts for when different parts of the planet would feel the effects of climate change.

Last year's paper predicted to within a year or two when different regions would consistently see temperatures exceeding the bounds of natural variability. Writing in Nature today, the paper's critics say that's a level of confidence that can't be supported by our current understanding of climate science.

What may sound like a fairly technical dispute raises some tricky questions about the limits of science, and the way journals choose what to publish.

"Unprecedented" climate change

In October last year a Nature  paper got quite a bit of attention from the media with some bold statements about when different regions of the world can expect to enter the realms of "unprecedented" climate change. We covered it, here.

Reuters talked about a "shift to a new climate", while the  Daily Mail opted for the punchier ''Apocalypse Now: Unstoppable man-made climate change will become reality by the end of the decade'.

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