the climate brief Accurate Reporting of Climate Science

The UK Met Office has just released its latest 30-year climate average. Readings show the UK's annual mean temperature calculated over a thirty year time period has risen 0.52 degrees Celsius over the past two decades. The data handily illustrates scientists' explanation that long-term warming is continuing despite temperature fluctuations over shorter timescales.

Warmer

The Met Office says the biggest departure from previous years is in the mean UK annual temperature. At 8.84 degrees Celsius, the annual mean temperature between 1981-2010 is 0.25 degrees Celsius higher than during the 1971-2000 period, and 0.52 degrees Celsius warmer than it was between 1961 and 1990.

Mike Kendon of the Met Office National Climate Information Centre says in a statement:

"At a regional level and for individual seasons we expect variability on decadal timescales, from natural cycles, to play a role. Nevertheless, the increases in UK annual mean temperature are consistent with the trend in warming observed globally over land."

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Jim Elliott/British Antarctic Survey/AP

Two new research papers published today improve our understanding of the planet's methane emissions, and might raise worries about the role of the gas in warming the planet. The first suggests that there may be extensive methane deposits under the Antarctic ice sheets. Meanwhile, the second concludes that emissions of the gas from Arctic permafrost have been underestimated.

Methane is a potent greenhouse gas - accounting for around  14 per cent of the warming effect of current man made greenhouse gas emissions. Recent research has focused on measuring emissions from methane sources, both natural and manmade.

Antarctic methane reservoirs

Scientists have been particularly interested in methane emitted from the Arctic. This is because the region is warming particularly rapidly. In addition, methane released from melting  permafrost and escaping  methane hydrate deposits could exacerbate climate change. But  research published today in the journal Nature suggests for the first time that there might also be large stores of methane at the other end of the planet, under the Antarctic ice sheet.

Plants thrived on Antarctica before the continent was covered by ice some 35 million years ago. Lab experiments show that microbes living beneath the ice are able to convert plant remains into methane, and scientists calculate that half of the West Antarctic Ice Sheet (1 million square kilometers) and a quarter of the East Antarctic Ice Sheet (2.5 million square kilometers) could cover carbon-rich sediments containing up to 4 billion metric tons of methane in the form of methane hydrates. These are an ice-like substance formed when methane and water combine.

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Energy and Climate Change (ECC) Committee chair Tim Yeo has argued that a third runway at London airport Heathrow will not lead to extra greenhouse gas emissions due to the aviation sector's inclusion in the EU Emissions Trading Scheme (ETS) this year. Could he be right?

Yeo was originally against the plan to increase Heathrow Airport's capacity because he said a new runway would lead to an increase in greenhouse gas emissions. But now, he's changed his mind.

As he wrote in a Telegraph column this weekend, he thinks the European Union's decision to include aircraft emissions in the overall EU emissions cap in January means that as long as other industries continue to cut their emissions, the UK can afford to increase its aviation capacity. He writes:

"Even if we covered the whole of Surrey and Berkshire in new runways it wouldn't actually lead to a single kilogram of extra greenhouse gas emissions taking place."

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Last week, a number of institutions announced that sea ice in the Arctic had reached its lowest since satellite records began in 1979. The Danish Meteorological Institute, the Japan Aerospace Exploration Agency and the Norwegian  Arctic ROOS all announced that according to their measurements, a record low had been reached.

These records had by and large failed to make the news until the prominent US research group the National Snow and Ice Data Centre (NSIDC)  reported on Monday that daily extent is now the lowest in the satellite era. It says: 

"Arctic sea ice extent fell to 4.10 million square kilometers (1.58 million square miles) on August 26, 2012. This was 70,000 square kilometers (27,000 square miles) below the September 18, 2007 daily extent of 4.17 million square kilometers (1.61 million square miles)."

Since it measures sea ice minimum extent over the course of the month, NSIDC says its announcement isn't yet official. But that didn't stop almost every major media outlet from reporting the figures. 

The media covers it

To find out what the new record low might mean for climate change, most outlets asked scientists.

Weather in the region affects how the ice melts. Both  The Independent  and  The Guardian, quoting Mark Serreze at NSIDC, report that beyond an early storm in August, weather patterns this summer have not been out of the ordinary, but after many years of warming "the ice is so thin and weak now, it doesn't matter how the winds blow." 

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Source: British Antarctic Survey

A  study published in Nature last week documents temperature changes in the Antarctic Peninsula over the last 15,000 years - and predicts that if recent rapid warming continues, previously stable ice shelves could be threatened. Although the research makes no attempt to attribute the warming effect to any one cause, it would be hard to work that out from some of the coverage of the report online and in the media, which has absorbed the findings into familiar arguments about whether climate change is happening or not.

The ice sheet covering Antarctica is simply enormous, concealing an entire continent and extending into the surrounding ocean as great ice shelves. The research concentrated on documenting temperature changes in just one part of the continent - the Antarctic Peninsula - which has experienced  rapid warming over the last few decades.

The study's authors were, in fact, very careful to put the modern changes observed in weather station records and satellite images into the context of longer-term climate trends - and they report these temperature changes without any attempt to attribute the causes.

That hasn't stopped several outlets from imposing their own narrative on the study. Climate skeptic IT blog  The Register claims, for example, that this latest research proves "warming is nothing unusual", despite the paper itself describing warming in recent decades as 'unusual'. Another skeptic blog,  Watts Up With That, headlines its article "Antarctic peninsula was 1.3°C warmer than today 11,000 years ago".

In contrast to the 'nothing to see here' stories, others have inferred that the warming is human-caused.  The Australian headlines its article 'Humans partly to blame for Antarctic ice shelf collapse: study'.  NPR, meanwhile, says 'Humans' Role In Antarctic Ice Melt Is Unclear'. But the study doesn't discuss the causes of warming.

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Photo: Dirk Ingo Franke

The Telegraph is claiming that the body that oversees visualisations for new UK wind turbine developments has accepted that photographers are using "tricks" to make windfarms seem smaller. We contacted the organisation, Scottish Natural Heritage (SNH), to find out more - and it turns out that's not quite true.
 
Small, or far away?

Is that windfarm small, or is it far away? According to the article, deciding how large something is in comparison to the landcape is more complicated than our normal sense of perspective might suggest.

The industry standard for wind farm visualisation involves imposing images of the proposed wind turbines onto a panoramic photograph taken using a 50mm lens. The Telegraph article, largely based on the views of Inverness-based architect Alan MacDonald, argues that this is misleading because it makes the wind turbines appear smaller. The article says:

"....the wider the angle and the further away the zoom, the smaller the objects in the picture will look.

"In the most extreme cases a turbine can be made to look four times smaller than the reality, according to Mr MacDonald. Expert analysis shows that a much more accurate picture of what people living by the wind turbine will see is using a single frame and 75mm focal length."

The expert analysis the article refers to is MacDonald's own assessment. His company, Architech, creates visualisations and 3D models for planning applications.

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New research monitoring cloud cover over the world's land areas for the last four decades agrees with previous studies indicating that the planet's tropical climate zones are expanding, and that consequently the atmospheric jet streams are shifting towards the poles, altering patterns of cloud cover. But skeptic blogger Anthony Watts claims the research provides evidence for the unconventional suggestion that clouds are responsible for global warming. We asked the researchers if they agree with his interpretation.

The  paper, currently in press at the Journal of Climate, also finds that cloud cover over land has decreased by around 0.4 per cent per decade, due to a decline in middle and high atmosphere clouds in the mid-latitudes - roughly between 30 and 60 degrees latitude.

The paper's authors write that their "dataset offers few surprises": it shows similar trends to the existing record of cloud observations that it updates. The researchers explain that the decrease in mid-latitude cloudiness over the last four decades is consistent with expanding tropical climate zones, adding further weight to the evidence that the planet is warming.

But climate skeptic blogger Anthony Watts interprets the new research differently. Watts suggests the research bolsters a hypothesis proposed by skeptic scientist Dr Roy Spencerthat runs counter to mainstream scientific thinking. Spencer  claims that clouds, not greenhouse gases, are causing the planet to warm.

We asked the paper's author Ryan Eastman, research scientist at the University of Washington, whether he agrees with Watts's interpretation of his research. Eastman, who seems surprised by the attention his research has generated, says that Watts' conclusions are "misleading".

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US carbon dioxide emissions fell to a 20-year low at the beginning of 2012, partly due to lower natural gas prices as a result of domestic production of shale gas -  a fact that hasn't escaped the attention of the press. But does this signify anything for the US's ability to reduce its energy-related emissions in the future? And what does it mean for the global picture?

The figures, which the US Energy Information Administration (EIA) released on 1st August show carbon dioxide emissions from the US energy sector during the first quarter of 2012 (January to March) were the lowest for that part of the year since 1992. See the graph below:

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A new analysis by Clara Deser and colleagues (accepted for Nature Climate Change), provides some fantastic visualisations of the crucial role of natural variability in how we will experience climate.

Essentially, Deser et al. perform 40 simulations with the same climate model and the same radiative forcings, but only change the initial state of the atmosphere. The only difference between the simulations will therefore be due to chaotic and rather unpredictable variability (the butterfly effect).

However, the trends in the simulations over the next 50 years can be remarkably different, with some showing little warming, and some showing a strong warming. It must be cautioned that they only use a single model, and other models might show different ranges of behaviour, but there is no indication that the variability in CCSM3 - the model used - is wildly wrong.

The examples they show are for North America (Fig. 1 below) - showing the average, warmest and coolest simulation for the U.S. with maps of the trend in winter (DJF) temperature. The timeseries show the maximum and minimum trends for the locations indicated, with the histograms showing the distribution of simulated trends. Globally, all the simulations warm by very similar amounts, but regionally the trends are extremely diverse. Versions of the figures for summer temperature and winter precipitation are also shown in the paper.

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Every year, sea ice in the Arctic grows and shrinks with the seasons. But it's also affected by other things like the weather, which play a large role in explaining changes from year to year. This means that although Arctic sea ice is  in long-term decline, that decline isn't uniform.

In 2007, the sea ice reached a record low - and since then a lot of attention has been paid to the summer melt season. The Arctic gets its fair share of misleading reporting, and with such a lot of coverage in the run up to the September sea ice minimum it can get confusing. To address this, we'll be regularly pulling together key points from the best coverage on Arctic summer melting.

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