the climate brief Accurate Reporting of Climate Science

A Nature study released yesterday says that warming of the Gulf Stream in the past 5000 years has triggered the release of methane into the ocean that was once locked up in the seafloor. Since methane is a potent greenhouse gas, we ask how will the release affect global warming. 

Under high pressure and low temperature in the sea bed, methane combines with water to form frozen methane hydrate. Some scientists have raised concern that rising ocean temperatures could thaw hydrates, potentially releasing methane to the atmosphere. Scientists have already found that  ten times more methane  is escaping from melting permafrost in the Arctic than previously thought.

Since methane is a powerful greenhouse gas, around 30 times  more potent than carbon dioxide, researchers fear that methane in large enough quantities in the atmosphere couldaccelerate global warming. This has led some media outlets to talk about gas hydrates as  "the methane time bomb". We have discussed the appropriateness - or otherwise - of this phrase before.

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Last week was a  big week for skeptics and climate scientists debating the long-standing (but  wrong) claim that global warming has stopped. Just to recap, skeptic journalist David Rose provoked  a huge response following his article in the Mail on Sunday last week, entitled "global warming stopped 16 years ago - and here's the graph to prove it". He suggested that the alleged finding was contained in a Met Office report that had been released under the radar. 

Although the Met Office and a host of scientists, commentators and bloggers criticised Rose's analysis, he published another article in this week's Mail on Sunday  sticking to his original story. Rather than treading more carefully around the scientific data this time, Rose made no acknowledgement of his previous mistakes and even threw a few more erroneous claims in for good measure.

The new article includes a climate Q and A and an invitation for readers to "decide what the real facts are". So we do just that by taking a look at what he says this time round.

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It's been a busy week for climate skeptics and myth debunkers alike. David Rose's Mail on Sunday  article, in which he rehashed an old and widely discredited claim that "global warming stopped 16 years ago", very quickly went viral. Many  media outlets  worldwide chose to accept Rose's version of events unquestioningly. But science hit back and this week has seen a plethora of rebuttals of Rose's claims, including one  we published  on Monday. Here's our pick of the best of the rest.

Rose's version of events

In his article, Rose presents the graph below, which shows global atmospheric temperature data for 1997 to 2012 compared to the average for this century, and uses it to claim that it is proof that global warming has stopped.

You can read our full explanation of why Rose's claim is unjustified  here. But to summarise, the period in question shows  reduced warming  compared to previous decades. Such periods are not unusual in the historical record, however. Natural variability in earth's climate, due to things like the  El Niňo/La Niňa cycle, also affect global temperature. This means you have to look at the trend over a much longer time period than 16 years. Just looking at land surface temperature also ignores all the other ways we know the planet is warming, like melting ice sheets and absorption of heat  by the oceans.

Six articles explain why different aspects of Rose's article are unfounded:

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Source: NOAA

The frequency and intensity of hurricanes making landfall in the United States is being carefully monitored, as scientists look for patterns in extreme weather. According to an article in the  Independent, a new study has found "support for the controversial idea that global warming is causing more frequent and destructive hurricanes" - but the authors say that's not what their research concludes.

The study was intended to create a record of hurricane activity which could look further back than the satellite record. It shows that during warm periods over the last 90 years, hurricane activity along the southeast coast of the United States was higher. It also found the chances of a major storm doubled compared to cool years. But this isn't quite the same as the Independent's headline, which says that "Global warming is 'causing more hurricanes'''

Linking climate change and hurricane activity is incredibly complex, and at the moment there isn't enough scientific evidence to definitively make the link. So how did the Independent come to this conclusion? We take a look at the study in more detail, and investigate the difficulties of attributing the longer trend.

More activity in warmer years

The study found evidence that hurricane activity increased in warmer years in tide gauge records, taken from 6 locations along the coastline. The records document times when the sea level rose rapidly due to the storm surges accompanying hurricanes. By looking at this, the researchers were able to determine how the activity of landfalling hurricanes changed between 1923 and present day.

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What do you get when a celebrity gardener and writer of  erotic fiction discusses the science of climate change with a climate skeptic weather forecaster and an astronomer? Answer: a misleading combination of half-truths and downright nonsense on the Alan Titchmarsh programme yesterday.

The segment in question kicked off with a discussion - in the loosest possible terms - on the UK's recent wet summer. Titchmarsh began by posing the question:

"Why is Britain experiencing such extreme weather? Is it something we have to get used to, or have we seen it all before?" 

Titchmarsh's guests were "stargazer and weather watcher" Mark Thompson and well-known climate skeptic Piers Corbyn. Corbyn is an  astrophysicist who runs WeatherAction, an organisation specialising in long-range weather forecasts - although it is notably cagey about its  secret forecasting formula. Suffice to say it is not based on mainstream climate science.

The bizarre exchange that followed led us to wonder: How many widely discredited skeptic myths about climate change (and some new weird ones) can you fit in one eight-minute slot?

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A group of world leading ocean scientists has written a letter to the Guardian today expressing serious concern about the 'world's biggest geoengineering experiment' that took place in the Pacific Ocean this summer. We take a closer look at the letter and scientists' fears about what the 'experiment' could mean for our oceans and the future of our climate. 

Yesterday, the  Guardian reported that controversial Californian businessman Russ George illegally dumped 100 tonnes of iron sulphate into the Pacific ocean. The dumping, which took place in July off the west coast of Canada, appears to have been an attempt at 'ocean fertilisation' - a proposed geoengineering method to reduce atmospheric carbon dioxide by locking it up in the deep ocean.

Carbon Brief has seen a letter sent to the Guardian by the In-Situ Iron Studies (ISIS)  consortium - an international group of scientific experts in ocean fertilisation. It voices concerns about George as a "rogue geoengineer". Professor Richard Lampitt, co-chair of the ISIS consortium, told us this morning:

"[W]e are writing to the Guardian to make absolutely clear that we deplore this irresponsible approach to such activity".

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COP11 in Hyderabad is probably the biggest climate adaptation conference you've never heard of.

Representatives from more than 192 countries have travelled to India, drawing a crowd of 14,000 delegates to the UN Convention on Biological Diversity's bi-annual summit.

But aside from a solitary New York Times journalist who arrived on Monday, media coverage outside India is fairly low-key. This is a pity, as the subjects up for discussion are fascinating, and directly relevant to the climate debate.

In the past week geo-engineering, biofuels, REDD+, coastal protection strategies and increased environmental finance commitments have all been on the agenda.

For delegates here it is simple. The future of the oceans, forests and endangered species all depend on how high global temperatures will rise.

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Based on mainstream media coverage from recent months, you'd be forgiven for being a little confused about what's going on with melting ice in the poles. Last week, the Daily Mail quoted scientists saying that sea ice is at record high levels in the Antarctic and calling the science of manmade climate change into question. We take a look at how the Mail has, once again, cherry-picked climate data to tell half of the story.

Half-truths

The Mail article explains, quite correctly, that the amount of ice that floats on the water around Antarctica - known as sea ice - is on the increase. The US National 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 on 26 September this year. The graph below shows the extent of sea ice this winter relative to the average between 1979 and 2008.

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We know that rising temperatures can lead to melting of some of earth's great bodies of ice - and given enough time, even their disappearance.

But a new study suggests that greenhouse gas emissions could affect the stability of ice in a much more fundamental way - at the atomic level. Theoretical modelling by physicists at the Massachusetts Institute of Technology suggests the presence of carbon dioxide makes ice weaker, and more prone to crack. 

The modelling simulates on a tiny scale how molecules of carbon dioxide can interfere with water crystals in ice. But what the consequences are for larger scale ice melt remains to be seen.

The theory

Normally, water molecules in ice are attracted to each other because their constituent parts have a small electrical charge. The hydrogen in one molecule of water, which is slightly positive, is attracted to the oxygen in another molecule, which is slightly negative. These attractions help give ice its structure.

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Despite it being a good idea to carry sunglasses, an umbrella and snow provisions at all times in the UK to be truly prepared, people generally want to be told something certain about the weather. But forecasting how earth's climate system will evolve in the next few hours, days, weeks and months is far from an exact science.

Following our blog last week from the Royal Society meeting on uncertainty in weather and climate prediction, we take a look at what uncertainty in forecasting means to the general public.

In forecasts we see online, climate scientists express some of the uncertainty by giving probabilities rather than a precise prediction. For example, the Met Office predict a 80 per cent chance of rain in London this afternoon. But when the Met Office started to do this last year, complaints in some parts of the media revealed some of the issues scientists face.

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