Analysis

How an IPCC graph linked fossil fuel use to climate change, and why it led to a heated debate

  • 18 Nov 2014, 12:45
  • Roz Pidcock

Earlier this month, the Intergovernmental Panel on Climate Change (IPCC) released a major new report, summarising scientific knowledge on climate change.

It contained something of a milestone in IPCC history - a chart linking greenhouse gas concentrations to fossil fuel emissions, rising global temperatures and sea level.

That might sound fairly innocuous. But some countries argued against its inclusion. So why was a figure outlining the well-understood link between carbon dioxide and climate change contentious?

Connecting the dots

The new figure charts the growth of atmospheric greenhouse gases over the industrial period, alongside rising emissions from fossil fuels and changes in global temperature and sea levels.

Synthesis Report _1point 1D

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Imported meat comes with a climate cost, new study warns

  • 17 Nov 2014, 15:03
  • Robert McSweeney

Cow and wind turbines | Shutterstock

A lot of the meat we eat is produced in a different country from the one we live in. A new study finds that greenhouse gas emissions from the beef, pork and chicken traded across borders have risen by 19 per cent in the past 20 years.

Not only might this affect diets of the climate-conscious, but a trend towards eating meat produced in a different country could make monitoring countries' individual emissions a far trickier task, say the researchers.

Livestock emissions

Carbon dioxide is the biggest contributor to climate change, but other greenhouse gases such as methane and nitrous oxide play a role too. The methane and nitrous oxide produced by livestock, such as cows, pigs and chickens, account for around nine per cent of all greenhouse gases emitted worldwide.

When you include methane and nitrous oxide emissions from transporting the animals and producing their feed, this proportion rises to 18 per cent.

A new study, published in Environmental Research Letters, finds that although the majority of meat is eaten in the country where it's produced, more and more meat is being exported.

So which country should be held responsible for the greenhouse gas emissions? The one where the meat is produced or the one where it's consumed?

The researchers say the growing demand for internationally-traded meat makes it harder to regulate emissions from farming.

Emissions from trade slipping through the cracks

All existing national or international policies to limit greenhouse gases take account of emissions from within specific countries only. So if the UK imports a tonne of beef, for example, the greenhouse gas emissions from producing it are not counted in our inventory.

You might think the emissions would be counted by the country producing the beef, but that might not be the case. The researchers say it's increasingly likely that meat is being imported from developing and emerging nations, which often have less stringent accounting of greenhouse emissions.

So the emissions from that tonne of beef may not be counted by either country, and instead may just 'leak' between the gaps in the system, say the researchers.

Beef the worst emitter, but others are catching up

Of the meat traded from one country to another, the study finds beef makes the biggest contribution to emissions, responsible for around three-quarters of the GHGs produced.

The research takes account of methane produced as livestock digest food (yes, farting) and the methane and nitrous oxide released as manure decomposes.

Emissions from traded pork (20 per cent) and chicken (six per cent) production are much lower by comparison, but are growing much more quickly. Between 1990 to 2010, the emissions from traded beef grew by around four per cent, while those from pork and chicken grew by 81 per cent and 360 per cent, respectively. You can see this in the charts below.

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US lightning strikes to increase under climate change

  • 13 Nov 2014, 19:25
  • Robert McSweeney

Lightning over field | Shutterstock

Climate change is likely to increase the number of lightning strikes, according to a study that models the effect of a warmer climate on lighting in the US.

Lightning already strikes the US about 25 million times each year, causing dozens of deaths and millions of dollars' worth of damage from fires. The study finds the number of strikes could increase by around 50 per cent through the 21st century.

Static electricity

When static electricity builds up in large storm clouds it can discharge as lightning, either extending into the air, within the cloud itself, or striking the Earth's surface. The electricity is generated as water droplets and ice crystals bump into each other as they rise and fall within the cloud.

There are around 25 million lightning strikes in the US every year, mostly on the eastern side of the country. The map below plots them.Romps Et Al (2014) Fig1

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Six years worth of current emissions would blow the carbon budget for 1.5 degrees

  • 13 Nov 2014, 11:00
  • Roz Pidcock and Rosamund Pearce

It will take just six years of current emissions to exhaust a carbon budget that would give a good chance of keeping global warming below 1.5 degrees Celsius, based on figures from the Intergovernmental Panel on Climate Change (IPCC).

The IPCC's new budget,  revealed earlier this month, calculates the remaining amount of carbon dioxide humans can emit and still hope to cap global warming at less than 1.5 degrees Celsius above preindustrial levels.

Limiting warming to 1.5 degrees has become a political rallying call for some nations and Non-Governmental Organisations (NGOs).

The IPCC's calculations suggest hopes of preventing temperatures from ever crossing the 1.5 degree threshold are slim to none. But the IPCC highlights that options to temporarily exceed the target and return to lower temperatures later in the century could still be on the table.

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Warmer temperatures and more acidic oceans put crabs into survival mode

  • 13 Nov 2014, 08:43
  • Robert McSweeney

Porcelain crab | Adam Paganini

The combined effect of rising temperatures and a more acidic ocean will make it harder for seashore crabs to grow and reproduce, a new study finds.

The results suggests that other marine species could be affected too, the researchers say.

Basic functions

The oceans absorbs around 30 per cent of the carbon dioxide we emit into the atmosphere. When carbon dioxide dissolves in water, carbonic acid is produced, which makes the oceans more acidic. The oceans have become around 26 per cent more acidic since the industrial revolution and this is projected to increase further under all scenarios of the Intergovernmental Panel on Climate Change.

New research, published in The Journal of Experimental Biology, studies the impact of ocean acidification and higher air temperatures on the porcelain crab, which lives in rocky shorelines on the coasts of the Indian and Pacific Oceans.

The results show that warmer, more acidic conditions mean the crabs have to put a greater proportion of energy into the basic functions of living and breathing, leaving less for anything else.

This could be an indicator for other species in the 'intertidal zone', or seashore, too. As co-author, Professor Jonathon Stillman, explains: "future intertidal zone animals may experience reduced rates of growth, behavior, or reproduction."

High- and low-tides

While previous studies have tested the impact of constant high temperatures and acidity on sea creatures, this isn't typical of the conditions on the seashore.

Air temperatures in the intertidal zone can change by 20°C within six hours, while acidity levels can vary between day and night and from one season to the next. This study tests temperature and acidity that peak and fall during the day.

In order to test the crabs under these conditions, researchers constructed a specially-designed aquarium, which could simulate high- and low-tide as well as different temperatures and acidity.

They simulated 'low-tide' in the aquarium for seven hours each day, reducing the water and increasing the air temperature. Then for five hours of 'high-tide' they submerged the crabs with water and brought the air temperature back down. They tested three scenarios of higher temperature and higher acidity (no change, moderate change and extreme change).

Combined effects

After two and a half weeks in those conditions, the researchers tested the metabolic rate and thermal tolerance of the crabs.

The findings show the combination of higher temperatures and more acidic water cause the crabs' metabolic rate to fall by as much as 25 per cent. You can see this by the green line in graph A below. The metabolism of the crabs slowed down, leaving them less energy to use in finding food, reproducing, or growth.

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Flood warnings could come three days earlier, study suggests

  • 11 Nov 2014, 16:26
  • Robert McSweeney

Flooding in Cambs | Shutterstock

This week the Met Office published its   three-month outlook, giving a glimpse of likely weather for this coming winter. The forecast says predictions "favour"  near-or above-average rainfall between now and the end of January.

This might not sound like good news for those affected by last year's wettest winter on record, which saw the Environment Agency issue 14 severe flood warnings and evacuate 1,000 homes in the Thames catchment alone.

But a crumb of comfort might be that scientists are working on a way to predict the heavy rainfall that can cause flooding further in advance. A new study says that forecasting of heavy rain and storms could be happen as much as three days earlier by tracking water vapour instead of rainfall.

Flood forecasting

The study, published in Nature Communications, suggests that examining water vapour provides a more reliable way of predicting flood events than rainfall. The researchers use the example of the widespread flooding in Europe last winter to test their theory.

The UK has a range of organisations that track flood risk. In England and Wales, responsibility for flood risk information for the government and emergency services falls to the Flood Forecasting Centre (FFC). It was established in 2009 following the Pitt Review of the summer floods of 2007, and is jointly managed by the Met Office and the Environment Agency. These bodies are likely to be interested in how this new work could improve their own forecasting methods.

Water vapour

Water vapour can get transported around in the form of giant atmospheric rivers, like the one shown in the figure below.

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Study links hot weather to violent conflict in Africa

  • 10 Nov 2014, 20:57
  • Robert McSweeney

UN Peacekeepers | Shutterstock

Analysis of violent events in the past 30 years in sub-Saharan Africa reveals a link to high temperatures, a new study finds.

However, the researchers say the impact of climate is less important than many other social and economic factors. 

Heated debate

The relationship between climate change and conflict has prompted much heated debate among academics. A recent review of 50 studies found they consistently supported the theory that changes in climate can cause conflict, but the conclusion was roundly criticised by a group of 26 other researchers.

On the face of it, the connections might seem obvious. Climate change risks exacerbating competition for natural resources, causing displacement through climate extremes and natural disasters, or just making it harder for governments to manage existing problems.

Yet there is limited evidence of a direct link, partly because there are so many political, social and economic factors involved in conflict. In its recent synthesis report, the IPCC says there is "medium confidence" that climate change can indirectly increase risks of violent conflict by amplifying poverty and economic shocks.

These other factors are considered alongside climate in a new study published in Proceedings of the National Academy of Sciences, which analyses high temperature extremes and violent events in sub-Saharan Africa.

Violent events

The study uses temperature and rainfall data alongside a dataset of armed conflict events from civil wars and periods of instability, for the period 1980 to 2012. The maps below show this data plotted as 100km grid squares across sub-Saharan Africa.

On Map A, the dark pink areas show where the highest number of violent events have occurred in recent decades. For example, the borders between the Democratic Republic of Congo and Rwanda and Burundi show a large patch of dark pink, as does much of Zimbabwe, and Somalia on the westernmost point of Africa.

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Remote-control robots reveal why the Antarctic ice sheet is melting

  • 10 Nov 2014, 18:23
  • Robert McSweeney

Research ship | Thomspson et al ( 2014)

At current rates, ice sheet loss will become the most significant contributor to global sea level rise during this century, yet there is still a lot that scientists don't know about the underlying causes. This is partly because Antarctica is such a difficult place to take measurements.

But now robotic underwater gliders are giving scientists new insight into why the Antarctic ice sheet is melting.

Ice sheets

An ice sheet is a huge layer of ice that sits on land. The two on the Earth today are found on Antarctica and Greenland, but in the last ice age there were also ice sheets on North America and northern Europe.

The Antarctic ice sheet spans more than 14 million square kilometers, which is roughly the same size as the US and Mexico put together. The ice sheet also spills out onto the surrounding ocean in the form of ice shelves.

The Intergovernmental Panel on Climate Change (IPCC) estimates that the Antarctic ice sheet is currently losing around 150 billion tonnes of ice per year. One of the main areas of ice loss is from the Antarctic Peninsula, shown in the red rectangle in the map below.

 

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Climate change puts bees and flowering plants out of sync

  • 06 Nov 2014, 17:02
  • Robert McSweeney

Female mining bee | Shutterstock

Warmer spring temperatures are causing bees to hatch earlier, putting them out of sync with the flowers that they pollinate, a new study shows.

The researchers say the study is the first of its kind to show climate change affecting the sort of relationships between species that have evolved together over millions of years.

Successful pollination

Pollination by insects is hugely important for many plants. Insects are responsible for pollinating around 80-85 per cent of commercial crops, for example, amounting to around a third of global food production.

Successful pollination depends on insects being active at the same time the plants are flowering, and many plants have evolved specifically to attract particular insects.

The flowers of the Ophrys sphegodes, or 'Early spider orchid', for example, look like the female of its principal pollinator, the Andrena nigroaenea bee. The orchid even gives off a similar scent as the female.

This fools the male bees into thinking the flowers are females, and so they try to mate with them. Through this process, known as 'pseudocopulation', the bees unwittingly spread the orchid's pollen as they fly from flower to flower.

So far, so sordid. But the new study, published in Current Biology, finds that climate change is affecting this relationship, with implications for spider orchids and other plants that rely on pollinators. 

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Media round-up: The IPCC synthesis report

  • 04 Nov 2014, 16:54
  • Robert McSweeney & Rosamund Pearce

Rajendra Pachauri on Sky News

On Sunday the Intergovernmental Panel on Climate Change (IPCC) published its synthesis report, which summarises the findings of three huge assessment reports. It prompted a flurry of media coverage. Here are some selected highlights.

Broadcast media

  • BBC News discusses the "controversial" recommendation that fossil fuels should be phased out by the end of the century - "a huge undertaking". Since every attempt to negotiate a new climate treaty has failed, and with Paris on the horizon, the BBC asks: "has anything really changed?"

  • With the "glacial" pace of the UN negotiating process,  Channel 4 news asks: can we adapt fast enough? Professor Joanna Haigh argues that climate change has not dropped of the agenda, discusses geoengineering versus preventative measures, and the value of the political process.

channel4news.png

  • In The IPCC report: why it matters, the BBC debates why another report was needed right now. Scientists believe that political leaders are in the process to agree a new climate deal - and they want to give them the most succinct report for this - "It may be the runt of the litter in size, but in political terms, it could turn out to be a real heavyweight".

  • In Climate change action will cost, the BBC broadcasts Ban Ki-moon's speech at the launch of the report.

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