Analysis

New study maps countries most at risk from El Niño flooding

  • 20 Oct 2014, 20:00
  • Roz Pidcock

From South America to the Sahel, scientists have for the first time mapped how flood risk rises and falls across the world each time the extreme weather phenomenon known as El Niño hits.

 

With an El Niño brewing in the Pacific right now, being prepared for flooding can help protect vulnerable communities and curb damages, say the researchers.

 

Changing rainfall

 

Every five years or so, a change in the winds in the equatorial Pacific causes a shift to warmer than normal ocean temperatures - known as El Niño, or cooler than normal - known as La Niña.

The warm and cool phases, together known as the El Niño Southern Oscillation (ENSO) affect rainfall patterns worldwide .

While scientists have looked before at the consequences for specific countries, such as Australia, the new study is the first to take a global view, mapping flood risk right across the world.

Flood _volume (Ward Et Al)

Percentage of land experiencing changes in flood volume with return periods of 100 years, during El Niño years (top) and La Niña years (bottom). Source: Ward et al. (2014)

 

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US military outlines plan to deal with increasing climate change threat

  • 14 Oct 2014, 15:00
  • Mat Hope

Flood trucks | US Navy

"A changing climate will have real impacts on [the US] military and the way it executes its missions", US Defense Secretary Chuck Hagel yesterday said. And the US military is planning how to deal with the threat now.

The Department of Defense's 2014 Climate Adaptation Roadmap, published yesterday, suggests climate change has the potential to exacerbate some of the world's most significant challenges, from disease to international conflict. It calls climate change a "threat multiplier" with the potential to increase the impact of numerous security concerns.

This  isn't the first time the US military has expressed its concerns about climate change. But the roadmap is one of the first documents to "really go into great detail about what the US military should be doing in response to climate change now" Francesco Femia, co-director of the Center for Climate and Security thinktank, tells Carbon Brief. The report shows that military has decided the risk from climate change "is great and it's immediate", Femia says.

New activities

The roadmap outlines a number of new ways climate change could cause the military to be called into action. Its findings are driven by two things, Femia says: developments in climate science and "what the military is seeing on the ground".

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How air pollution caused Europe’s rivers to fill

  • 06 Oct 2014, 17:02
  • Robert McSweeney

River Wisla | Shutterstock

Air pollution from Europe resulted in a 25 per cent increase in river flows in Poland and Germany during the late 20th century, a new study finds. The researchers say their findings show how the impact of burning fossil fuels is not just limited to increasing temperatures.

Solar dimming

In the sixties and seventies, air quality across much of Europe was very poor. Coal power stations and inefficient cars belched out tiny particles, known as aerosols, into the atmosphere. These aerosols caused widespread health problems and contributed to the famous 'pea-souper' smogs in London.

This new piece of research, published in Nature Geoscience, finds that these aerosols also caused an increase in the amount of water flowing in rivers across Europe.

Some sources of aerosols are natural, such as volcanoes, plant vapours and chemicals released by tiny sea creatures. However, since the industrial revolution, humans have been emitting more and more aerosols through fossil fuel burning.

One type of aerosols, called sulphate aerosols, are emitted from cars and power stations. Once in the atmosphere, these aerosols affect the climate in two ways. They directly scatter sunlight and reflect it back out to space. They can also react with clouds in complex ways, causing the clouds to reflect more light back out to space. This process, known as 'solar dimming', reduces the amount of the sun's energy that reaches the Earth's surface.

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Scientists weigh in on two degrees target for curbing global warming

  • 02 Oct 2014, 13:15
  • Roz Pidcock

Yesterday, two scientists published a  stern critique of the longstanding target to limit global warming to two degrees above pre-industrial levels.

Branding the target "wrong-headed" and "tenuous", the authors argue we should ditch the two degree target in favour of a suite of "vital signs" that would let us track the Earth's health.

The  commentary, published in the journal Nature, has  generated a  certain  amount of  interest. We asked climate scientists for their thoughts.

Setting a target

In 1992, the United Nations Framework Convention on Climate Change (UNFCCC) decided the objective of global climate policy should be to stabilise humans' influence on the climate below the level at which it can be considered "dangerous".

As temperatures rise, so do the risks of climate change. As the recent report on climate change impacts from the Intergovernmental Panel on Climate Change (IPCC) puts it:

"Increasing magnitudes of warming increase the likelihood of severe, pervasive, and irreversible impacts."

With governments worldwide recognising the need to keep rising temperatures in check, it's important to have a goal, Professor Nigel Arnell, director of the Walker Institute for Climate System Research, tells us:

"When we're trying to work out what future climate change might do and how to reduce it, you need some form of metric or indicator on order to judge how well particular policies achieve that goal."

A good indicator

Curbing temperature rise has been central tenet of climate policy for two decades. One of Victor and Kennel's main criticisms in the Nature commentary is the international community's narrow focus on temperatures at earth's surface.

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Get ready for hotter summers and more flooding in the UK, say scientists

  • 29 Sep 2014, 16:10
  • Roz Pidcock

Weather-wise, the UK saw it all last year. The coldest spring for 50 years, a sweltering summer heat wave and the wettest winter since records began. Today, a new report examines whether climate change is upping the odds of these events occurring.

The collection of papers, published in a  bumper edition of journal Bulletin of the American Meteorological Society, looks at 16 weather events that took place last year across the world. From Colorado to Korea, the scientists examine heatwaves, droughts, heavy rain and storms.

Human fingerprints

Globally, there is  evidence for changes in some types of extreme weather, and evidence for a human fingerprint in those changes. But different types of event are affected differently.

Climate change is greatly increasing the odds of heatwaves worldwide, today's report concludes. For storms, rainfall and drought the picture is less clear, however. Big differences between regions, natural variability in the climate and limited data make detecting changes over time far more difficult.

The science of disentangling human and natural influences on our climate is known as attribution. Dr Peter Stott, head of the climate change detection and attribution team at the Met Office and an editor on the report, explained more in a recent  guest blog  for us:

"[The aim is] to compare what actually happened with what might have happened in a world without anthropogenic climate change."

Understanding how our activities are changing the risk of some types of extremes is important for making decisions about how we can prepare for the future.

Hot summers

In summer 2013, western Europe experienced an extreme heatwave. Average temperatures for the June to August period sit just below those of 2003 - the hottest summer in Europe for at least  500 years.

At the same time, the UK experienced its hottest day since 2006 with temperatures of 33.5 degrees Celsius recorded at Heathrow airport, the report notes.

UKheatwave 2014

Sun-seekers flock to Margate in July 2013. Source:   UK heatwave via Shutterstock

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California is in drought, but is climate change to blame?

  • 29 Sep 2014, 15:43
  • Robert McSweeney

California dry ground | Shutterstock

On the 17th January 2014, California's Governor declared a State of Emergency. The drought that had taken hold the year before was showing no signs of abating, with rivers and reservoirs at record lows.

As the situation worsened through 2014, one question was asked again and again - to what extent was human-caused climate change playing a role? A new report out today says the evidence is inconclusive, although it says there are still questions to be explored.

'Ridiculously Resilient Ridge'

Over 95 per cent of California is currently experiencing at least 'severe' drought (shown in orange in the map below), with almost 60 per cent in 'exceptional' drought (deep red).

 

 

 

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China tops new list of countries most at risk from coastal flooding

  • 25 Sep 2014, 12:14
  • Robert McSweeney

Ride on flood | Shutterstock

Over 50 million people in China will be at risk from coastal flooding by the end of the century if greenhouse gas emissions continue to stay high, a new study finds.

The research shows Asian countries dominate a top-20 ranking of most vulnerable nations from rising sea levels, with China topping the list.

Interactive map

A team of researchers from the US climate news website Climate Central mapped sea levels around the world using a global database of tide gauge measurements. They then combined these measurements with projections of how much scientists expect sea levels to rise with climate change.

The result is an interactive map, showing the number of people in each country likely to be living with significant risk of flooding by the end of the century. The map can be adjusted for different scenarios of future carbon emissions and sea level rise.

The size of squares shows population at risk, while the colour indicates the proportion of total population at risk.

Climate Central _floodmap

Global estimates of population number (square size) and proportion (square colour) at risk from coastal flooding by 2100 by country. Assumes current emissions trends continue, and a central estimate of sea level rise.   New York Times

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Why isn’t the Arctic sea ice free already?

  • 23 Sep 2014, 13:30
  • Roz Pidcock

Diminishing Arctic sea ice is perhaps the most iconic impact of climate change. There's a good chance that before too long we'll lose it altogether in summer unless we cut emissions, scientists say.

But according to polar scientist Dr Dirk Notz, the question isn't why is Arctic sea ice melting so fast, it's how come we have any left at all?

Notz told a Royal Society conference in London this morning that with the additional heat earth is absorbing Arctic sea ice "should be long gone by now".

So why isn't it?

Arctic decline

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

                      Arctic Sea Ice Low _Sep 17

The National Snow and Ice Data Centre announced this year's Arctic sea ice minimum on the 17th September. At 5.02 million square kilometers, it was the 6th lowest on record. Orange line is 1981 to 2010 average extent for that day. Source:  NSIDC

 

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How TV news covered the Intergovernmental Panel on Climate Change’s three big reports

  • 23 Sep 2014, 00:01
  • Mat Hope

TV studio | Shutterstock

TV audiences around the world aren't hearing much about climate science.

That's the main conclusion of a new study looking at how TV news covered the Intergovernmental Panel on Climate Change's (IPCC) three big reports earlier this year.

While the IPCC's reports made a  small splash in the print media, the same wasn't true of television news. Media in many countries barely covered the reports. And when they did, they used an old-fashioned "doom" narrative to explain them, research by Oxford University's Reuters Institute finds.

That's concerning, because many people still get their news from the TV, and place particular trust in TV news to deliver a balanced account of climate science.

Here's which channels covered the reports, how, and why it matters.

Country divergence

The IPCC's first report on the science behind climate change was launched in October 2013. A second report on the impacts of climate change was released the final day of March 2014, with a  third report looking at policies to cut emissions following a couple of weeks later.

The Reuters Institute looked at how a selection of news bulletins in the UK, China, India, Brazil, Australia and Germany covered all three reports on their launch day, and the day before.

13 out of the 36 main news bulletins the Reuters Institute studied covered the IPCC reports. That adds-up to about 34 minutes of airtime.

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How climate-ready is your house?

  • 18 Sep 2014, 17:22
  • Robert McSweeney

Sandbags | Shutterstock

Are you pulling out all the stops to climate-proof your home? Have you installed ceiling fans, planted trees for shade and taken out flood insurance? It's unlikely you have, according to a new study of household actions in the UK.

While we make simple actions to deal with a cold snap or heatwave, the research finds, households are struggling to prepare for long-term changes in climate.

What action can you take?

As global leaders prepare to convene in New York to discuss how to curb greenhouse gas emissions, a new paper discusses another side to limiting climate change - adaptation.

Adaptation means taking steps to increase our resilience against climate change that our past emissions have already committed us to, impacts that are now unavoidable.

The study, published in the journal Climatic Change, looks at adaptation measures people can take in their own homes. And the good news, is some actions are easy.  You've probably done many without realising. Putting on an extra jumper in a cold spell or eschewing the Sunday roast in favour of a salad during a heatwave are both adaptive responses.

Some actions aren't as simple as changing your diet or dipping into your wardrobe, however.

The study looks reviews published research on climate adaptation in UK households and finds that while we're pretty good at doing the easy things, we're not so great at making plans for the long-term.

A checklist

The paper runs through some adaptation options available to UK households, which we've illustrated in a checklist below. The list on the left are examples of actions for managing current risks, while the list on the right shows how to climate-proof for the longer-term.

 

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