Blog

Preserving corals could save billions in coastal defences - new study

  • 13 May 2014, 16:00
  • Ros Donald

In 2005, Hurricane Wilma whipped up 13-metre waves off the coast of Mexico. Yet when the waves reached the Caribbean sea's  Meso-American coral reef, the natural structure sucked 99 per cent of their power. 

This isn't an isolated incident. Scientists have found that not only do reefs reduce wave energy by an average of 97 per cent. 

Nearly 40 per cent of the world's population lives within 100 kilometres of the coast, and that figure is set to rise. As the risk of extreme weather events like floods and tropical storms  increases, so does the danger to populations and their livelihoods. 

Protecting coastlines is big business, and the cost of building defences is expected to rise significantly by the end of the century. So natural solutions could provide cost-effective options for adapting to the effects of climate change. 

In a new paper in the journal Nature Communications, scientists have collected available data on the role coral reefs could play in reducing climate risks to coastlines. 

They found that reefs perform as well as artificial defences like breakwaters, reducing wave energy by an average of 97 per cent. Better still, they're relatively cheap. The paper shows that restoring reefs costs one tenth of the outlay for building tropical breakwaters. 

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Scientists say West Antarctic ice sheet "collapse is under way" as temperatures rise

  • 12 May 2014, 18:00
  • Roz Pidcock

Scientists have long suspected the west Antarctic ice sheet is vulnerable to collapsing under rising temperatures - potentially raising global sea levels by several metres. Now new research suggests the process may already be underway.

It won't happen quickly - probably taking several centuries, say the researchers. But beyond a certain point, the process will be irreversible, they warn.

Scientists know from  satellite data that Antarctica is losing ice - more than  70 billion tonnes of it between 1992 to 2011.

But ice loss isn't happening at the same speed everywhere on the continent. Together with glaciers in the Antarctic peninsula, thinning glaciers along the Amundsen Coast on the West Antarctic Ice Sheet (WAIS) are responsible for most of Antarctica's contribution to sea level rise, which currently  totals about 0.27 mm per year.

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Hotter and wetter extremes: How scientists know our weather’s getting more erratic as climate change bites

  • 12 May 2014, 11:00
  • Roz Pidcock

From rising flood risk in the UK to record-breaking heatwaves across Australia, elevated greenhouse gases mean we're seeing warmer and wetter extremes in our weather than a century ago, says Dr Markus Donat.

Markus Donat researches extreme weather at the Centre of Excellence for Climate System Science and the Climate Change Research Centre at the University of New South Wales, Australia.

1. What type of weather events do you look at, and how do you define "extreme"?

My work focuses on temperature and precipitation extremes. In both cases, "extreme" means particularly high and particularly low values, compared to the expected range in a given region.

That means we look at peak temperatures and heat waves, as well as cold spells. For precipitation, "extreme" can mean unusually heavy rainfall over a single day or over several consecutive days. Unusually long periods without any rain are also a type of extreme event.

2. How do scientists measure extreme heat and rainfall events? How good is the data?

We've been working on creating a global database of observations, which means overcoming several big challenges. One issue is data gaps. We have very good observational coverage in the northern hemisphere and in Australia, for example, but large gaps in Africa and South America. Sometimes data exists in written archives, but has never been digitised.

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Adapting to climate change calls for a local approach, new research shows

  • 07 May 2014, 14:45
  • Roz Pidcock

Climate change affects every corner of the United States, concludes a new report for the White House. But while the northeast faces heavier rain and greater flooding, hotter and drier weather ups the risk of wildfires in the West Since climate change's impacts vary dramatically from place to place, so should the responses, the report notes. And as it happens, two more papers this week make a similar point for different parts of the world.

Assessing the climate

Yesterday, the United States government released a brand new National Climate Assessment for 2014 - a detailed look at climate change impacts across the country.

The report warns that climate change's ecological, economic and social impacts are already being seen across the country and in all sectors. But as well as talking about country-wide trends in temperature and precipitation, it focuses on smaller-scale climatic effects. It says:

"Because human-induced warming is superimposed on a naturally varying climate, rising temperatures are not evenly distributed across the country or over time"

Regional rainfall

Globally, a warmer atmosphere means a  shift towards  heavier downpours. The map below from the new report highlights how different regions have seen different increases in the frequency of extremely heavy rainfall, however.

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Q & A: What’s El Niño - and why does it matter that scientists say one is on the way?

  • 24 Apr 2014, 12:50
  • Roz Pidcock

Forecasters worldwide are issuing alerts. Later this year, we're likely to be in the midst of an El Niño - a phenomenon driving severe weather worldwide. So when can we expect it to kick in, and what will the consequences be for global temperature? Find this and more in our quick Q & A.

What is an El Niño?

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

Both phases together are known as the El Niño Southern Oscillation (ENSO), and are responsible for most of the fluctuations in global weather we see from one year to the next.

ENSO

Sea surface temperature during El Niño (left) and La Niña (right). Red and blue show warmer and cooler temperatures than the long term average. [Credit: Steve Albers, NOAA]

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IPCC review of farming and forests leaves key questions about effect on climate change "unresolved"

  • 17 Apr 2014, 12:15
  • Robin Webster

The rate at which we're chopping down the world's forests is declining - and in future, crops and newly planted forests could help prevent more climate change, according to the UN.

But uncertainties surrounding how we measure emissions, and what changing temperatures will mean for the world's forests, mean it's hard to be sure this is a good news story.

Emissions from farming, deforestation and other land use are going down, and are expected to continue doing so in the future. By the end of the century, humanity could use the land as a carbon sink, rather than a source of emissions, according to the Panel on Climate Change (IPCC)'s latest  report

It sounds like one piece of good news among  gloomy predictions from the IPCC. But human land use is only one part of a complex picture. 

Climate change could lead to forests  drying out, releasing more carbon dioxide in the atmosphere. And using trees, crops and plants as a source of energy instead of fossil fuels could also lead to more forest destruction.  

Declining emissions

Agriculture, forestry and other land use account for about a quarter (24 per cent) of man-made greenhouse gas emissions. Most of these emissions come from deforestation, changes to the soil and livestock farming.

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Degrees of change: the IPCC’s projections for future temperature rise

  • 15 Apr 2014, 12:00
  • Robin Webster

Many governments are trying to reduce greenhouse gas emissions. But unless policymakers raise their ambition significantly, temperatures are likely to rise beyond safe levels. We examine the pathways that could take us towards a two degrees temperature rise by the end of the century - or considerably higher. 

On Sunday, the Intergovernmental Panel on Climate Change (IPCC) released the last in a series of three reports, which together assess the physical evidence that climate change is happening, the  expected impacts over the course of this century and what would need to happen to curb the rise in greenhouse gases.

Embedded in the reports are the scientists' predictions for how high temperatures are likely to rise this century - and what that's likely to mean for ecosystems and societies around the world. 

Comparing scenarios 

The IPCC bases its projections for future temperature rise on two different techniques. 

First, the IPCC has created its own storylines, or scenarios, describing how high temperatures are likely to rise in the future and what that might mean. The scenarios vary according to different predictions for how societies develop and how much effort we make to reduce greenhouse gas emissions over the course of this century.

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Climate fixes and Plan Bs: The IPCC’s guide to staying below two degrees of global warming

  • 14 Apr 2014, 13:10
  • Roz Pidcock

Cutting emissions, ramping up renewable energy, adapting to a new way of life and sucking carbon dioxide out of the air: recent reports from the Intergovernmental Panel on Climate Change (IPCC) appear to offer a number of ways to limit the scale and seriousness of climate change.

Which are the real climate solutions, and which are pretty risky bets? Here's what the IPCC says about what will and won't work when it comes to fixing the climate.

The two degree target

What we can do to curb the  impacts of climate change is the topic of the  third in a series of recent reports from the IPCC. But when we talk about limiting climate change, what do we really mean?

The idea that we should avoid "dangerous" interference with the climate has been around for a while. But at the UN climate summit in  Cancun in 2010, governments made the goal of keeping warming to no more two degrees Celsius above pre-industrial levels an official target.

The world has already warmed by 0.85 degrees over the industrial period and if emissions stay high, we're on course for more like three to five degrees by 2100, the IPCC  noted in its September report.

In other words, without efforts to reduce warming, we're set to fall a long way short of the target.

RCP2.6-8.0

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Media reaction: The Intergovernmental Panel on Climate Change's big climate mitigation report

  • 14 Apr 2014, 12:50
  • Mat Hope

While many were still engulfed in their duvets recovering from the night before, the UN spent Sunday morning launching a big report on strategies to tackle climate change. The report was the third instalment of the Intergovernmental Panel on Climate Change's (IPCC) major review of the most up-to-date climate change research.

If you've been too busy to catch up on the swathes of media coverage since then, have no fear - we've speed-read it all for you:

International cooperation

A significant proportion of the media focused on the report's message that there is still time for countries to act to avoid the worst impacts of climate change - but only if they work together.

  • The  Financial Times said the IPCC was sure there is "still time to save the world". It quotes one of the report's co-chairs, Ottmar Edenhofer, saying the report carried "a message of hope"  that tackling climate change "can be done".
  • Doing so would mean cutting emissions "by up to 70% by 2050 if it is to prevent global temperatures rising by more than two degrees", the  Sunday Times reports. The IPCC's research shows "stabilising climate is humanity's biggest challenge", it adds.
  • Newswire  Agence France Presse described the report's findings as a "wake up call" for governments. It said the IPCC identifies a 15-year window in which countries' will be able to act to avoid the worst impacts of climate change.
  • That means "governments must do more" to address rising emissions, the Washington Post argues. Countries must work together to lower emissions by 40 to 70 percent, according to the IPCC's findings, it said.
  • Taking a slightly different angle, the  Independent on Sunday was the only major UK newspaper to focus on the consequences of inaction. Unless the world acts soon, the IPCC says emissions could reach a level "that could reap devastating effects on the planet", the newspaper reports.

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Not just another climate report: main messages from the UN report on tackling emissions

  • 13 Apr 2014, 14:15
  • Robin Webster

If we're going to curb the rise in greenhouse gas emissions, the world's governments need to co-operate - and they're running out of time to do it. That's one of the top-line messages from the Intergovernmental Panel on Climate Change (IPCC)'s latest mega-report into current and future greenhouse gas emissions. 

Today's report is the last in a series of three from the IPCC. The first two summarised the physical evidence base for climate change and its potential  impacts on ecosystems and human societies. Now the organisation is looking at what's likely to happen to greenhouse gas emissions over the course of this century - and what possibilities there are for reversing the upwards trend. 

The full report runs to thousands of pages, providing an overview of all the research in the area. In order to complete it, the scientists assessed more than 1200 scenarios for how the future might unfold from different studies. The report's  summary is slightly more digestible, at just 33 pages. Here's our run-down of its key points. 

Emissions rising

Between 2000 and 2010, greenhouse gas emissions grew at 2.2 per cent a year -  a faster rate of increase than over the previous three decades. Human-caused emissions were "the highest in human history" in the first decade of this century, the IPCC says. 

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