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Surface warming ‘hiatus’ could stick around for another decade, say scientists

  • 21 Aug 2014, 19:00
  • Roz Pidcock

A flip-flopping natural fluctuation in the Atlantic is behind a recent slowdown in surface warming - and it's not due to reverse for another ten years, according to new research.

The theory outlined in a paper  published today in the journal Science disagrees with other research, which pins the blame for the so-called "pause" on changes in the Pacific.

We talked to some other scientists working in the field - and they don't seem convinced.

Puzzle solving

Scientists know greenhouse gases are driving up  global temperature. But data on land and  the surface of the ocean shows  slower than expected warming in the last 15 years or so.

Periods of slower and faster warming  aren't unusual. Scientists say the main reason we're seeing one now is because more heat is finding its way to the  deeper ocean, rather than staying at the surface.

But which ocean? Knowing where the heat is ending up might help scientists predict how long the hiatus will last.

Where Is Global Warming Going _infographic

More than 93 per cent of the heat reaching earth's surface goes into the oceans. Just 2.3 per cent stays in the atmosphere. Source: Skeptical Science

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‘Hiatus’ in surface warming is upping the odds of UK cold winters, say scientists

  • 17 Aug 2014, 20:20
  • Roz Pidcock

If you follow climate science, you'll be familiar with the so-called surface warming "hiatus". It's the fact that temperatures at earth's surface haven't climbed as much as expected in the last 15 years.

Now a  new paper published in Nature Climate Change says the slowdown in surface warming could be behind a spell of colder than average winters in the UK recently.

Screen Shot 2014-08-17 At 20.07.46

UK winters in 2009/10 were two degrees and 1.3 degrees Celsius below the 1971-2010 long term average, respectively. The 2012/13 winter was 0.4 degrees below the 1981-2010 average. Source: Met Office

Cause of the pause

Scientists know greenhouse gases are driving up  global temperature. But data on land and from the surface of the ocean shows  slower than expected warming in the last 15 years or so.

Scientists say periods of slower and faster warming  aren't unusual. Most of  why we're seeing one now is down to natural climate cycles causing the surface of the  Pacific Ocean to cool.

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Government data hints at future challenges for curbing natural gas emissions

  • 05 Aug 2014, 16:30
  • Mat Hope

CC 2.0

Gas plays an essential role in the UK's energy mix, providing heat for homes and electricity to sockets. While that's not likely to change in the short term, the fuel will need to be increasingly phased out as the government seeks to  decarbonise the energy sector.

A trawl through new government  data shows how far the UK's come in recent years, and hints at challenges to come.

Gas trends

The UK currently uses three trillion cubic feet of gas each year. That demand may need to fall by as much as  20 per cent over the next two decades if the UK is going to hit its  climate targets.

The Department of Energy and Climate Change's  Digest of UK Energy Statistics, released last week, shows how much would need to change for that to happen.

DECC's data shows gas demand has fallen 17 per cent in the last five years. But while demand has fallen significantly from 2011's high, its plateaued in recent years. Demand was only one per cent lower in 2013 compared to a year before.

Gas is mainly used for two things, as the blue and purple sections of the graph below show: generating electricity, and heating people's homes.

DUKES 2014 UK gas consumptionDECC's data shows gas is being used increasingly sparingly to generate electricity. The amount of gas used in electricity generation fell by 13 per cent last year. But that doesn't necessarily spell good news for the UK's emissions.  

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Climate scientists dub this year’s El Niño “a real enigma”

  • 04 Aug 2014, 14:40
  • Roz Pidcock

Last month, forecasters were predicting with  90 per cent certainty we'd see an El Niño by the end of the year, driving severe weather patterns worldwide. But with little sign so far of the ocean and atmospheric changes scientists expected, those odds have dropped off quite a bit.

We'll probably still see an El Niño before the year's out but it's unlikely to be a strong one, scientists are saying.  

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 - a phenomena known as El Niño.

Together, El Niño and its cooler counterpart La Niña are known as the El Niño Southern Oscillation (ENSO). Between them, they're 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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Three White House charts showing why the world needs to take immediate action on climate change

  • 30 Jul 2014, 13:40
  • Mat Hope

CC2.0 Intel Photos

President Obama has taken significant, if limited, steps to try and curb the US's emissions and tackle climate change. A new White House report explains why he appears to be acting with a sense of urgency: "delay is costly".

Yesterday, the White House's Council of Economic Advisers released a  report suggesting a 10 year delay could increase the cost of taking climate action by 40 per cent, as the world would have to take larger steps to curb emissions down the line. Furthermore, each degree of warming could lead to billions of dollars worth of additional damage, it says.

Here's three charts from the report showing why the council says policymakers need to act now.

Additional damage

The more the world warms, the more damaging the  impacts of climate change are likely to be - from more intense weather events, to diminishing crop yields and species migration and extinction. All these things have an economic cost, even if it's sometimes  hard to define.

And the council's study says the costs will rise as the world warms - as the blue bars on this graph show:

Additional Costs Chart

The White House report uses a model by Yale economist Bill Nordhaus to put a number on the potential impact of additional warming.

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Air pollution and climate change could mean 50 per cent more people going hungry by 2050, new study finds

  • 30 Jul 2014, 12:20
  • Roz Pidcock

The combination of rising temperatures and air pollution could substantially damage crop growth in the next 40 years, according to a new paper. And if emissions stay as high as they are now, the number of people who don't get enough food could grow by half by the middle of the century.

Burning question

Feeding the world's rapidly growing population is a serious concern.

Research shows  rising temperatures are likely to lead to lower crop yields. Other work suggests air pollution might reduce the amount of food produced worldwide. But nobody has considered both effects together, say the paper's authors.

The two effects are closely related as warmer temperatures increase the production of ozone in the atmosphere, the paper explains. 

The  new study looks at global yields of the four principle food crops - wheat, rice, corn and soybean - and how they're expected to change by 2050 under different levels of future emissions.

Together, these provide nearly  60 per cent of all the calories consumed by humans worldwide.

Global losses

The maps below show some of the results.

The top panel shows an optimistic scenario in which greenhouse gases stabilise at 630 parts per million (ppm) by 2100. For reference, we're at about 400 ppm now.

The team compared this with what might happen if greenhouse gases continue to rise as rapidly as they are now. That's the bottom panel.

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Why measuring fugitive methane emissions from shale gas production matters

  • 24 Jul 2014, 14:40
  • Mat Hope

CC 2.0 Tim Evanson

As an ever-increasing number of countries consider exploiting their shale gas resources, and researchers scramble to understand what a production boom could mean for the climate, two new pieces of research appear to come to opposite conclusions.

What is the climate impact of shale gas?

Since gas has about half the emissions of coal when it's burned for electricity, it has been touted as  a 'bridging fuel' for countries seeking to decarbonise their economies to use as a stop gap on the way to a low carbon electricity system.

But as we've  explored before, scientists are struggling to establish the full impact of increased shale gas production on the climate, due to methane that escapes during the extraction process - known as fugitive methane emissions.

Two papers released this month examine what the actual climate impact of natural gas is. At first glance they seem to show opposite things. The graph on the left, taken from a paper by Robert Howarth appears to show natural gas electricity generation emissions - the towering left bar - can be much higher than coal's. The second graph, from  Heath et al, appears to show the opposite - that coal's generation emissions (on the left) are much higher than those from both conventional and shale gas.

Howarth Vs Heath Coal And Gas Emissions

Both papers examine the 'lifecycle emissions' of the fuels: the amount of gas emitted from extraction to combustion. So why is there such a large discrepancy between two papers?

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Have satellites overestimated Antarctic sea ice growth?

  • 22 Jul 2014, 15:30
  • Roz Pidcock

It's puzzling why Antarctic sea ice seems to be growing while earth's other icy expanses are shrinking as temperatures rise.

Now new research questions whether there has been much of a rise in Antarctic sea ice after all. The paper suggests the small but significant growth scientists thought had occurred since 1979 could be little more than a "spurious artifact" of how satellite data is interpreted.

But other polar scientists tell us the implications of the new findings" are very limited indeed" and they're confident Antarctic sea ice is still growing.

Bucking the trend

Scientists know ice is being lost from both the Greenland and Antarctic ice sheets. They also know the amount of sea ice in the Arctic is rapidly decreasing.

But satellite data suggest the amount of sea ice around Antarctica has been growing since 1979. A report from the Intergovernmental Panel on Climate Change (IPCC) last year put the size of the increase at  1.5 per cent on average per decade.

For comparison, that's about a third of the rate of sea ice retreat in the Arctic. A  new paper just published in journal The Cryosphere explains the puzzle this poses for scientists:

"[T]here has been substantial interest in the trend in Antarctic sea ice extent … primarily because of the observed asymmetry between increasing ice extent in the Antarctic and rapidly diminishing ice extent in the Arctic, and the inability of current climate models to capture this."

The new paper raises an interesting point. It notes that the growth in Antarctic sea ice in the latest IPCC report is much bigger than suggested in the previous one in 2007. The authors say:

"[The 2007 report] reported the trend in Antarctic sea ice extent to be small and statistically indistinguishable from zero".

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Slow surface warming since 1998 is “not exceptional”, say scientists

  • 21 Jul 2014, 19:30
  • Roz Pidcock

Scientists know greenhouse gases are causing the world to warm. But an interesting question is why warming at earth's surface speeds up and slows down.

new paper shows surface temperature "slowdowns" like we're experiencing now aren't unusual - and capturing the timing of natural ups and down in the climate is key to predicting them.

But as a  second paper explains, the planet as a whole has warmed up in the last decade even as surface temperature rise has been sluggish.

Model mismatch

Temperatures are rising due to long term greenhouse gas warming. But natural variability causes temperatures to go up and down from one year to the next.

Natural variability can at least partly explain slower surface warming in the last 15 years, the Intergovernmental Panel on Climate Change (IPCC)  concluded in its latest report. Recent evidence  points to changes in the  Pacific causing the deep oceans to absorb more heat.

But most climate models didn't predict the slowdown. And as a  new paper in Nature Climate Change explains, some parts of the media have argued that since models don't replicate recent temperatures, we shouldn't trust their predictions for future warming.

But the paper, lead by Australian climate scientist Dr James Risbey, finds that 15 years of temperatures rising slower than models predict "does not constitute evidence against the fidelity" of models in general. Let's take a closer look at why not.

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New mega-map details all the ways climate change will affect our everyday lives

  • 18 Jul 2014, 00:00
  • Roz Pidcock

From flood barriers to fish stocks, a new super-graphic from the Met Office and the UK Foreign and Commonwealth Office shows how climate change is likely to alter human activity.

Looking at where our food comes from and how countries interact through travel and trade, it makes for a stark visualisation of what different regions can expect as climate change kicks in.

Mega-map

The  Human Dynamics of Climate Change project is a huge venture, designed to illustrate the range and complexity of the potential impacts of unmitigated climate change.

It contains a massive amount of information but a good place to start is the map below, which shows how humans interact in today's world.

The colours, arrows, symbols and shading show shipping routes, population density, crop importers and exporters, areas under water stress, busy ports and airports, fishing regions, tropical cyclone regions and melting glaciers.

HDCC_map _present

Present day human dynamics (1981-2010). Source: Human Dynamics of Climate Change  ( HDCC), a joint project from the Met Office and UK Foreign and Commonwealth Office.

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