Warming slowdown puzzles scientists

2013-04-16 16:01

(Jewel Samad, AFP)

Multimedia   ·   User Galleries   ·   News in Pictures Send us your pictures  ·  Send us your stories

Oslo – Scientists are struggling to explain a slowdown in climate change that has exposed gaps in their understanding and defies a rise in global greenhouse gas emissions.

Often focused on century-long trends, most climate models failed to predict that the temperature rise would slow, starting around 2 000. Scientists are now intent on figuring out the causes and determining whether the respite will be brief or a more lasting phenomenon.

Getting this right is essential for the short and long-term planning of governments and businesses ranging from energy to construction, from agriculture to insurance. Many scientists say they expect a revival of warming in coming years.

Theories for the pause include that deep oceans have taken up more heat with the result that the surface is cooler than expected, that industrial pollution in Asia or clouds are blocking the sun, or that greenhouse gases trap less heat than previously believed.

The change may be a result of an observed decline in heat-trapping water vapour in the high atmosphere, for unknown reasons. It could be a combination of factors or some as yet unknown natural variations, scientists say.

Weak economic growth and the pause in warming are undermining governments' willingness to make a rapid billion-dollar shift from fossil fuels. Almost 200 governments have agreed to work out a plan by the end of 2015 to combat global warming.

"The climate system is not quite as simple as people thought," said Bjorn Lomborg, a Danish statistician and author of "The Skeptical Environmentalist" who estimates that moderate warming will be beneficial for crop growth and human health.

Some experts say their trust in climate science has declined because of the many uncertainties. The UN's Intergovernmental Panel on Climate Change (IPCC) had to correct a 2007 report that exaggerated the pace of melt of the Himalayan glaciers and wrongly said they could all vanish by 2035.

"My own confidence in the data has gone down in the past five years," said Richard Tol, an expert in climate change and professor of economics at the University of Sussex in England.

Swedish chemist Svante Arrhenius first showed in the 1890s how man-made carbon dioxide, from coal for instance, traps heat in the atmosphere. Many of the exact effects are still unknown.

Greenhouse gas emissions have hit repeated record highs with annual growth of about 3% in most of the decade to 2010, partly powered by rises in China and India. World emissions were 75% higher in 2010 than in 1970, UN data show.

UN panel seeks explanation

A rapid rise in global temperatures in the 1980s and 1990s, when clean air laws in developed nations cut pollution and made sunshine stronger at the earth's surface, made for a compelling argument that human emissions were to blame.

The IPCC will seek to explain the current pause in a report to be released in three parts from late 2013 as the main scientific roadmap for governments in shifting from fossil fuels towards renewable energies such as solar or wind power, the panel's chairman Rajendra Pachauri said.

According to Pachauri, temperature records since 1850 "show there are fluctuations. They are 10 to 15 years in duration. But the trend is unmistakable."

The IPCC has consistently said that fluctuations in the weather, perhaps caused by variations in sunspots or a La Nina cooling of the Pacific, can mask any warming trend and the panel has never predicted a year-by-year rise in temperatures.

Experts say short-term climate forecasts are vital to help governments, insurers and energy companies to plan.

Governments will find little point in reinforcing road bridges over rivers, for instance, if a prediction of more floods by 2100 doesn't apply to the 2020s.

A section of a draft IPCC report, looking at short-term trends, says temperatures are likely to be 0.4°C to 1.0°C warmer from 2016 to 2035 than in the two decades to 2005. Rain and snow may increase in areas that already have high precipitation and decline in areas with scarcity, it says.

Exceptions and challenges

Pachauri said climate change can have counter-intuitive effects, like more snowfall in winter that some people find hard to accept as side-effects of a warming trend. An IPCC report last year said warmer air can absorb more moisture, leading to heavier snowfall in some areas.

A study by Dutch experts this month sought to explain why there is now more sea ice in winter. It concluded melted ice from Antarctica was refreezing on the ocean surface, this fresh water freezes more easily than dense salt water.

Some experts challenged the findings.

"The hypothesis is plausible I just don't believe the study proves it to be true," said Paul Holland, an ice expert at the British Antarctic Survey.

Concern about climate change is rising in some nations, however, opinion polls show. Extreme events, such as Superstorm Sandy that hit the US east coast last year, may be the cause.

A record heatwave in Australia this summer forced weather forecasters to add a new dark magenta colour to the map for temperatures up to 54°C.

Read more on:    research  |  climate change
NEXT ON NEWS24X
SHARE:

Read News24’s Comments Policy

24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
10 comments
Add your comment
Comment 0 characters remaining
 

Inside News24

 
/News
 

Joburg hot spots for cocktails, craft beer, tapas and wine!

It’s the season to be jolly – so we’ve rounded up some new Joburg hot spots!

 
 

I love summer.24

Summer Survey!
Great ideas for the best summer sandwiches!
Christmas lingerie to make this festive season the best one ever!
13 things you might not know about Disneyland

Jobs in Cape Town [change area]

Property [change area]

Travel - Look, Book, Go!

Kalahari.com - shop online today

2DAYS ONLY – 30% off Appliances

Coffee makers, blenders, fans, juicers and more. T&Cs apply. Shop now!

2 DAYS ONLY – 40% off books

Get 40% off when you buy 2 books. For two days only! T&Cs apply. Buy now!

Up to 50% off on outdoor gear

Save on chairs, blankets, cooler bags, umbrellas and more. Shop now!

Save on Samsung

Cameras, mobile phones, TVs, Tablets and more. While stocks last. Shop now!

Grand Theft Auto 5

Now available on PS4, Xbox One and PC from R649. Buy now!

OLX Free Classifieds [change area]

Samsung Galaxy s4

Mobile, Cell Phones in South Africa, Western Cape, Cape Town. Date October 24

Best bargain in big bay

Real Estate, Houses - Apartments for Sale in South Africa, Western Cape, Cape Town. Date October 25

VW Golf 6, 1.6 Trendline (Excellent condition)

Vehicles, Cars in South Africa, Western Cape, Cape Town. Date October 25

Horoscopes
Aquarius
Aquarius

At last you are able to see the light. You are able to break through obstacles in an innovative and original way. Visualisation is...read more

There are new stories on the homepage. Click here to see them.
 
English
Afrikaans
isiZulu

Hello 

Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.


Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire 24.com network.

Settings

Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.








Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.