* New buildings, cars keep emissions up in a downturn
* May need economic rethink of GDP, CO2 growth-study
By Alister Doyle
OSLO, Oct 7 (Reuters) - Greenhouse gas emissions rise wheneconomies expand but don't fall as quickly when recessionstrikes, perhaps because people stick with a higher-emittinglifestyle from the boom times, a study showed.
The report in Monday's edition of the journal Nature ClimateChange dents many governments' hopes that recession can at leastbring the consolation of a sharp contraction in greenhouse gasemissions.
Emissions of carbon dioxide, the main greenhouse gas, roseby an average of 0.73 percent for every 1 percent growth ingross domestic product (GDP) per capita, Richard York of theUniversity of Oregon wrote in his report.
But emissions fell just 0.43 percent for every percentdecline in GDP per capita, he added, based on a review of WorldBank statistics of more than 150 nations from 1960 to 2008.
"Economic decline ... doesn't lead to as big a decline inemissions as a comparable amount of economic growth leads togrowth in emissions," York told Reuters.
He said the difference might be because new infrastructureadded during times of economic growth - new homes, roads orfactories - is still used during recession. Carbon dioxide ismainly emitted by burning fossil fuels.
"When economies decline, factories don't shut downimmediately, people don't stop driving (although they may deferbuying a new car)," he wrote in a email. And many new buildingsstill needed heating or air-conditioning.
Even since 1990, when many developed nations started tryingto curb their greenhouse gases under a U.N. treaty, emissionshad also fallen less in recession than they rose when theeconomy grew, he said.
York said economists may have to re-think how they projectfuture growth of carbon dioxide. Most studies assume that GDPand emissions move in lockstep, both up and down.
The findings "don't necessarily suggest future emissionswill generally be higher or lower than current projections, butthey suggest that this will depend more sensitively on howexactly economies grow (or shrink)," he said.
"It doesn't only matter how big GDP is in the future, butalso how it gets there, such as by slow steady growth, or byperiods of rapid growth mixed with recession," he said.
Almost 200 nations are aiming to agree a new global pact tocombat climate change by 2015 that would enter into force in2020. World leaders failed to agree a new deal at the lastattempt, at the Copenhagen summit in 2009.
The U.N. panel of climate scientists says the build-up ofgreenhouse gases is raising temperatures and will bring morefloods, droughts, heatwaves, dust storms and rising sea levels.
Its scenarios foresee the world economy expanding steadilyto anywhere from $235 trillion to $550 trillion by 2100, from$21 trillion in 1990. That would raise world temperatures bybetween 1.1 and 6.4 degrees Celsius (2.0-11.5F), it says.
The world economy is expected to grow by 3.5 percent in2012, including a 0.3 percent contraction in the euro zone,according to the International Monetary Fund.
(Reporting by Alister Doyle; Editing by Mark Potter)
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Keywords: CLIMATE EMISSIONS/