Fonte: The Ecologist (Clique aqui para visualizar na fonte)

Levels of CO2 are at their the highest in 800,000 years, writes Tim Radford, but news of a probable decline in emissions this year is providing welcome cheer at the COP21 climate summit: thanks to renewables, economic growth and falling emissions can go hand in hand.
This could be the year when carbon emissions stopped rising and when greater efficiency and a shift to wind and solar power began to slow the rate at which humans dump carbon dioxide from fossil fuels into the atmosphere.
The news of apossible halt in greenhouse gas emissions comes as government ministers from 190 nations enter the second week of negotiations at the COP21 summit in Paris to agree worldwide action on climate change.
“What we are now seeing is that emissions appear to have stalled, and they could even decline slightly in 2015”, says Corinne Le Quéré, director of the Tyndall Centre for Climate Change Research at the University of East Anglia, UK.
“But it is important to remember that our projection for 2015 is an estimate, and there will always be a range of uncertainty. In this case, the 2015 projection ranges from a global decline in emissions of up to 1.5% – or, at the other end of the spectrum, a small rise of 0.5%.”
It could be just a statistical blip. But, if not, the news augurs well for a concerted effort to switch the world towards renewable sources of energy and to limit climate change.
Economic growth
The findings are in two papers by Le Quéré, Robert Jackson, professor of Earth system science at Stanford University, and colleagues, published sumultaneously in the journalsNature Climate Change and Earth System Science Data.
They say that emissions could decline by 0.6%. And although declines have happened before – an economic slump means a drop in energy demand – this is the first to happen in a period of strong economic growth. For most of this century, emissions have risen every year by 2% or 3%. But 2015 could be different.

Video: ‘Arctic Song’. Composed and sung by Nádia Figueiredo, arranged by Rafael Langoni Smith.
China, the world’s biggest emitter, has burned less coal, and whether the reduction is sustained continues to depend on the nation’s use of coal. But more than half of all its new energy demand in 2014 was met from hydro, nuclear, wind and solar power.
China is responsible for 27% of global emissions, the US 15%, the EU 10% and India 7%. But in terms of energy emissions per head of population, the picture is different: the US total is 17.4 tonnes per capita, China 7.1 tonnes, the EU 6.8 tonnes, and India 2 tonnes.
“The most promising finding in our report is the coupling of lower carbon emissions with a strong economic growth of more than 3%”, said Professor Jackson, of the Stanford Woods Institute for the Environment and the Precourt Institute for Energy.
Good news – but CO2 is still increasing in the atmosphere
But while the news may be giving the COP21 climate conference some welcome cheer, the climate change problem is far from solved, he adds: “even if we reach peak global emissions within a decade or two, we’ll still be emitting massive amounts of CO2 from burning fossil fuels.”
Professor Le Quéré also warns that the stall in emissions may not be permanent and, even if it is, that would still not be enough: “Global emissions need to decrease to near zero to achieve climate stabilisation.
“We are still emitting massive amounts of CO2 annually – around 36 billion metric tons from fossil fuels and industry alone. There is a long way to near-zero emissions. Today’s news is encouraging, but world leaders at COP21 need to agree on the substantial emission reductions needed to keep warming below two degrees Celsius.
“And despite the slowing of CO2 emissions globally, the amount of CO2 in the atmosphere has now reached 400 parts per million – its highest level in at least 800,000 years.”