The French energy company GDF Suez posted solid first quarter 2012 earnings on Monday owing in part to cold weather that boosted natural gas sales in France. GDF said sales climbed by 10.5 percent from the same period a year earlier to 28.16 billion euros ($37 billion). Core operating earnings were 5.7 percent stronger at 5.82 billion euros, a statement added. As of March 31, the group\'s net debt stood at 37.1 billion euros, a decrease of 500 million euros from the end of December. GDF Suez employs almost 219,000 people worldwide.