Cap and trade is an environmental policy tool that delivers results with a mandatory cap on emissions while providing sources flexibility in how they comply. Successful cap and trade programs reward innovation, efficiency, and early action and provide strict environmental accountability without inhibiting economic growth.

Arabic version;
وأنشأت القواعد التنظيمية الأوروبية هيكلا سوقيا على مستوى القارة للتعامل مع هذه القطاعات التجارية، أطلق عليه اسم نظام الحد الأقصى والاتجار cap-and-trade-system وقد صمم على غرار برنامج ناجح أنشأته الولايات المتحدة خلال عقد التسعينات لخفض انبعاثات ثنائي أكسيد الكبريت، المسبب الرئيسي للمطر الحمضي

Also, I would like to point out that this question was already asked by an other colleague, but I don't think it's correct. I just thought of giving you more options.

http://www.proz.com/kudoz/english_to_arabic/petroleum_eng_sc...

Regards

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Note added at 1 day2 hrs (2012-01-19 14:35:13 GMT) Post-grading
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I am glad I could help!