Thanks for your question regarding potential long-term impacts of GM crops on the environment. We are getting close to having 20 years of commercial experience with the first GM crops, and to date there have not been any notable negative environmental impacts associated with these products. GM crops have been integrated into existing agricultural systems and, in many instances, have prompted a reduction in the impacts that agriculture can have on the environment.
For additional information to answer your question, take a look at this previous answer by Bruce Chassy, professor emeritus of food safety and nutritional sciences at University of Illinois at Urbana-Champaign: Are there any long term (30+ years) studies done on the full spectrum ecological impact of transgenic GMO organisms? If there are no long term, full spectrum studies done, then why is GMO considered "safe" and approved for public use?
In addition, the developers of GM crops, namely those companies that have been supporting GMO Answers, have also made an international commitment to stand behind the safety of their products via a binding contract known as the Compact. The Compact created an international arbitration system that provides a legally binding mechanism for parties to seek redress and compensation if the release of a GMO causes damage to biological diversity.
This agreement was implemented in 2010 and was a clear signal to regulators, policy-makers and the public around world that the developers of GM crops were willing to back up their statements regarding the safety of their products. Under the Compact, the GM crop developer has a contractual obligation to take responsibility for any damage to biological diversity caused by its GM product. The Compact is designed to be a complement to both domestic law and international agreements, such as the Nagoya-Kuala Lumpur Supplementary Protocol on Liability and Redress, which is part of the Cartegena Biosafety Protocol. For more information on the Compact, you can check out the Compact FAQs at CropLife International.