translate English to French: He also gives us his estimate, ~0.8 C for the global warming that will occur over the next century and claims that, since models differ by 400% in their estimates, his guess is as good as theirs.
Il donne aussi son estimation (~0,8°C) du réchauffement global pour le 21ème siècle et prétend que, puisque les modèles diffèrents de 400% dans leurs estimations, sa supposition est aussi bonne que les leurs.