Weather will change, that's for sure.
In many million years climate will change due two major tectonic shifts: Northern America will move toward northern pole, and Greenland will be further north making continental ice shield possible. Second shift will be collision of Africa with Europe and uplifting mountains through Mediterranean and thus ending any traces of ancient Tethys sea. Earth will become dryer due larger land mass and much of the world salt would be trapped on land. Somalian land will secede from Africa and prevent ocean current circulating through Indian Ocean. Either way, climate is not constant. However, present global climate change is due man-made pollution.