He would've responded to 9/11 by hitting Afghanistan and hitting it harder than Bush did. This mean Bin Laden is likely captured sooner and Al Qaeda is weaker than in real life. With that said, Afghanistan is still likely to be a thorn in our rear for years on end for one reason or another. Gore stays out of Iraq unless 9/11 is avoided, if it is than there's a slight chance he invades at some point. The sanction are continued and they probably get bombed a few times. Gore likely narrowly loses in 2004 to someone like McCain, which means the Supreme Court stays the same as O'Conner and Rehnquist still would leave the court with a Republican in the White House. Gore winning in 2000 likely delays the financial crisis by a year or two, so incumbent Republican likely wins another term in 2008, only to have a second term even more hellish than Bush 43's was. Gore probably does little if anything with Climate change as the GOP still would control the Congress.
This, except Gore would invade Iraq and the financial recession would probably happen at roughly the same time.