The story...up till now
For things like the nasty crystal creatures, see the novels, Ghosts of Ascalon and Edge of Destiny. They give some history of the periods immediately leading up to the game, and are much closer to GW2 lore than GW1. They’re referred to throughout the game, too.
The Movement of the World has basically the history of things between GW1 and GW2, filling in some gaps. It might not mean as much if you haven’t played GW1, but it does explain some important things (if you can read through it all).
I don’t have a summary of the GW1 plots handy, but I’m sure someone else will.
The think in particular your are talking about is called the Brand and it was caused by the Elder Dragon Kralkatorik when he woke up 5 years prior to the start of the game.
You can get alot of this information in game. Its worth keeping an eye out for any named NPCs or NPCs which get speech bubbles when you put your mouse over them. Generally they will have something to say. You can get alot of lore this way.
As for a single place to find lore unfortunately the Wiki is the best option at the moment. If you look at the top of this page youll see a tab that will take you to it.
There should also be a couple GW1 timelines available on the GW1 wiki that go over ancient past (that has some relevence in late game GW2) and more recent past that was covered by the GW1 campaigns.