"The Drowned World" and "The Wind from Nowhere" by J.G. Ballard (1961 and 1962)
"The birth of a child had become a comparative rarity, and only one marriage in ten yielded any offspring. As Kerans sometimes reminded himself, the geneaological tree of mankind was systematically pruning itself, apparently moving backwards in time, and a point might ultimately be reached where a second Adam and Eve found themselves alone in a new Eden."
J.G. Ballard was a British writer best known for his books Empire of the Sun and Crash. His earliest fiction, however, falls within the category of science fiction. The Wind From Nowhere was his first published novel, and The Drowned World was his second.
In The Drowned World, solar flares have warmed the globe to the point that the polar ice caps are melting, and the equatorial regions have become uninhabitable. In The Wind From Nowhere, a global cyclone rips across the surface of the Earth, quickly eroding the foundations of human civilization. In both books mankind faces the prospect of its own obsolescence, and in both books one finds the depth of characterization, intellectual weight, and skillful prose that would later make the author famous.
And really, in this time of global warming and weird weather you don't get more prescient than The Wind From Nowhere and The Drowned World. At times it seems as if Ballard was describing the present day. Not only this, but the reasons behind these catastrophes are well thought out, and explored with a thoroughness that few other science fiction writers could have matched.
This said, I think there are really two kinds of "hard science fiction," (or, I'm tempted to say, "deeper science fiction"). There are the books so brilliant that it's hard to understand why they weren't more popular, and there are books so brilliant it's easy to understand why they never found an audience. Thinking back to the time when these two books were first published, it's easy to assign both The Wind From Nowhere and The Drowned World to the second category. Their quality is in no doubt, but it's obvious that they must have gone over the heads of most science fiction fans at the time. Lovers of rocket ships and Martian landscapes wouldn't have had the patience for these books, and this fact is far from surprising.
If you can wade through books like Solaris and The Castaways of Tanagar, you'll love this book. If Heinlein and Le Guin are more your thing, I would recommend looking elsewhere.