Published: Apr 07, 2010 2:36 PM EDT

"Solar" (Nan A. Talese/Doubleday, 287 pages, $26.95), by Ian McEwan: It is hard to like Michael Beard, a physicist whose work exploring the nature of light once earned him a Nobel Prize, but who now lends his name to letterheads and honorary university posts.

The middle-aged, increasingly corpulent philanderer recycles the same series of lectures on his award-winning Beard-Einstein Conflation and is long past his scientific prime. "Two decades had passed since he had last sat down in silence and solitude for hours on end, pencil and pad in hand, to do some thinking, to have an original hypothesis. ... He had no new idea."

At the beginning of "Solar," the latest novel from Booker Prize winner Ian McEwan, Beard heads the National Center for Renewable Energy (although he is "unimpressed by some of the wild commentary that suggested the world was in peril"). He is also humiliating himself in an attempt to hold on to the vestiges of his fifth marriage (although he relentlessly cheated on his wife throughout the relationship).

"Solar" is a story about an existence in crisis. Not just Beard's, but also the life of planet Earth. Here, McEwan explores the issues of global warming, the search for new energy sources and the politicization of environmental causes.

Beard — bloated, balding and unable to resist the excesses of food and sex — serves as a metaphor for the gluttonous practices that have affected Earth's climate.

Unfortunately, the considerably large portions of the novel devoted to the issue of climate change often feel tedious, and the science is sometimes difficult to wade through. The most rewarding parts of "Solar" are the keenly etched descriptions of Beard's personal humiliations, those telling intimate glimpses into his self-absorption and self-doubt.

One especially comic, and mortifying, moment occurs early on, when Beard is forced to urinate outdoors during an expedition to the Arctic. Subzero temperatures and exposed skin combine for a moment of utter, hilarious panic.

As the novel progresses, Beard grows sloppier, fatter and less likable. He slips from selfishness to acts of pure evil. As a result, "Solar" loses power and chugs to an unsatisfying ending.