First, absorption helps people by preventing high-energy radiation from reaching the surface which limits our exposure to harmful radiation. The atmosphere absorbs most of the radiation from the ultraviolet region through the X-ray region. The second way in which absorption helps the earth is as a heat source for it.
*lean times (ahead). Fig. a future period of lowered income or revenue; a future period when there will be shortages of goods and suffering. (*Typically: be ~; cause ~; have ~; mean ~ .) The economy is going sour which means lean times ahead.
The core idea is to maximize customer value while minimizing waste. Simply, lean means creating more value for customers with fewer resources.