GEOGRAPHY IN THE NEWS:

The Sahara is the second largest desert on earth, but that was not always the case. More interestingly, it may not be the case in the future either. "[R]esearchers at MIT have analyzed dust deposited off the coast of west Africa over the last 240,000 years, and found that the Sahara, and North Africa in general, has swung between wet and dry climates every 20,000 years. They say that this climatic pendulum is mainly driven by changes to the Earth's axis as the planet orbits the sun, which in turn affect the distribution of sunlight between seasons -- every 20,000 years, the Earth swings from more sunlight in summer to less, and back again. For North Africa, it is likely that, when the Earth is tilted to receive maximum summer sunlight with each orbit around the sun, this increased solar flux intensifies the region's monsoon activity, which in turn makes for a wetter, 'greener' Sahara. When the planet's axis swings toward an angle that reduces the amount of incoming summer sunlight, monsoon activity weakens, producing a drier climate similar to what we see today." news.mit.edu/2019/study-regulating-north-african-climate-0102