Will one day, the whole earth become like African deserts?

It's unlikely that you'd get that particular scenario. Different parts of the earth have different local climates because of variations in where the oceans are, where the land masses are, latitude, etc. read more

The largest hot desert in the world is the Sahara, which is 9 million square kilometers (3.5 million square miles). It isn't the hottest place on Earth, though. That distinction belongs to Death Valley, in California's Mojave Desert. The highest temperature on Earth was recorded there: 56.7 C (134.1 F). read more

In addition, some deserts at higher latitudes (which is to say north or south of the tropics) experience seasons just like other nearby land. An example is the Gobi Desert in Asia, which is a rain shadow desert that experiences temperatures of 20 degrees Celsius below freezing during the winter. read more

Not all deserts are hot. Some of these drylands, like the Atacama of Chile, the Namib and Kalahari of southern Africa, and the western Australian desert, are the result of cold oceanic currents that divert rain-laden air away from coastlines. read more