In a hypothetical scenario where the Earth begins to rotate at the speed of light, the consequences would be catastrophic. To understand the impact, one must consider the implications of such a scenario. The speed of light is incredibly fast, reaching approximately 299,792 kilometers per second. With this velocity, the Earth's rotational speed would be so immense that unimaginable destruction would occur.

Firstly, with the Earth rotating at the speed of light, the centrifugal forces would be intensified to an unprecedented level. This increased force would result in the planet's surface gradually tearing apart, causing massive earthquakes and volcanic eruptions.

The energy released by these catastrophic events would be on an unprecedented scale, leading to global devastation.

Furthermore, the intense rotational speed would cause a deformation in the shape of the Earth. The planet would flatten at the poles while bulging at the equator due to the centrifugal forces. Such deformations would lead to significant changes in climate patterns and weather systems, resulting in extreme and unpredictable weather phenomena.

Moreover, the speed of light rotation would have drastic effects on the Earth's atmosphere and oceans.

The sheer forces generated by this velocity would generate massive winds and ocean currents, leading to colossal storms, tornadoes, and tsunamis. The impact on the environment and ecosystems would be devastating, causing untold damage to life forms across the planet.

In conclusion, if the Earth were to rotate at the speed of light, the consequences would be catastrophic. The immense centrifugal forces, deformation of the planet, and the resulting destruction would change the face of the Earth completely. However, it is essential to remember that this scenario exists purely as a thought experiment, as the laws of physics as we currently understand them do not permit such a situation to occur.