Kardashev scale

The Kardashev scale is a method of measuring a civilization's level of technological advancement based on the amount of energy they are able to use. The measure was proposed by Soviet astronomer Nikolai Kardashev in 1964. The scale has three designated categories:
In 1964, Kardashev defined three levels of civilizations, based on the order of magnitude of power available to them:
; Type I
; Type II
; Type III
Kardashev believed that a Type 4 civilization was impossible, so he did not go past Type 3. However, new types have been proposed.

Current status of human civilization

At the current time, humanity has not yet reached Type 1 civilization status.
Physicist and futurist Michio Kaku suggested that, if humans increase their energy consumption at an average rate of 3 percent each year, they may attain Type I status in 100–200 years, Type II status in a few thousand years, and Type III status in 100,000 to a million years.
Carl Sagan suggested defining intermediate values by interpolating and extrapolating the values given above for types I, II and III, which would produce the formula
where value K is a civilization's Kardashev rating and P is the power it uses, in watts. Using this extrapolation, a "Type 0" civilization, not defined by Kardashev, would control about 1 MW of power, and humanity's civilization type as of 1973 was about 0.7.
In 2018, the total world energy consumption was 13864.9 Mtoe, equivalent to an average power consumption of 18.40 TW or 0.73 on Sagan's interpolated Kardashev scale.

Observational evidence

In 2015, a study of galactic mid-infrared emissions came to the conclusion that "Kardashev Type-III civilizations are either very rare or do not exist in the local Universe".
On October 14, 2015, the detection of an unusual light curve for star KIC 8462852 raised speculation that a Dyson swarm may have been discovered. The SETI Institute's initial radio reconnaissance of KIC 8462852, however, found no evidence of technology-related radio signals from the star.
In 2016, Paul Glister, author of the Centauri Dreams website, described a signal apparently from the star HD 164595 as requiring the power of a Type I or Type II civilization, if produced by extraterrestrial lifeforms. However, in August 2016 it was discovered that the signal's origin was most likely a military satellite orbiting the Earth.

Energy development

Type I civilization methods

Type II civilization methods

There are many historical examples of human civilization undergoing large-scale transitions, such as the Industrial Revolution. The transition between Kardashev scale levels could potentially represent similarly dramatic periods of social upheaval, since they entail surpassing the hard limits of the resources available in a civilization's existing territory. A common speculation suggests that the transition from Type 0 to Type I might carry a strong risk of self-destruction since, in some scenarios, there would no longer be room for further expansion on the civilization's home planet, as in a Malthusian catastrophe. Excessive use of energy without adequate disposal of heat, for example, could plausibly make the planet of a civilization approaching Type I unsuitable to the biology of the dominant life-forms and their food sources. If Earth is an example, then sea temperatures in excess of would jeopardize marine life and make the cooling of mammals to temperatures suitable for their metabolism difficult if not impossible. Of course, these theoretical speculations may not become problems possibly through the applications of future engineering and technology. Also, by the time a civilization reaches Type I it may have colonized other planets or created O'Neill-type colonies, so that waste heat could be distributed throughout the planetary system
The limitation of biological life-form and the evolution of computing technology may lead to the transformation of the civilization through Mind uploading during the transition from Type I to Type II, leading to a digitalized civilization.

Extensions to the original scale

Many extensions and modifications to the Kardashev scale have been proposed.
It has been argued that, because we cannot understand advanced civilizations, we cannot predict their behavior. Thus, the Kardashev scale may not be relevant or useful for classifying extraterrestrial civilizations. This central argument is found in the 2002 book .