Abstract Fossil fuels production peaks, declines and depletions depend on their proved reserves, exploration and consumption rates. Worldwide proven oil, gas and coal reserves are 1688 billion barrels (Bb), 6558 trillion cubic feet (TCF) and 891 billion tons (Bt) being consumed at rates of 0.092 Bb, 0.329 TCF and 7.89 BT per day, respectively. The oil, gas and coal reserves are increasing at the rate of 600 million barrels (Mb), 400 billion cubic feet (BCF) and 19.2 Giga tons of oil equivalents (GTOE) per year. While the rate of annual increase in consumption of oil, gas and coal is 1.4 Mb, 4.5 BCF and 3.1 million tons (Mt). Global annual energy demand of over 12 billion tons of oil equivalent (BTOE) results in the emission of 39.5 Giga tons of carbon dioxide (Gt-CO2), and the annual CO2 emission would increase up to 75 Gt-CO2 when future energy demand will rise to 24–25 BTOE. Oil, gas and coal may continue to exist for next several decades, yet the energy transition to low carbon intensity fuels is necessary to cope with rampant climate change. Renewable and alternative energy sources hold key to the solution of twin problems, energy and climate change, with a high initial investment. Transition from fossil fuels to sustainable and renewable energy resources of 150 Petawatt hours (PWh) requires major investment and innovatory technologies. Perhaps CO2 and H2O based fuel systems would facilitate climate change and grand energy transition. An energy mix consisting of fossil fuels, hydrogen, bio-fuels, and renewable energy sources seems to be a good initiative. This paper reviews evidence of hydrocarbons decline scenarios and timelines of future energy technologies.