Arctic sea ice hits its annual minimum as seen in this satellite picture provided by the Japan Aerospace Exploration Agency GCOM-W1 satellite and NASA taken September 17, and released September 22, 2014. The red line in this image shows the 1981-2010 average minimum extent. Over the 2014 summer, Arctic sea ice melted back from its maximum extent reached in March to a coverage area of 1.94 million square miles (5.02 million square kilometers), according to analysis from NASA and NASA-supported National Snow and Ice Data Center (NSIDC) scientists. The melting continues. REUTERS/NASA/Goddard Scientific Visualization Studio/Handout via Reuters

After February recording hottest temperature in decades, the planet can see more hotter days and extreme climate, going by trends. 

It is almost impossible to limit global warming to less than two degrees Celsius above pre-Industrial period level, says a new study that modeled population growth, energy consumption and fossil fuel reserves to arrive at the conclusion. This is the threshold temperature beyond which scientists have warned of irreversible climate change.

It would require immense efforts like a drastic change in energy infrastructure and an energy mix with 50 percent renewables in 2028 from the current 9 percent. This means a 37-fold increase in wind energy from levels in 2015 as also similar increases with other renewable sources.

The study by two Texas A&M University at Galveston researchers Glenn Jones and Kevin Warner was published in the international journal Energy Policy. "Just considering wind power, we found that it would take an annual installation of 485,000 5-megawatt wind turbines by 2028. The equivalent of about 13,000 was installed in 2015. That's a 37-fold increase in the annual installation rate in only 13 years to achieve just the wind power goal," said Jones.

The authors refer to historical lethargy by government officials to agree on making such large-scale changes happen in such a short timeframe. But insist that such a large shift to renewables alone can check global warming while also providing electricity to the millions.

If the 50 percent renewable energy is achieved only by 2054, the warming will exceed 2.5 to 3 degrees Celsius.

The duo point out that every hour of every day around 3.7 million barrels of oil are extracted from the Earth, 932,000 tons of coal and 395 million cubic meters of natural gas extracted from Earth and a whopping 4 million tonnes of carbon dioxide put into the Earth's atmosphere. Around 9,300 people are born every hour.

"There will be about 11 billion people on Earth by 2100 (compared to 7.2 billion today)," Jones added. "So the question becomes, how will they be fed and housed and what will be their energy source?

Considering that a person living today uses about four times as much energy as a person did in the early 1900s, by 2100, that figure will go up to five times, said Jones. Regardless of the Paris agreement, by then around 87 to 94 percent of all energy used will be from renewable sources, going by trends.

Even today, there are 1.2 billion people living outside the grid and attempts to get them in will also be adding to the carbon emitted.

The Paris Agreement in December last year saw 190 nations agree to replace fossil fuels and other measures to reduce global warming and keep it within safe levels. The present study shows how unrealistic it is under present trends to stay within the two degree limit.

The carbon budget that is left for the world as a whole to burn to avoid the threshold is a little less than a 1000 bn tonnes. Around 40 bn tonnes is emitted every year on an average and this could rise, which means we could finish it in two decades. The world has already locked into a 1.5C rise and experts have warned this could go as high as 4C by end of the century.

The carbon dioxide content of the atmosphere now stands at over 142% that of pre-industrial revolution levels in 1850s, with concentrations crossing 400 parts per million last year.