Question: By what year will the global population be double ?
About the article "Global warming", section "Food security".

Candidate passages:
Using linear interpolation and extrapolation of UNDESA population estimates, the world population has doubled, or will double, in the following years (with two different starting points).
Note how, during the 2nd millennium, each doubling took roughly half as long as the previous doubling, fitting the hyperbolic growth model mentioned above.
However, after 2025 it is unlikely that there will be another doubling of the global population in the 21st century. 
Muslim population growth refers to the topic of population growth of the global Muslim community.
In 2006, countries with a Muslim majority had an average population growth rate of 1.8% per year (when weighted by percentage Muslim and population size).
This compares with a world population growth rate of 1.12% per year.
As of 2011, it is predicted that the world's Muslim population will grow twice as fast as non-Muslims over the next 20 years.
By 2030, Muslims will make up more than a quarter of the global population. 
Global efforts to tackle climate change could result in millions of "green" jobs over the coming decades, according to a 2008 study prepared by the Worldwatch Institute with funding from the United Nations Environment Programme (UNEP).
The study found that the global market for environmental products and services is projected to double from $1.37 trillion per year at present to $2.74 trillion by 2020, with half of that market in efficient energy use.
In terms of energy supply, the renewable energy industry will be particularly important.
Some 2.3 million people have found renewable energy jobs in recent years, and projected investments of $630 billion by 2030 would translate into at least 20 million additional jobs. 
Global human population growth is around 81 million annually, or 1.2% per year.
The global population has grown from 1 billion in 1800 to 7 billion in 2012.
It is expected to keep growing to reach 11 billion by the end of the century.
Most of the growth occurs in the nations with the most poverty, showing the direct link between high population growth and low standards of living.
The nations with high standards of living generally have low or zero rates of population growth.
Australia's population growth is around 400,000 annually, or 1.8% p.a., which is nearly double the global average.
It is caused mainly by very high immigration of around 200,000 p.a., the highest immigration rate in the world.
Australia remains the only nation in the world with both high population growth and high standards of living. 
 The underlying logic of the prognosis Global forecast.
Randers's reflections are based on two central questions: "What will happen to the consumer over the next 40 years?"
and "Under what conditions – in which social and natural environment – will this future consumption take place?"
(p. 78).
He uses computer models to make sure feedback effects are not overlooked.
Forecast on population and consumption World population will decline from about 2040.
The working population will peak around 2030.
Productivity will grow, but encounter obstacles.
The gross domestic product will grow, but more and more slowly.
Investments – forced and voluntary – will increase.
New costs will be incurred.
Adaptation and disaster costs will explode.
The state will become more involved.
Consumption will stagnate and decline in some places.
Forecast on energy and CO2 Energy efficiency will continue to increase.
Energy demand is expected to rise, but not indefinitely.
CO2 emissions from energy consumption will peak in 2030.
The average global temperature will rise by more than two degrees, causing serious problems.
Forecast on nutrition and ecological footprint The race for natural resources will be hard, the biocapacity of the world will be exploited more and more.
The cities will become richer sources of raw materials for metal than the mineral deposits in nature (urban mining).
In the same way that zoos have already become the last refuge for many endangered species, parks will assume this role for nature in general.
The non-physical future Randers argues that the global gross domestic product will fail to increase as it has in the past because of population decline, general aging and declining productivity growth.
The Internet will give rise to a completely new understanding of what is private and public.
Knowledge will not be a scarce resource any more, but this will not lead to more rational decisions in most cases because knowledge on its own is not sufficient to change behavior when strong interests are involved.
Therefore, it is likely that a "greenkeeping force" will be set up to enforce environmentally positive behavior, similar to the peacekeeping forces (blue berets) of today.