Query: With more CO2 in the atmosphere, the challenge [feeding 2.5 billion more people] can and will be met.

Relevant passages:
Carbon footprint <=SEP=> A carbon footprint is historically defined as the total set of greenhouse gas emissions caused by an individual , event , organisation , or product , expressed as carbon dioxide equivalent .   In most cases , the total carbon footprint can not be exactly calculated because of inadequate knowledge of and data about the complex interactions between contributing processes , especially which including the influence on natural processes storing or releasing carbon dioxide . For this reason , Wright , Kemp , and Williams , have suggested to define the carbon footprint as :   A measure of the total amount of carbon dioxide ( CO2 ) and methane ( CH4 ) emissions of a defined population , system or activity , considering all relevant sources , sinks and storage within the spatial and temporal boundary of the population , system or activity of interest . Calculated as carbon dioxide equivalent using the relevant 100-year global warming potential ( GWP100 ) .   Greenhouse gases ( GHGs ) can be emitted through land clearance and the production and consumption of food , fuels , manufactured goods , materials , wood , roads , buildings , transportation and other services . For simplicity of reporting , it is often expressed in terms of the amount of carbon dioxide , or its equivalent of other GHGs , emitted .   Most of the carbon footprint emissions for the average U.S. household come from `` indirect '' sources , i.e. fuel burned to produce goods far away from the final consumer . These are distinguished from emissions which come from burning fuel directly in one 's car or stove , commonly referred to as `` direct '' sources of the consumer 's carbon footprint .   The concept name of the carbon footprint originates from ecological footprint , discussion , which was developed by Rees and Wackernagel in the 1990s which estimates the number of `` earths '' that would theoretically be required if everyone on the planet consumed resources at the same level as the person calculating their ecological footprint . However , given that ecological footprints are a measure of failure , Anindita Mitra ( CREA , Seattle ) chose the more easily calculated `` carbon footprint '' to easily measure use of carbon , as an indicator of unsustainable energy use . In 2007 , carbon footprint was used as a measure of carbon emissions to develop the energy plan for City of Lynnwood , Washington . Carbon footprints are much more specific than ecological footprints since they measure direct emissions of gases that cause climate change into the atmosphere .   Carbon footprint is one of a family of footprint indicators , which also includes water footprint and land footprint .

Greenhouse gas <=SEP=> A greenhouse gas ( abbrev . GHG ) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range . This process is the fundamental cause of the greenhouse effect . The primary greenhouse gases in Earth 's atmosphere are water vapor , carbon dioxide , methane , nitrous oxide , and ozone . Without greenhouse gases , the average temperature of Earth 's surface would be about -18 ° C , rather than the present average of 15 ° C . In the Solar System , the atmospheres of Venus , Mars and Titan also contain gases that cause a greenhouse effect .   Human activities since the beginning of the Industrial Revolution ( taken as the year 1750 ) have produced a 40 % increase in the atmospheric concentration of carbon dioxide , from 280 ppm in 1750 to 406 ppm in early 2017 . This increase has occurred despite the uptake of a large portion of the emissions by various natural `` sinks '' involved in the carbon cycle . Anthropogenic carbon dioxide emissions ( i.e. , emissions produced by human activities ) come from combustion of fossil fuels , principally coal , oil , and natural gas , along with deforestation , soil erosion and animal agriculture .   It has been estimated that if greenhouse gas emissions continue at the present rate , Earth 's surface temperature could exceed historical values as early as 2047 , with potentially harmful effects on ecosystems , biodiversity and the livelihoods of people worldwide . Recent estimates suggest that on the current emissions trajectory the Earth could pass a threshold of 2 ° C global warming , which the United Nations ' IPCC designated as the upper limit to avoid `` dangerous '' global warming , by 2036 .

Environmental degradation <=SEP=> Environmental degradation is the deterioration of the environment through depletion of resources such as air , water and soil ; the destruction of ecosystems ; habitat destruction ; the extinction of wildlife ; and pollution . It is defined as any change or disturbance to the environment perceived to be deleterious or undesirable . As indicated by the I = PAT equation , environmental impact ( I ) or degradation is caused by the combination of an already very large and increasing human population ( P ) , continually increasing economic growth or per capita affluence ( A ) , and the application of resource depleting and polluting technology ( T ) .   Environmental degradation is one of the ten threats officially cautioned by the High-level Panel on Threats , Challenges and Change of the United Nations . The United Nations International Strategy for Disaster Reduction defines environmental degradation as `` The reduction of the  capacity of the environment to meet social and ecological objectives , and needs '' . Environmental degradation is of many types . When natural habitats are destroyed or natural resources are depleted , the environment is degraded . Efforts to counteract this problem include environmental protection and environmental resources management .