Observed trends in Earth System behavior

The 420,000‐year Vostok (Antarctica) ice core record showing the regular pattern of atmospheric CO₂ and CH₄ concentration and inferred temperature through four glacial–interglacial cycles (Adapted with permission from Ref 5. Copyright 1999 Nature).

The scope, degree, and interactive nature of human alteration of the Earth System (Adapted with permission from Ref 7. Copyright 1997 Science).

World agricultural area under irrigation.11.

The causative patterns of tropical deforestation from 1850 to 1997 based on a synthesis of 152 case studies that examined both proximate and underlying causes.23.

Overview of human‐driven changes in global land cover over the last 300 years.27.

Atmospheric changes in concentrations of (a) CO₂47; (b) CH₄48,49; and (c) N₂O50 over the last 300 years, as reconstructed from Greenland and Antarctic ice core studies.41.

Rates of observed surface elevation change for Greenland (left, 1989–2005) and Antarctica (right, 1992–2005). Red colors indicate a rise in elevation, which generally mean an increase in ice mass, whereas blue colors indicate a drop in elevation and a loss of ice mass. The letters along the Greenland coast refer to outlet glaciers and the small inset shows their change in mass balance with time. For Antarctica, the triangles along the coast show trends in ice shelves; purple triangles show thinning of ice, and red triangles show thickening of ice (Reprinted with permission from Ref 8. Copyright 2007 Cambridge University Press).

Aging of river water, as computed at the mouth of each of the 236 regulated drainage basins.57 Aging varies due to river regulations on the reservoirs.

The global carbon budget from 1850 to 2007. (Data are from Refs 59,60)..

Atmospheric CO₂ concentration over the past 420,000 years from the Vostok ice core with the recent human perturbation superimposed.5,67.

Global terrestrial nitrogen budget for (a) 1890 and (b) 1990 in Tg N/year. The emissions to the NO_y box from the coal represent fossil fuel combustion. Those from the vegetation include agricultural and natural soil emissions and combustion of biofuel, biomass (savanna and forests), and agricultural waste. The emissions to the NH_x box from the agricultural field include emissions from agricultural land and combustion of biofuel, biomass (savanna and forests), and agricultural waste. The NH_x emissions from the cow and feedlot reflect emissions from animal waste. The transfers to the fish box represent the lateral flow of dissolved inorganic nitrogen from terrestrial systems to the coastal seas (based on Ref 68).

Model‐calculated partitioning of the human‐induced nitrogen perturbation fluxes in the global coastal margin for the period since 1850 to the present (2000) and projected to 2035 under a business‐as‐usual scenario.70.

Comparison of the extinction rate in the rate past and the rate projected for the 21st century with the long‐term background rate of species loss estimated from the fossil record (Reprinted with permission from Ref 76. Copyright 2005 Island Press).

Thresholds and abrupt changes. Many processes within the Earth System are well‐buffered and appear to be unresponsive to a forcing factor (e.g., between T1 and T2 in lower figure) until a threshold is crossed and then a major change occurs abruptly (Reprinted with permission from Ref 6. Copyright 2004 Springer‐Verlag).

The increasing rates of change in human activity since the beginning of the Industrial Revolution. Sharp changes in the slope of the curves occur around the 1950s in each case and illustrate how the past 50 years have been a period of dramatic and unprecedented change in human history (see Ref 6, which includes references to the individual data sets).

Global‐scale changes in the Earth System as a result of the dramatic increase in human activity shown in Figure 15 (see Ref 6, which includes references to the individual data sets).