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| Observed changes in the climate system SupportiveArgument1 #287961 Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased. | 
Source: IPCC – Working Group 1 2013 (a) Observed global mean combined land and ocean surface temperature anomalies, from 1850 to 2012 from three data sets. Top panel: annual mean values, bottom panel: decadal mean values including the estimate of uncertainty for one dataset (black). Anomalies are relative to the mean of 1961−1990.
(b) Map of the observed surface temperature change from 1901 to 2012 derived from temperature trends determined by linear regression from one dataset (orange line in panel a). Trends have been calculated where data availability permits a robust estimate (i.e., only for grid boxes with greater than 70% complete records and more than 20% data availability in the first and last 10% of the time period). Other areas are white. Grid boxes where the trend is significant at the 10% level are indicated by a + sign. |
+Citations (1) - CitationsAdd new citationList by: CiterankMapLink[1] Working Group I Contribution to the IPCC Fifth Assessment Report Climate Change 2013: The Physical Science Basis Summary for Policymakers
Author: IPCC Working Group I
Publication info: 2013 September, 27
Cited by: David Price 12:59 PM 4 October 2013 GMT
Citerank: (12) 5202Earth's globally averaged surface temperature is risingObserved increases in the Earth's globally averaged surface temperature offer credible evidence of significant climate change.1198CE71, 5203Observed increases in global average ocean temperatureObserved increases in global average ocean temperature [citation needed].1198CE71, 5204Observed melting of snow and iceObservations of widespread melting of snow and ice.1198CE71, 5205Observed rises in global average sea levelThe rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence). Over the period 1901–2010, global mean sea level rose by 0.19 [0.17 to 0.21] m1198CE71, 14564Scientific measurements provide strong supporting evidenceScientific measurements provide strong support for the case for significant anthropogenic climate change.1198CE71, 39977Global CO2 emissions from fossil fuels 40% higher in 2008 than 1990Global carbon dioxide emissions from fossil fuels in 2008 were nearly 40% higher than those in 1990.1198CE71, 287960Warming of the climate system is unequivocalWarming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased.
959C6EF, 287962Observed changes in the atmosphereEach of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. In the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the last 1400 years (medium confidence).1198CE71, 287963Ocean warmingOcean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010 (high confidence). It is virtually certain that the upper ocean (0-700 m) warmed from 1971 to 2010 and it likely warmed between the 1870s and 1971.1198CE71, 287964Observed cryospheric changesOver the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent (high confidence).1198CE71, 287965Observed sea level changesThe rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence). Over the period 1901–2010, global mean sea level rose by 0.19 [0.17 to 0.21] m.1198CE71, 287966Observed changes in carbon and other biogeochemical cyclesThe atmospheric concentrations of carbon dioxide (CO2), methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. CO2 concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions. The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification.1198CE71 URL:
| | Excerpt / Summary Observations of the climate system are based on direct measurements and remote sensing from satellites and other platforms. Global-scale observations from the instrumental era began in the mid-19th century for temperature and other variables, with more comprehensive and diverse sets of observations available for the period 1950 onwards. Paleoclimate reconstructions extend some records back hundreds to millions of years. Together, they provide a comprehensive view of the variability and long-term changes in the atmosphere, the ocean, the cryosphere, and the land surface. |
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