Monday, March 31, 2014

Climate Models Show Remarkable Agreement with Recent Surface Warming

The animation shows the CMIP5 model simulations compared to the HADCRUT4 surface temperature dataset. As allowances are made for better global coverage of temperature observations, El Niño/La Niña, solar radiation, and volcanic aerosols, the simulated surface temperature moves back toward the actual measured temperature over this period. (Credit: / Animation by Kevin C.) Click to enlarge.
Key points:
  • Despite warming over the last 16 years, global surface temperatures have warmed at a slower rate than the previous 16 years and, at first glance, it appears that the climate models may have overestimated the amount of surface warming over this period.
  • Climate models, however, cannot predict the timing and intensity of La Niña and El Niño, natural cycles that greatly affect global temperature in the short-term by dictating the amount of heat available at the ocean surface.
  • Nor can the climate models predict the timing and duration of volcanic eruptions and industrial pollution, both of which eject light-scattering aerosols into the atmosphere and therefore reduce surface warming.
  • By failing to account for these and other factors, the CMIP5 collection of climate models erroneously simulate more warming of Earth's surface than would be expected.
  • When the input into the climate models is adjusted to take into consideration both the warming and cooling influences on the climate that actually occurred, the models demonstrate remarkable agreement with the observed surface warming in the last 16 years.
Climate Models Show Remarkable Agreement with Recent Surface Warming

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