The latest global climate models (GCMs) have performed pre-industrial control simulations as part of the CMIP5 coordinated experiments. In these simulations there are no changes to radiative forcings, which are kept fixed at year 1850 values – all the variability is therefore generated internally to the climate system. How different can this variability be? Continue reading Variable variability
All posts by Ed Hawkins
Global temperatures: 75 years after Callendar
Could varying concentrations of atmospheric carbon dioxide cause the planet to warm and cool? This was a key question facing scientists from the mid-1800s onwards – not because of a concern over man-made emissions of CO2, but because of a desire to understand the causes of the ice ages (identified by Louis Agassiz in 1837).
Then, 75 years ago, in February 1938, a little appreciated scientist, Guy Stewart Callendar, presented the first evidence that the planet had recently warmed. Callendar also suggested that changes in atmospheric CO2 had caused a large part of this observed warming. A new paper reanalyses Callendar’s work to mark the 75th anniversary of his landmark study. Continue reading Global temperatures: 75 years after Callendar
Reliability of regional climate trends
Climate information for the future is usually presented in the form of scenarios: plausible and consistent descriptions of future climate without probability information. This suffices for many purposes, but for the near term, say up to 2050, scenarios of emissions of greenhouse gases do not diverge much and we could work towards climate forecasts: calibrated probability distributions of the climate in the future. Continue reading Reliability of regional climate trends
Constraining projections with observations
Can past observations be used to help constrain future temperature projections? This question is particularly relevant given the last decade which has shown relatively less warming than expected. Continue reading Constraining projections with observations
Updated comparison of simulations and observations
Now that 2012 is over, it is time to update a comparison of simulations and observations of global mean temperatures.
Continue reading Updated comparison of simulations and observations
What will the simulations do next?
Recent conversations on the recent slowdown in warming has inspired an animation on how models simulate this phenomenon, and what it means for the evolution of global temperatures over the next few decades. Continue reading What will the simulations do next?
Months since below average temperatures
NOAA have recently been promoting that November 2012 was the 333rd month in a row with above average global temperatures, and this has been widely picked up by the media (e.g. here). But, how useful is this statistic? Continue reading Months since below average temperatures
Predictions of the past & the future
What will happen to the climate over the next decade? Two new analyses consider real climate predictions made in the past and of the future decade. Continue reading Predictions of the past & the future