Category Archives: temperature

Comparing global temperature observations and simulations, again

Posted on May 28, 2013 by Ed Hawkins

A recent comparison of global temperature observations and model simulations on this blog prompted a rush of media and wider interest, notably in the Daily Mail, The Economist & in evidence to the US House of Representatives. Given the widespread … Continue reading →

Posted in observations, projections, temperature, uncertainty, variability | 26 Comments

Variable variability

Posted on May 9, 2013 by Ed Hawkins

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 … Continue reading →

Posted in temperature, variability | 3 Comments

Global temperatures: 75 years after Callendar

Posted on April 22, 2013 by Ed Hawkins

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 … Continue reading →

Posted in history, observations, temperature, variability | 19 Comments

Reliability of regional climate trends

Posted on April 15, 2013 by Ed Hawkins

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 … Continue reading →

Posted in GCMs, observations, projections, temperature, uncertainty, variability | 3 Comments

Constraining projections with observations

Posted on February 20, 2013 by Ed Hawkins

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.

Posted in GCMs, observations, projections, temperature, uncertainty | 16 Comments

Updated comparison of simulations and observations

Posted on February 8, 2013 by Ed Hawkins

Now that 2012 is over, it is time to update a comparison of simulations and observations of global mean temperatures.

Posted in GCMs, observations, projections, temperature, uncertainty | 51 Comments

What will the simulations do next?

Posted on January 18, 2013 by Ed Hawkins

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.

Posted in temperature, variability, visualisation | 24 Comments

Months since below average temperatures

Posted on December 20, 2012 by Ed Hawkins

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?

Posted in temperature, variability | 9 Comments

Predictions of the past & the future

Posted on December 11, 2012 by Ed Hawkins

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.

Posted in predictability, temperature | 6 Comments

Temperatures in Mongolia

Posted on December 5, 2012 by Ed Hawkins

I was alerted to an article on climate change in Mongolia which claims that temperatures there have already risen by more than 2C since the 1940s. A few minutes on Climate Explorer allowed me to check.

Posted in history, temperature, variability | 4 Comments

Visualising the role of natural variability

Posted on August 22, 2012 by Ed Hawkins

A new analysis by Clara Deser and colleagues (accepted for Nature Climate Change), provides some fantastic visualisations of the crucial role of natural variability in how we will experience climate.

Posted in GCMs, projections, temperature, uncertainty, variability, visualisation | 14 Comments

Global temperatures over the past decade

Posted on July 9, 2012 by Ed Hawkins

It is well known that the past decade or so has seen less global warming than might have been expected – but what is the cause? This is more of a discussion post, rather than any new analysis.

Posted in GCMs, projections, temperature, variability | 31 Comments

Projections of maize yields in France

Posted on June 14, 2012 by Ed Hawkins

A rather specific question today – what will happen to maize yields in France in 2016-2035?

Posted in crops, precipitation, projections, temperature, uncertainty, variability | 3 Comments

A 150 year temperature history from Berkshire

Posted on June 7, 2012 by Ed Hawkins

At a recent weather festival, Roger Brugge presented a reconstruction of temperatures from 1863 to 2011 for a small patch of the UK, namely Berkshire, which I found interesting.

Posted in history, temperature | 8 Comments

Time of emergence of climate signals

Posted on December 5, 2011 by Ed Hawkins

The time at which the signal of climate change emerges from the ‘noise’ of natural climate variability (Time of Emergence, ToE) is a key variable for climate predictions and risk assessments.

Posted in GCMs, temperature, uncertainty, variability | 3 Comments

Uncertainty in temperature variability

Posted on November 13, 2011 by Ed Hawkins

It is well known that there is considerable uncertainty in the projected response of climate models to increases in radiative forcing. However, there is also considerable uncertainty in the model simulated internal variability.

Posted in GCMs, temperature, uncertainty, variability | 1 Comment

Climate uncertainty: moving from ‘what’ to ‘when’

Posted on September 27, 2011 by Ed Hawkins

Update (23/10/11): The full article has now been published in Nature Climate Change Climate projections (such as from the IPCC) usually consider the question of “what will happen to our future climate”. But, this question may be more informative if … Continue reading →

Posted in GCMs, projections, temperature, uncertainty | 7 Comments

Uncertainty in uncertainty

Posted on August 24, 2011 by Ed Hawkins

There has been much discussion recently on whether GCMs participating in intercomparisons, such as CMIP3 and CMIP5, are ‘independent’. But if they are not, how does this make a difference to the uncertainty in our projections for future climate?

Posted in GCMs, projections, temperature, uncertainty | 3 Comments

Trends in Central England Temperature

Posted on August 10, 2011 by Ed Hawkins

Previous posts have discussed climate variability in general, and modelled decadal trends in temperature specifically. However, I should have considered decadal trends in observations as well, especially as there is a long temperature record available for the UK.

Posted in GCMs, temperature, variability | 5 Comments

What is a year?

Posted on March 17, 2011 by Ed Hawkins

A rather surprising question perhaps, but the answer is, ‘it depends’. There is no climatic reason to define a year from January to December, but that is what is generally done. But, is this the best definition?

Posted in SSTs, temperature, variability | 3 Comments

Communicating climate variability

Posted on August 11, 2010 by Ed Hawkins

Update 10/03/11 – Accepted article also online. Comments very welcome. Communicating the differences and links between climate variability and climate change is of growing importance, and I am currently writing an article for “Weather” on this.

Posted in GCMs, projections, temperature, uncertainty, variability | Leave a comment

Global mean temperature variability in observations and GCMs

Posted on June 24, 2010 by Ed Hawkins

I am often surprised at how different climate models can be. Shown below is the annual mean, global mean surface air temperature from control runs of 21 of the AR4 GCMs, along with the observations (HadCRUT3). The spread in the magnitude of variability is enormous, as seen by eye, but also the timeseries have very different ‘memory’ characteristics. Continue reading →

Posted in GCMs, temperature, variability | 7 Comments