Category Archives: variability

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

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

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

How “weird” has UK weather been in 2012?

Posted on October 22, 2012 by Ed Hawkins

A recent article on the BBC website said: The UK has experienced its “weirdest” weather on record in the past few months, scientists say. The question today is then, is this true?

Posted in history, precipitation, variability, weather | 6 Comments

Arctic sea ice in 2013

Posted on August 31, 2012 by Ed Hawkins

A very simple straw poll today – will the Arctic sea ice extent in September 2013 be more or less than September 2012? Hoping for views and expectations from public and scientists alike. UPDATE: (06/09/12) Around 80% of the ~100 … Continue reading →

Posted in Arctic, predictability, variability | 11 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

Predicting changes in North Atlantic temperatures

Posted on June 28, 2012 by Jon Robson

The Earth is a complex system of interacting components, such as the atmosphere and ocean, which produce a wide variety of natural variability. This natural variability ensures that the evolution of a particular region’s climate, e.g. that of Western Europe, … Continue reading →

Posted in Atlantic, GCMs, MOC, predictability, SSTs, variability | 1 Comment

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

On comparing models and observations

Posted on March 14, 2012 by Ed Hawkins

There has been some recent blog discussion on comparing observations and climate models consistently. Here is my effort at such a comparison using the CMIP5 models which are already available.

Posted in GCMs, projections, uncertainty, variability | 97 Comments

The value of old weather observations

Posted on March 6, 2012 by Ed Hawkins

Previous posts have described some initial analysis of the data from the Old Weather project, which is using public volunteers to digitise new historical weather observations from Royal Navy ships during World War 1. The good news is that these … Continue reading →

Posted in history, variability, weather | Leave a comment

Reconstructing Atlantic atmospheric variability

Posted on February 8, 2012 by Ed Hawkins

In a previous post I discussed the Old Weather project which is using volunteers to transcribe the hand-written weather data from Royal Navy ships logs in the World War 1 period. The good news is the first 243 ships have … Continue reading →

Posted in Atlantic, history, variability, weather | 4 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

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

Learning about past climate from ships logs

Posted on June 17, 2011 by Ed Hawkins

Understanding the climate of the past is extremely valuable to help put modern weather observations into a long-term context. Although we have considerable records of past weather, especially over land, more data is always welcome. Given the British obsession with … Continue reading →

Posted in Arctic, history, sea-ice, variability, weather | Leave a comment

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

Arctic predictability

Posted on November 1, 2010 by Ed Hawkins

After attending a recent workshop on Arctic predictability, I thought a brief discussion on sea-ice variability and potential predictability might be of interest.

Posted in Arctic, GCMs, predictability, sea-ice, SSTs, variability | Leave a comment

Atlantic multi-decadal variability

Posted on August 20, 2010 by Ed Hawkins

Observations of Atlantic SSTs show significant multi-decadal variability since 1870 (see red line in figure 2 below), often termed the Atlantic Multi-Decadal Oscillation (AMO), though there is no clear evidence that it is really an ‘oscillation’.

Posted in Atlantic, GCMs, SSTs, variability | 2 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

Consensus in precipitation projections

Posted on June 25, 2010 by Ed Hawkins

In the AR4, the IPCC presented this figure showing the consensus in precipitation projections for the 21st century, designed to be of use to planning for adaptation and mitigation. The coloured regions show where changes are likely to occur. My … Continue reading →

Posted in GCMs, precipitation, projections, variability | 2 Comments