2015 was hot. Globally, it was the warmest year on record by a large margin. But, there was an El Nino event in the Pacific which probably boosted temperatures slightly (by up to 0.1°C).
So, what can we expect for 2016? Using an analogy of similar El Nino events we can make some suggestions. Continue reading Expectations for 2016 global temperatures
Surface temperature rise is often thought of as synonymous with climate change. However a recently published paper in Nature Climate Change argues that Earth’s energy imbalance (EEI) is what ultimately sets the pace of climate change and that substantive progress can be made by monitoring this key climate variable.
Guest post by Matt Palmer and Doug McNeall (UK Met Office) Continue reading Earth’s energy imbalance
Much evidence has accumulated that temperature extremes and variability are changing. Accurately diagnosing such changes is of vital societal interest, not least because human induced climate change is often expected to materialise primarily through changes in the extreme tails.
Quantifying these features of climate time series statistically in climate models and observations is not straightforward. To a large extent, that is because extreme events are rare by definition, a fact that seems hardly surprising. This fact implies, however, that conventional methods quickly break down when it comes to the tails. This blog post serves s a cautionary note, in which we discuss how apparently very simple methods can result in severely biased estimates, and how this can be avoided1,2.
Guest post by Sebastian Sippel, MPIB, based on Sippel et al. (2015) Continue reading How to quantify changes in climate extremes without inducing artefacts?
2015 has seen some significant climate events, both meteorological and political. Continue reading 2015 in review
What have we learnt at COP21 so far? The 147 world leaders who turned up spoke passionately. The negotiators seem determined to get a strong agreement, already working past midnight each evening. The process of the negotiations seems to be much improved from previous COPs, with small groups doing much of the hard work.
Continue reading Reflections from Paris COP – day 3
The Paris COP21 continues. The atmosphere today was far more relaxed after the excitement of the speeches from world leaders yesterday. Negotiations have started more seriously with discussions over decarbonisation – perhaps this should be called carbon austerity! Continue reading Reflections from Paris COP – day 2
Today, the 21st Conference of the Parties (COP) began in Paris. The aim of the conference is to finalise an international 195-nation agreement to reduce global emissions of carbon dioxide, and to address issues such as deforestation & climate finance. I am attending for three days as part of the University of Reading ‘observer’ delegation. Continue reading Reflections from Paris COP – day 1
How will global temperatures evolve over the next 20 years? The IPCC AR5 made an assessment that average global temperatures in the 2016-2035 period would likely be 0.3 – 0.7°C above the 1986-2005 average. Some climate scientists disagree with that assessment. Continue reading Near-term global temperature forecasts
As you may have noticed, there have been some recent problems with the Climate Lab Book blog. These have now largely been resolved. The site is hosted on one of our University servers which suffered a disk failure. Also, some of the backup systems had not been working properly. The site has now been restored to a backup from 11th November. Comments since that time have been lost – many apologies. I will happily reinstate any that are reposted.
Often when analysing and comparing climate data we have to choose a reference period (or baseline) to calculate anomalies. But it is not often discussed why a particular baseline is chosen. Our new paper (open access in BAMS) considers this issue and asks: does the choice of reference period matter?
Continue reading Connecting climate model projections with the real world
In Weather this month, a paper by Colin Clark discusses temperature data from two rural stations in Somerset (UK). These two stations show a cooling trend over the last two decades which Clark suggests is opposite to that expected. The associated editorial suggests that this is a controversial finding.
Continue reading Comment on Clark (2015)
Much attention is rightly given to changes in global mean surface temperature – it is the key metric for assessing how our climate is changing and evaluating mitigation strategies. However, no-one directly experiences changes in global mean temperature – it is only through local variations that changes in climate are felt.
So, what have global temperatures ever done for us? Continue reading What have global temperatures ever done for us?
The importance of the ‘pause’ in global temperatures has never been about whether some particular trend is just below or just above zero, or about whether a specific period shows a statistically significant trend (whatever that actually means), or even about whether the trend has changed. The ‘pause’ has always been about understanding whether Earth’s climate is evolving in line with our expectations. Continue reading Was there ever a ‘pause’?
Transient climate response (TCR) is defined as the change in global temperature after a doubling of CO2 during a simulation where atmospheric CO2 increases at 1%/year. But, is TCR a constant? Continue reading Does climate sensitivity change with time?
The slower warming of global temperatures in the early 2000s has motivated many papers examining the modulation of global trends by climate variability. One question that has emerged is: what happens after a pause? Continue reading Are pauses followed by surges?