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?
On 1 May 2015, the UK’s First-Tier Tribunal unanimously dismissed David Holland’s appeal for copies of the Zero-Order Draft (ZOD) of the IPCC’s Fourth Assessment Report (AR4) made under Freedom of Information legislation. Their decision is available here. They considered Holland’s appeal to be “entirely without merit”.
Guest post by Tim Osborn, University of East Anglia (UEA)
Note that this post is slightly outside the usual topics discussed on this blog, but it is relevant to the climate science community. The Comments will be moderated. – Ed
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.
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?
Uncertainty in climate projections arises from several different sources. For example, the future emissions scenario is not known, so the usual approach is to run several to compare plausible futures. In addition, each climate model produces a different change in climate. However, on regional spatial scales and for the next couple of decades, it is the internal variability of climate which dominates. These natural climate fluctuations provide an irreducible limit on the precision with which we can make predictions on such spatial and temporal scales – but how large is this limit? Continue reading Irreducible uncertainty in near-term climate projections
September is an important month for the Arctic. As the midnight sun begins to set and summer draws to a close, the melt of the Arctic sea ice cover grinds to a halt and the annual ‘sea ice minimum’ is set – usually some time around mid-September.
When comparing global temperatures estimated from observations with climate model simulations it is necessary to compare ‘apples with apples’. Previous posts have discussed the issues of incomplete observational data, but a new paper by Cowtan et al. quantifies the influence of different observational data types. Continue reading An apples to apples comparison of global temperatures
Many of those skeptical about the causes of climate change suggest that the complex global climate models (GCMs) often used to make attribution statements are not trustworthy. Here I highlight that GCMs are not needed to roughly attribute nearly all of the observed warming (at least) to changes in greenhouse gases. Continue reading Back-of-the-envelope attribution of global temperature changes
Today, twenty-four UK learned and professional societies express their joint views on the risks of climate change and the opportunities for innovation to address those risks.
The signatories include societies of physical scientists, engineers, medical scientists, social scientists & artists, amongst others. This is the first time such a broad range of professional bodies have issued such a unanimous text.
The scientific evidence is now overwhelming that the climate is warming and that human activity is largely responsible for this change through emissions of greenhouse gases. Continue reading Climate Communiqué
Below is a simple example of using different colour maps to show the same UK mean temperature data for both normal vision and a simulation of colour blindness.
Which do you prefer?