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'?
All posts by Ed Hawkins
Does climate sensitivity change with time?
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?
Are pauses followed by surges?
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?
Irreducible uncertainty in near-term climate projections
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
The sea ice orchestra
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.
Guest post by Alek Petty (@AlekPetty), University of Maryland
Continue reading The sea ice orchestra
An apples to apples comparison of global temperatures
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
Back-of-the-envelope attribution of global temperature changes
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
Climate Communiqué
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.
Climate communiqué
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