One possible criticism of global temperature datasets is that before around 1900 the observed data is too sparse to reliably infer changes in global temperature. Although we cannot travel back in time to take extra measurements to fill the gaps we can test whether the available observations are enough. Continue reading Sparse coverage of temperature observations
There had been speculation that record low temperatures would be coming to the United States in early December, and this had been framed as either evidence against global warming in general or that cold air outbreaks are increasing due to climate change.
World Weather Attribution (WWA) presents a quantitative study of this cold air outbreak. WWA researchers compute how rare the outbreak was and how it is affected by human-caused greenhouse gases. The analysis uses the same methods as WWA used in the peer-reviewed analysis of the cold extremes in the Midwest in the winter of 2013 – 2014 (van Oldenborgh et al, 2015). Continue reading U.S. Deep Freeze, December 2016
2016 has been quite a year for the climate. Warmest year ever recorded. Record low sea ice extents at both poles. It has also seen many amazing climate visualisations and animations. I have collected some of my favourites on this storify page, including graphics for temperature, sea ice, pressure observations and Hurricane Matthew.
One of the graphics is shown below, mapping temperature changes from 1850-2016, and including the decadal averages of global temperatures. This graphic has been updated from a previous version.
Some of the biggest questions about the future climate we have are: “how much could the climate change this century?”, “how reliable are climate projections?” and “what could happen on the way to 2100?” Also, most people want to know about regional change rather than change to the global mean climate. We have recently produced two papers relevant to these questions in terms of temperature change, now available (one on limits to temperature change this century and another on regional projections and variability).
Guest post by Michael Grose, CSIRO
Continue reading Regional temperature this century
This visualisation of temperatures in Lancashire (UK) shows annual mean data from 1754-2015. The long-term warming trend is clear, with variability from year to year, and some temporary cooler periods due to large volcanic eruptions. The average of the 19th century (black line) separates the warm and cold colours.
Continue reading Lancashire temperatures, visualised
The visualisation technique of ‘small multiples’ is often used to communicate a simple message. The above example shows maps of temperature change from 1850-2016 – the overall warming trend is obvious even though the details are fuzzy. Continue reading Mapping global temperature change
The melt of the summer sea ice in the Arctic is dramatic. Each September, when the ice reaches its annual minimum, there used to be around 7.5 million sq km of ice. It is now regularly below 5 million sq km, and hit a record low of 3.6 million sq km in 2012. This downward trend is projected to continue as global temperatures increase, but somewhat erratically.
The year at which the Arctic first becomes ‘ice-free’ (traditionally defined as 1 million sq km) is much discussed by scientists and the media, but is often a controversial topic. Continue reading Predicting an ice-free Arctic summer
If you watched the opening ceremony of the Olympics, you would have noticed a segment discussing climate change, accompanied by graphics of CO2 emissions, Arctic sea ice melting, sea level rise and a somewhat familiar spiral representation of rising global temperatures (above), a version of which you may have seen somewhere before.
Needless to say, I was rather shocked while watching!