Defining ‘pre-industrial’

history, temperature

The UN Paris Agreement on climate change aims to ensure increases in global temperature are less than 2°C above ‘pre-industrial’ levels, with an aspirational 1.5°C limit. However, the ‘starting line’ of the pre-industrial era is not defined by the UN agreements, or by the Intergovernmental Panel on Climate Change (IPCC).

A new analysis by an international team of researchers aims to better define the pre-industrial baseline, informing the world’s decision makers on the required limits to greenhouse gas emissions needed to meet the terms of the Paris agreement. The study concludes that 2015 was likely the first time in recorded history that global temperatures were more than 1°C above pre-industrial levels. Continue reading Defining ‘pre-industrial’ →

U.S. Deep Freeze, December 2016

events, statistics, weather

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 →

Climate graphics of 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.

Mapping global temperature changes from 1850-2016. Click for high-resolution version.

Regional temperature this century

climate sensitivity, GCMs, projections, temperature

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 →

Lancashire temperatures, visualised

Temperatures for Lancashire from 1754-2015
Temperatures in Lancashire from 1754-2015. Click the image for a larger version.

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 →

Predicting an ice-free Arctic summer

Arctic, forecast

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 →