In the spirit of experimentation, here are three types, successively getting more complicated. After comments from several people I have made both portrait & landscape versions. I would be interested to know which works best for you. Continue reading Global temperature change as polka-dots→
The term ‘Little Ice Age’ refers to a period of cooler temperatures between around 1400 and 1850, although a range of dates are used. This climate feature has been inferred from various types of direct and indirect evidence, but it is still not clear how widespread these cooler temperatures were.
A new article by Lockwood et al explores some of the commonly used indirect evidence such as paintings and the occurrence of ‘frost fairs’ on the Thames. We also address the common assumption that the cooler temperatures were solely due to a reduction in solar activity (the Spörer and Maunder minima). Although this assumption is almost certainly wrong, the two features are sometimes considered to be synonymous.
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’→
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→
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).
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→
Climate sensitivity characterises the response of the climate to changes in radiative forcing and can be measured in many different ways. However, estimates derived from observations of historical global temperatures have tended to be lower than those suggested by state-of-the-art climate simulators. Are the models too sensitive?
A new study largely explains the difference – it is because the comparison has not been done ‘like-with-like’.