Category Archives: history

Global temperatures: 75 years after Callendar

Could varying concentrations of atmospheric carbon dioxide cause the planet to warm and cool? This was a key question facing scientists from the mid-1800s onwards – not because of a concern over man-made emissions of CO2, but because of a desire to understand the causes of the ice ages (identified by Louis Agassiz in 1837).

Then, exactly 75 years ago, in April 1938, a little appreciated scientist, Guy Stewart Callendar, presented the first evidence that the planet had recently warmed. Callendar also suggested that changes in atmospheric CO2 had caused a large part of this observed warming. A new paper reanalyses Callendar’s work to mark the 75th anniversary of his landmark study. Continue reading Global temperatures: 75 years after Callendar

Reconstructing Atlantic atmospheric variability

In a previous post I discussed the Old Weather project which is using volunteers to transcribe the hand-written weather data from Royal Navy ships logs in the World War 1 period. The good news is the first 243 ships have been completed (providing data scattered throughout the period 1914-1923), and some simple analysis shows whether this data can help reconstruct past Atlantic atmospheric variability. Continue reading Reconstructing Atlantic atmospheric variability

Learning about past climate from ships logs

Understanding the climate of the past is extremely valuable to help put modern weather observations into a long-term context. Although we have considerable records of past weather, especially over land, more data is always welcome. Given the British obsession with the weather it is perhaps of no surprise that more data is available, it is just buried in hand-written logbooks. Transcribing this data is normally a time-consuming and expensive task…. Continue reading Learning about past climate from ships logs