Climate scientists were shocked by the unexpected increase in global temperatures

Over the past nine months, average land and sea surface temperatures have exceeded previous records by up to 0.2°C each month – a huge difference on a planetary scale. A general warming trend is expected due to rising greenhouse gas emissions, but this sudden increase in heat far exceeds the predictions of statistical climate models, which rely on past observations. Many reasons have been proposed for this discrepancy, but so far none have been able to reconcile our theories with what happened. (Gavin Schmidt, more at nature.com)