The Holocene Temperature Conundrum

The Holocene is the current geological era, which started 11,700 years before present and is divided into three stages: 8, 200, and 4,200 years before present. The early stage is the Greenlandian, the middle stage is the Northgrippian, and the late stage is the Meghalayan. According to proxy-based climate reconstructions, the global mean surface temperature during the Greenlandian and the Northgrippain was warmer than the Pre-industrial (PI). However, most model-based reconstructions, including those used by the Intergovernmental Panel on Climate Change (IPCC), indicate it was colder than PI. This is known as the Holocene temperature conundrum (HTC), which raises concerns regarding the model's ability to predict future climate change. The HTC is introduced, current knowledge is reviewed, and future direction of research is discussed.