Comets and climate

No connection between comets and climate has been proposed until now; here, we show that such a connection exists. We use a model to evaluate the shadowing effect due to cometary dust released by comet 1P/Halley in the inner solar system. We find that comet Halley has left a detectable fingerprint in the climate records of the last two millennia. The print shows up as a periodic cooling of the order of 0.08 °C. This temperature drop is comparable with other natural fluctuations. The finding will add a brick to our knowledge of the climate system and could allow to improve our predictive capacity of future climate.