The last deglaciation (21 to 7 thousand years ago) was punctuated by several abrupt meltwater pulses, which sometimes caused noticeable climate change. Around 14 thousand years ago, meltwater pulse 1A (MWP-1A), the largest of these events, produced a sea level rise of 14–18 metres over 350 years. Although this enormous surge of water certainly originated from retreating ice sheets, there is no consensus on the geographical source or underlying physical mechanisms governing the rapid sea level rise.