The main aim of our project is to obtain the first record of past climate change from Greenland caves. This important record will provide information about a past period of warm climate, and will be older than the current limit of the Greenland ice cores, thus contributing significantly to our understanding of long-term climate change in Greenland and the Arctic.
Why is there a need for past climate-change records?
The Earth’s climate is changing.
How will it develop in the future?
What will be the effects on environmental, ecological, and socio-economic systems?
These are simply a couple of questions related to the changes that the Earth system is about to face. In order to help us answer them, we look to the past. Records of past climate change hold useful information regarding the Earth’s natural climatic response; they help us understand how the Earth system has changed on timescales longer than short instrumental records; they enable us to document changes from one climate state to another; they provide a baseline against which we can assess whether or not the current changes are unusual, and; their information can be fed into predictive climate-change models.
One way of trying to understand what scenarios are possible in a future warming climate, is to look at past periods of warm climate known as interglacials. The last interglacial period took place about 130,000 to 118,000 years ago, and during this time air temperature in Greenland was about 3-5°C higher than today. Deep ice core climate records drilled from the Greenland ice sheet extend back continuously 123,000 years, to the final stages of the last interglacial (NGRIP core). The NEEM ice core extends back 128,500 years, to the early stages of the last interglacial, but the basal ice is folded and incomplete making interpretation difficult. The need for information about climate dynamics during past interglacials is thus still a major, and increasingly important concern.
How will this project advance our knowledge of climate change?
Using cave deposits in Northeast Greenland, we have an opportunity here to improve our knowledge of climate dynamics during a past interglacial. The cave record will most certainly cover a time period that pre-dates the last interglacial and hence the oldest limit of the Greenland ice-core records.
Calcite cave deposits are formed from drip waters that have percolated from the surface, through soil and limestone, and into a cave. Since the drip waters were once connected with the atmosphere and soil above the cave, they contain valuable information related to temperature, moisture, and vegetation processes, which are then locked layer upon layer into the cave deposit.
The climate record is created by analysing the chemical signature of each layer. For high-resolution studies, the Innsbruck Quaternary Research Group typically analyses between 4-10 samples per millimetre, allowing us the greatest chance of capturing rapid climate change events in our record. Understanding how fast the climate is capable of changing from one state to another is currently one of the key questions that climate-change scientists are working to answer.