Why have climate impacts been underestimated?
Gérard COLLIN and Tom Harris | Read the entire article on Climate Uncovered
Records are tumbling and impacts not expected until mid-century are now hitting every continent – what happened?
If you wanted to summarise the countless published observations and studies on climate disruption in a single word, it would be the noun: underestimation.
This is in no way a criticism of the scientific community. The unprecedented climate impacts we are now experiencing are occurring at a pace tens of times faster than those seen in previously stable climates of the geologic past. No evolution of CO₂ levels this rapid has been observed in the 800,000 years of ice core data, nor in the last 66 million years of geological data, and the current level of 430 ppm has not been seen for 5 to 8 million years. Even the Palaeocene Eocene Thermal Maximum (PETM), 56 million years ago, only saw CO₂ levels and temperatures rise at one tenth of today’s rate. The closest parallels are from Heinrich Events during the last glacial period which were caused by dramatic changes and collapse episodes of the Atlantic Meridional Overturning Circulation (AMOC). Scientists therefore do not have comparable past examples for many of today’s rapid changes, from which to draw comparisons or create prognoses for the future.
Even though today’s temperatures have existed in the past, and today’s CO₂ concentrations have also been reached in the past, they have never occurred at the same time before. This is due to the incredible speed by which we have accumulated CO₂ emissions in the atmosphere, overwhelming nature’s ability to respond with anything like an equilibrium. Even the peak volcanic emissions of the PETM, which created a 5-8°C temperature rise over 5,000 years, are dwarfed by our current burn rate of fossil fuels. We are in uncharted territory.1
This means that some effects and feedbacks were unexpected…continue reading on Climate Uncovered.
