Reacción a "Sea level rise may be higher than previously thought, according to a study"

This is a groundbreaking piece of science that has clearly taken some years to put together and is extremely robust. This paper brings some profound bad news to the assessment of sea level rise and coastal impacts. It essentially shows that most previous assessments of the impacts of sea level rise based on satellite data have likely systematically underestimated exposure to severe risks as well as the rate at which these risks will increase in the future.

Very substantial progress has been made in projecting sea level rise in recent years, most of which has shown that sea level rise is likely to be higher than previously thought. Previous research was already showing we are at major risk of sea level rise of up to one metre by 2100. This new science shows that the projected impacts from SLR are likely to be much higher than previously thought. And extra risk of damage is much greater than previously forecast, particularly in the most vulnerable countries, especially small island states, low lying developing countries and the large archipelago of Southeast Asia.

The methods and results in this paper appear quite robust and challenge sea level rise impact assessments based on satellite data. The geoid method that has been used historically worked very well in the global north where most research has originated. But few were aware that in other parts of the world, this method has been producing very large discrepancies.

Based on the evaluation made from literature, it is clear that the impacts of this underestimation of satellite-based sea level rise impact assessments are very large and very significant. This is particularly true for the developing countries where the gap between sea levels estimated by land or sea is the largest. We have always known that sea level rise is a relative phenomenon – sea levels do not rise evenly across the world and in some places will go down.  Properly estimating sea level rise impacts requires taking into account the position on the Earth, and whether or not land is rising or subsiding – often due to human effects.

The results here could add a staggering new dimension to sea level rise impact assessments – particularly given that many impact assessments cited by the authors as underestimations have been used to guide coastal impact, vulnerability and adaptation risks and measures. The two regions where the gap in estimation is the largest, Southeast Asia and the Pacific, are home to many Small Island Developing States (SIDS) and Least Developed Countries (LDCs), which were already the most vulnerable to the impacts from sea level rise and other climate impacts. The paper identifies low-lying atoll countries in the Pacific as places where the assumed sea levels are lower than actual measurements (in two out of three scenarios). Under these new circumstances, they will face increased vulnerability and likely higher costs to deal with adaptation and minimise the impacts of disasters. The urgency to mitigate emissions to minimise sea level rise impact and improve access to finance for adaptation and loss and damage is ever clear.

Germany and Northwest Europe, according to the authors Figure 3 are amongst the least affected globally. The largest number of people affected are in the Global South.

Given the significance of what has been discovered there needs to be an urgent program to review, and reanalyse and assessments to determine is coastal adaptation strategies need to be updated and timelines expedited.

The study argues for the application of new methodologies based on their findings. The authors themselves make clear that this does not mean that the majority of the evaluated studies make errors, or that the IPCC reports that cite these studies are wrong or are containing errors. This is important to bring across in the reporting. Otherwise the study may be misused to disqualify previous insights on SLR or the scientific process as a whole, undermining the basis for climate action.

This study is part of the scientific process in which the evidence base on climate change, impacts and risks continues to evolve based on new evidence and methodologies. If anything, this new assessment is in line with other new findings in relation to climate change, where risks are increasingly being assessed to occur sooner than previously estimated.

This is not a matter of disqualifying the science so far, but a further line of evidence that shows that we must err on the side of caution when it comes to climate impacts and act sooner rather than later to curb adverse impacts, of which SLR is one of the most severe.