Global sea-level rise
The climate is changing and the world is warming. The oceans have taken up most of the additional heat so far, and as the water warms up, it expands. In combination with melt water from the melting of land-based ice, this causes rising sea levels.
On average, global sea-level rose about 19 cm between 1901 and 2010 (compared to sea-level during 1985-2008), at an average rate of 1.7 mm per year. But this process is accelerating. From 1993 to 2016, global sea-level rose at an average rate of about 3.4 mm per year. Climate trends and gravitational effects differ for each region and the seas don’t rise uniformly across the globe.
The data from the IPCC we use to create our projections involves the pathways the world could take, depending on the amount of CO2 equivalent gases. Over the past few years, an international team of climate scientists, economists and energy systems modellers have built a range of new “pathways” that examine how global society, demographics and economics might change over the next century. They are collectively known as the Shared Socioeconomic Pathways.
However, local sea-level rise around the coast of Aotearoa is also affected by up and down movements of our land. We are very aware when these vertical land movements occur in large jumps during earthquakes, but less obvious to us all is that smaller shifts occur continuously in between large seismic events. You can find out more about vertical land movement here.
