Professor Han said this ice flows into the ocean, causing the sea level to rise by 1.5 millimetres a year.

"There is more evidence that this rate is being accelerated over some areas, including the Pacific islands," the northern NSW-based Professor said.

When combined with land subsidence associated with earthquakes in these areas, "more drastic sea level rise" was occurring and "threatening people living there".

He said these "unequivocal measurements" had been observed over the last 20 years from NASA's GRACE [Gravity Recovery and Climate Experiment] satellites.

IN OTHER NEWS:

Professor Han is the principal investigator of NASA's GRACE-FO science project.

The team is investigating the use of satellites for research into the climate and natural hazards.

GRACE-FO consists of two identical satellites flying in formation around Earth.

They travel at a velocity of more than 27,000 kilometres per hour about 500 kilometres above Earth.

The instruments on board the two satellites measure changes in the distance between them, due to orbital perturbations caused by variations in Earth's gravitational field.

Professor Han said the University of Newcastle team's research with GRACE-FO involves precision lasers to "measure changes at seasonal and longer-term time scales".

This includes measurements of polar region ice melt, sea level and groundwater depletion.

It's estimated that global sea level rise caused by ice sheet melt in Antarctica will put almost a billion people at risk from coastal flooding.

The team is also able to investigate shorter-scale events such as floods and drought.

"As far as flooding is concerned, we can look at the soil moisture condition over wide areas," he said.

Soil moisture is a critical factor in flood severity.

"We are looking into this problem to see how much we can advance our capability of flood forecasting."

Professor Han said the years 2020 and 2021 on Australia's east coast were a stark contrast.

He said rainfall in February and March was similar in those years, but much more flooding happened in 2021 due to soil moisture.

"The soil was already too wet to capture rainfall in 2021," he said.

"These contrasting events reiterated the importance of monitoring soil wetness over wider areas."

This information provided "quantitative information on flooding potential".

"We are building new methodologies of utilising near real time datasets, jointly working with the NASA Jet Propulsion Laboratory."

The aim is to integrate this information into forecasting models for flood and drought.

"We are trying to push more beyond scientific analysis by making these observations helpful to the community," he said.

The GRACE-FO project continuously measures distances between the two satellites. Changes on the surface of the Earth involve changes in gravitation.

"The gravitation change makes the satellite orbit change. The onboard satellite laser system measures such tiny variations in the orbit.

"We analyse them to study what has happened at the surface. For instance, distances between two satellites shorten when there is flooding beneath. That was exactly how we detected the flooding in 2021."

He said the team had noticed over many years that the "two satellites are pulled away every year, when they orbit around the western Antarctica".

This was due to "ongoing ice melt" of the Pine Island Glacier at the West Antarctic Ice Sheet.

The satellite distance data measures how much ice melts into the ocean and how much the sea level subsequently rises.

Water and ice cycles, land deformation like earthquakes, sea level rise and tsunami "manifest as mass changes".

"GRACE-FO is sensitive to all of these important natural hazards and climate change phenomena," he said.

As such, it can give a "comprehensive look" into changes on Earth.

Professor Han studies a discipline called "space geodesy", which is about studying Earth and satellite motion and precision orbit determination.

"The satellite orbit is governed primarily by Earth's gravity. Gravity is central to any satellite technology including GPS."